Polymers

2021

Jump to: 2020, 2019

11 pages, 2943 KiB

Open AccessArticle

Fluorescence Modulation of Conjugated Polymer Nanoparticles Embedded in Poly(N-Isopropylacrylamide) Hydrogel

by Ho Namgung, Seonyoung Jo and Taek Seung Lee

Polymers 2021, 13(24), 4315; https://doi.org/10.3390/polym13244315 - 9 Dec 2021

Cited by 7 | Viewed by 3173

Abstract

A series of conjugated polymers (CPs) emitting red, green, and blue (RGB) fluorescence were synthesized via the Suzuki coupling polymerization. Polymer dots (Pdots) were fabricated by the reprecipitation method from corresponding CPs, in which the Pdot surface was functionalized to have an allyl [...] Read more.

A series of conjugated polymers (CPs) emitting red, green, and blue (RGB) fluorescence were synthesized via the Suzuki coupling polymerization. Polymer dots (Pdots) were fabricated by the reprecipitation method from corresponding CPs, in which the Pdot surface was functionalized to have an allyl moiety. The CP backbones were based on the phenylene group, causing the Pdots to show identical ultraviolet-visible absorption at 350 nm, indicating that the same excitation wavelength could be used. The Pdots were covalently embedded in poly(N-isopropylacrylamide) (PNIPAM) hydrogel for further use as a thermoresponsive moiety in the polymer hydrogel. The polymer hydrogel with RGB emission colors could provide thermally reversible fluorescence changes. The size of the hydrogel varied with temperature change because of the PNIPAM’s shrinking and swelling. The swollen and contracted conformations of the Pdot-embedded PNIPAM enabled on-and-off fluorescence, respectively. Fluorescence modulation with 20 to 80% of the hydrogel was possible via thermoreversibility. The fluorescent hydrogel could be a new fluorescence-tuning hybrid material that changes with temperature. Full article

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16 pages, 5216 KiB

Open AccessArticle

Coating of ZnO Nanoparticle on Cotton Fabric to Create a Functional Textile with Enhanced Mechanical Properties

by Imana Shahrin Tania and Mohammad Ali

Polymers 2021, 13(16), 2701; https://doi.org/10.3390/polym13162701 - 13 Aug 2021

Cited by 37 | Viewed by 7619

Abstract

The goal of this research is to develop a functional textile with better mechanical properties. Therefore, nano ZnO is synthesized, characterized, and applied to cotton fabric by mechanical thermo-fixation techniques. The synthesized nanoparticles are characterized by SEM and XRD analysis. The ZnO nanoparticle [...] Read more.

The goal of this research is to develop a functional textile with better mechanical properties. Therefore, nano ZnO is synthesized, characterized, and applied to cotton fabric by mechanical thermo-fixation techniques. The synthesized nanoparticles are characterized by SEM and XRD analysis. The ZnO nanoparticle alone, ZnO nanoparticle with a binder, and ZnO with a binder and wax emulsion are then applied on cotton woven fabrics using three different recipes. The surface morphology of the treated fabric is studied using SEM and EDS. Antimicrobial activity, UV protection property, and crease resistance are all tested for their functional characteristics. In addition, all vital mechanical characteristics are assessed. The results suggest that using only nano ZnO or nano ZnO with a binder enhances functional features while deteriorating mechanical capabilities. Nano ZnO treatment with the third recipe, which includes the addition of an emulsion, on the other hand, significantly enhances mechanical and functional characteristics. Consequently, this study provides information to optimize the confidence of textile researchers and producers in using nano ZnO and understanding its features in key functional fabrics. Full article

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13 pages, 30036 KiB

Open AccessArticle

Electrical Heating Performance of Graphene/PLA-Based Various Types of Auxetic Patterns and Its Composite Cotton Fabric Manufactured by CFDM 3D Printer

by Hyelim Kim and Sunhee Lee

Polymers 2021, 13(12), 2010; https://doi.org/10.3390/polym13122010 - 19 Jun 2021

Cited by 5 | Viewed by 2403

Abstract

To evaluate the electrical heating performance by auxetic pattern, re-entrant honeycomb (RE), chiral truss (CT), honeycomb (HN), and truss (TR), using graphene/PLA (Polylactic acid) filament, were manufactured by CFDM (conveyor fused deposition modelling) 3D printer. In addition, HN and TR, which was indicated [...] Read more.

To evaluate the electrical heating performance by auxetic pattern, re-entrant honeycomb (RE), chiral truss (CT), honeycomb (HN), and truss (TR), using graphene/PLA (Polylactic acid) filament, were manufactured by CFDM (conveyor fused deposition modelling) 3D printer. In addition, HN and TR, which was indicated to have an excellent electrical heating property, were selected to verify the feasibility of applying fabric heating elements. The result of morphology was that the number of struts constituting the unit cell and the connected points were TR < HN < CT < RE. It was also influenced by the surface resistivity and electrical heating performance. RE, which has the highest number of struts constituting the unit cell and the relative density, had the highest value of surface resistivity, and the lowest value was found in the opposite TR. In the electrical heating performance of samples, the heat distribution of RE was limited even when the applied voltage was increased. However, HN and TR were diffused throughout the sample. In addition, the surface temperature of RE, CT, HN, and TR was about 72.4 °C, 83.1 °C, 94.9 °C, and 85.9, respectively as applied at 30 V. When the HN and TR were printed on cotton fabric, the surface resistivity of HN/cotton and TR/cotton was about 10³ Ω/sq, which showed conductive material. The results of electrical heating properties indicated that the heat distribution of HN/cotton showed only in the region where power was supplied, but the TR/cotton was gradually expanded and presented stable electric heating properties. When 30 V was applied, the surface temperature of both samples showed more than 80 °C, and the shape was maintained stably due to the high thermal conductivity of the cotton fabric. Therefore, this study ensured that HN and TR show excellent electrical heating performance among four types of auxetic patterns with continuity. Full article

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12 pages, 29174 KiB

Open AccessArticle

Microstructure and Mechanical Properties of Polyacrylonitrile Precursor Fiber with Dry and Wet Drawing Process

by Hyunchul Ahn, Jae-Hyung Wee, Yong Min Kim, Woong-Ryeol Yu and Sang-Young Yeo

Polymers 2021, 13(10), 1613; https://doi.org/10.3390/polym13101613 - 17 May 2021

Cited by 13 | Viewed by 4283

Abstract

Polyacrylonitrile (PAN) fibers are typically used as precursor fibers for carbon fiber production, produced through wet-spinning processes. The drawing process of the spun fiber can be classified into dry and wet drawing processes. It is known that the drawing stability and stretching ratio [...] Read more.

Polyacrylonitrile (PAN) fibers are typically used as precursor fibers for carbon fiber production, produced through wet-spinning processes. The drawing process of the spun fiber can be classified into dry and wet drawing processes. It is known that the drawing stability and stretching ratio differ depending on the drawing process; however, the elementary characteristics are approximately similar. In this study, the mechanical properties of PAN fibers have been examined based on these two drawing processes with the differences analyzed through the analysis of microstructures. Further, to examine the composition of the fiber, element analysis has been conducted, and thereafter, the microstructure of the fiber is examined through X-ray diffraction analysis. Finally, the characteristics of PAN fibers and its mechanical properties has been examined according to each drawing condition. There are differences in moisture content and microstructure according to the drawing process, and it affects the tensile behavior. The results obtained could have potential implications if the processes are combined, as it could result in a design for a stable and highly efficient drawing process. Full article

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11 pages, 2796 KiB

Open AccessArticle

Bio-Based Polyurethane Foams with Castor Oil Based Multifunctional Polyols for Improved Compressive Properties

by Joo Hyung Lee, Seong Hun Kim and Kyung Wha Oh

Polymers 2021, 13(4), 576; https://doi.org/10.3390/polym13040576 - 14 Feb 2021

Cited by 48 | Viewed by 7184

Abstract

Currently, most commercial polyols used in the production of polyurethane (PU) foam are derived from petrochemicals. To address concerns relating to environmental pollution, a sustainable resource, namely, castor oil (CO), was used in this study. To improve the production efficiency, sustainability, and compressive [...] Read more.

