Polymers

2024

Jump to: 2023, 2022

14 pages, 4029 KiB

Open AccessArticle

Improving Crystallization Properties, Thermal Stability, and Mechanical Properties of Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) Bioplastic by Incorporating Cerium Lactate

by Arriya Chuangchai and Yodthong Baimark

Polymers 2024, 16(23), 3367; https://doi.org/10.3390/polym16233367 - 29 Nov 2024

Viewed by 433

Abstract

The more flexible and faster biodegradation rate of poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-PEG-PLLA) triblock copolymer makes it a promising bioplastic compared to PLLA. However, finding effective additives for this triblock copolymer remains a research challenge for their wider applications. This work [...] Read more.

The more flexible and faster biodegradation rate of poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-PEG-PLLA) triblock copolymer makes it a promising bioplastic compared to PLLA. However, finding effective additives for this triblock copolymer remains a research challenge for their wider applications. This work involved the melt-blending of a cerium lactate (Ce-LA) antibacterial agent with a triblock copolymer. The thermal properties, crystalline structures, mechanical properties, and phase morphology of the PLLA-PEG-PLLA/Ce-LA composites were examined. With 0.5 wt% Ce-LA, the composite exhibited the best crystallization properties. The crystallinity of the composite contained 0.5 wt% Ce-LA increased from 11.8 to 15.9%, and the half-time of crystallization decreased from 3.37 to 1.28 min at 120 °C, compared with the pure triblock copolymer. The incorporation of Ce-LA did not result in any changes to the crystalline structure of the triblock copolymer matrix. The best improvement in thermal stability and tensile properties of the composites was achieved with the addition of 1.5 wt% Ce-LA. When compared to the pure triblock copolymer, the temperature at maximum decomposition rate of PLLA blocks shifted from 310 °C to 327 °C, the tensile strength increased from 14.3 MPa to 19.5 MPa, and the Young’s modulus increased from 204 MPa to 312 MPa. This study concludes that the incorporation of Ce-LA enhanced the crystallizability, thermal stability, and mechanical properties of PLLA-PEG-PLLA, indicating that Ce-LA could serve as a versatile additive to the PLLA-PEG-PLLA bioplastic. Full article

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22 pages, 6396 KiB

Open AccessArticle

Innovative Poly(lactic Acid) Blends: Exploring the Impact of the Diverse Chemical Architectures from Itaconic Acid

by Miriam Carrasco-Fernández, Erika Ivonne López-Martínez, Sergio Gabriel Flores-Gallardo, Iván Alziri Estrada-Moreno, Mónica Elvira Mendoza-Duarte and Alejandro Vega-Rios

Polymers 2024, 16(19), 2780; https://doi.org/10.3390/polym16192780 - 30 Sep 2024

Viewed by 1068

Abstract

Environment-friendly polymer blends of poly(lactic acid) (PLA) and itaconic acid (IA), poly(itaconic acid) (PIA), poly(itaconic acid)-co-poly(methyl itaconate) (Cop-IA), and net-poly(itaconic acid)-ν-triethylene glycol dimethacrylate (Net-IA) were performed via melt blending. The compositions studied were 0.1, 1, 3, and 10 [...] Read more.

Environment-friendly polymer blends of poly(lactic acid) (PLA) and itaconic acid (IA), poly(itaconic acid) (PIA), poly(itaconic acid)-co-poly(methyl itaconate) (Cop-IA), and net-poly(itaconic acid)-ν-triethylene glycol dimethacrylate (Net-IA) were performed via melt blending. The compositions studied were 0.1, 1, 3, and 10 wt% of the diverse chemical architectures. The research aims to study and understand the effect of IA and its different architectures on the mechanical, rheological, and thermal properties of PLA. The PLA/IA, PLA/PIA, PLA/Cop-IA, and PLA/Net-IA blends were characterized by dynamic mechanical thermal analysis, rotational rheometer (RR), thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. The complex viscosity, storage module, and loss module for the RR properties were observed in the following order: PLA/Cop-IA, PLA/Net-IA, and PLA/PIA > PLA > PLA/IA. Thermal stability improved with increasing concentrations of Cop-IA and Net-IA. In the same way, the mechanical properties were enhanced. In addition, the micrographs illustrated the formation of fibrillar structures for all blends. The crystallinity degree displayed higher values for the blends that contain Net-IA > Cop-IA than IA > PIA. Therefore, IA and its architectures can influence these studied properties, which have potential applications in disposable food packing. Full article

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16 pages, 4292 KiB

Open AccessArticle

Synergistic Reinforcement with SEBS-g-MAH for Enhanced Thermal Stability and Processability in GO/rGO-Filled PC/ABS Composites

by Fatin Najwa Joynal Abedin, Ahmad Noor Syimir Fizal, Abbas F. M. Alkarkhi, Nor Afifah Khalil, Ahmad Naim Ahmad Yahaya, Md. Sohrab Hossain, Sairul Izwan Safie, Nurul Ain Ismail and Muzafar Zulkifli

Polymers 2024, 16(18), 2554; https://doi.org/10.3390/polym16182554 - 10 Sep 2024

Viewed by 1133

Abstract

The integration of compatibilisers with thermoplastics has revolutionised the field of polymer composites, enhancing their mechanical, thermal, and rheological properties. This study investigates the synergistic effects of incorporating SEBS-g-MAH on the mechanical, thermal, and rheological properties of polycarbonate/acrylonitrile-butadiene-styrene/graphene oxide (PC/ABS/GO) (PAGO) and the [...] Read more.

