Environmental Friendly Synthesis, Modification and Application of Polymer

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Applications".

Deadline for manuscript submissions: 28 February 2025 | Viewed by 10406

Special Issue Editor

School of Materials Science and Technology, Shandong University of Science and Technology, Qingdao, China
Interests: flame retardant; photoinitiator; antioxidant; polymer

Special Issue Information

Dear Colleagues,

Polymers are widely used in industry and daily life. Traditional synthesis of polymer has the drawback of high energy consumption. New strategies are needed, and great efforts have been made on the development of environmentally friendly and low-energy consumption methods. Photopolymerization is one promising solution that attracts much attention. During the application of polymers, lots of synthetic additives have been introduced into the packing of polymers to improve their properties, but the high cost and potential harm of synthetic additives to humans and the environment should be considered. New strategies for enhancing polymer properties without any harmful effects are urgently needed, and exploring natural compounds and new additives are possible solutions.

This Special Issue plans to give an overview of the most recent advances in the fields of environmentally friendly synthesis and modification of polymers, together with the application of polymers in environmental protection. Potential topics include but are not limited to light-induced synthesis of polymers; antioxidative modification of polymers; flame-retardant modification of polymers; application of polymers in environmental protection; role of phosphorous in polymer synthesis; role of phosphorous in polymer modification; future perspectives for antioxidant polymers; future perspectives for flame-retardant polymers.

Dr. Qing Yu
Guest Editor

Manuscript Submission Information

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Keywords

  • light-induced
  • polymer
  • antioxidant
  • flame retardant
  • photopolymerization

Published Papers (6 papers)

