Polymers

2021

Jump to: 2020, 2019

19 pages, 5827 KiB

Open AccessArticle

A Simple Approach to Control the Physical and Chemical Features of Custom-Synthesized N-Doped Carbon Nanotubes and the Extent of Their Network Formation in Polymers: The Importance of Catalyst to Substrate Ratio

by Elnaz Erfanian, Milad Kamkar, Shital Patangrao Pawar, Yalda Zamani Keteklahijani, Mohammad Arjmand and Uttandaraman Sundararaj

Polymers 2021, 13(23), 4156; https://doi.org/10.3390/polym13234156 - 27 Nov 2021

Cited by 3 | Viewed by 2600

Abstract

This study intends to reveal the significance of the catalyst to substrate ratio (C/S) on the structural and electrical features of the carbon nanotubes and their polymeric nanocomposites. Here, nitrogen-doped carbon nanotube (N-MWNT) was synthesized via a chemical vapor deposition (CVD) method using [...] Read more.

This study intends to reveal the significance of the catalyst to substrate ratio (C/S) on the structural and electrical features of the carbon nanotubes and their polymeric nanocomposites. Here, nitrogen-doped carbon nanotube (N-MWNT) was synthesized via a chemical vapor deposition (CVD) method using three ratios (by weight) of iron (Fe) catalyst to aluminum oxide (Al₂O₃) substrate, i.e.,1/9, 1/4, and 2/3, by changing the Fe concentration, i.e., 10, 20, and 40 wt.% Fe. Therefore, the synthesized N-MWNT are labelled as (N-MWNTs)₁₀, (N-MWNTs)₂₀, and (N-MWNTs)₄₀. TEM, XPS, Raman spectroscopy, and TGA characterizations revealed that C/S ratio has a significant impact on the physical and chemical properties of the nanotubes. For instance, by increasing the Fe catalyst from 10 to 40 wt.%, carbon purity increased from 60 to 90 wt.% and the length of the nanotubes increased from 1.2 to 2.6 µm. Interestingly, regarding nanotube morphology, at the highest C/S ratio, the N-MWNTs displayed an open-channel structure, while at the lowest catalyst concentration the nanotubes featured a bamboo-like structure. Afterwards, the network characteristics of the N-MWNTs in a polyvinylidene fluoride (PVDF) matrix were studied using imaging techniques, AC electrical conductivity, and linear and nonlinear rheological measurements. The nanocomposites were prepared via a melt-mixing method at various loadings of the synthesized N-MWNTs. The rheological results confirmed that (N-MWNTs)₁₀, at 0.5–2.0 wt.%, did not form any substantial network through the PVDF matrix, thereby exhibiting an electrically insulative behavior, even at a higher concentration of 3.0 wt.%. Although the optical microscopy, TEM, and rheological results confirmed that both (N-MWNTs)₂₀ and (N-MWNTs)₄₀ established a continuous 3D network within the PVDF matrix, (N-MWNTs)₄₀/PVDF nanocomposites exhibited approximately one order of magnitude higher electrical conductivity. The higher electrical conductivity of (N-MWNTs)₄₀/PVDF nanocomposites is attributed to the intrinsic chemical features of (N-MWNTs)₄₀, such as nitrogen content and nitrogen bonding types. Full article

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15 pages, 4473 KiB

Open AccessArticle

Waste to Value-Added Product: Developing Electrically Conductive Nanocomposites Using a Non-Recyclable Plastic Waste Containing Vulcanized Rubber

by Amir Hosein Ahmadian Hoseini, Elnaz Erfanian, Milad Kamkar, Uttandaraman Sundararaj, Jian Liu and Mohammad Arjmand

Polymers 2021, 13(15), 2427; https://doi.org/10.3390/polym13152427 - 23 Jul 2021

Cited by 9 | Viewed by 4006

Abstract

This study intends to show the potential application of a non-recyclable plastic waste towards the development of electrically conductive nanocomposites. Herein, the conductive nanofiller and binding matrix are carbon nanotubes (CNT) and polystyrene (PS), respectively, and the waste material is a plastic foam [...] Read more.

This study intends to show the potential application of a non-recyclable plastic waste towards the development of electrically conductive nanocomposites. Herein, the conductive nanofiller and binding matrix are carbon nanotubes (CNT) and polystyrene (PS), respectively, and the waste material is a plastic foam consisting of mainly vulcanized nitrile butadiene rubber and polyvinyl chloride (PVC). Two nanocomposite systems, i.e., PS/Waste/CNT and PS/CNT, with different compositions were melt-blended in a mixer and characterized for electrical properties. Higher electrical conduction and improved electromagnetic interference shielding performance in PS/Waste/CNT system indicated better conductive network of CNTs. For instance, at 1.0 wt.% CNT loading, the PS/Waste/CNT nanocomposites with the plastic waste content of 30 and 50 wt.% conducted electricity 3 and 4 orders of magnitude higher than the PS/CNT nanocomposite, respectively. More importantly, incorporation of the plastic waste (50 wt.%) reduced the electrical percolation threshold by 30% in comparison with the PS/CNT nanocomposite. The enhanced network of CNTs in PS/Waste/CNT samples was attributed to double percolation morphology, evidenced by optical images and rheological tests, caused by the excluded volume effect of the plastic waste. Indeed, due to its high content of vulcanized rubber, the plastic waste did not melt during the blending process. As a result, CNTs concentrated in the PS phase, forming a denser interconnected network in PS/Waste/CNT samples. Full article

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9 pages, 1486 KiB

Open AccessArticle

The Influence of Nano CaCO₃ on Nucleation and Interface of PP Nano Composite: Matrix Processability and Impact Resistance

by Meshal Al-Samhan, Fatema Al-Attar, Jamal Al-Fadhli and Mustafa Al-Shamali

Polymers 2021, 13(9), 1389; https://doi.org/10.3390/polym13091389 - 25 Apr 2021

Cited by 7 | Viewed by 2707

Abstract

Polypropylene (PP) is a commodity material that has been increasingly used in different industries in the past two decades due to its versatile properties when enhanced with additives. Homo polypropylene, in general, has weak mechanical properties and limited chemical resistance; thus, using a [...] Read more.