The integration of compatibilisers with thermoplastics has revolutionised the field of polymer composites, enhancing their mechanical, thermal, and rheological properties. This study investigates the synergistic effects of incorporating SEBS-g-MAH on the mechanical, thermal, and rheological properties of polycarbonate/acrylonitrile-butadiene-styrene/graphene oxide (PC/ABS/GO) (PAGO) and the properties of polycarbonate/acrylonitrile-butadiene-styrene/graphene oxide (PC/ABS/rGO) (PArGO) composites through the melt blending method. The synergistic effects on thermal stability and processability were analysed by using thermogravimetry (TGA), melt flow index (MFI), and Fourier-transform infrared spectroscopy (FTIR). The addition of SEBS-g-MAH improved the elongation at break (EB) of PAGO and PArGO up to 33% and 73%, respectively, compared to the uncompatibilised composites. The impact strength of PAGO was synergistically enhanced by 75% with the incorporation of 5 phr SEBS-g-MAH. A thermal analysis revealed that SEBS-g-MAH improved the thermal stability of the composites, with an increase in the degradation temperature (T_80%) of up to 17% for PAGO at 1 phr SEBS-g-MAH loading. The compatibilising effect of SEBS-g-MAH was confirmed by FTIR analysis, which indicated interactions between the maleic anhydride groups and the PC/ABS matrix and GO/rGO fillers. The rheological measurements showed that the incorporation of SEBS-g-MAH enhanced the melt flowability (MFI) of the composites, with a maximum increase of 38% observed for PC/ABS. These results demonstrate the potential of SEBS-g-MAH as a compatibiliser for improving the unnotched impact strength (mechanical), thermal, and rheological properties of PC/ABS/GO and PC/ABS/rGO composites, achieving a synergistic effect. Full article

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17 pages, 11240 KiB

Open AccessArticle

Epoxidized Soybean Oil Toughened Poly(lactic acid)/Lignin-g-Poly(lauryl methacrylate) Bio-Composite Films with Potential Food Packaging Application

by Yingxin Zhou, Kang Shi, Guoshuai Liu, Hui Sun and Yunxuan Weng

Polymers 2024, 16(14), 2025; https://doi.org/10.3390/polym16142025 - 16 Jul 2024

Viewed by 1210

Abstract

The application of lignin as a filler for poly (lactic acid) (PLA) is limited by their poor interfacial adhesion. To address this challenge, lignin-graft-poly(lauryl methacrylate) (LG-g-PLMA) was first blended with poly (lactic acid), and then epoxidized soybean oil (ESO) was also added to [...] Read more.

The application of lignin as a filler for poly (lactic acid) (PLA) is limited by their poor interfacial adhesion. To address this challenge, lignin-graft-poly(lauryl methacrylate) (LG-g-PLMA) was first blended with poly (lactic acid), and then epoxidized soybean oil (ESO) was also added to prepare PLA/LG-g-PLMA/ESO composite, which was subsequently hot pressed to prepare the composite films. The effect of ESO as a plasticizer on the thermal, mechanical, and rheological properties, as well as the fracture surface morphology of the PLA/LG-g-PLMA composite films, were investigated. It was found that the compatibility and toughness of the composites were improved by the addition of ESO. The elongation at break of the composites with an ESO content of 5 phr was increased from 5.6% to 104.6%, and the tensile toughness was increased from 4.1 MJ/m³ to 44.7 MJ/m³, as compared with the PLA/LG-g-PLMA composite without ESO addition. The toughening effect of ESO on composites is generally attributed to the plasticization effect of ESO, and the interaction between the epoxy groups of ESO and the terminal carboxyl groups of PLA. Furthermore, PLA/LG-g-PLMA/ESO composite films exhibited excellent UV barrier properties and an overall migration value below the permitted limit (10 mg/dm²), indicating that the thus-prepared biocomposite films might potentially be applied to environmentally friendly food packaging. Full article

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18 pages, 16666 KiB

Open AccessArticle

The Role of Surface Treatment and Coupling Agents for Adhesion between Stainless Steel (SUS) and Polyamide (PA) of Heterojunction Bilayer Composites

by Hayeong Lee, Seung-In Song and Keon-Soo Jang

Polymers 2024, 16(7), 896; https://doi.org/10.3390/polym16070896 - 25 Mar 2024

Cited by 1 | Viewed by 1286

Abstract

The growing demand for lightweight and durable materials in industries, such as the automotive, aerospace, and electronics industries, has spurred the development of heterojunction bilayer composites, combining the structural integrity of metals with the versatility of polymers. This study addresses the critical interface [...] Read more.