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Research

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12 pages, 2622 KiB  
Article
Effects of Recycled Polyethylene on Natural Rubber Composite Blends Filled with Aluminum Trihydroxide and Polyurethane Waste: Mechanical and Dynamic Mechanical Properties, Flammability
by Varanya Tilokavichai, Onanong Pannarungsee, Piyawadee Luangchuang and Yeampon Nakaramontri
Polymers 2024, 16(12), 1657; https://doi.org/10.3390/polym16121657 - 11 Jun 2024
Viewed by 278
Abstract
This research studies natural rubber (NR) composite blends prepared with recycled polyethylene (PE), polyurethane waste (PU), silica (SiO2), and aluminum trihydroxide (ATH) under the proper mixing conditions using an internal mixer and a two-roll mill. The mechanical, impact, dynamic mechanical, and [...] Read more.
This research studies natural rubber (NR) composite blends prepared with recycled polyethylene (PE), polyurethane waste (PU), silica (SiO2), and aluminum trihydroxide (ATH) under the proper mixing conditions using an internal mixer and a two-roll mill. The mechanical, impact, dynamic mechanical, and thermal properties, together with flammability, were investigated. NR/PU composites filled with a specific SiO2/ATH concentration resulted in excellent flame-retardant properties without using PE. Adding PE causes poor flammability, while using PU and SiO2 prevents flame extensibility of the composites. In addition, SiO2 and ATH synergistically improved both mechanical and dynamical mechanical properties. This is attributed to the reinforcement of SiO2 particles inside the matrix, whereas the ATH releases water as a flame retardant. The V-0 composites tested with UL-94 showed acceptable heat resistance, strength, and durability, making them suitable for interior and exterior applications in buildings without the lightweight requirement. Full article
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18 pages, 5028 KiB  
Article
Sustainable Asphalt Mixtures with Enhanced Water Resistance for Flood-Prone Regions Using Recycled LDPE and Carnauba–Soybean Oil Additive
by Yeong-Min Kim, Kyungnam Kim and Tri Ho Minh Le
Polymers 2024, 16(5), 600; https://doi.org/10.3390/polym16050600 - 22 Feb 2024
Viewed by 686
Abstract
This manuscript presents a comprehensive study on the sustainable optimization of asphalt mixtures tailored for regions prone to flooding. The research addresses the challenges associated with water damage to asphalt pavements by incorporating innovative additives. The study centers on incorporating recycled Low-Density Polyethylene [...] Read more.
This manuscript presents a comprehensive study on the sustainable optimization of asphalt mixtures tailored for regions prone to flooding. The research addresses the challenges associated with water damage to asphalt pavements by incorporating innovative additives. The study centers on incorporating recycled Low-Density Polyethylene (LDPE) and a tailored Carnauba–Soybean Oil Additive, advancing asphalt mixtures with a Control mix, LDPE (5%) + Control, and LDPE (5%) + 3% Oil + Control. A critical aspect of the research involves subjecting these mixtures to 30 wetting and drying cycles, simulating the conditions prevalent in tropical flood-prone areas. The incorporation of innovative additives in asphalt mixtures has demonstrated significant improvements across various performance parameters. Tensile Strength Ratio (TSR) tests revealed enhanced tensile strength, with the LDPE (5%) + 3% Oil-modified mixture exhibiting an impressive TSR of 85.7%. Dynamic Modulus tests highlighted improved rutting resistance, showcasing a remarkable increase to 214 MPa in the LDPE (5%) with a 3% Oil-modified mixture. The Semi-Circular Bending (SCB) test demonstrated increased fracture resistance and energy absorption, particularly in the LDPE (5%) with 3% Oil-modified mixture. Hamburg Wheel-Tracking (HWT) tests indicated enhanced moisture resistance and superior rutting resistance at 20,000 cycles for the same mixture. Cantabro tests underscored improved aggregate shatter resistance, with the LDPE (5%) + 3% Oil-modified mixture exhibiting the lowest weight loss rate at 9.820%. Field tests provided real-world insights, with the LDPE (5%) + 3% Oil mixture displaying superior stability, a 61% reduction in deflection, and a 256% improvement in surface modulus over the control mixture. This research lays the groundwork for advancing the development of sustainable, high-performance road pavement materials, marking a significant stride towards resilient infrastructure in flood-prone areas. Full article
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20 pages, 8887 KiB  
Article
Eco-Friendly Blends of Recycled PET Copolymers with PLLA and Their Composites with Chopped Flax Fibres
by Martial Aimé Kuété, Pascal Van Velthem, Wael Ballout, Nathan Klavzer, Bernard Nysten, Maurice Kor Ndikontar, Thomas Pardoen and Christian Bailly
Polymers 2023, 15(14), 3004; https://doi.org/10.3390/polym15143004 - 10 Jul 2023
Cited by 1 | Viewed by 1327
Abstract
The structure and properties of blends of a novel polyethylene terephthalate copolymer (COPET) obtained by chemical recycling of commercial PET with high-molar-mass poly-L-lactide (PLLA) are investigated and compared to corresponding composites with chopped flax fibres. The focus is on the morphology at nano- [...] Read more.
The structure and properties of blends of a novel polyethylene terephthalate copolymer (COPET) obtained by chemical recycling of commercial PET with high-molar-mass poly-L-lactide (PLLA) are investigated and compared to corresponding composites with chopped flax fibres. The focus is on the morphology at nano- and micro-scales, on the thermal characteristics and on the mechanical behaviour. The blends are immiscible, as evidenced by virtually unchanged glass transition temperatures of the blend components compared to the neat polymers (49 °C for COPET and 63 °C for PLLA by DSC). At low PLLA content, the blends display a sea–island morphology with sub-micron to micron droplet sizes. As the composition approaches 50/50, the morphology transitions to a coarser co-continuous elongated structure. The blends and composites show strongly improved stiffness compared to COPET above its glass transition temperature, e.g., from melt behaviour at 60 °C for COPET alone to almost 600 MPa for the 50/50 blend and 500 MPa for the 20% flax composite of the 80/20 COPET/PLLA blend. The flax fibres increase the crystallisation rate of PLLA in blends with dispersed PLLA morphology. The evidence of cavitation on the fracture surfaces of blends shows that despite the immiscibility of the components, the interfacial adhesion between the phases is excellent. This is attributed to the presence of aliphatic ester spacers in COPET. The tensile strength of the 80/20 blend is around 50 MPa with a Young’s modulus of 2250 MPa. The corresponding 20% flax composite has similar tensile strength but a high Young’s modulus equal to 6400 MPa, which results from the individual dispersion and strong adhesion of the flax fibres and leads close to the maximum possible reinforcement of the composite, as demonstrated by tensile tests and nano-indentation. The Ashby approach to eco-selection relying on the embodied energy (EE) further clarifies the eco-friendliness of the blends and their composites, which are even better positioned than PLLA in a stiffness versus EE chart. Full article
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15 pages, 4666 KiB  
Article
Flame Retardancy of Epoxy Resins Modified with Few-Layer Black Phosphorus
by Yongzheng Zhao, Yan Li, Jiaxuan Li, Yifan Xiao, Wenmin Mu, Zhongwei Wang, Liang Song and Jinhong Yu
Polymers 2023, 15(7), 1655; https://doi.org/10.3390/polym15071655 - 27 Mar 2023
Cited by 1 | Viewed by 1933
Abstract
Few-layer black phosphorus (BP)- and red phosphorus (RP)-modified diglycidyl ether of bisphenol A-based epoxy resins (EP) was prepared with 4,4′-diaminodiphenylsulfone as a curing agent. The thermal stability and flame-retardant properties of the modified EPs were compared. Both BP and RP were able to [...] Read more.
Few-layer black phosphorus (BP)- and red phosphorus (RP)-modified diglycidyl ether of bisphenol A-based epoxy resins (EP) was prepared with 4,4′-diaminodiphenylsulfone as a curing agent. The thermal stability and flame-retardant properties of the modified EPs were compared. Both BP and RP were able to improve the flame-retardant properties of EPs, while the BP showed higher flame-retardant efficiency than RP. As a two-dimensional nanomaterial, BP exhibited good compatibility, high flame-retardant efficiency, and negligible impact on the mechanical and thermal stability of EP. Pyrolysis-gas Fourier-transform infrared spectroscopic analysis of EP showed that the addition of BP significantly inhibited the release of pyrolysis products in the gas phase. The modes of action for flame-retardant BPs in gas phase and condensed phase were proposed. Full article
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10 pages, 2412 KiB  
Article
Effects of Pine Needle Extracts on the Degradation of LLDPE
by Xiangyao Li, Jie Zhang, Chengchao Liu, Wenmin Mu, Zhe Kong, Yan Li, Zhongwei Wang, Qing Yu, Guiqing Cheng and Long Chen
Polymers 2023, 15(1), 32; https://doi.org/10.3390/polym15010032 - 22 Dec 2022
Cited by 5 | Viewed by 1757
Abstract
Polyolefin suffers from degradation during processing and application. To prolong the service life, antioxidants are needed in the packing formula of polyolefin products. The usage of natural antioxidants could avoid potential health hazards aroused by synthetic ones. Pine needles have long lives and [...] Read more.
Polyolefin suffers from degradation during processing and application. To prolong the service life, antioxidants are needed in the packing formula of polyolefin products. The usage of natural antioxidants could avoid potential health hazards aroused by synthetic ones. Pine needles have long lives and hardly rot, suggesting their high resistance to degradation. To provide a new candidate of natural antioxidants and add more value to pine needles, pine needle extracts (PNE) were investigated as the antioxidant of linear low-density polyethylene (LLDPE). PNE-modified LLDPE (PE-PNE) exhibited much better short-term and long-term aging resistance than pure LLDPE (PE): Oxidation induction time (OIT) of PE-PNE was 52 times higher than that of PE, and the increments of carbonyl index (CI) of PE-PNE-1st samples placed under daylight and in the dark were approximately 75% and 63% of PE under the same conditions. It could be attributed to the attractive antioxidant capacity of PNE (IC50 of DPPH radical scavenging was 115 μg/mL). In addition, the PE-PNE sample showed high processing stability and maintenance of the mechanical property during multiple extrusions: only a 0.2 g/10 min decrease in melting flow rate was found after five extrusions; the tensile strength and elongation at break were almost unchanged. All results reveal that pine needle extracts could play a role in LLDPE stabilization. Moreover, as pine needles are mainly considered a kind of waste, the present study would benefit the budget-reducing polyolefin industry. Full article
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Review