Currently, most commercial polyols used in the production of polyurethane (PU) foam are derived from petrochemicals. To address concerns relating to environmental pollution, a sustainable resource, namely, castor oil (CO), was used in this study. To improve the production efficiency, sustainability, and compressive strength of PU foam, which is widely used as an impact-absorbing material for protective equipment, PU foam was synthesized with CO-based multifunctional polyols. CO-based polyols with high functionalities were synthesized via a facile thiol-ene click reaction method and their chemical structures were analyzed. Subsequently, a series of polyol blends of castor oil and two kinds of castor oil-based polyols with different hydroxyl values was prepared and the viscosity of the blends was analyzed. Polyurethane foams were fabricated from the polyol blends via a free-rising method. The effects of the composition of the polyol blends on the structural, morphological, mechanical, and thermal properties of the polyurethane foams were investigated. The results demonstrated that the fabrication of polyurethane foams from multifunctional polyol blends is an effective way to improve their compressive properties. We expect these findings to widen the range of applications of bio-based polyurethane foams. Full article

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2020

Jump to: 2021, 2019

16 pages, 32777 KiB

Open AccessArticle

Characterization of Electrical Heating Performance of CFDM 3D-Printed Graphene/Polylactic Acid (PLA) Horseshoe Pattern with Different 3D Printing Directions

by Hyelim Kim and Sunhee Lee

Polymers 2020, 12(12), 2955; https://doi.org/10.3390/polym12122955 - 10 Dec 2020

Cited by 11 | Viewed by 2594

Abstract

This study manufactured a horseshoe pattern (HP)-type electrical heating element based on a graphene/polylactic acid (GR/PLA) filament using CFDM (conveyor-fused deposition modeling) 3D printing technology, which is a new manufacturing process technology. CFDM 3D printing HP was fabricated in the different printing directions [...] Read more.

This study manufactured a horseshoe pattern (HP)-type electrical heating element based on a graphene/polylactic acid (GR/PLA) filament using CFDM (conveyor-fused deposition modeling) 3D printing technology, which is a new manufacturing process technology. CFDM 3D printing HP was fabricated in the different printing directions of 0°, 45°, and 90°. To confirm the effects of different 3D printing directions, the morphology, surface resistivity, and electrical heating properties of the different HPs were analyzed. In addition, the CFDM 3D-printed HPs made using different printing directions were printed on cotton fabric to confirm their applicability as fabric heating elements, and their electrical heating properties were measured. Regarding the morphology of the GR/PLA-HP, each sample was stacked according to the printing direction. It was also confirmed through FE-SEM images that the graphene was arranged according to the printing direction in which the nozzle moved. In the XRD pattern analysis, the GR/PLA-HP samples showed two diffraction peaks of PLA and graphene. The sizes of those peaks were increased in the order of 90° < 45° ≤ 0° according to the printing direction, which also affected the electrical and electric heating properties. The surface resistivities of the GR/PLA-HP samples were shown to be increased in the order of 0° < 45° < 90°, indicating that the electrical properties of GR/PLA HP printed at 0° were improved compared to those of the other samples. When 30 V was applied to three GR/PLA-HP samples according to the printing direction, the surface temperatures were decreased in the order of 0° < 45° < 90°, and the samples were indicated as 83.6, 80.6, and 52.5 °C, respectively; the same result was shown when the samples were printed on cotton fabric. Therefore, it was confirmed that the GR/PLA CFDM 3D-printed HP sample printed at 0° direction showed low surface resistivity and high surface temperature, so that improving the electrical heating properties. Full article

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13 pages, 3542 KiB

Open AccessArticle

EMG Measurement with Textile-Based Electrodes in Different Electrode Sizes and Clothing Pressures for Smart Clothing Design Optimization

by Siyeon Kim, Sojung Lee and Wonyoung Jeong

Polymers 2020, 12(10), 2406; https://doi.org/10.3390/polym12102406 - 19 Oct 2020

Cited by 45 | Viewed by 6785

Abstract

The surface electromyography (SEMG) is one of the most popular bio-signals that can be applied in health monitoring systems, fitness training, and rehabilitation devices. Commercial clothing embedded with textile electrodes has already been released onto the market, but there is insufficient information on [...] Read more.

The surface electromyography (SEMG) is one of the most popular bio-signals that can be applied in health monitoring systems, fitness training, and rehabilitation devices. Commercial clothing embedded with textile electrodes has already been released onto the market, but there is insufficient information on the performance of textile SEMG electrodes because the required configuration may differ according to the electrode material. The current study analyzed the influence of electrode size and pattern reduction rate (PRR), and hence the clothing pressure (P_c) based on in vivo SEMG signal acquisition. Bipolar SEMG electrodes were made in different electrode diameters Ø 5–30 mm, and the clothing pressure ranged from 6.1 to 12.6 mmHg. The results supported the larger electrodes, and P_c showed better SEMG signal quality by showing lower baseline noise and a gradual increase in the signal to noise ratio (SNR). In particular, electrodes, Ø ≥ 20 mm, and P_c ≥ 10 mmHg showed comparable performance to Ag-Ag/Cl electrodes in current textile-based electrodes. The current study emphasizes and discusses design factors that are particularly required in the designing and manufacturing process of smart clothing with SEMG electrodes, especially as an aspect of clothing design. Full article

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17 pages, 42513 KiB

Open AccessArticle

Study of Shape Memory and Tensile Property of 3D Printed Sinusoidal Sample/Nylon Composite Focused on Various Thicknesses and Shape Memory Cycles

by Shahbaj Kabir and Sunhee Lee

Polymers 2020, 12(7), 1600; https://doi.org/10.3390/polym12071600 - 18 Jul 2020

Cited by 24 | Viewed by 3768

Abstract

This study evaluated the shape memory and tensile property of 3D-printed sinusoidal sample/nylon composite for various thickness and cycles. Sinusoidal pattern of five thicknesses: 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, and 1.0 mm were 3D-printed on nylon fabric by the fused [...] Read more.

This study evaluated the shape memory and tensile property of 3D-printed sinusoidal sample/nylon composite for various thickness and cycles. Sinusoidal pattern of five thicknesses: 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, and 1.0 mm were 3D-printed on nylon fabric by the fused deposition modeling (FDM) 3D printer using shape memory thermoplastic polyurethane (SMTPU). Afterward, shape memory and tensile property was investigated up to 50 shape memory cycles. The study found that 3D-printed sinusoidal sample/nylon composite had a 100% shape recovery ratio for various thicknesses up to 50 cycles. The average shape recovery rate gradually decreased from 3.0°/s to 0.7°/s whereas the response time gradually increased with the increase of a 3D-printed pattern thickness. The stress and initial modulus gradually increased with the increase of the cycle’s number. Thus, the shape memory property had a similar tendency for various cycles whereas the tensile property gradually increased with the increase of the cycle number. Moreover, this study demonstrated that this 3D-printed sinusoidal sample/nylon composite can go through more than 50 cycles without losing its tensile or shape memory property. This 3D-printed sinusoidal sample/nylon composite has vast potential as smart, reinforced, and protective clothing that requires complex three-dimensional shapes. Full article

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10 pages, 4024 KiB

Open AccessArticle

Preparation and Characterization of Zinc Hydroxystannate Coated by Aluminum Phosphate and Its Application in Poly(acrylonitrile-co-vinylidene chloride)

by Ji Eun Song, Ji Su Kim, Daeyoung Lim and Wonyoung Jeong

Polymers 2020, 12(6), 1365; https://doi.org/10.3390/polym12061365 - 17 Jun 2020

Cited by 4 | Viewed by 2872

Abstract

In this study, zinc hydroxystannate ([ZnSn(OH)₆], ZHS) was coated with aluminum phosphate (AlPO₄, ALP) to prepare the ZHS-ALP composite. During the coating process, the reaction conditions, such as the ALP to ZHS molar ratio, were controlled, and the morphology [...] Read more.

In this study, zinc hydroxystannate ([ZnSn(OH)₆], ZHS) was coated with aluminum phosphate (AlPO₄, ALP) to prepare the ZHS-ALP composite. During the coating process, the reaction conditions, such as the ALP to ZHS molar ratio, were controlled, and the morphology of the products was characterized by scanning electron microscopy (SEM). The prepared composites were introduced into poly(acrylonitrile-co-vinylidene chloride) (PANVDC), and the change in compatibility between ZHS and the polymer matrix was characterized. The results showed that ALP-ZHS (1:1), which was prepared by ALP-ZHS composite molar ratio of 1:1, could improve the dispersion and compatibility of ZHS in the polymer matrix and decrease the hydrophilicity and viscosity. Moreover, the ALP-ZHS composite had a better flame-retardant effect on PANVDC than ZHS alone. PANVDC could pass the V-0 rating in UL94, particularly the highest limiting oxygen index (LOI) value of 33.2% obtained when the ALP-ZHS (1:1) composite was added to PANVDC. Full article

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14 pages, 4284 KiB

Open AccessArticle

Alkaline Hydrolysis and Dyeing Characteristics of Sea-Island-Type Ultramicrofibers of PET Tricot Fabrics with Black Disperse Dye

by Jeong Min Kang, Min Gu Kim, Ji Eun Lee, Jae Wang Ko, Il Jin Kim, Jae Yeon Lee, Dong Jin Lee, Seong Ik Ko, Dae Ho Jung and Seung Geol Lee

Polymers 2020, 12(6), 1243; https://doi.org/10.3390/polym12061243 - 29 May 2020

Cited by 10 | Viewed by 3570

Abstract

In this study, we investigated conditions for the alkaline hydrolysis and black-disperse dyeing of sea-island-type polyethylene terephthalate (PET) ultramicrofiber tricot fabric. We examined the weight loss ratios and tensile strengths according to the NaOH content (10–30% on mass of fabric (omf)) during treatment; [...] Read more.

