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Polymer degradation and stability
Applied Science Publishers Ltd.
Polymer degradation and stability

Applied Science Publishers Ltd.

0141-3910

Polymer degradation and stability/Journal Polymer degradation and stabilitySCIEI
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    Thermo-oxidative ageing of photo-crosslinked polyethylene pipes for thermal energy storage

    Giulia Simao de SousaAndrew RootIvo HeinmaaAdib Kalantar Mehrjerdi...
    111365.1-111365.17页
    查看更多>>摘要：This study presents a comprehensive evaluation of the thermo-oxidative stability of crosslinked polyethylene (PEX) pipes designed for borehole thermal energy storage (BTES) systems, with a particular focus on a novel PEX type produced via a photo-initiated crosslinking process (PEX-e). Two formulations, PEX-el and PEX-e2, were assessed and compared to commercial peroxide-crosslinked polyethylene (PEX-a) and bimodal polyethylene (PE100) pipes. The pipes were aged in distilled water at the intended BTES service temperature for 210 days, with periodic analyses conducted to monitor antioxidant (AO) depletion and the formation of degradation products. Advanced analytical techniques were employed, including Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy, gel content analysis, colorimetry, differential scanning calorimetry (DSC), oxidation induction time (OIT), and dynamic mechanical analysis (DMA). FTIR analysis revealed the presence of degradation-related peaks on the pipe surfaces, while the formation of oxidation products in the bulk material was limited. Phase composition analysis showed that physical ageing dominated during the first 30 days, leading to increased crystallinity and enhanced lamellar thickness. Over time, chain scission emerged as the primary degradation mechanism, resulting in molecular weight reductions, with PEX-a being the most severely affected. No abrupt changes in phase composition or mechanical properties were observed after 210 days of ageing, indicating that the pipes remained in the induction phase of degradation. Interestingly, despite their high OIT levels, both PEX-e formulations exhibited accelerated AO depletion during prolonged exposure, suggesting the need for further optimization of PEX-e formulations to ensure long-term stability under demanding BTES conditions.
      原文链接:
    • NETL
    • NSTL
    • Elsevier

    Sulfenamides, sulfinamides and sulfonamides as flame retardants - similarities and differences in the mechanism of action

    Timo AEaeritaloYury BrusentsevTeija TirriCarl-Eric Wilen...
    111370.1-111370.11页
    查看更多>>摘要：A series of sulfenamides, sulfinamides and sulfonamides have been synthesized and their thermal degradation pathways have been determined by TGA, GC/MS and !H NMR and their flame retardant properties in polypropylene and polyamide 6 have been investigated. The results reveal, that sulfenamides and sulfinamides have the specific feature of generating highly reactive aminyl and sulfenyl radicals during pyrolysis that provide flame retardancy for polymeric materials by triggering rapid degradation of polymer chains in the solid phase and by quenching of active fire propagating radicals in the flame zone. In contrast, the sulfonamides thermally decomposed via a non-radical mechanism and their main flame retardancy effect was instead attributed to increased charring of polymeric materials. The thermal stabilities for sulfenamides and sulfonamides were high ranging from 266 ℃ to 290 ℃, Whereas the mass loss of 5 wt% of the corresponding sulfinamide was recorded already at 212 ℃. Investigation of synergistic effects with two conventional phosphorous flame retardants, i.e. cyclic dimethyl spirophosphonate and diethyl phosphinic acid aluminium salt revealed that sulfenamides, sulfinamides and sulfonamides display a significantly stronger synergistic effect in combination with dimethyl spirophosphonate compared to diethyl phosphonic acid aluminium salt. The flame retardant efficacies as standalone flame retardants and as adjuvants in polypropylene films increased in the following order sulfenamides > sulfinamide > sulfonamides. On the contrary, only sulfonamides in this series were able to provide UL 94 V2 rating in polyamide 6 with very short burning times at the loading of 2.5 wt%.
      原文链接:
    • NETL
    • NSTL
    • Elsevier