Polypropylene (PP) is a commodity material that has been increasingly used in different industries in the past two decades due to its versatile properties when enhanced with additives. Homo polypropylene, in general, has weak mechanical properties and limited chemical resistance; thus, using a different type of fillers to adjust such properties to fit the required applications opened a large market for this commodity. Understanding the interface constituent between the polymer matrix and the added filler and the nucleation behavior is a key to fine control of the enhancement of PP properties. In this study, PP was incorporated with nano calcium carbonate (CaCO₃) at 2 and 5 wt% in the presence of maleic anhydride (MAH) to overcome the weak interface due to low polymer polarity. The mix was compounded in a twin screws extruder at a temperature range of 180–200 °C ; then, the prepared samples were left to dry for 24 h at 25 °C. Nuclear Magnetic Resonance (NMR) was used to study the interface adhesion of the nanofiller and the curved revealed that at 2% of nano CaCO₃ PP structure remained the same and the nano experienced good adhesion to the polymer matrix. The mechanical impact resistance results showed a real enhancement to the polymer matrix of the nanocomposite by 37%. Moreover, DSC results showed a faster crystallinity rate due to the nanofiller acting as a nucleating agent and rheology tests indicated that low content of nano additive (2%) has better processability behavior, with suitable viscosity complex values at high frequencies. Full article

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24 pages, 53442 KiB

Open AccessArticle

Morphology Evolution, Molecular Simulation, Electrical Properties, and Rheology of Carbon Nanotube/Polypropylene/Polystyrene Blend Nanocomposites: Effect of Molecular Interaction between Styrene-Butadiene Block Copolymer and Carbon Nanotube

by Ivonne Otero Navas, Milad Kamkar, Mohammad Arjmand and Uttandaraman Sundararaj

Polymers 2021, 13(2), 230; https://doi.org/10.3390/polym13020230 - 11 Jan 2021

Cited by 18 | Viewed by 4952

Abstract

This work studied the impact of three types of styrene-butadiene (SB and SBS) block copolymers on the morphology, electrical, and rheological properties of immiscible blends of polypropylene:polystyrene (PP:PS)/multi-walled carbon nanotubes (MWCNT) with a fixed blend ratio of 70:30 vol.%. The addition of block [...] Read more.

This work studied the impact of three types of styrene-butadiene (SB and SBS) block copolymers on the morphology, electrical, and rheological properties of immiscible blends of polypropylene:polystyrene (PP:PS)/multi-walled carbon nanotubes (MWCNT) with a fixed blend ratio of 70:30 vol.%. The addition of block copolymers to PP:PS/MWCNT blend nanocomposites produced a decrease in the droplet size. MWCNTs, known to induce co-continuity in PP:PS blends, did not interfere with the copolymer migration to the interface and, thus, there was morphology refinement upon addition of the copolymers. Interestingly, the addition of the block copolymers decreased the electrical resistivity of the PP:PS/1.0 vol.% MWCNT system by 5 orders of magnitude (i.e., increase in electrical conductivity). This improvement was attributed to PS Droplets-PP-Copolymer-Micelle assemblies, which accumulated MWCNTs, and formed an integrated network for electrical conduction. Molecular simulation and solubility parameters were used to predict the MWCNT localization in the immiscible blend. The simulation results showed that diblock copolymers favorably interact with the nanotubes in comparison to the triblock copolymer, PP, and PS. However, the interaction between the copolymers and PP or PS is stronger than the interaction of the copolymers and MWCNTs. Hence, the addition of copolymer also changed the localization of MWCNT from PS to PS–PP–Micelles–Interface, as observed by TEM images. In addition, in the last step of this work, we investigated the effect of the addition of copolymers on inter- and intra-cycle viscoelastic behavior of the MWCNT incorporated polymer blends. It was found that addition of the copolymers not only affects the linear viscoelasticity (e.g., increase in the value of the storage modulus) but also dramatically impacts the nonlinear viscoelastic behavior under large deformations (e.g., higher distortion of Lissajous–Bowditch plots).] Full article

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2020

Jump to: 2021, 2019

19 pages, 5118 KiB

Open AccessArticle

Polyaspartate-Ionene/Na⁺-Montmorillonite Nanocomposites as Novel Adsorbent for Anionic Dye; Effect of Ionene Structure

by Hany El-Hamshary, Abeer S. Elsherbiny, Mohamed H. El-Newehy and Mohamed E. EL-Hefnawy

Polymers 2020, 12(12), 2843; https://doi.org/10.3390/polym12122843 - 29 Nov 2020

Cited by 9 | Viewed by 2254

Abstract

Surface modification of sodium montmorillonite (Na⁺-Mt) was performed using antimicrobial agents to produce an ecofriendly nanocomposite. The adsorption performance of the nanocomposite has been evaluated for the removal of Acid Blue 25 dye (AB25) as a model organic pollutant from wastewater. [...] Read more.

Surface modification of sodium montmorillonite (Na⁺-Mt) was performed using antimicrobial agents to produce an ecofriendly nanocomposite. The adsorption performance of the nanocomposite has been evaluated for the removal of Acid Blue 25 dye (AB25) as a model organic pollutant from wastewater. Sodium montmorillonite (Na⁺-Mt) was modified with three different ionene compounds through ion exchange, and further modified through reaction with polyaspartate to provide three ecofriendly nanocomposites (denoted ICP-1–3). The nanocomposites were characterized using FTIR, PXRD, TEM, SEM, and BET surface area. The adsorption isotherm of AB25 onto ICP-1, ICP-2 and ICP-3 was analyzed using the Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) models. The adsorption isotherm was found to be best fitted by a Freundlich model. The thermodynamic parameters were calculated. The kinetics of the adsorption data were analyzed and the adsorption behavior was found to obey pseudo-second-order kinetics, and the intraparticle diffusion model. The adsorption mechanism was studied by FTIR. Full article

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14 pages, 5822 KiB

Open AccessArticle

Influence of Antimony Oxide on Epoxy Based Intumescent Flame Retardation Coating System

by Riyazuddin, Samrin Bano, Fohad Mabood Husain, Rais Ahmad Khan, Ali Alsalme and Jamal Akhter Siddique

Polymers 2020, 12(11), 2721; https://doi.org/10.3390/polym12112721 - 17 Nov 2020

Cited by 11 | Viewed by 2777

Abstract

Ethylenediamine modified Ammonium polyphosphate (EDA-MAPP), and Charring-Foaming Agents (CFA) was prepared via a simple chemical approach and further utilizes for the preparation of Epoxy resin based intumescent flame retardation coatings. The ratio belongs to MAPP and CFA was fixed at 2:1 ratio. Comparative [...] Read more.