In this study, we investigated conditions for the alkaline hydrolysis and black-disperse dyeing of sea-island-type polyethylene terephthalate (PET) ultramicrofiber tricot fabric. We examined the weight loss ratios and tensile strengths according to the NaOH content (10–30% on mass of fabric (omf)) during treatment; the optimal conditions used 25% omf NaOH for 30 min at 100 °C for an average weight loss ratio of 23.47%. By scanning electron microscope (SEM) analysis, the ‘sea’ components are extracted with increasing NaOH concentration until 25% omf NaOH, and damage of the ‘island’ components above 25% omf NaOH leads to a reduction in tensile strength. The dyeing conditions, including temperature (95–135 °C), time (20–60 min), pH buffer solution concentration (1–9 g/L), and contents of dispersant (1–9 g/L) and UV-absorbent (5–25% omf) were also explored. The optimal dyeing conditions were established as a dye concentration of 8% omf with 1 g/L dispersant, 1 g/L pH buffer solution concentration, and 10% omf UV-absorbent at 135 °C for 40 min at a 1:10 goods-to-liquor ratio. The rubbing colorfastness values for the fabrics dyed with the black disperse dye spanned four grades under dry and wet conditions. The light colorfastness values of the dyed fabrics were good to excellent in the range of 4–5 grades. Full article

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15 pages, 6807 KiB

Open AccessArticle

Influence of Fabric Weave on Thermal Radiation Resistance and Water Vapor Permeability

by Ana Kiš, Snježana Brnada and Stana Kovačević

Polymers 2020, 12(3), 525; https://doi.org/10.3390/polym12030525 - 1 Mar 2020

Cited by 8 | Viewed by 4793

Abstract

In this work, aramid fibers were used to develop new, high-performance fabrics for high-temperature protective clothing. The research was based on the impact of the weave structure on fabric resistance to radiant heat. The goals of the research were primarily related to the [...] Read more.

In this work, aramid fibers were used to develop new, high-performance fabrics for high-temperature protective clothing. The research was based on the impact of the weave structure on fabric resistance to radiant heat. The goals of the research were primarily related to the development of new fabric structures created by the weave structure, which gives better protection of the body against high temperatures in relation to the standard weave structures that are used today. According to the results obtained it can be concluded that the fabric weave significantly affects the fabric structure, which consequently determines the effectiveness of protection against high temperatures. The justification for the use of multi-weft and strucks weave structure, which provides greater thermal protection and satisfactory breathability than commonly used weave structures, was ascertained. Full article

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12 pages, 8116 KiB

Open AccessArticle

Fabrication of Colorimetric Textile Sensor Based on Rhodamine Dye for Acidic Gas Detection

by Young Ki Park, Byeong M. Oh, A Ra Jo, Ji Hyeon Han, Jee Young Lim, Hyun Ju Oh, Seung Ju Lim, Jong H. Kim and Woo Sung Lee

Polymers 2020, 12(2), 431; https://doi.org/10.3390/polym12020431 - 12 Feb 2020

Cited by 22 | Viewed by 4850

Abstract

For the immediate detection of gaseous strong acids, it is advantageous to employ colorimetric textile sensors based on halochromic dyes. Thus, a rhodamine dye with superior pH sensitivity and high thermal stability was synthesized and incorporated in nylon 6 and polyester fabrics to [...] Read more.

For the immediate detection of gaseous strong acids, it is advantageous to employ colorimetric textile sensors based on halochromic dyes. Thus, a rhodamine dye with superior pH sensitivity and high thermal stability was synthesized and incorporated in nylon 6 and polyester fabrics to fabricate textile sensors through dyeing and printing methods. The spectral properties and solubility of the dye were examined; sensitivity to acidic gas as well as durability and reversibility of the fabricated textile sensors were investigated. Both dyed and printed sensors exhibited a high reaction rate and distinctive color change under the acidic condition owing to the high pH sensitivity of the dye. In addition, both sensors have outstanding durability and reversibility after washing and drying. Full article

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18 pages, 7354 KiB

Open AccessArticle

Sound Absorption Properties of Perforated Recycled Polyurethane Foams Reinforced with Woven Fabric

by Roberto Atiénzar-Navarro, Romina del Rey, Jesús Alba, Víctor J. Sánchez-Morcillo and Rubén Picó

Polymers 2020, 12(2), 401; https://doi.org/10.3390/polym12020401 - 10 Feb 2020

Cited by 13 | Viewed by 4231

Abstract

The acoustic properties of recycled polyurethane foams are well known. Such foams are used as a part of acoustic solutions in different fields such as building or transport. This paper aims to seek improvements in the sound absorption of these recycled foams when [...] Read more.

The acoustic properties of recycled polyurethane foams are well known. Such foams are used as a part of acoustic solutions in different fields such as building or transport. This paper aims to seek improvements in the sound absorption of these recycled foams when they are combined with fabrics. For this aim, foams have been drilled with cylindrical perforations, and also combined with different fabrics. The effect on the sound absorption is evaluated based on the following key parameters: perforation rate (5% and 20%), aperture size (4 mm and 6 mm), and a complete perforation depth. Experimental measurements were performed by using an impedance tube for the characterization of its acoustic behavior. Sound absorption of perforated samples is also studied—numerically by finite element simulations, where the viscothermal losses were considered; and analytically by using models for the perforated foam and the fabric. Two textile fabrics were used in combination with perforated polyurethane samples. Results evidence a modification of the sound absorption at mid frequencies employing fabrics that have a membrane-type acoustic response. Full article

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18 pages, 5999 KiB

Open AccessArticle

Core/Sheath-Structured Composite Nanofibers Containing Cinnamon Oil: Their Antibacterial and Antifungal Properties and Acaricidal Effect against House Dust Mites

by Yoonwon Jung, Hyukjoo Yang, In-Yong Lee, Tai-Soon Yong and Seungsin Lee

Polymers 2020, 12(1), 243; https://doi.org/10.3390/polym12010243 - 20 Jan 2020

Cited by 17 | Viewed by 3920

Abstract

This study aimed to fabricate core/sheath-structured composite nanofibers containing cinnamon oil by emulsion electrospinning and to investigate their acaricidal effect on house dust mites as well as their antibacterial and antifungal properties in relation to cinnamon oil concentration in the nanofibers. An oil-in-water [...] Read more.

This study aimed to fabricate core/sheath-structured composite nanofibers containing cinnamon oil by emulsion electrospinning and to investigate their acaricidal effect on house dust mites as well as their antibacterial and antifungal properties in relation to cinnamon oil concentration in the nanofibers. An oil-in-water emulsion, which comprised cinnamon oil and poly(vinyl alcohol) solution as oil and water phases, respectively, was used to prepare core/sheath-structured nanofibers. The morphology and the inner structure of the electrospun nanofibers were observed by scanning electron microscopy and confocal laser scanning microscopy. Core/sheath-structured nanofibers containing cinnamon oil were successfully prepared by emulsion electrospinning. The composite nanofibers prepared from an emulsion containing 20 wt% of cinnamon oil exhibited a strong acaricidal effect against house dust mites (Dermatophagoides farinae). The composite nanofibers fabricated from an emulsion containing 4.29 wt% of cinnamon oil showed excellent antimicrobial effects against Staphylococcus aureus and a series of fungi that can trigger respiratory- and skin-related diseases. The release profile of cinnamon oil from the core/sheath-structured nanofibers showed a continuous release of functional ingredients over 28 days. Our findings demonstrate that the use of such fibrous structures could be a promising approach for delivering naturally derived bioactive agents in a controlled way. Full article

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25 pages, 10125 KiB

Open AccessReview

Functional Fibers, Composites and Textiles Utilizing Photothermal and Joule Heating

by Juhyun Park

Polymers 2020, 12(1), 189; https://doi.org/10.3390/polym12010189 - 10 Jan 2020

Cited by 47 | Viewed by 10486

Abstract

This review focuses on the mechanism of adjusting the thermal environment surrounding the human body via textiles. Recently highlighted technologies for thermal management are based on the photothermal conversion principle and Joule heating for wearable electronics. Recent innovations in this technology are described, [...] Read more.