The growing demand for lightweight and durable materials in industries, such as the automotive, aerospace, and electronics industries, has spurred the development of heterojunction bilayer composites, combining the structural integrity of metals with the versatility of polymers. This study addresses the critical interface between stainless steel (SUS) and polyamide 66 (PA66), focusing on the pivotal role of surface treatments and various silane coupling agents in enhancing the adhesion strength of heterojunction SUS/PA66 bilayer composites. Through systematic surface modifications—highlighted by scanning electron microscopy, atomic force microscopy, and contact angle analyses—the study assessed the impact of increasing the surface area, roughness, and energy of SUS. X-ray photoelectron spectroscopy evaluations confirmed the strategic selection of specific silane coupling agents. Although some coupling agents barely influenced the mechanics, notably, aminopropyl triethoxysilane (A1S) and 3-glycidyl oxypropyl trimethoxysilane (ES) significantly enhanced the mechanical properties of the heterojunction bilayer composites, evidenced by the improved lap shear strength, elongation at break, and toughness. These advancements were attributed to the interfacial interactions at the metal–polymer interface. This research underscored the significance of targeted surface treatment and the judicious selection of coupling agents in optimizing the interfacial adhesion and overall performance of metal–polymer composites, offering valuable insights for the fabrication of materials where reduced weight and enhanced durability are paramount. Full article

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2023

Jump to: 2024, 2022

16 pages, 5949 KiB

Open AccessArticle

Investigation of the Effects of Chain Extender on Material Properties of PLA/PCL and PLA/PEG Blends: Comparative Study between Polycaprolactone and Polyethylene Glycol

by Karabo Innocent Matumba, Mpho Phillip Motloung, Vincent Ojijo, Suprakas Sinha Ray and Emmanuel Rotimi Sadiku

Polymers 2023, 15(9), 2230; https://doi.org/10.3390/polym15092230 - 8 May 2023

Cited by 21 | Viewed by 3233

Abstract

This study investigated the effect of the Joncryl concentration on the properties of polylactide/poly(ε-caprolactone) (PLA/PCL) and PLA/poly(ethylene glycol) (PEG) blends. The addition of Joncryl influenced the properties of both PLA-based blends. In the blend of PLA/PCL blends, the addition of Joncryl reduced the [...] Read more.

This study investigated the effect of the Joncryl concentration on the properties of polylactide/poly(ε-caprolactone) (PLA/PCL) and PLA/poly(ethylene glycol) (PEG) blends. The addition of Joncryl influenced the properties of both PLA-based blends. In the blend of PLA/PCL blends, the addition of Joncryl reduced the size of PCL droplets, which implies the compatibility of the two phases, while PLA/PEG blends showed a co-continuous type of morphology at 0.1% and 0.3 wt.% of Joncryl loading. The crystallinity of PCL and PEG was studied on both PLA/PCL and PLA/PEG blend systems. In both scenarios, the crystallinity of the blends decreased upon the addition of Joncryl. Thermal stabilities were shown to depend on the addition of Joncryl. The toughness increased when 0.5 wt.% of Joncryl was added to both systems. However, the stiffness of PLA/PCL decreased, while the stiffness of PLA/PEG increased with the increasing concentration of Joncryl. This study provides new insight into the effect of chain extenders on the compatibility of PLA-based blends. Full article

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17 pages, 6747 KiB

Open AccessArticle

Antibacterial Composite Material Based on Polyhydroxybutyrate and Zn-Doped Brushite Cement

by Inna V. Fadeeva, Dina V. Deyneko, Alexander V. Knotko, Anatoly A. Olkhov, Pavel V. Slukin, Galina A. Davydova, Taisiia A. Trubitsyna, Ilya I. Preobrazhenskiy, Alevtina N. Gosteva, Iulian V. Antoniac and Julietta V. Rau

Polymers 2023, 15(9), 2106; https://doi.org/10.3390/polym15092106 - 28 Apr 2023

Cited by 8 | Viewed by 2165

Abstract

A composite material based on electrospinning printed polyhydroxybutyrate fibers impregnated with brushite cement containing Zn substitution was developed for bone implant applications. Powder X-ray Diffraction (PXRD), Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy were applied for materials characterization. Soaking the composite in [...] Read more.