Ethylenediamine modified Ammonium polyphosphate (EDA-MAPP), and Charring-Foaming Agents (CFA) was prepared via a simple chemical approach and further utilizes for the preparation of Epoxy resin based intumescent flame retardation coatings. The ratio belongs to MAPP and CFA was fixed at 2:1 ratio. Comparative thermo gravimetric analysis TGA study of Modified Ammonium polyphosphate (MAPP) and Ammonium polyphosphate (APP) investigated. Sb₂O₃ was introduced into flame retardation coating formulation at various amounts to evaluate the synergistic action of Sb₂O₃ along with flame retardant coating system. The synergistic action of Sb₂O₃ on flame retardation coating formulation was studied by vertical burning test (UL-94V), thermo gravimetric analysis (TGA), Limited Oxygen Index (LOI), and Fourier Transform Infra-Red spectroscopy (FTIR). The UL-94V results indicated that adding Sb₂O₃ effectively increased flame retardancy and meets V-0 ratings at each concentration. The TGA results revealed that the amalgamation of Sb₂O₃ at each concentration effectively increased the thermal stability of the flame retardant coating system. Cone-calorimeter study results that Sb₂O₃ successfully minimized the combustion parameters like, Peak Heat Release Rate (PHRR), and Total Heat Release (THR). The FTIR result shows that Sb₂O₃ can react with MAPP and generates the dense-charred layer which prevents the transfer of heat and oxygen. Full article

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19 pages, 6496 KiB

Open AccessArticle

Hydrophobic Shape-Memory Biocomposites from Tung-Oil-Based Bioresin and Onion-Skin-Derived Nanocellulose Networks

by Sunanda Sain, Dan Åkesson, Mikael Skrifvars and Souvik Roy

Polymers 2020, 12(11), 2470; https://doi.org/10.3390/polym12112470 - 25 Oct 2020

Cited by 12 | Viewed by 3359

Abstract

The fabrication of smart biocomposites from sustainable resources that could replace today’s petroleum-derived polymer materials is a growing field of research. Here, we report preparation of novel biocomposites using nanocellulose networks extracted from food residue (onion skin) and a vegetable oil-based bioresin. The [...] Read more.

The fabrication of smart biocomposites from sustainable resources that could replace today’s petroleum-derived polymer materials is a growing field of research. Here, we report preparation of novel biocomposites using nanocellulose networks extracted from food residue (onion skin) and a vegetable oil-based bioresin. The resin was synthesized via the Diels-Alder reaction between furfuryl methacrylate and tung oil at various ratios of the components. The onion-skin-extracted cellulose nanofiber and cellulose nanocrystal networks were then impregnated with the resins yielding biocomposites that exhibited improved mechanical strength and higher storage modulus values. The properties of the resins, as well as biocomposites, were affected by the resin compositions. A 190–240-fold increase in mechanical strength was observed in the cellulose nanofiber (CNF) and cellulose nanocrystal (CNC)-reinforced biocomposites with low furfuryl methacrylate content. The biocomposites exhibited interesting shape-memory behavior with 80–96% shape recovery being observed after 7 creep cycles. Full article

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20 pages, 7596 KiB

Open AccessArticle

Radiation Processing and Characterization of Some Ethylene-propylene-diene Terpolymer/Butyl (Halobutyl) Rubber/Nanosilica Composites

by Elena Manaila, Anton Airinei, Maria Daniela Stelescu, Maria Sonmez, Laurentia Alexandrescu, Gabriela Craciun, Daniela Pamfil, Nicusor Fifere, Cristian-Dragos Varganici, Florica Doroftei and Adrian Bele

Polymers 2020, 12(10), 2431; https://doi.org/10.3390/polym12102431 - 21 Oct 2020

Cited by 6 | Viewed by 2828

Abstract

Composites based on ethylene–propylene–diene terpolymer (EPDM), butyl/halobutyl rubber and nanosilica were prepared by melt mixing and subjected to different doses of electron beam irradiation. The effect of irradiation dose on the mechanical properties, morphology, glass transition temperature, thermal stability and water uptake [...] Read more.

Composites based on ethylene–propylene–diene terpolymer (EPDM), butyl/halobutyl rubber and nanosilica were prepared by melt mixing and subjected to different doses of electron beam irradiation. The effect of irradiation dose on the mechanical properties, morphology, glass transition temperature, thermal stability and water uptake was investigated. The efficiency of the crosslinking by electron beam irradiation was analyzed by Charlesby–Pinner parameter evaluation and crosslink density measurements. The scanning electron microscopy data showed a good dispersion of nanosilica in the rubber matrix. An improvement in hardness and 100% modulus was revealed by increasing irradiation dose up to 150 kGy. The interaction between polymer matrix and nanosilica was analyzed using the Kraus equation. Additionally, these results indicated that the mechanical properties, surface characteristics, and water uptake were dependent on crosslink characteristics. Full article

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17 pages, 4815 KiB

Open AccessArticle

Polyvinyl Alcohol/Calcium Carbonate Nanocomposites as Efficient and Cost-Effective Cationic Dye Adsorbents

by Davoud Jahani, Amin Nazari, Jaber Ghourbanpour and Amir Ameli

Polymers 2020, 12(10), 2179; https://doi.org/10.3390/polym12102179 - 24 Sep 2020

Cited by 21 | Viewed by 4994

Abstract

A novel polyvinyl alcohol (PVA)/calcium carbonate-based double-layer cationic dye adsorbent was developed. Polyvinyl alcohol (50 wt %) and calcium carbonate (50 wt %) were used together with borax as a cross-linking agent. The nanocomposite was prepared using only water, without the need for [...] Read more.

A novel polyvinyl alcohol (PVA)/calcium carbonate-based double-layer cationic dye adsorbent was developed. Polyvinyl alcohol (50 wt %) and calcium carbonate (50 wt %) were used together with borax as a cross-linking agent. The nanocomposite was prepared using only water, without the need for any toxic solvent or hazardous chemical. The final samples were obtained by the solvent casting method. The nanocomposite adsorbent was characterized using a Fourier transform infrared (FTIR) spectroscope and a scanning electron microscope (SEM). The adsorption performance on two cationic dyes, i.e., methylene blue and safranin was studied. Dye adsorption was quantified by measuring the nanocomposite swelling, contact time, and dye concentration. Pseudo first-order and pseudo second-order kinetic models as well as intraparticle diffusion model were used to model the adsorption kinetics. Moreover, the isotherm dye adsorption was investigated by Langmuir and Freundlich models. The results revealed that the developed nanocomposite has relatively high adsorption efficiency and short adsorption time and retains its performance after several successive absorption–desorption processes. The results also showed that the pseudo-second-order model best describes the adsorption kinetics, and the Freundlich isotherm model has a better compatibility with the experimental data. Finally, an adsorption mechanism was proposed for the dye removal process. The developed PVA/CaCO₃ nanocomposite can be potentially used for efficient dye removal in wastewater treatments. Full article

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14 pages, 3448 KiB

Open AccessArticle

Effect of Alumina Nanowires on the Thermal Conductivity and Electrical Performance of Epoxy Composites

by Liangsong Huang, Xitao Lv, Yongzhe Tang, Guanghui Ge, Peng Zhang and Yuxia Li

Polymers 2020, 12(9), 2126; https://doi.org/10.3390/polym12092126 - 17 Sep 2020

Cited by 35 | Viewed by 3250

Abstract

Alumina nanowires (Al₂O₃-NWs)/epoxy resin composites have been thoroughly studied due to their excellent insulating and dielectric performance. In particular, understanding the effect of nano-alumina with different morphologies on the dielectric performance of composites is of great significance. In this [...] Read more.