This review focuses on the mechanism of adjusting the thermal environment surrounding the human body via textiles. Recently highlighted technologies for thermal management are based on the photothermal conversion principle and Joule heating for wearable electronics. Recent innovations in this technology are described, with a focus on reports in the last three years and are categorized into three subjects: (1) thermal management technologies of a passive type using light irradiation of the outside environment (photothermal heating), (2) those of an active type employing external electrical circuits (Joule heating), and (3) biomimetic structures. Fibers and textiles from the design of fibers and textiles perspective are also discussed with suggestions for future directions to maximize thermal storage and to minimize heat loss. Full article

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12 pages, 4365 KiB

Open AccessArticle

Properties of Conductive Polyacrylonitrile Fibers Prepared by Using Benzoxazine Modified Carbon Black

by Damiro Ahn, Hyun-Jung Choi, Ho-dong Kim and Sang Young Yeo

Polymers 2020, 12(1), 179; https://doi.org/10.3390/polym12010179 - 9 Jan 2020

Cited by 16 | Viewed by 5336

Abstract

Composites of carbon black (CB) and polymers are attractive for producing conductive fibers. Herein, to achieve improved interactions with polymers, the surface of CB was modified to form 4-aminobenzoyl-functionalized carbon black (ABCB), benzoxazine-functionalized carbon black (BZCB), and Ag-anchored carbon black (Ag-ABCB). The surface-modified [...] Read more.

Composites of carbon black (CB) and polymers are attractive for producing conductive fibers. Herein, to achieve improved interactions with polymers, the surface of CB was modified to form 4-aminobenzoyl-functionalized carbon black (ABCB), benzoxazine-functionalized carbon black (BZCB), and Ag-anchored carbon black (Ag-ABCB). The surface-modified CBs were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis, and X-ray photoelectron spectroscopy was utilized to confirm the presence of Ag in Ag-ABCB. Conductive polyacrylonitrile (PAN) fibers were wet-spun with conductive fillers (CB, ABCB, Ag-ABCB, and BZCB) to investigate the effects of various functional groups on the electrical and mechanical properties. After annealing the conductive PAN fibers, the conductivity and tensile strength greatly increased, whereas the diameter decreased. Notably, the fiber with a BZCB/PAN weight ratio of 12/88 possessed a conductivity of 8.9 × 10⁻⁴ S/cm, and strength of 110.4 MPa, and thus the highest conductivity and best mechanical properties in the conductive PAN fiber. These results indicate that the annealed BZCB/PAN fibers have potential applications in the manufacturing of antistatic fabrics. Full article

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16 pages, 4869 KiB

Open AccessArticle

Surface Alkylation of Cellulose Nanocrystals to Enhance Their Compatibility with Polylactide

by Joo Hyung Lee, Sang Ho Park and Seong Hun Kim

Polymers 2020, 12(1), 178; https://doi.org/10.3390/polym12010178 - 9 Jan 2020

Cited by 40 | Viewed by 5048

Abstract

Effective surface alkylation of cellulose nanocrystals (CNCs) was developed using a nucleophilic substitution reaction with an alkyl bromide to convert hydrophilic groups on the CNCs into alkyl groups and the degree of substitution was quantitatively determined. The resultant alkylated CNCs exhibited improved dispersion [...] Read more.

Effective surface alkylation of cellulose nanocrystals (CNCs) was developed using a nucleophilic substitution reaction with an alkyl bromide to convert hydrophilic groups on the CNCs into alkyl groups and the degree of substitution was quantitatively determined. The resultant alkylated CNCs exhibited improved dispersion in a nonpolar environment and increased hydrophobicity, compared with unmodified and acetylated CNCs. Polylactide (PLA) nanocomposites reinforced with unmodified and modified CNCs were prepared by a solution casting method and the effects of reinforcement on the thermal stability, mechanical properties, morphology, and barrier properties were investigated. In addition, modeling of the mechanical properties was evaluated to simulate the modulus of the PLA nanocomposites and results were compared with the experimental values. PLA nanocomposites reinforced with alkylated CNCs exhibited superior properties in terms of thermal stability, tensile strength, Young’s modulus, and barrier properties because of the uniform dispersion and strong interfacial adhesion between filler and matrix. This high performance and fully return-to-nature nanocomposite is expected to expand the utilization of CNCs from sustainable bioresources and the practical application of biodegradable plastics. Full article

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2019

Jump to: 2021, 2020

14 pages, 3349 KiB

Open AccessArticle

Tuning the Density of Zwitterionic Polymer Brushes on PET Fabrics by Aminolysis: Effect on Antifouling Performances

by Emanuela Lorusso, Wael Ali, Michael Leniart, Beate Gebert, Markus Oberthür and Jochen S. Gutmann

Polymers 2020, 12(1), 6; https://doi.org/10.3390/polym12010006 - 18 Dec 2019

Cited by 15 | Viewed by 4308

Abstract

Here, we synthesize zwitterionic polymer brushes on polyester fabrics by atom transfer radical polymerization (ATRP) after a prefunctionalization step involving an aminolysis reaction with ethylenediamine. Aminolysis is an easy method to achieve homogeneous distributions of functional groups on polyester fibers (PET) fabrics. Varying [...] Read more.

Here, we synthesize zwitterionic polymer brushes on polyester fabrics by atom transfer radical polymerization (ATRP) after a prefunctionalization step involving an aminolysis reaction with ethylenediamine. Aminolysis is an easy method to achieve homogeneous distributions of functional groups on polyester fibers (PET) fabrics. Varying the polymerization time and the prefunctionalization conditions of the reaction, it is possible to tune the amount of water retained over the surface and study its effect on protein adhesion. This study revealed that the polymerization time plays a major role in preventing protein adhesion on the PET surface. Full article

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14 pages, 3738 KiB

Open AccessArticle

Effect of Polycondensation Catalyst on Fiber Structure Development in High-Speed Melt Spinning of Poly (Ethylene Terephthalate)

by Eun Seon Kim, Hyun Ju Oh, Hyun-Joong Kim, Chun Gi Kim, Seong Yoon Park, Young Gyu Jeong and Wan-Gyu Hahm

Polymers 2019, 11(12), 1931; https://doi.org/10.3390/polym11121931 - 22 Nov 2019

Cited by 5 | Viewed by 4587

Abstract

We conducted a preliminary study on fiber structural development in the high-speed melt spinning of environmentally friendly polyethylene terephthalate (Ti-PET) synthesized with 25 ppm of titanium-based catalyst, which was compared with conventional PET (Sb-PET) synthesized with 260 ppm of antimony-based catalyst. Gel permeation [...] Read more.

We conducted a preliminary study on fiber structural development in the high-speed melt spinning of environmentally friendly polyethylene terephthalate (Ti-PET) synthesized with 25 ppm of titanium-based catalyst, which was compared with conventional PET (Sb-PET) synthesized with 260 ppm of antimony-based catalyst. Gel permeation chromatography of Ti- and Sb-PET resins of intrinsic viscosity 0.63 confirmed that both resins have similar molecular weights and distributions. However, differential scanning calorimetry revealed that the Ti-PET resin exhibited a lower melt–crystallization peak and isothermal melt-crystallization rate than the Sb-PET resin. High-speed melt spinning of the Ti- and Sb-PET was possible up to a spinning velocity of 6 km/min. Two-dimensional wide-angle X-ray diffraction analyses showed that the molecular orientation of the obtained as-spun Ti- and Sb-PET fibers increased with spinning velocity, and a highly oriented, crystalline structure by orientation-induced crystallization started to appear from 5 km/min. Notably, Ti-PET fibers showed a lower degree of crystalline structural development and lower tensile strength compared with Sb-PET fibers under the high-speed spinning conditions. Our results suggest that the catalyst in PET resins can act as nucleating agents in thermal- and orientation-induced crystallization, and that differences in catalyst content can influence PET fiber structure development under extreme conditions in high-speed melt spinning. Full article

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11 pages, 1915 KiB

Open AccessArticle

Influence of Optical Brightening Agent Concentration on Properties of Cotton Fabric Coated with Photochromic Microcapsules Using a Pad-Dry-Cure Process

by Mateja Kert, Vida Krkoč and Marija Gorjanc

Polymers 2019, 11(12), 1919; https://doi.org/10.3390/polym11121919 - 21 Nov 2019

Cited by 9 | Viewed by 4247

Abstract

The weak photostability of photochromic dyes applied to textile substrates is one of the disadvantages of the broader use of photochromic dyes in the textile industry. Therefore, the influence of optical brightener concentration on both the photocoloration and photostability of cotton fabric coated [...] Read more.