A composite material based on electrospinning printed polyhydroxybutyrate fibers impregnated with brushite cement containing Zn substitution was developed for bone implant applications. Powder X-ray Diffraction (PXRD), Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy were applied for materials characterization. Soaking the composite in Ringer’s solution led to the transformation of brushite into apatite phase, accompanied by the morphology changes of the material. The bending strength of the composite material was measured to be 3.1 ± 0.5 MPa. NCTC mouse fibroblast cells were used to demonstrate by means of the MTT test that the developed material was not cytotoxic. The behavior of the human dental pulp stem cells on the surface of the composite material investigated by the direct contact method was similar to the control. It was found that the developed Zn containing composite material possessed antibacterial properties, as testified by microbiology investigations against bacteria strains of Escherichia coli and Staphylococcus aureus. Thus, the developed composite material is promising for the treatment of damaged tissues with bacterial infection complications. Full article

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14 pages, 3431 KiB

Open AccessArticle

Water Soluble PMPC-Derived Bright Fluorescent Nitrogen/Phosphorous-Doped Carbon Dots for Fluorescent Ink (Anti-Counterfeiting) and Cellular Multicolor Imaging

by Suguna Perumal, Raji Atchudan, Thomas Nesakumar Jebakumar Immanuel Edison, Sambasivam Sangaraju, Weslen Vedakumari Sathyaraj and Yong Rok Lee

Polymers 2023, 15(6), 1352; https://doi.org/10.3390/polym15061352 - 8 Mar 2023

Viewed by 2391

Abstract

Here, a simple one-step hydrothermal-assisted carbonization process was adopted for the preparation of nitrogen/phosphorous-doped carbon dots from a water-soluble polymer, poly 2-(methacryloyloxy)ethyl phosphorylcholine (PMPC). By the free-radical polymerization method, PMPC was synthesized using 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) and 4,4′-azobis (4-cyanovaleric acid). The water-soluble polymers, [...] Read more.

Here, a simple one-step hydrothermal-assisted carbonization process was adopted for the preparation of nitrogen/phosphorous-doped carbon dots from a water-soluble polymer, poly 2-(methacryloyloxy)ethyl phosphorylcholine (PMPC). By the free-radical polymerization method, PMPC was synthesized using 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) and 4,4′-azobis (4-cyanovaleric acid). The water-soluble polymers, PMPC, that have nitrogen/phosphorus moieties are used to prepare carbon dots (P-CDs). The resulting P-CDs were thoroughly characterized by various analytical techniques such as field emission-scanning electron microscopy (FESEM) with energy-dispersive X-ray spectroscopy (EDS), high-resolution transmittance electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible (UV-vis) spectroscopy and fluorescence spectroscopy to determine their structural and optical properties. The synthesized P-CDs displayed bright/durable fluorescence, were stable for long periods, and confirmed the enrichment of functionalities including oxygen, phosphorus, and nitrogen heteroatoms in the carbon matrix. Since the synthesized P-CDs showed bright fluorescence with excellent photostability, excitation-dependent fluorescence emission, and excellent quantum yield (23%), it has been explored as a fluorescent (security) ink for drawing and writing (anti-counterfeiting). Further, cytotoxicity study results advised for biocompatibility and thus were used for cellular multicolor imaging in nematodes. This work not only demonstrated the preparation of CDs from polymers that can be used as advanced fluorescence ink, a bioimaging agent for anti-counterfeiting, and cellular multicolor imaging candidate, but additionally prominently opened a new perspective on the bulk preparation of CDs simply and efficiently for various applications. Full article

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2022

Jump to: 2024, 2023

12 pages, 1500 KiB

Open AccessArticle

A Comparison of Unmodified and Sawdust Derived-Cellulose Nanocrystals (CNC)-Modified Polyamide Membrane Using X-ray Photoelectron Spectroscopy and Zeta Potential Analysis

by Amos Adeniyi, Danae Gonzalez-Ortiz, Celine Pochat-Bohatier, Sandrine Mbakop and Maurice S. Onyango

Polymers 2023, 15(1), 57; https://doi.org/10.3390/polym15010057 - 23 Dec 2022

Cited by 1 | Viewed by 2113

Abstract

Cellulose nanocrystals (CNC) obtained from waste sawdust were used to modify the polyamide membrane fabricated by interfacial polymerization of m-phenylene-diamine (MPDA) and trimesoyl chloride (TMC). The efficiency of the modification with sawdust-derived CNC was investigated using zeta potential and X-ray photoelectron spectroscopy (XPS). [...] Read more.