Alumina nanowires (Al₂O₃-NWs)/epoxy resin composites have been thoroughly studied due to their excellent insulating and dielectric performance. In particular, understanding the effect of nano-alumina with different morphologies on the dielectric performance of composites is of great significance. In this study, Al₂O₃-NWs with lengths of approximately 100 nm and diameters of approximately 5 nm were prepared and blended with anepoxy resin to form composites, and the effect of the mass fraction of fillers on the thermal conductivity of the composites was investigated. Specifically, the effect of alumina fillers with ananowire structure on the insulating and dielectric performance and breakdown strength of the epoxy composites were analyzed. The influence principle of the interfacial effect and heat accumulation on the dielectric and insulating properties of the composites were described. The results demonstrated that the thermal conductivity of Al₂O₃-NWs/epoxy resin composites was higher than that of the bare epoxy resin. The thermal conductivity of Al₂O₃-NWs/epoxy resin composites increased with increasing mass fraction of fillers. When the mass fraction of fillers was 10%, the thermal conductivity of the composite was 134% higher than that of the epoxy resin matrix. The volume resistivity of the composites first increased and then decreased as the mass fraction of fillers increased, while the dielectric constant of the composites increased with increasing mass fraction of fillers and decreasing frequency. The dielectric loss of the composites decreased and then increased as the mass fraction of fillers increased, and it increased with increasing frequency. Additionally, the alternating current breakdown strength of the composites first increased and then decreased withincreasingmass fraction of fillers. Full article

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12 pages, 2298 KiB

Open AccessArticle

Effect of a Monomer Composition on the Mechanical Properties and Glass Transition Temperature of a Waterborne Polyurethane/Graphene Oxide and Waterborne Polyurethane/MWCNT Nanocomposite

by Hyung Joong Kim, Jihye Han and Younggon Son

Polymers 2020, 12(9), 2013; https://doi.org/10.3390/polym12092013 - 3 Sep 2020

Cited by 9 | Viewed by 2892

Abstract

Anionic waterborne polyurethane (aWPU) is not compatible with graphene oxide (GO) due to the repulsive force acting on identical ionic charges. In this study, we fabricated cationic surfactant treated GO and cationic surfactant treated carbon nanotube (CNT) to increase the compatibility with aWPU. [...] Read more.

Anionic waterborne polyurethane (aWPU) is not compatible with graphene oxide (GO) due to the repulsive force acting on identical ionic charges. In this study, we fabricated cationic surfactant treated GO and cationic surfactant treated carbon nanotube (CNT) to increase the compatibility with aWPU. Cationic waterborne polyurethane (WPU) and nanocomposites thereof were also prepared. On the basis of the mechanical properties of the nanocomposites, glass transition temperature (T_g), and a stability test, it was found that the compatibility between WPU and a nanofiller (NF) was enhanced to a great extent when WPU and NF had opposite ionicity. The T_g and mechanical properties of WPU increased with the addition of NF, showed the maximum value and thereafter decreased with further addition. The effect of composition of ionic monomer in WPU was also investigated. As the composition of the ionic monomer increases, the concentration of NF for the maximum T_g and mechanical properties increases. This was attributed to the ionic association between the NF and WPU. Full article

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13 pages, 5803 KiB

Open AccessArticle

Effects of Carbonyl Iron Powder (CIP) Content on the Electromagnetic Wave Absorption and Mechanical Properties of CIP/ABS Composites

by Wenwen Lai, Yan Wang and Junkun He

Polymers 2020, 12(8), 1694; https://doi.org/10.3390/polym12081694 - 29 Jul 2020

Cited by 29 | Viewed by 3942

Abstract

Three-dimensional (3D) printing technology has proven to be a convenient and effective method to fabricate structural electromagnetic wave (EMW) absorbers with tunable EMW absorption properties. To obtain a functional material with strong EMW absorbing performance and excellent mechanical properties for fused deposition modeling [...] Read more.

Three-dimensional (3D) printing technology has proven to be a convenient and effective method to fabricate structural electromagnetic wave (EMW) absorbers with tunable EMW absorption properties. To obtain a functional material with strong EMW absorbing performance and excellent mechanical properties for fused deposition modeling (FDM) 3D printing technology, in this work, carbonyl iron powder (CIP)/acrylonitrile-butadiene-styrene copolymer (ABS) composites with different CIP contents were prepared by the melt-mixing process. The effects of the CIP content on the EMW absorption and mechanical properties of CIP/ABS composites were investigated. The CIP/ABS composite with a CIP content of 40 wt.% presented the lowest reflection loss (RL) of −48.71 dB for the optimal impedance matching. In addition, this composite exhibited optimal mechanical properties due to the good dispersion of the CIPs in the matrix ABS. Not only were the tensile and flexural strength similar to pure ABS, but the tensile and flexural modulus were 32% and 37% higher than those of pure ABS, respectively. With a CIP content of 40 wt.%, the CIP/ABS composite proved to be a novel functional material with excellent EMW absorbing and mechanical properties, providing great potential for the development of structural absorbers via FDM 3D printing technology. Full article

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12 pages, 2542 KiB

Open AccessArticle

Targeting Delivery System for Lactobacillus Plantarum Based on Functionalized Electrospun Nanofibers

by Hongliang Yu, Weihua Liu, Dongmei Li, Chunhong Liu, Zhibiao Feng and Bin Jiang

Polymers 2020, 12(7), 1565; https://doi.org/10.3390/polym12071565 - 15 Jul 2020

Cited by 39 | Viewed by 3645

Abstract

With the increased interest in information on gut microbes, people are realizing the benefits of probiotics to health, and new technologies to improve the viability of probiotics are still explored. However, most probiotics have poor resistance to adverse environments. In order to improve [...] Read more.