The weak photostability of photochromic dyes applied to textile substrates is one of the disadvantages of the broader use of photochromic dyes in the textile industry. Therefore, the influence of optical brightener concentration on both the photocoloration and photostability of cotton fabric coated with photochromic microcapsules using a pad-dry-cure process, as well as the physical-mechanical properties and colorfastness properties, were studied in this research. Coated samples were subjected to different tests according to valid EN ISO standards; namely mass per unit area, fabric stiffness, breaking force and elongation, air permeability, and different colorfastness properties (rubbing, domestic and commercial laundering, and light). Results showed that the coated fabric had higher mass per unit area, stiffness, breaking force and elongation and lower air permeability compared to uncoated fabric, irrespective of the padding bath composition. Coated fabric has better colorfastness to wet than dry rubbing. The colorfastness to washing decreases with the increased number of washing cycles. The use of optical brightener decreases the photocoloration of coated fabric and increases the photostability of coated fabric after the exposure of samples to a Xenotest apparatus for longer than 12 h. Full article

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10 pages, 1838 KiB

Open AccessArticle

Improvement of the Rubbing Fastness of Cotton Fiber in Indigo/Silicon Non-Aqueous Dyeing Systems

by Yuni Luo, Liujun Pei, Hongjuan Zhang, Qi Zhong and Jiping Wang

Polymers 2019, 11(11), 1854; https://doi.org/10.3390/polym11111854 - 11 Nov 2019

Cited by 17 | Viewed by 4810

Abstract

In order to solve the poor rubbing fastness of dyed cotton fiber in the indigo/silicon non-aqueous dyeing system, the process parameters of the silicon non-aqueous dyeing system were optimized. Dyed cotton fiber was post-treated to achieve the optimum dyeing conditions for obtaining a [...] Read more.

In order to solve the poor rubbing fastness of dyed cotton fiber in the indigo/silicon non-aqueous dyeing system, the process parameters of the silicon non-aqueous dyeing system were optimized. Dyed cotton fiber was post-treated to achieve the optimum dyeing conditions for obtaining a better rubbing fastness. Meanwhile, the dyeing performance of cotton fiber in a traditional water bath and silicon non-aqueous dyeing system was compared. The results showed that the rubbing fastness of dyed cotton fiber in the silicon non-aqueous dyeing system (one dyeing) was lower than that of traditional water bath (twelve cycles), although the color depth of dyed cotton fiber was deeper. For obtaining a good rubbing fastness, the optimum temperature was about 70 °C and the optimal dyeing cycle was one. Moreover, fixing agents can significantly improve the rubbing fastness of dyed cotton fiber. Especially, cationic waterborne polyurethane had an optimal fixing effect on the dyed cotton fiber. Soft finishing would weaken the effect of fixing finishing on the dyed cotton fiber, but the softener can significantly improve the handle of dyed cotton fiber. Full article

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14 pages, 8147 KiB

Open AccessArticle

Developing Fall-impact Protection Pad with 3D Mesh Curved Surface Structure using 3D Printing Technology

by Jung Hyun Park and Jeong Ran Lee

Polymers 2019, 11(11), 1800; https://doi.org/10.3390/polym11111800 - 1 Nov 2019

Cited by 14 | Viewed by 6799

Abstract

In this study, we present the development of fall-impact protection pads for elderly people using three-dimensional (3D) printing technology. To develop fall-impact protection clothing, it is important to maintain the functionality of the protection pad while ensuring that its effectiveness and appearance remain [...] Read more.

In this study, we present the development of fall-impact protection pads for elderly people using three-dimensional (3D) printing technology. To develop fall-impact protection clothing, it is important to maintain the functionality of the protection pad while ensuring that its effectiveness and appearance remain optimal in the process of inserting it. Therefore, this study explores the benefit of exploiting 3D scan data of the human body using 3D printing technology to develop a fall-impact protection pad that is highly suited to the human body shape. The purpose of this study was to present a 3D modeling process for creating curved protective pads comprising a hexagonal mesh with a spacer fabric structure and to verify the impact protection performance by printing curved pads. To this end, we set up a section that includes pads in the 3D human body scan data and extracted body surface information to be applied in the generation of the pad surface. The sheet-shaped hexagonal mesh structure was cut and separated according to the pad outline, and then deformed according to the curved surface of the human body. The pads were printed, and their protection performance was evaluated; a 79.2–81.8% reduction in impact force was observed compared to similar cases in which the pads were not used. Full article

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16 pages, 2154 KiB

Open AccessArticle

Photothermal Polymer Nanocomposites of Tungsten Bronze Nanorods with Enhanced Tensile Elongation at Low Filler Contents

by Byoungyun Jeon, Taehyung Kim, Dabin Lee, Tae Joo Shin, Kyung Wha Oh and Juhyun Park

Polymers 2019, 11(11), 1740; https://doi.org/10.3390/polym11111740 - 24 Oct 2019

Cited by 9 | Viewed by 3769

Abstract

We present polymer nanocomposites of tungsten bronze nanorods (TBNRs) and ethylene propylene diene monomers (EPDM). The combination of these components allows the simultaneous enhancement in the mechanical and photothermal properties of the composites at low filler contents. The as-synthesized TBNRs had lengths and [...] Read more.

We present polymer nanocomposites of tungsten bronze nanorods (TBNRs) and ethylene propylene diene monomers (EPDM). The combination of these components allows the simultaneous enhancement in the mechanical and photothermal properties of the composites at low filler contents. The as-synthesized TBNRs had lengths and diameters of 14.0 ± 2.4 nm and 2.5 ± 0.5 nm, respectively, and were capped with oleylamine, which has a chemical structure similar to EPDM, making the TBNRs compatible with the bulk EPDM matrix. The TBNRs absorb a wide range of near-infrared light because of the sub-band transitions induced by alkali metal doping. Thus, the nanocomposites of TBNRs in EPDM showed enhanced photothermal properties owing to the light absorption and subsequent heat emission by the TBNRs. Noticeably, the nanocomposite with only 3 wt% TBNRs presented significantly enhanced tensile strain at break, in comparison with those of pristine EPDM, nanocomposites with 1 and 2 wt % TBNRs, and those with tungsten bronze nanoparticles, because of the alignment of the nanorods during tensile elongation. The photothermal and mechanical properties of these nanocomposites make them promising materials for various applications such as in fibers, foams, clothes with cold weather resistance, patches or mask-like films for efficient transdermal delivery upon heat generation, and photoresponsive surfaces for droplet transport by the thermocapillary effect in microfluidic devices and microengines. Full article

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12 pages, 3517 KiB

Open AccessArticle

Blowing Properties and Functionality of Thermoplastic Polyester Film Using Thermally Expandable Microcapsules

by A Ram Pak, Jung Hyun Park and Seung Geol Lee

Polymers 2019, 11(10), 1652; https://doi.org/10.3390/polym11101652 - 11 Oct 2019

Cited by 9 | Viewed by 4080

Abstract

Blowing film was prepared using a polyester elastomer with thermally expandable microcapsules to investigate its blowing properties and functionality. Film with 11% microcapsule contents showed the lowest specific gravity and the highest blowing efficiency. However, the collapse and merging of blowing cells with [...] Read more.

Blowing film was prepared using a polyester elastomer with thermally expandable microcapsules to investigate its blowing properties and functionality. Film with 11% microcapsule contents showed the lowest specific gravity and the highest blowing efficiency. However, the collapse and merging of blowing cells with 11% microcapsule contents was found by SEM. Therefore, film with 9% microcapsule contents was shown to have better blowing and cell stability than that of film with 11% microcapsule contents. Tensile strength and elongation decreased by increasing microcapsule contents. Film curl and film shrinkage properties were unaffected by microcapsule contents. Water vapor permeability and hydrostatic pressure was decreased by increasing microcapsule contents. Full article

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11 pages, 2764 KiB

Open AccessArticle

Electrical Properties of Silver-Attached Amine Functionalized Carbon Black/Polyethylene Terephthalate Fibers Prepared by Melt-Spinning

by Hyun-Jung Choi, Damiro Ahn, Sohee Lee and Sang Young Yeo

Polymers 2019, 11(10), 1611; https://doi.org/10.3390/polym11101611 - 3 Oct 2019

Cited by 4 | Viewed by 3436

Abstract

In this study, amine functionalized carbon black (ABCB) was synthesized using 4-aminobenzoic acid in a phosphoric acid (PPA)/phosphorus pentoxide (P₂O₅) medium, and silver-attached carbon black (Ag-ABCB) was prepared by reducing AgNO₃ with NaBH₄ in the presence of [...] Read more.

In this study, amine functionalized carbon black (ABCB) was synthesized using 4-aminobenzoic acid in a phosphoric acid (PPA)/phosphorus pentoxide (P₂O₅) medium, and silver-attached carbon black (Ag-ABCB) was prepared by reducing AgNO₃ with NaBH₄ in the presence of ABCB in ethanol. Elemental, thermogravimetric, and Fourier transform-infrared analyses showed that carbon black (CB) had a well-functionalized 4-aminobenzoic acid. In addition, X-ray photoelectron spectroscopy and X-ray diffraction were used to examine the crystal structure of Ag nanoparticles. Conductive fibers were prepared by melt-spinning using ABCB, Ag-ABCB as a conductive filler, and polyethylene terephthalate (PET) as a polymer matrix. Results confirmed that the fiber that had Ag-ABCB as a conductive filler exhibited the best electrical conductivity. The dispersibility and morphology of the conductive filler in the PET matrix were confirmed through scanning electron microscopy analysis, and Ag-ABCB was the most uniformly dispersed filler in the PET matrix, with good structure. Full article

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11 pages, 6827 KiB

Open AccessArticle

Preparation and Properties of Carbon Fiber/Carbon Nanotube Wet-Laid Composites

by Suhyun Lee, Kwangduk Ko, Jiho Youk, Daeyoung Lim and Wonyoung Jeong

Polymers 2019, 11(10), 1597; https://doi.org/10.3390/polym11101597 - 30 Sep 2019

Cited by 28 | Viewed by 5407

Abstract

In this study, carbon nanotubes (CNTs) were introduced into carbon fiber (CF) wet-laid composites as functional nano-fillers to fabricate multi-functional composites with improved mechanical, electrical, and thermal properties. It was considered that the wet-laid process was most suitable in order to introduce filler [...] Read more.