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25 pages, 7515 KiB  
Review
Recycling and Reutilization of Waste Carbon Fiber Reinforced Plastics: Current Status and Prospects
by Pi-Yu Chen, Ran Feng, Ying Xu and Ji-Hua Zhu
Polymers 2023, 15(17), 3508; https://doi.org/10.3390/polym15173508 - 23 Aug 2023
Cited by 8 | Viewed by 3780
Abstract
The extensive use of carbon fiber-reinforced plastics (CFRP) in aerospace, civil engineering, and other fields has resulted in a significant amount of waste, leading to serious environmental issues. Finding appropriate methods for recycling CFRP waste and effectively reusing recycled carbon fibers (rCFs) has [...] Read more.
The extensive use of carbon fiber-reinforced plastics (CFRP) in aerospace, civil engineering, and other fields has resulted in a significant amount of waste, leading to serious environmental issues. Finding appropriate methods for recycling CFRP waste and effectively reusing recycled carbon fibers (rCFs) has become a challenging task. This paper presents an overview of the current status of CFRP waste and provides a systematic review and analysis of recycling technologies. In addition to discussing mechanical recycling, thermal decomposition, and chemical solvent degradation methods, the organic alkali/organic solvent method for recycling resins is also elucidated. By introducing the recycling conditions and outcomes of the organic alkali/organic solvent method, the study highlights its significance as a reference for carbon fiber recycling. Furthermore, the paper reviews the current state of rCFs utilization based on its application domains, focusing on research advancements in fiber composites and cementitious composites. Based on these findings, the paper summarizes the existing research limitations and identifies specific areas that require further attention in recycling techniques and rCFs utilization. Lastly, this review provides a prospect on the future of recycling and reusing CFRP waste. Full article
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