With the increased interest in information on gut microbes, people are realizing the benefits of probiotics to health, and new technologies to improve the viability of probiotics are still explored. However, most probiotics have poor resistance to adverse environments. In order to improve the viability of lactic acid bacteria, polylactic acid (PLA) nanofibers were prepared by coaxial electrospinning. The electrospinning voltage was 16 kV, and the distance between spinneret and collector was 15 cm. The feed rates of the shell and core solutions were 1.0 and 0.25 mL/h, respectively. The lactic acid bacteria were encapsulated in the coaxial electrospun nanofibers with PLA and fructooligosaccharides (FOS) as the shell materials. Scanning electron microscopy, transmission electron microscopy, and laser scanning confocal microscopy showed that lactic acid bacteria were encapsulated in the coaxial electrospun nanofibers successfully. The water contact angle test indicated that coaxial electrospun nanofiber films had good hydrophobicity. An in vitro simulated digestion test exhibited that the survival rate of lactic acid bacteria encapsulated in coaxial electrospun nanofiber films was more than 72%. This study proved that the viability of probiotics can be improved through encapsulation within coaxial electrospun PLA nanofibers and provided a novel approach for encapsulating bioactive substances. Full article

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22 pages, 7073 KiB

Open AccessArticle

Superior X-ray Radiation Shielding Effectiveness of Biocompatible Polyaniline Reinforced with Hybrid Graphene Oxide-Iron Tungsten Nitride Flakes

by Seyyed Alireza Hashemi, Seyyed Mojtaba Mousavi, Reza Faghihi, Mohammad Arjmand, Mansour Rahsepar, Sonia Bahrani, Seeram Ramakrishna and Chin Wei Lai

Polymers 2020, 12(6), 1407; https://doi.org/10.3390/polym12061407 - 23 Jun 2020

Cited by 46 | Viewed by 4396

Abstract

X-ray radiation is a harmful carcinogenic electromagnetic source that can adversely affect the health of living species and deteriorate the DNA of cells, thus it’s vital to protect vulnerable sources from them. To address this flaw, the conductive polymeric structure of polyaniline (PANi) [...] Read more.

X-ray radiation is a harmful carcinogenic electromagnetic source that can adversely affect the health of living species and deteriorate the DNA of cells, thus it’s vital to protect vulnerable sources from them. To address this flaw, the conductive polymeric structure of polyaniline (PANi) was reinforced with diverse filler loadings (i.e., 25 wt % and 50 wt %) of hybrid graphene oxide-iron tungsten nitride (ITN) flakes toward attenuation of X-ray beams and inhabitation of microorganisms’ growth. Primary characterizations confirmed the successful decoration of graphene oxide (GO) with interconnected and highly dense structure of iron tungsten nitride with a density of about 24.21 g·cm⁻³ and reinforcement of PANi with GO-ITN. Additionally, the outcome of evaluations showed the superior performance of developed shields, where a shield with 1.2 mm thickness containing 50 wt % GO-ITN showed 131.73% increase in the electrical conductivity (compared with neat PANi) along with 78.07%, 57.12%, and 44.99% decrease in the amplitude of the total irradiated X-ray waves at 30, 40, and 60 kVp tube voltages, respectively, compared with control X-ray dosage. More importantly, the developed shields not only showed non-toxic nature and improved the viability of cells, but also completely removed the selected microorganisms at a concentration of 1000 µg·mL⁻¹. Full article

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10 pages, 1921 KiB

Open AccessArticle

Dental Sealant Empowered by 1,3,5-Tri Acryloyl Hexahydro-1,3,5-Triazine and α-Tricalcium Phosphate for Anti-Caries Application

by Juliana Caletti Monteiro, Michele Stürmer, Isadora Martini Garcia, Mary Anne Melo, Salvatore Sauro, Vicente Castelo Branco Leitune and Fabrício Mezzomo Collares

Polymers 2020, 12(4), 895; https://doi.org/10.3390/polym12040895 - 12 Apr 2020

Cited by 10 | Viewed by 3388

Abstract

: Quaternary ammonium compounds and calcium phosphates have been incorporated into dental materials to enhance their biointeractivity and preventive effects. This study aimed at evaluating the physical and chemical properties and effects against Streptococcus mutans of a dental sealant containing 1,3,5-tri acryloyl hexahydro-1,3,5-triazine [...] Read more.

: Quaternary ammonium compounds and calcium phosphates have been incorporated into dental materials to enhance their biointeractivity and preventive effects. This study aimed at evaluating the physical and chemical properties and effects against Streptococcus mutans of a dental sealant containing 1,3,5-tri acryloyl hexahydro-1,3,5-triazine (TAT) and α-tricalcium phosphate (α‐TCP). A methacrylate-based dental sealant was initially formulated. α‐TCP and TAT (G_α-TCPTAT) were added to the experimental sealant at 2 wt.% each. One group was formulated without α‐TCP and TAT and used as control (G_CTRL). All tested resins were analyzed for polymerization kinetics and degree of conversion (DC %), Knoop hardness (KHN), softening in solvent (∆KHN%), ultimate tensile strength (UTS), the contact angle with water or with α-bromonaphthalene, surface free energy (SFE) and antibacterial activity against Streptococcus mutans in biofilm and in planktonic cells. The polymerization kinetic was different between groups, but without statistical differences in the DC % (p<0.05). KHN and ΔKHN% did not change between groups (p>0.05), but G_α-TCPTAT presented greater UTS compared to G_CTRL (p<0.05). No differences were found for contact angle (p>0.05) or SFE (p>0.05). G_α-TCPTAT showed greater antibacterial activity in comparison to G_CTRL (p<0.05). The formulation of dental sealants containing TAT and α-TCP can be characterized by improved mechanical and antibacterial properties. Full article

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13 pages, 3599 KiB

Open AccessArticle

A Novel Zirconium Modified Arylacetylene Resin: Preparation, Thermal Properties and Ceramifiable Mechanism

by Qilin Mei, Honghua Wang, Xiaocheng Chen, Ying Wang and Zhixiong Huang

Polymers 2020, 12(3), 684; https://doi.org/10.3390/polym12030684 - 19 Mar 2020

Cited by 9 | Viewed by 3212

Abstract

With the rapid development of thermal protection systems for the aerospace industry and power electronics, polyarylacetylene (PAA) resin plays an important role because of its good mechanical properties, high glass transition temperature (T_g), low water absorption, high char yield (Y_c [...] Read more.