In this study, carbon nanotubes (CNTs) were introduced into carbon fiber (CF) wet-laid composites as functional nano-fillers to fabricate multi-functional composites with improved mechanical, electrical, and thermal properties. It was considered that the wet-laid process was most suitable in order to introduce filler into brittle and rigid carbon fiber substrates, and we established the conditions of the process that could impart dispersibility and bonding between the fibers. We introduced polyamide 6 (PA6) short fiber, which is the same polymeric material as the stacking film, into carbon fiber and CNT mixture to enhance the binding interactions between carbon fiber and CNTs. Various types of CNT-reinforced carbon fiber wet-laid composites with PA6 short fibers were prepared, and the morphology, mechanical and electrical properties of the composites were estimated. As CNT was added to the carbon fiber nonwoven, the electrical conductivity increased by 500% but the tensile strength decreased slightly. By introducing short fibers of the same material as the matrix between CNT–CF wet-laid nonwovens, it was possible to find optimum conditions to increase the electrical conductivity while maintaining mechanical properties. Full article

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12 pages, 1870 KiB

Open AccessArticle

Immobilization of Trypsin from Porcine Pancreas onto Chitosan Nonwoven by Covalent Bonding

by Jung Soo Kim and Sohee Lee

Polymers 2019, 11(9), 1462; https://doi.org/10.3390/polym11091462 - 6 Sep 2019

Cited by 21 | Viewed by 4432

Abstract

The present study deals with the potential application of chitosan nonwoven for biomedical textiles based on enzyme immobilization. For this, chitosan nonwoven was first cross-linked with glutaraldehyde to introduce aldehyde groups at optimal conditions. To immobilize the enzyme trypsin onto glutaraldehyde-pre-activated chitosan nonwoven, [...] Read more.

The present study deals with the potential application of chitosan nonwoven for biomedical textiles based on enzyme immobilization. For this, chitosan nonwoven was first cross-linked with glutaraldehyde to introduce aldehyde groups at optimal conditions. To immobilize the enzyme trypsin onto glutaraldehyde-pre-activated chitosan nonwoven, several parameters such as pH, enzyme concentration, and reaction times were investigated. In addition, the pH, thermal stability, storage stability, and reusability of immobilized trypsin were examined. We found that the optimal immobilization conditions for trypsin were pH 8.5, enzyme concentration of 8% (owf), and treatment time of 30 min. Trypsin was immobilized at 25 °C efficiently. The immobilized trypsin showed lower pH stability and better thermal stability than free trypsin. The immobilized trypsin showed 50% of its initial activity after being used 15 times and 80% of that after 20 days of storage at 4 °C. SEM analysis also confirmed that trypsin was immobilized on chitosan nonwoven. Full article

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7 pages, 1783 KiB

Open AccessArticle

Comparative Study of Triboelectric Nanogenerators with Differently Woven Cotton Textiles for Wearable Electronics

by Jaebum Jeong, Jin-Hyuk Kwon, Kyungmin Lim, Swarup Biswas, Alexandra Tibaldi, Suwoong Lee, Hyun Ju Oh, Jong-Hyoung Kim, Jaehoon Ko, Dong-Wook Lee, Hanchul Cho, Philippe Lang, Jaewon Jang, Sohee Lee, Jin-Hyuk Bae and Hyeok Kim

Polymers 2019, 11(9), 1443; https://doi.org/10.3390/polym11091443 - 3 Sep 2019

Cited by 13 | Viewed by 5085

Abstract

A comparative study of the electrical performance of triboelectric nanogenerators (TENGs) with plain- and 2/1 twill-woven cotton textiles was conducted. Furthermore, the microstructures of the cotton fiber surfaces were examined to understand the fundamental mechanical interaction among the cotton fibers in the TENGs. [...] Read more.

A comparative study of the electrical performance of triboelectric nanogenerators (TENGs) with plain- and 2/1 twill-woven cotton textiles was conducted. Furthermore, the microstructures of the cotton fiber surfaces were examined to understand the fundamental mechanical interaction among the cotton fibers in the TENGs. The TENG with 2/1 twill-woven cotton textiles exhibited higher output voltages compared to that with plain-woven cotton textiles. The difference in the output voltage between the two types of TENGs resulted from the difference in triboelectric charge generation between the constituent cotton textiles. The higher output voltage of the TENG with 2/1 twill-woven cotton textiles was attributed to the higher density in triboelectric interactions among the cotton fiber molecules. Full article

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12 pages, 5724 KiB

Open AccessArticle

Evaluation of Thermal Properties of 3D Spacer Technical Materials in Cold Environments using 3D Printing Technology

by Ran-i Eom, Hyojeong Lee and Yejin Lee

Polymers 2019, 11(9), 1438; https://doi.org/10.3390/polym11091438 - 2 Sep 2019

Cited by 19 | Viewed by 4137

Abstract

Novel materials have been recently developed for coping with various environmental factors. Generally, to improve the thermal comfort to humans in cold environments, securing an air layer is important. Therefore, this study analyzed the thermal properties of 3D spacer technical materials, 3D printed [...] Read more.

Novel materials have been recently developed for coping with various environmental factors. Generally, to improve the thermal comfort to humans in cold environments, securing an air layer is important. Therefore, this study analyzed the thermal properties of 3D spacer technical materials, 3D printed using thermoplastic polyurethane, according to the structural changes. Four 3D spacer technical material structures were designed with varying pore size and thickness. These samples were moved into a cold climate chamber (temperature 5 ± 1 °C, relative humidity (60 ± 5)%, wind velocity ≤0.2 m/s) and placed on a heating plate set to 30 °C. The surface and internal temperatures were measured after 0, 10, 20, and 30 min and then 10 min after turning off the heating plate. When heat was continuously supplied, the 3D spacer technical material with large pores and a thick air layer showed superior insulation among the materials. However, when no heat was supplied, the air gap thickness dominantly affected thermal insulation, regardless of the pore size. Hence, increasing the air gap is more beneficial than increasing the pore size. Notably, we found that the air gap can increase insulation efficiency, which is of importance to the new concept of 3D printing an interlining. Full article

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18 pages, 10431 KiB

Open AccessArticle

Complementary Assessment of Commercial Photoluminescent Pigments Printed on Cotton Fabric

by Selestina Gorgieva, Natalija Virant and Alenka Ojstršek

Polymers 2019, 11(7), 1216; https://doi.org/10.3390/polym11071216 - 20 Jul 2019

Cited by 11 | Viewed by 4612

Abstract

The presented study focuses on photoluminescent pigments applied on cotton fabric by a screen-printed procedure using polydimethylsiloxane (PDMS) as a binder. Microscopic data depicts irregular shapes and relatively wide size distribution (3–80 µm) of pigments. Regarding composition, the Energy-Dispersive X-ray (EDX) and Fourier [...] Read more.

The presented study focuses on photoluminescent pigments applied on cotton fabric by a screen-printed procedure using polydimethylsiloxane (PDMS) as a binder. Microscopic data depicts irregular shapes and relatively wide size distribution (3–80 µm) of pigments. Regarding composition, the Energy-Dispersive X-ray (EDX) and Fourier Transform Infrared (FTIR) spectroscopy data complement findings suggesting the presence of Eu-doped strontium aluminate in the yellow-green, calcium aluminate in the violet pigment, and metal oxides in the blue pigment. The optical properties of pigment-enriched PDMS-coated cotton fabric were assessed and reflectance intensity was found to be concentration-dependent only in the blue pigment. The luminescence decay data show that luminescence intensity decreased with the reduction of pigment concentration in the following order, yellow-green > blue > violet pigments. Relying on absorption and emission data of powdered pigments, the confocal microscopy enables visualization of the pigments’ distribution within a 3D image projection. This identifies the most homogeneous distribution in the case of the blue pigment, as well as the presence of a continuous fluorescing signal in the z projection when 5% pigment was used. This was, for the first time, presented as a powerful tool for non-destructive visualization of photoluminescent pigments’ spatial distribution when printed on textile (cotton) fabric. Finally, the photoluminescent PDMS coating demonstrates high washing and abrasion resistance, contributing to overall functionality of printed cotton fabrics when commercial types of pigments are applied. Full article

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15 pages, 5365 KiB

Open AccessArticle

Electroactive Textile Actuators for Breathability Control and Thermal Regulation Devices

by Chaoqun Xiang, Jianglong Guo, Rujie Sun, Andrew Hinitt, Tim Helps, Majid Taghavi and Jonathan Rossiter

Polymers 2019, 11(7), 1199; https://doi.org/10.3390/polym11071199 - 18 Jul 2019

Cited by 12 | Viewed by 5576

Abstract

Smart fabrics offer the potential for a new generation of soft robotics and wearable technologies through the fusion of smart materials, textiles and electrical circuitries. Conductive and stretchable textiles have inherent compliance and low resistance that are suitable for driving artificial muscle actuators [...] Read more.