Cellulose nanocrystals (CNC) obtained from waste sawdust were used to modify the polyamide membrane fabricated by interfacial polymerization of m-phenylene-diamine (MPDA) and trimesoyl chloride (TMC). The efficiency of the modification with sawdust-derived CNC was investigated using zeta potential and X-ray photoelectron spectroscopy (XPS). The effect of the modification on membrane mechanical strength and stability in acidic and alkaline solutions was also investigated. Results revealed that the negative zeta potential decreased at a high pH and the isoelectric point shifted into the acidic range for both modified and unmodified membranes. However, the negative charges obtained on the surface of the modified membrane at a pH lower than 8 were higher than the pristine membrane, which is an indication of the successful membrane modification. The XPS result shows that the degree of crosslinking was lowered due to the presence of CNC. Enhanced stability in solution in all pH ranges and the increase in mechanical strength, as indicated by higher Young’s modulus, maximum load, and tensile strength, confirmed the robustness of the modified membrane. Full article

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11 pages, 16581 KiB

Open AccessArticle

Composite Polymer Electrolytes Based on (PEO)₄CF₃COOLi and Multi-Walled Carbon Nanotube (MWCNT)

by Miguel I. Delgado-Rosero, Nori M. Jurado-Meneses and Ramiro Uribe-Kaffure

Polymers 2023, 15(1), 49; https://doi.org/10.3390/polym15010049 - 23 Dec 2022

Cited by 2 | Viewed by 2242

Abstract

The addition of nanoparticles as fillers has a significant influence in modifying the dynamic conditions and avoiding crystallization in polymer composites. In this work, (PEO)₄CF₃COOLi electrolyte and multi-walled carbon nanotubes (MWCNTs) were used to prepare composites by a solution [...] Read more.

The addition of nanoparticles as fillers has a significant influence in modifying the dynamic conditions and avoiding crystallization in polymer composites. In this work, (PEO)₄CF₃COOLi electrolyte and multi-walled carbon nanotubes (MWCNTs) were used to prepare composites by a solution method. The formation of the new composite was evidenced by the experimental results obtained from DSC analysis and infrared spectroscopy (FTIR). The impedance spectroscopy analysis shows a notable decrease in the resistance, which is attributed to an interaction between the oxygen of the polymer and the Li⁺ cations of the salt, and the interactions between the electrolyte and the MWNTs. Values of dc conductivity of 8.42 × 10⁻⁴ S cm⁻¹ at room temperature are obtained at a concentration of 2.0 wt.% MWCNT in the whole electrolyte. The results indicate that membranes can be used in technological devices such as batteries and gas or moisture sensors. Full article

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16 pages, 5433 KiB

Open AccessArticle

Fabrication of Europium-Doped Barium Titanate/Polystyrene Polymer Nanocomposites Using Ultrasonication-Assisted Method: Structural and Optical Properties

by Umesh Kumar, Diwakar Padalia, Prabhakar Bhandari, Pawan Kumar, Lalit Ranakoti, Tej Singh and László Lendvai

Polymers 2022, 14(21), 4664; https://doi.org/10.3390/polym14214664 - 1 Nov 2022

Cited by 7 | Viewed by 2301

Abstract

In the current work, europium-doped barium titanate particles were used as filler material and polystyrene was used as a matrix to fabricate Ba_1−3x/2Eu_xTiO₃/PS polymer nanocomposites with x = 0, 0.005, 0.015 and 0.025. A solid-state reaction [...] Read more.

In the current work, europium-doped barium titanate particles were used as filler material and polystyrene was used as a matrix to fabricate Ba_1−3x/2Eu_xTiO₃/PS polymer nanocomposites with x = 0, 0.005, 0.015 and 0.025. A solid-state reaction was used to synthesize filler particles and the solvent evaporation method was used to form polymer nanocomposites. The effects of ultrasonic treatment were also studied in the formation of nanocomposite materials. The quantitative and qualitative studies were conducted using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), and ultraviolet-visible (UV-Vis) characterization techniques. The XRD data and FTIR data confirm the incorporation of filler particles in the polymer matrix. FE-SEM data confirms that the particles are in the nanophase. The optical band gap was directly affected by the filler particles and it started to reduce as Eu concentration started to increase. Full article

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17 pages, 3495 KiB

Open AccessArticle

Fire Retardancy and Dielectric Strength of Cyclotriphosphazene Compounds with Schiff Base and Ester Linking Units Attached to the Electron-Withdrawing Side Arm

by Siti Nur Khalidah Usri, Zuhair Jamain and Mohamad Zul Hilmey Makmud

Polymers 2022, 14(20), 4378; https://doi.org/10.3390/polym14204378 - 17 Oct 2022

Cited by 1 | Viewed by 1977

Abstract

A series of compounds with Schiff base and ester linking units attached to the electron-withdrawing side arm (Cl, NO₂, and OH) have been successfully synthesized through four schemes of the chemical route. These compounds were characterized using Fourier Transform Infrared spectroscopy [...] Read more.