With the rapid development of thermal protection systems for the aerospace industry and power electronics, polyarylacetylene (PAA) resin plays an important role because of its good mechanical properties, high glass transition temperature (T_g), low water absorption, high char yield (Y_c), and the fact that there is no byproduct released in the curing process. In order to further improve the thermal property of PAA based FRP for the thermal protection field, the introduction of a zirconium element into arylacetylene is promising. In this paper, zirconium modified arylacetylene (ZAA) resin was prepared by two-step synthesis. The FTIR analysis characterized its molecular structure and confirmed the products. The viscosity of ZAA was about 6.5 Pa·s when the temperature was above 120 °C. The DSC analysis showed that the ZAA had a low curing temperature, and its apparent activation energy was 103.86 kJ/mol in the Kissinger method and 106.46 kJ/mol in the Ozawa method. The dielectric constant at 1 MHz of poly(zirconium modified arylacetylene) (PZAA) was 3.4. The TG analysis showed that the temperatures of a weight loss of 5% (T_d5) and char yield (Y_c) at 800 °C of PZAA were 407.5 °C and 61.4%, respectively. The XRD results showed the presence of SiO₂ and ZrO₂ in the PZAA residue after ablation. The XRF results showed that the contents of SiO₂ and ZrO₂ in PZAA residual after ablation were, respectively, 15.3% and 12.4%. The SEM showed that the surface of PZAA after ablation had been covered with a dense and rigid ceramic phase composed of ZrO₂ and SiO₂. Therefore, the introduction of Zr into arylacetylene greatly improved the densification of the surface after ablation, and improved the heat resistant property. Full article

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15 pages, 4707 KiB

Open AccessArticle

Effects of Zirconium Silicide on the Vulcanization, Mechanical and Ablation Resistance Properties of Ceramifiable Silicone Rubber Composites

by Jiuqiang Song, Zhixiong Huang, Yan Qin, Honghua Wang and Minxian Shi

Polymers 2020, 12(2), 496; https://doi.org/10.3390/polym12020496 - 24 Feb 2020

Cited by 39 | Viewed by 4017

Abstract

Ceramifiable silicone rubber composites play important roles in the field of thermal protection systems (TPS) for rocket motor cases due to their advantages. Ceramifiable silicone rubber composites filled with different contents of ZrSi₂ were prepared in this paper. The fffects of ZrSi [...] Read more.

Ceramifiable silicone rubber composites play important roles in the field of thermal protection systems (TPS) for rocket motor cases due to their advantages. Ceramifiable silicone rubber composites filled with different contents of ZrSi₂ were prepared in this paper. The fffects of ZrSi₂ on the vulcanization, mechanical and ablation resistance properties of the composites were also investigated. The results showed that the introduction of ZrSi₂ decreased the vulcanization time of silicone rubber. FTIR spectra showed that ZrSi₂ did not participate in reactions of the functional groups of silicone rubber. With the increasing content of ZrSi₂, the tensile strength increased first and then decreased. The elongation at break decreased and the permanent deformation increased gradually. The thermal conductivity of the composite increased from 0.553 W/(m·K) to 0.694 W/(m·K) as the content of the ZrSi₂ increased from 0 to 40 phr. In addition, the thermal conductivity of the composite decreased with the increase of temperature. Moreover, thermal analysis showed that the addition of ZrSi₂ increased the initial decomposition temperature of the composite, but had little effect on the peak decomposition temperature in nitrogen. However, the thermal decomposition temperature of the composite in air was lower than that in nitrogen. The addition of ZrSi₂ decreased the linear and mass ablation rate, which improved the ablative resistance of the composite. With the ZrSi₂ content of 30 phr, the linear and mass ablation rate were 0.041 mm/s and 0.029 g/s, decreasing by 57.5% and 46.3% compared with the composite without ZrSi₂, respectively. Consequently, the ceramifiable silicone rubber composite filled with ZrSi₂ is very promising for TPS. Full article

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16 pages, 8268 KiB

Open AccessArticle

Surface Modification Design for Improving the Strength and Water Vapor Permeability of Waterborne Polymer/SiO₂ Composites: Molecular Simulation and Experimental Analyses

by Yingke Wu, Jianzhong Ma, Chao Liu and Hongxia Yan

Polymers 2020, 12(1), 170; https://doi.org/10.3390/polym12010170 - 9 Jan 2020

Cited by 27 | Viewed by 4991

Abstract

Polymer-based nanocomposites properties are greatly affected by interfacial interaction. Polyacrylate nanocomposites have been widely studied, but few studies have been conducted on their interface mechanism. Therefore, there was an urgent demand for providing a thorough understanding of the polymethyl acrylate/SiO₂ (PMA/SiO₂ [...] Read more.

Polymer-based nanocomposites properties are greatly affected by interfacial interaction. Polyacrylate nanocomposites have been widely studied, but few studies have been conducted on their interface mechanism. Therefore, there was an urgent demand for providing a thorough understanding of the polymethyl acrylate/SiO₂ (PMA/SiO₂) nanocomposites to obtain the desired macro-performance. In this paper, a methodology, which combined molecular dynamics simulation with experimental researches, was established to expound the effect of the surface structure of SiO₂ particles which were treated with KH550, KH560 or KH570 (KH550-SiO₂, KH560-SiO₂ and KH570-SiO₂) on the mechanical characteristic and water vapor permeability of polymethyl acrylate/SiO₂ nanocomposites. The polymethyl acrylate/SiO₂ nanocomposites were analyzed in binding energy and mean square displacement. The results indicate that PMA/KH570-SiO₂ had the highest tensile strength, while PMA/KH550-SiO₂ had the highest elongation at break at the same filler content; KH550-SiO₂ spheres can significantly improve water vapor permeability of polyacrylate film. Full article

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2019

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11 pages, 3918 KiB

Open AccessArticle

Improved Processing and Properties for Polyphenylene Oxide Modified by Diallyl Orthophthalate Prepolymer

by Honghua Wang, Qilin Mei, Yujie Ding, Zhixiong Huang and Minxian Shi

Polymers 2019, 11(12), 2016; https://doi.org/10.3390/polym11122016 - 5 Dec 2019

Viewed by 3284

Abstract

Diallyl orthophthalate (DAOP) prepolymer was investigated as a reactive plasticizer to improve the processability of thermoplastics. The rheology of blends of DAOP prepolymer initiated by 2,3-dimethyl-2,3-diphenylbutane (DMDPB) and polyphenylene oxide (PPO) was monitored during the curing process, and their thermal properties and morphology [...] Read more.

Diallyl orthophthalate (DAOP) prepolymer was investigated as a reactive plasticizer to improve the processability of thermoplastics. The rheology of blends of DAOP prepolymer initiated by 2,3-dimethyl-2,3-diphenylbutane (DMDPB) and polyphenylene oxide (PPO) was monitored during the curing process, and their thermal properties and morphology in separated phases were also studied. Differential scanning calorimetry (DSC) results showed that the cure degree of the reactively plasticized DAOP prepolymer was reduced with increasing PPO due to the dilution effect. The increasing amount of the DAOP prepolymer led to a gradual decrease in the viscosity of the blends and the rheology behavior was consistent with the chemical gelation of DAOP prepolymer in blends. This indicated that the addition of the DAOP prepolymer effectively improved processability. The phase separation occurring during curing of the blend and the transition from the static to dynamic mode significantly influences the development of the morphology of the blend corresponding to limited evolution of the conversion around the gel point. Full article

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14 pages, 5432 KiB

Open AccessArticle

Investigation on Plugging and Profile Control of Polymer Microspheres as a Displacement Fluid in Enhanced Oil Recovery

by Xiangrong Nie, Junbin Chen, Yi Cao, Jinyuan Zhang, Wenjing Zhao, Yanlong He, Yunyi Hou and Shaomin Yuan

Polymers 2019, 11(12), 1993; https://doi.org/10.3390/polym11121993 - 2 Dec 2019

Cited by 19 | Viewed by 3553

Abstract

Polymer microspheres (PMs) are used as a new material to recover residual oil left in unswept oil areas after secondary recovery methods. The fact that the PMs plug the macropores causes the flow direction of the injection fluid to be transferred from macropores [...] Read more.