Smart fabrics offer the potential for a new generation of soft robotics and wearable technologies through the fusion of smart materials, textiles and electrical circuitries. Conductive and stretchable textiles have inherent compliance and low resistance that are suitable for driving artificial muscle actuators and are potentially safer electrode materials for soft actuation technologies. We demonstrate how soft electroactive actuating structures can be designed and fabricated from conducting textiles. We first quantitatively analyse a range of stretchable conductive textiles for dielectric elastomer actuators (DEAs). We found that conductive-knit textiles are more suitable for unidirectional DEA applications due to the largest difference (150%) in principle strain axes, whereas isotropic textiles are more suited to bidirectional DEA applications due to the smallest (11.1%) principle strain difference. Finally, we demonstrate controllable breathability through a planar e-textile DEA-driven skin and show thermal regulation in a wearable prototype that exploits soft actuation and kirigami. Full article

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16 pages, 5004 KiB

Open AccessArticle

Integration of Polypyrrole Electrode into Piezoelectric PVDF Energy Harvester with Improved Adhesion and Over-Oxidation Resistance

by Kyungha Baik, Sohyun Park, Changsang Yun and Chung Hee Park

Polymers 2019, 11(6), 1071; https://doi.org/10.3390/polym11061071 - 21 Jun 2019

Cited by 9 | Viewed by 4974

Abstract

Smart textiles for wearable devices require flexibility and a lightweight, so in this study, a soft polypyrrole (PPy) electrode system was integrated into a piezoelectric polyvinylidenefluoride (PVDF) energy harvester. The PVDF energy harvester integrated with a PPy electrode had the piezoelectric output voltage [...] Read more.

Smart textiles for wearable devices require flexibility and a lightweight, so in this study, a soft polypyrrole (PPy) electrode system was integrated into a piezoelectric polyvinylidenefluoride (PVDF) energy harvester. The PVDF energy harvester integrated with a PPy electrode had the piezoelectric output voltage of 4.24–4.56 V, while the PVDF energy harvester with an additional aluminum-foil electrode exhibited 2.57 V. Alkaline treatment and chemical vapor deposition with n-dodecyltrimethoxysilane (DTMS) were employed to improve the adhesion between the PVDF and PPy and the resistance to over-oxidation in aqueous solutions. The PVDF film modified by an alkaline treatment could have the improved adhesion via the introduction of polar functional groups to its surface, which was confirmed by the ultrasonication. The surface hydrophobicity of the PPy electrode was enhanced by the DTMS coating, resulting in the improvement of the resistance to over-oxidation with a water contact angle of 111°. Even with the hydrophobic coating, the electrodes remained electroconductive and continued to transfer an electric charge, maintaining the piezoelectricity of the PVDF film. The developed electrode-integrated energy harvester is expected to be applied to smart textiles because it offers the advantages of efficient piezoelectric generation, flexibility, and durability. Full article

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13 pages, 3617 KiB

Open AccessArticle

In-Plane Behavior of Auxetic Non-Woven Fabric Based on Rotating Square Unit Geometry under Tensile Load

by Polona Dobnik Dubrovski, Nejc Novak, Matej Borovinšek, Matej Vesenjak and Zoran Ren

Polymers 2019, 11(6), 1040; https://doi.org/10.3390/polym11061040 - 12 Jun 2019

Cited by 33 | Viewed by 5187

Abstract

This paper reports the auxetic behavior of modified conventional non-woven fabric. The auxetic behavior of fabric was achieved by forming rotating square unit geometry with a highly ordered pattern of slits by laser cutting. Two commercial needle-punched non-woven fabric used as lining and [...] Read more.

This paper reports the auxetic behavior of modified conventional non-woven fabric. The auxetic behavior of fabric was achieved by forming rotating square unit geometry with a highly ordered pattern of slits by laser cutting. Two commercial needle-punched non-woven fabric used as lining and the reinforcement fabric for the footwear industry were investigated. The influence of two rotating square unit sizes was analyzed for each fabric. The original and modified fabric samples were subjected to quasi-static tensile load by using the Tinius Olsen testing machine to observe the in-plane mechanical properties and deformation behavior of tested samples. The tests were recorded with a full high-definition (HD) digital camera and the video recognition technique was applied to determine the Poisson’s ratio evolution during testing. The results show that the modified samples exhibit a much lower breaking force due to induced slits, which in turn limits the application of such modified fabric to low tensile loads. The samples with smaller rotating cell sizes exhibit the highest negative Poisson’s ratio during tensile loading through the entire longitudinal strain range until rupture. Non-woven fabric with equal distribution and orientation of fibers in both directions offer better auxetic response with a smaller out-of-plane rotation of rotating unit cells. The out-of-plane rotation of unit cells in non-homogenous samples is higher in machine direction. Full article

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15 pages, 49403 KiB

Open AccessArticle

Characterization of Electrical Heating Textile Coated by Graphene Nanoplatelets/PVDF-HFP Composite with Various High Graphene Nanoplatelet Contents

by Hyelim Kim and Sunhee Lee

Polymers 2019, 11(5), 928; https://doi.org/10.3390/polym11050928 - 27 May 2019

Cited by 19 | Viewed by 5666

Abstract

We prepared a horseshoe-pattern type electrical heating textile that was coated with high graphene nanoplatelet (GNP) content (32 wt% to 64 wt%) of graphene nanoplatelet/poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) composite. Silver-coated conductive yarn is used as electrode in the sample to improve its [...] Read more.

We prepared a horseshoe-pattern type electrical heating textile that was coated with high graphene nanoplatelet (GNP) content (32 wt% to 64 wt%) of graphene nanoplatelet/poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) composite. Silver-coated conductive yarn is used as electrode in the sample to improve its flexibility and applicability as wearable textile. These graphene nanoplatelet/PVDF-HFP coated samples with various high-contents of graphene were characterized using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), sheet resistance analysis, and electrical heating performance analysis. Graphene nanoplatelet/PVDF-HFP coated cotton fabric improved the crystallinity and thermal stability with increasing thw high-content of GNP. With an increasing of the high-content of graphene nanoplatelet in the PVDF-HFP composite solution, the sheet resistance of samples tended to gradually decrease. That of, 64 wt% graphene nanoplatelet/PVDF-HFP composite coated sample (64 GR/cotton) was 44 Ω/sq. The electrical heating performance of graphene nanoplatelet/PVDF-HFP composite coated cotton fabric was improved with increasing the high-content of graphene nanoplatelet. When 5 V was applied to 64 GR/cotton, its surface temperature has been indicated to be about 48 °C and it could be used at a low voltage (<10 V). Thus, a horseshoe-pattern type electrical heating textile that is coated by high content of graphene nanoplatelet/PVDF-HFP composite solution sewn with silver-coated conductive yarn is expected to be applied to glove, shoes, jacket, and so on to improve its wearability and applicability. Full article

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15 pages, 10397 KiB

Open AccessArticle

The Effect of Polydopamine on an Ag-Coated Polypropylene Nonwoven Fabric

by Chuanmei Liu, Jie Liu, Xin Ning, Shaojuan Chen, Zhengqin Liu, Shouxiang Jiang and Dagang Miao

Polymers 2019, 11(4), 627; https://doi.org/10.3390/polym11040627 - 4 Apr 2019

Cited by 29 | Viewed by 4668

Abstract

A practical method for preparing multifunctional polypropylene (PP) nonwoven fabrics with excellent stability and durability was explored. First, the PP nonwoven fabric was sputtered by a magnetron sputtering system to form an Ag film on the surface of the fabric. Subsequently, the coated [...] Read more.