A series of compounds with Schiff base and ester linking units attached to the electron-withdrawing side arm (Cl, NO₂, and OH) have been successfully synthesized through four schemes of the chemical route. These compounds were characterized using Fourier Transform Infrared spectroscopy (FTIR), Nuclear Magnetic Resonance spectroscopy (NMR), and Carbon, Hydrogen and Nitrogen (CHN) elemental analysis. The epoxy resin was used as a matrix of molding to observe the refinement of fire-retardant properties of the modified cyclotriphosphazene compounds. The fire-retardant testing was done using Limiting Oxygen Index (LOI). The LOI value of pure epoxy resin was increased from 22.75% to 24.71% when incorporated with 1 wt.% of hexasubstituted cyclotriphosphazene (HCCP). Interestingly, all the final compounds gave a positive increment in the LOI value and the highest LOI value was obtained from the compound containing a nitro side arm with LOI value of 26.90%. In order to understand the thermal stability of these compounds, Thermogravimetric Analysis (TGA) was carried out. The compound with the nitro group at the terminal end has the highest char residue which is 34.2% at 700 °C. This indicated that the presence of the nitro withdrawing group was able to enhance the fire retardancy of the materials. Based on SEM observation, the shape of the final compound’s char residue demonstrated the formation of a porous protective layer with a dense surface. The dielectric property was conducted according to ASTM D149 AC breakdown voltage to determine its dielectric strength. The results showed that the highest dielectric strength value belonged to the compound containing a nitro group side arm with 24.41 kV/mm⁻¹ due to the π electron delocalization. Full article

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22 pages, 13311 KiB

Open AccessReview

Advanced Carbon-Based Polymeric Nanocomposites for Forensic Analysis

by Ana M. Díez-Pascual, Daniel Lechuga Cruz and Alba Lomas Redondo

Polymers 2022, 14(17), 3598; https://doi.org/10.3390/polym14173598 - 31 Aug 2022

Cited by 7 | Viewed by 3882

Abstract

Nanotechnology is a powerful tool and fast-growing research area in many novel arenas, ranging from biomedicine to engineering and energy storage. Nanotechnology has great potential to make a significant positive contribution in forensic science, which deals with the identification and investigation of crimes, [...] Read more.

Nanotechnology is a powerful tool and fast-growing research area in many novel arenas, ranging from biomedicine to engineering and energy storage. Nanotechnology has great potential to make a significant positive contribution in forensic science, which deals with the identification and investigation of crimes, finding relationships between pieces of evidence and perpetrators. Nano-forensics is related to the development of nanosensors for crime investigations and inspection of terrorist activity by analyzing the presence of illicit drugs, explosives, toxic gases, biological agents, and so forth. In this regard, carbon nanomaterials have huge potential for next-generation nanosensors due to their outstanding properties, including strength combined with flexibility, large specific surface area, high electrical conductivity, and little noise. Moreover, their combination with polymers can provide nanocomposites with novel and enhanced performance owed to synergy between the composite components. This review concisely recapitulates up-to-date advances in the development of polymer composites incorporating carbon-based nanomaterials for forensic science. The properties of the different carbon nanomaterials, several methods used to analyze functional polymeric nanocomposites, and their applications in forensic investigation are discussed. Furthermore, present challenges and forthcoming outlooks on the design of new polymer/carbon nanomaterial composites for crime prevention are highlighted. Full article

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14 pages, 4848 KiB

Open AccessArticle

Investigation of the Crystallization Kinetics and Melting Behaviour of Polymer Blend Nanocomposites Based on Poly(L-Lactic Acid), Nylon 11 and TMDCs WS₂

by Mohammed Naffakh and Peter S. Shuttleworth

Polymers 2022, 14(13), 2692; https://doi.org/10.3390/polym14132692 - 30 Jun 2022

Viewed by 1896

Abstract

The aim of this work was to study the crystallization kinetics and melting behaviour of polymer blend nanocomposites based on poly (L-lactic acid) (PLLA), nylon 11 and tungsten disulfide nanotubes (INT-WS₂), which are layered transition metal dichalcogenides (TMDCs), using non-isothermal differential [...] Read more.

The aim of this work was to study the crystallization kinetics and melting behaviour of polymer blend nanocomposites based on poly (L-lactic acid) (PLLA), nylon 11 and tungsten disulfide nanotubes (INT-WS₂), which are layered transition metal dichalcogenides (TMDCs), using non-isothermal differential scanning calorimetry (DSC). Blends containing different nylon 11 contents ranging from 20 to 80 wt.% with or without INT-WS₂ were prepared by melt mixing. Evaluation of their morphology with high-resolution SEM imaging proved that the incorporation of inorganic nanotubes into the immiscible PLLA/nylon 11 mixtures led to an improvement in the dispersibility of the nylon 11 phase, a reduction in its average domain size and, consequently, an increase in its interfacial area. The crystallization temperatures of these PLLA/nylon 11-INT blends were influenced by the cooling rate and composition. In particular, the DSC results appear to demonstrate that the 1D-TMDCs WS₂ within the PLLA/nylon 11-INT blend nanocomposites initiated nucleation in both polymeric components, with the effect being more pronounced for PLLA. Moreover, the nucleation activity and activation energy were calculated to support these findings. The nucleation effect of INT-WS₂, which influences the melting behaviour of PLLA, is highly important, particularly when evaluating polymer crystallinity. This study opens up new perspectives for the development of advanced PLA-based nanomaterials that show great potential for ecological and biomedical applications. Full article

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19 pages, 39023 KiB

Open AccessReview

A Review of Polymeric Micelles and Their Applications

by Suguna Perumal, Raji Atchudan and Wonmok Lee

Polymers 2022, 14(12), 2510; https://doi.org/10.3390/polym14122510 - 20 Jun 2022

Cited by 136 | Viewed by 15822

Abstract

Self-assembly of amphiphilic polymers with hydrophilic and hydrophobic units results in micelles (polymeric nanoparticles), where polymer concentrations are above critical micelle concentrations (CMCs). Recently, micelles with metal nanoparticles (MNPs) have been utilized in many bio-applications because of their excellent biocompatibility, pharmacokinetics, adhesion to [...] Read more.