Polymer microspheres (PMs) are used as a new material to recover residual oil left in unswept oil areas after secondary recovery methods. The fact that the PMs plug the macropores causes the flow direction of the injection fluid to be transferred from macropores to micropores. In order to investigate the plugging and profile control mechanisms of PMs in reservoirs, four kinds of PMs with different particle sizes and four kinds of artificial cores with different permeability were selected for flooding tests, including plugging experiments and profile control experiments. The pore throat size distribution of cores was characterized by nuclear magnetic resonance (NMR) technology. The particle size distribution of PMs used in the experiment was characterized using a laser particle size analyzer. The results showed that there are six matching relationships existing simultaneously between pore throats and PMs based on theoretical analysis, which are completely plugging, single plugging, bridge plugging, smooth passing, deposition, and deformable passing. A key principle for optimizing PMs in profile control is that the particle size of the selected PMs can enter the high permeability layer well, but it is difficult for it to enter the low permeability layer. The results of this paper provide a theoretical basis for the optimal particle size of PMs during the oil field profile control process. Full article

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18 pages, 7067 KiB

Open AccessArticle

Nanofiller Dispersion, Morphology, Mechanical Behavior, and Electrical Properties of Nanostructured Styrene-Butadiene-Based Triblock Copolymer/CNT Composites

by Ulrike Staudinger, Bhabani K. Satapathy and Dieter Jehnichen

Polymers 2019, 11(11), 1831; https://doi.org/10.3390/polym11111831 - 7 Nov 2019

Cited by 6 | Viewed by 3838

Abstract

A nanostructured linear triblock copolymer based on styrene and butadiene with lamellar morphology is filled with multiwalled carbon nanotubes (MWCNTs) of up to 1 wt% by melt compounding. This study deals with the dispersability of the MWCNTs within the nanostructured matrix and its [...] Read more.

A nanostructured linear triblock copolymer based on styrene and butadiene with lamellar morphology is filled with multiwalled carbon nanotubes (MWCNTs) of up to 1 wt% by melt compounding. This study deals with the dispersability of the MWCNTs within the nanostructured matrix and its consequent impact on block copolymer (BCP) morphology, deformation behavior, and the electrical conductivity of composites. By adjusting the processing parameters during melt mixing, the dispersion of the MWCNTs within the BCP matrix are optimized. In this study, the morphology and glass transition temperatures (T_g) of the hard and soft phase are not significantly influenced by the incorporation of MWCNTs. However, processing-induced orientation effects of the BCP structure are reduced by the addition of MWCNT accompanied by a decrease in lamella size. The stress-strain behavior of the triblock copolymer/MWCNT composites indicate higher Young’s modulus and pronounced yield point while retaining high ductility (strain at break ~ 400%). At a MWCNT content of 1 wt%, the nanocomposites are electrically conductive, exhibiting a volume resistivity below 3 × 10³ Ω·cm. Accordingly, the study offers approaches for the development of mechanically flexible functional materials while maintaining a remarkable structural property profile. Full article

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20 pages, 6975 KiB

Open AccessArticle

Adsorption of Pb²⁺ from Aqueous Solutions Using Novel Functionalized Corncobs via Atom Transfer Radical Polymerization

by Shanglong Chen and Wei Zhao

Polymers 2019, 11(10), 1715; https://doi.org/10.3390/polym11101715 - 19 Oct 2019

Cited by 10 | Viewed by 2977

Abstract

The present study developed novel functionalized corncobs introducing brushes with dense and active carboxyl groups (–COOH), named MC-g-PAA, for the highly efficient adsorption of Pb²⁺ from aqueous solutions. MC-g-PAA were synthesized via atom transfer radical polymerization (ATRP) and characterized by Fourier transform [...] Read more.

The present study developed novel functionalized corncobs introducing brushes with dense and active carboxyl groups (–COOH), named MC-g-PAA, for the highly efficient adsorption of Pb²⁺ from aqueous solutions. MC-g-PAA were synthesized via atom transfer radical polymerization (ATRP) and characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The amount of Pb²⁺ adsorbed on MC-g-PAA by hydrolysis with t-BuOK was 2.28 times greater than that with NaOH, attributed to the larger steric effect of t-BuOK, which reduced the hydrolysis of the bromo-ester groups. The influence of different parameters including the solid/liquid ratio, working solution pH, sorption temperature, and initial concentration and sorption time on the adsorption of Pb²⁺ were investigated in detail in batch experiments. Thermodynamic studies have shown that the adsorption process was spontaneous, endothermic, and accompanied by an increase in randomness. A better fit for the isotherm data was obtained using the Langmuir model than for the other four models and the maximum amount (

q_{\max}

) of Pb²⁺ adsorbed on MC-g-PAA was 342.47 mg/g, which is 21.11 times greater when compared with that of pristine corncobs (16.22 mg/g). The adsorption of Pb²⁺ on MC-g-PAA was very fast and followed the pseudo-second-order kinetic equation with a correlation coefficient of 0.99999. This monolayer adsorption process was dominated by chemical adsorption, and may proceed according to complexation and electrostatic interactions between Pb²⁺ and the carboxylate groups. This study indicated that MC-g-PAA could be successfully used as an adsorbent for the removal of Pb²⁺ from aqueous solutions due to its excellent efficiency. Full article

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14 pages, 4797 KiB

Open AccessArticle

Selective Localization of Carbon Black in Bio-Based Poly (Lactic Acid)/Recycled High-Density Polyethylene Co-Continuous Blends to Design Electrical Conductive Composites with a Low Percolation Threshold

by Xiang Lu, Benhao Kang and Shengyu Shi

Polymers 2019, 11(10), 1583; https://doi.org/10.3390/polym11101583 - 27 Sep 2019

Cited by 16 | Viewed by 4239

Abstract

The electrically conductive poly (lactic acid) (PLA)/recycled high-density polyethylene (HDPE)/carbon black (CB) composites with a fine co-continuous micro structure and selective localization of CB in the HDPE component were fabricated by one-step melt processing via a twin-screw extruder. Micromorphology analysis, electrical conductivity, thermal [...] Read more.