A practical method for preparing multifunctional polypropylene (PP) nonwoven fabrics with excellent stability and durability was explored. First, the PP nonwoven fabric was sputtered by a magnetron sputtering system to form an Ag film on the surface of the fabric. Subsequently, the coated fabric was treated with dopamine. The fabrics were characterized by scanning electron microscopy (SEM), an energy dispersive spectrometer (EDS), electrical conductivity, electromagnetic interference shielding effectiveness (EMI SE), antibacterial activity, stability, and laundering durability. The results of the study revealed that the fabric was coated with Ag, and after the treatment with dopamine, the surfaces of Ag-coated fibers were coated with polydopamine (PDA). The fabrics still had a sheet resistance below ~15 Ω/sq and exhibited excellent EMI SE above ~25 dB, though few differences existed from the single Ag-coated sample. After the treatment with dopamine, the antibacterial activity of the fabric was enhanced. Meanwhile, the treated samples exhibited excellent resistance against sodium sulfide corrosion, which could enhance the stability of the Ag-coated fabric. Moreover, the laundering durability of the treated fabric was improved in the same process, whose lowest sheet resistance was ~18 Ω/sq and the EMI SE was ~8 dB more than single Ag-coated PP nonwoven fabrics. In conclusion, this method was considered to be effective in fabricating multifunctional, stable, and durable fabrics. Full article

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11 pages, 1941 KiB

Open AccessArticle

Optimized Dyeing Process for Enhancing the Functionalities of Spent Coffee Dyed Wool Fabrics Using a Facile Extraction Process

by Jihyun Bae and Kyung Hwa Hong

Polymers 2019, 11(4), 574; https://doi.org/10.3390/polym11040574 - 28 Mar 2019

Cited by 15 | Viewed by 4920

Abstract

Spent coffee grounds are the byproduct of coffee brewing and are generally discarded as waste. However, spent coffee has high levels of organic compounds that have multiple biological effects, including antibacterial and antioxidant activities. In this light, spent coffee grounds were tested for [...] Read more.

Spent coffee grounds are the byproduct of coffee brewing and are generally discarded as waste. However, spent coffee has high levels of organic compounds that have multiple biological effects, including antibacterial and antioxidant activities. In this light, spent coffee grounds were tested for fabric dyeing to both functionalize as well as color the fabrics. The dyeing solution was prepared by extracting spent coffee grounds collected from a local coffee house by using a manual espresso machine. The spent coffee extract was applied to wool fabrics using a laboratory infrared dyeing machine. After the dyeing process was completed, the fabrics were mordanted with a tannic acid aqueous solution. To optimize the dyeing conditions, the times and temperatures during the process were varied, and the functionalities and other properties including color and strength of the wool fabrics dyed with the spent coffee extract were investigated. The wool fabrics dyed with the spent coffee extract were significantly colored, and the color withstands the effect of washing and light exposure. Moreover, the dyeing process with the spent coffee extract and the mordanting process with tannic acid gave the wool fabrics antibacterial and antioxidant properties. Full article

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9 pages, 2364 KiB

Open AccessArticle

Mechanism of Accelerant on Disperse Dyeing for PET Fiber in the Silicone Solvent Dyeing System

by Jiping Wang, Wenqing Cheng, Yuanyuan Gao, Lei Zhu and Liujun Pei

Polymers 2019, 11(3), 520; https://doi.org/10.3390/polym11030520 - 19 Mar 2019

Cited by 39 | Viewed by 5615

Abstract

Disperse dyeing for polyethylene terephthalate (PET) fiber in different non-aqueous solvent dyeing systems have been extensively studied over the past decades. In the present work, disperse dyeing for PET was investigated in a silicone solvent dyeing system. The influence of accelerant on the [...] Read more.

Disperse dyeing for polyethylene terephthalate (PET) fiber in different non-aqueous solvent dyeing systems have been extensively studied over the past decades. In the present work, disperse dyeing for PET was investigated in a silicone solvent dyeing system. The influence of accelerant on the fiber swelling, uptake of dye, K/S value of dyed fiber, and dye solubility in the silicone solvent were systematically investigated. Compared with no accelerant, the final uptake of the disperse dye (C. I. Disperse Blue 367) could increase to 81% with 20% accelerant in the silicone solvent dyeing system, and the K/S value of dyed fiber was also higher (3.3 for no accelerant vs. 13.2 for accelerant). The influence of accelerant on the performance of disperse dyeing was also studied. Firstly, the solubility of the disperse dye in the silicone solvent can be decreased by the accelerant. Moreover, the solubility of the disperse dye is inversely proportional to the K/S value and the uptake of the dye. In addition, although the silicone solvent can diffuse to the inner fiber and has a partial swelling in the PET fiber, the swelling of PET can be improved by the accelerant. Furthermore, the swelling of fiber can reach equilibrium when the amount of accelerant was 15% (the weight of fiber). Therefore, this eco-friendly dyeing technology has considerable potential for application to a broad array of chemical fibers. Full article

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10 pages, 7207 KiB

Open AccessArticle

Diffusion Mechanism of Aqueous Solutions and Swelling of Cellulosic Fibers in Silicone Non-Aqueous Dyeing System

by Liujun Pei, Yuni Luo, Xiaomin Gu, Huashu Dou and Jiping Wang

Polymers 2019, 11(3), 411; https://doi.org/10.3390/polym11030411 - 4 Mar 2019

Cited by 26 | Viewed by 4723

Abstract

The main goal of this article is to study the diffusion mechanism of aqueous solutions and the swelling of cellulosic fibers in the silicone non-aqueous dyeing system via fluorescent labeling. Due to non-polar media only adsorbing on the surface of fiber, cellulosic fiber [...] Read more.

The main goal of this article is to study the diffusion mechanism of aqueous solutions and the swelling of cellulosic fibers in the silicone non-aqueous dyeing system via fluorescent labeling. Due to non-polar media only adsorbing on the surface of fiber, cellulosic fiber could not swell as a result of the non-polar media. However, because water molecules can diffuse into the non-crystalline region of the fiber, cellulosic fiber could swell by water which was dispersed or emulsified in a non-aqueous dyeing system. To study the diffusion mechanism of an aqueous solution in the siloxane non-aqueous dyeing system, siloxane non-aqueous media was first diffused to the cellulosic fiber because of its lower surface tension. The resulting aqueous solution took more time to diffuse the surface of the cellulosic fiber, because water molecules must penetrate the siloxane non-aqueous media film. Compared with the fluorescent intensity of the fiber surface, the siloxane film could be re-transferred to the dye bath under the emulsification of the surfactant and the mechanical force. Therefore, a longer diffusion time of the aqueous solution ensured the dyeing feasibility for cellulosic fiber in the non-aqueous dyeing system. Full article

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13 pages, 3718 KiB

Open AccessArticle

Environmentally Friendly Flexible Strain Sensor from Waste Cotton Fabrics and Natural Rubber Latex

by Xinzhu Chen, Jing An, Guangming Cai, Jin Zhang, Wu Chen, Xiongwei Dong, Licheng Zhu, Bin Tang, Jinfeng Wang and Xungai Wang

Polymers 2019, 11(3), 404; https://doi.org/10.3390/polym11030404 - 1 Mar 2019

Cited by 55 | Viewed by 7085

Abstract

A green approach was successfully developed to fabricate flexible sensors by utilizing carbonized waste cotton fabrics in combination with natural rubber latex. Waste cotton fabrics were firstly carbonized by heat treatment in the nitrogen atmosphere before they were combined with natural rubber latex [...] Read more.

A green approach was successfully developed to fabricate flexible sensors by utilizing carbonized waste cotton fabrics in combination with natural rubber latex. Waste cotton fabrics were firstly carbonized by heat treatment in the nitrogen atmosphere before they were combined with natural rubber latex using three methods, i.e., vacuum bagging, negative pressure adsorption and drop coating. After impregnation with natural rubber, the carbonized cotton maintained the fabric structure and showed good conductivity. More importantly, the electric resistance of the textile composites changed with the tensile strain. The cyclic stretching-releasing tests indicated that the prepared wearable flexible strain sensors were sensitive to strain and stable under cyclic loading. The flexible strain sensor also demonstrated the capability of monitoring human finger and arm motion. Full article

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12 pages, 5162 KiB

Open AccessArticle

Manufacture and Property of Warp-Knitted Fabrics with Polylactic Acid Multifilament

by Tong Yang, Wei Zhou and Pibo Ma

Polymers 2019, 11(1), 65; https://doi.org/10.3390/polym11010065 - 4 Jan 2019

Cited by 7 | Viewed by 6060

Abstract

This study investigates the properties of polylactic acid (PLA) multifilament and its warp-knitted fabrics. Multifilament properties were tested and compared with PET multifilament with different diameters. The 83.3 dtex PLA multifilament was used to knit the fabric, and the fabric properties before and [...] Read more.

This study investigates the properties of polylactic acid (PLA) multifilament and its warp-knitted fabrics. Multifilament properties were tested and compared with PET multifilament with different diameters. The 83.3 dtex PLA multifilament was used to knit the fabric, and the fabric properties before and after dyeing were studied. Results showed that the mechanical properties of PLA multifilament were comparable to those of PET. However, PLA had a higher heat shrinkage rate. The dyed PLA warp-knitted fabric has excellent color fastness. Due to the influence of temperature and dye particles during the dyeing process, the breaking strength, air permeability and moisture permeability of the fabric were decreased. On the contrary, the elongation at break, abrasion resistance, anti-pilling properties, drape and crochet value of the fabric were increased. Full article

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