Self-assembly of amphiphilic polymers with hydrophilic and hydrophobic units results in micelles (polymeric nanoparticles), where polymer concentrations are above critical micelle concentrations (CMCs). Recently, micelles with metal nanoparticles (MNPs) have been utilized in many bio-applications because of their excellent biocompatibility, pharmacokinetics, adhesion to biosurfaces, targetability, and longevity. The size of the micelles is in the range of 10 to 100 nm, and different shapes of micelles have been developed for applications. Micelles have been focused recently on bio-applications because of their unique properties, size, shape, and biocompatibility, which enhance drug loading and target release in a controlled manner. This review focused on how CMC has been calculated using various techniques. Further, micelle importance is explained briefly, different types and shapes of micelles are discussed, and further extensions for the application of micelles are addressed. In the summary and outlook, points that need focus in future research on micelles are discussed. This will help researchers in the development of micelles for different applications. Full article

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17 pages, 5194 KiB

Open AccessArticle

Mechanical Properties of PALF/Kevlar-Reinforced Unsaturated Polyester Hybrid Composite Laminates

by Siti Nadia Mohd Bakhori, Mohamad Zaki Hassan, Noremylia Mohd Bakhori, Ahmad Rashedi, Roslina Mohammad, Mohd Yusof Md Daud, Sa’ardin Abdul Aziz, Faizir Ramlie, Anil Kumar and Naveen J

Polymers 2022, 14(12), 2468; https://doi.org/10.3390/polym14122468 - 17 Jun 2022

Cited by 11 | Viewed by 3392

Abstract

Natural and synthetic fibres are in high demand due to their superior properties. Natural fibres are less expensive and lighter as compared to synthetic fibres. Synthetic fibres have drawn much attention, especially for their outstanding properties, such as durability, and stability. The hybridisation [...] Read more.

Natural and synthetic fibres are in high demand due to their superior properties. Natural fibres are less expensive and lighter as compared to synthetic fibres. Synthetic fibres have drawn much attention, especially for their outstanding properties, such as durability, and stability. The hybridisation between natural and synthetic fibres composite are considered as an alternative to improve the current properties of natural and synthetic fibres. Therefore, this study aimed to determine the physical and mechanical properties of pineapple leaf fibre (PALF) and Kevlar reinforced unsaturated polyester (UP) hybrid composites. The PALF/Kevlar hybrid composites were fabricated by using hand layup method utilising unsaturated polyester as the matrix. These composites were laid up to various laminated configurations, such as [PKP]s, [PPK]s, [KPP]s, [KKP]s, [PPP]s and [KKK]s, whereby PALF denoted as P and Kevlar denoted as K. Next, they were cut into size and dimensions according to standards. Initially, the density of PALF/Kevlar reinforced unsaturated polyester were evaluated. The highest density result was obtained from [KKK]s, however, the density of hybrid composites was closely indistinguishable. Next, moisture absorption behaviour and its effects on the PALF/Kevlar reinforced unsaturated polyester were investigated. The water absorption studies showed that the hybridisation between all PALF and Kevlar specimens absorbed moisture drastically at the beginning of the moisture absorption test and the percentage of moisture uptake increased with the volume fraction of PALF in the samples. The tensile test indicated that all specimens exhibited nonlinear stress-strain behaviour and shown a pseudo-ductility behaviour. [KKP]s and [KPK]s hybrid composites showed the highest tensile strength and modulus. The flexural test showed that [KPK]s had the highest flexural strength of 164.0 MPa and [KKP]s had the highest flexural modulus of 12.6 GPa. In terms of the impact strength and resistance, [KKP]s outperformed the composite laminates. According to SEM scans, the hybrid composites demonstrated a stronger interfacial adhesion between the fibres and matrix than pure PALF composite. Full article

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13 pages, 6901 KiB

Open AccessArticle

A Low-Density Polyethylene (LDPE)/Macca Carbon Advanced Composite Film with Functional Properties for Packaging Materials

by Jitladda Sakdapipanich, Phawasoot Rodgerd and Natdanai Sakdapipanich

Polymers 2022, 14(9), 1794; https://doi.org/10.3390/polym14091794 - 27 Apr 2022

Cited by 2 | Viewed by 3359

Abstract

Macca carbon (MC) powder, a biomass derived from macadamia nut cultivation that emits far-infrared (FIR) radiation, was incorporated into low-density polyethylene (LDPE) by melt-compounding and subsequent melt-extrusion operations. Optical microscopy, scanning electron microscopy, differential scanning calorimetry, thermal gravitational analysis, mechanical properties, FIR emission [...] Read more.