The electrically conductive poly (lactic acid) (PLA)/recycled high-density polyethylene (HDPE)/carbon black (CB) composites with a fine co-continuous micro structure and selective localization of CB in the HDPE component were fabricated by one-step melt processing via a twin-screw extruder. Micromorphology analysis, electrical conductivity, thermal properties, thermal stability, and mechanical properties were investigated. Scanning electron microscope (SEM) images indicate that a co-continuous morphology is formed, and CB is selectively distributed in the HDPE component. With the introduction of CB, the phase size of the PLA component and the HDPE component in PLA/HDPE blends is reduced. In addition, differential scanning calorimetry (DSC) and thermos gravimetric analysis (TGA) results show that the introduction of CB promotes the crystallization behavior of the PLA and HDPE components, respectively, and improves the thermal stability of PLA70/30HDPE/CB composites. The electrically conductive percolation threshold of the PLA70/30HDPE/CB composites is around 5.0 wt %, and the electrical conductivity of PLA70/30HDPE/CB composites reaches 1.0 s/cm and 15 s/cm just at the 10 wt % and 15 wt % CB loading, respectively. Further, the tensile and impact tests show that the PLA70/30HDPE/CB composites have good mechanical properties. The excellent electrical conductivity and good mechanical properties offer the potential to broaden the application of PLA/HDPE/CB composites. Full article

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13 pages, 4222 KiB

Open AccessArticle

Tensile and Interfacial Loading Characteristics of Boron Nitride-Carbon Nanosheet Reinforced Polymer Nanocomposites

by Venkatesh Vijayaraghavan and Liangchi Zhang

Polymers 2019, 11(6), 1075; https://doi.org/10.3390/polym11061075 - 21 Jun 2019

Cited by 15 | Viewed by 4436

Abstract

The discovery of hybrid boron nitride–carbon (BN–C) nanostructures has triggered enormous research interest in the design and fabrication of new generation nanocomposites. The robust design of these nanocomposites for target applications requires their mechanical strength to be characterized with a wide range of [...] Read more.

The discovery of hybrid boron nitride–carbon (BN–C) nanostructures has triggered enormous research interest in the design and fabrication of new generation nanocomposites. The robust design of these nanocomposites for target applications requires their mechanical strength to be characterized with a wide range of factors. This article presents a comprehensive study, with the aid of molecular dynamics analysis, of the tensile loading mechanics of BN–C nanosheet reinforced polyethylene (PE) nanocomposites. It is observed that the geometry and lattice arrangement of the BN–C nanosheet influences the tensile loading characteristics of the nanocomposites. Furthermore, defects in the nanosheet can severely impact the tensile loading resistance, the extent of which is determined by the defect’s location. This study also found that the tensile loading resistance of nanocomposites tends to weaken at elevated temperatures. The interfacial mechanics of the BN–C nanocomposites are also investigated. This analysis revealed a strong dependency with the carbon concentration in the BN–C nanosheet. Full article

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15 pages, 1575 KiB

Open AccessEditor’s ChoiceArticle

Thermal Conductivity and Electrical Resistivity of Melt-Mixed Polypropylene Composites Containing Mixtures of Carbon-Based Fillers

by Beate Krause, Piotr Rzeczkowski and Petra Pötschke

Polymers 2019, 11(6), 1073; https://doi.org/10.3390/polym11061073 - 21 Jun 2019

Cited by 49 | Viewed by 7242

Abstract

Melt-mixed composites based on polypropylene (PP) with various carbon-based fillers were investigated with regard to their thermal conductivity and electrical resistivity. The composites were filled with up to three fillers by selecting combinations of graphite nanoplatelets (GNP), carbon fibers (CF), carbon nanotubes (CNT), [...] Read more.

Melt-mixed composites based on polypropylene (PP) with various carbon-based fillers were investigated with regard to their thermal conductivity and electrical resistivity. The composites were filled with up to three fillers by selecting combinations of graphite nanoplatelets (GNP), carbon fibers (CF), carbon nanotubes (CNT), carbon black (CB), and graphite (G) at a constant filler content of 7.5 vol%. The thermal conductivity of PP (0.26 W/(m·K)) improved most using graphite nanoplatelets, whereas electrical resistivity was the lowest when using multiwalled CNT. Synergistic effects could be observed for different filler combinations. The PP composite, which contains a mixture of GNP, CNT, and highly structured CB, simultaneously had high thermal conductivity (0.5 W/(m·K)) and the lowest electrical volume resistivity (4 Ohm·cm). Full article

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14 pages, 1965 KiB

Open AccessArticle

Carbon Nanotube versus Graphene Nanoribbon: Impact of Nanofiller Geometry on Electromagnetic Interference Shielding of Polyvinylidene Fluoride Nanocomposites

by Mohammad Arjmand, Soheil Sadeghi, Ivonne Otero Navas, Yalda Zamani Keteklahijani, Sara Dordanihaghighi and Uttandaraman Sundararaj

Polymers 2019, 11(6), 1064; https://doi.org/10.3390/polym11061064 - 20 Jun 2019

Cited by 33 | Viewed by 5339

Abstract

The similar molecular structure but different geometries of the carbon nanotube (CNT) and graphene nanoribbon (GNR) create a genuine opportunity to assess the impact of nanofiller geometry (tube vs. ribbon) on the electromagnetic interference (EMI) shielding of polymer nanocomposites. In this regard, GNR [...] Read more.

The similar molecular structure but different geometries of the carbon nanotube (CNT) and graphene nanoribbon (GNR) create a genuine opportunity to assess the impact of nanofiller geometry (tube vs. ribbon) on the electromagnetic interference (EMI) shielding of polymer nanocomposites. In this regard, GNR and its parent CNT were melt mixed with a polyvinylidene fluoride (PVDF) matrix using a miniature melt mixer at various nanofiller loadings, i.e., 0.3, 0.5, 1.0 and 2.0 wt%, and then compression molded. Molecular simulations showed that CNT would have a better interaction with the PVDF matrix in any configuration. Rheological results validated that CNTs feature a far stronger network (mechanical interlocking) than GNRs. Despite lower powder conductivity and a comparable dispersion state, it was interestingly observed that CNT nanocomposites indicated a highly superior electrical conductivity and EMI shielding at higher nanofiller loadings. For instance, at 2.0 wt%, CNT/PVDF nanocomposites showed an electrical conductivity of 0.77 S·m⁻¹ and an EMI shielding effectiveness of 11.60 dB, which are eight orders of magnitude and twofold higher than their GNR counterparts, respectively. This observation was attributed to their superior conductive network formation and the interlocking ability of the tubular nanostructure to the ribbon-like nanostructure, verified by molecular simulations and rheological assays. Full article

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