Macca carbon (MC) powder, a biomass derived from macadamia nut cultivation that emits far-infrared (FIR) radiation, was incorporated into low-density polyethylene (LDPE) by melt-compounding and subsequent melt-extrusion operations. Optical microscopy, scanning electron microscopy, differential scanning calorimetry, thermal gravitational analysis, mechanical properties, FIR emission power, barrier properties, transmission properties, antimicrobial activity assays, and storage tests were used to evaluate the manufactured LDPE/MC composite viability sheets for antimicrobial packaging applications. The physical properties and antibacterial activity of composite films were significantly correlated with the amount of MC powder used. The higher the MC powder content in the LDPE/MC composite film, the better the FIR emission ability. Only the MC powder at 0.5% by weight displayed adequate fundamental film characteristics, antibacterial activity, and storage performance, allowing lettuce and strawberries to remain fresh for more than 7 and 5 days, respectively, outside the refrigerator. This study demonstrates that FIR composites made from MC powder are a distinct and potential packaging material for future application in the food industry. Full article

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18 pages, 6808 KiB

Open AccessArticle

Effects of Peroxide Initiator on the Structure and Properties of Ultralow Loss Thermosetting Polyphenylene Oxide-Based Composite

by Xueyi Yu, Zeming Fang, Qianfa Liu, Dan Li, Yundong Meng, Cheng Luo, Ke Wang and Zhiyong Lin

Polymers 2022, 14(9), 1752; https://doi.org/10.3390/polym14091752 - 26 Apr 2022

Cited by 12 | Viewed by 4080

Abstract

Although thermosetting polyphenylene oxide- (PPO) based composites with excellent dielectric properties have been widely accepted as superior resin matrices of high-performance copper clad laminate (CCL) for 5G network devices, there has been limited information regarding the composition–process–structure–property relationships of the systems. In this [...] Read more.

Although thermosetting polyphenylene oxide- (PPO) based composites with excellent dielectric properties have been widely accepted as superior resin matrices of high-performance copper clad laminate (CCL) for 5G network devices, there has been limited information regarding the composition–process–structure–property relationships of the systems. In this work, the effects of peroxide initiator concentration on the structure and dielectric properties of a free radical cured ultralow loss PPO/Triallyl isocyanate (TAIC) composite system were studied. As expected, the glass transition temperature (T_g) and storage modulus increased with the advancing of crosslinking, whereas the dielectric loss showed an “abnormal” rise with the increase in crosslink density. Extensive studies were carried out by varying the initiator contents and characterizing the structure with spectroscopy, thermal analysis, and positron annihilation lifetime spectrum (PALS) techniques. The results show that the competition of polarity, crosslink density, free volume, and free TAIC are the key factors determining the dielectric properties of the composites. Full article

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12 pages, 7801 KiB

Open AccessArticle

Green Composites Based on Hedysarum coronarium with Outstanding FDM Printability and Mechanical Performance

by Roberto Scaffaro, Emmanuel Fortunato Gulino, Maria Clara Citarrella and Andrea Maio

Polymers 2022, 14(6), 1198; https://doi.org/10.3390/polym14061198 - 16 Mar 2022

Cited by 29 | Viewed by 3058

Abstract

The addition of natural scraps to biodegradable polymers has gained particular interest in recent years, allowing reducing environmental pollution related to traditional plastic. In this work, new composites were fabricated by adding 10% or 20% of Hedysarum coronarium (HC) flour to Poly (lactic [...] Read more.

The addition of natural scraps to biodegradable polymers has gained particular interest in recent years, allowing reducing environmental pollution related to traditional plastic. In this work, new composites were fabricated by adding 10% or 20% of Hedysarum coronarium (HC) flour to Poly (lactic acid) (PLA). The two formulations were first produced by twin screw extrusion and the obtained filaments were then employed for the fabrication of composites, either for compression molding (CM) or by fused deposition modeling (FDM), and characterized from a morphological and mechanical point of view. Through FDM it was possible to achieve dense structures with good wettability of the filler that, on the contrary, cannot be obtained by CM. The results indicate that the filler effectively acts as reinforcement, especially for FDM composites. The most remarkable enhancement was found in the flexural properties (+100% of modulus and ultimate strength), followed by tensile resistance and stiffness (+60%) and impact strength (+50%), whereas a moderate loss in tensile deformability was observed, especially at the highest loading. By adding HC to the polymeric matrix, it was possible to obtain a green, high-performance, and cost-effective composite, which could find applications for the fabrication of panels for furniture or the automotive industry. Full article

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