    Flame-retardant polyurethane and glass fiber-reinforced polymer composites enabled by aromatic heterocyclic liquid mixture flame retardants

    Qiang LvFu-Rong ZengLei HeShuai-qi Guo...
    111371.1-111371.11页
    查看更多>>摘要：With the rapid development of the pultrusion molding process, glass fiber-reinforced polyurethane composites have become increasingly prominent in industrial applications due to their unique advantages. However, their high flammability significantly limits their potential uses. Here, hexaphenoxycyclotriphosphazene and hexakis (methoxymethyl)melamine resin were combined to create a novel liquid mixture flame retardant (LMFR) for polyurethane and its glass fiber-reinforced polymer composites. The resultant polyurethane exhibited excellent flame retardancy, achieving a V-0 rating in the UL-94 vertical burning test, and a 64.5 % reduction in the peak heat release rate. Similarly, its composite achieved a limiting oxygen index of 58.0 %, a UL-94 V-0 rating, and a 31.9 % reduction in total heat release. Notably, this flame retardant significantly reduced both the smoke production rate and total smoke production in polyurethane and its composite. Meanwhile, LMFR exhibited excellent heat resistance with minimal impact on the thermal stability of polyurethane resin. Mechanistic studies revealed that the LMFR achieved flame retardancy and smoke suppression through a synergistic interaction between the gas and condensed phases, providing an effective approach to improving the safety and performance of glass fiber-reinforced polyurethane composites.
      原文链接:
    • NETL
    • NSTL
    • Elsevier

    Thermal decomposition mechanism of poly(vinyl butyral) with random structure revealed through TG-FTIR-MS, GC-MS, and SVUV PIMS

    Tianyi ChenHong WangYushen YuQi Yan...
    111373.1-111373.15页
    查看更多>>摘要：Understanding thermal decomposition mechanism of polymers with a random structure is essential for both academic research and industrial applications, but remains a complex and less studied area due to its complexity. In this study, we investigated the oxygen-free thermal decomposition behavior of poly(vinyl butyral) (PVB), a polymer with random structure, using a combination of thermogravimetry-Fourier infrared spectroscopy-mass spectrometry (TG-FTIR-MS), gas chromatography-mass spectrometry (GC-MS), and synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV PIMS). Specific structures of dozens of products and some corresponding free radicals during decomposition were successfully identified and distinguished in detail for the first time. According to the temperature dependent evolution behavior, the products can be categorized into several types: "type A product" (n-butanal), "type B products" (lower aldehydes, lower ketones, alkenals, alke-nones, etc.), and "type C products" (alkenes, butanoic acid, aromatic and cyclic aliphatic compounds, etc.). Their source reactions leading to the formation of each product type were thoroughly discussed respectively. A comprehensive scheme of the thermal decomposition mechanism of PVB was proposed, which cannot be simply classified into any of the three major thermal decomposition categories. Our work provides valuable insights into the thermal decomposition mechanism of PVB and offers a valuable approach for studying the thermal decomposition behavior of other polymers with random structures.
      原文链接:
    • NETL
    • NSTL
    • Elsevier

    H_3PO_3-modified hyperbranched polyethyleneimine/montmorillonite coatings for flame-retardant polyester/cotton fabrics

    Chunyuan LuoNan LiPing ZhuYuanyuan Yin...
    111374.1-111374.8页
    查看更多>>摘要：Polyelectrolyte complex coatings have been developed for flame-retardant fabrics, which demonstrate advantages in simplified operations and high flame retardancy. In this study, a polyelectrolyte complex coating (called PPM) was developed through the integration of H_3PO_3, hyperbranched polyethyleneimine, and montmorillonite, and was subsequently applied onto polyester/cotton fabrics using a one-step blade coating method. We thoroughly investigated the chemical structure, surface morphology, flame retardancy performance, thermal decomposition behavior, and mechanical properties of the coated fabrics. It was found that H3PO3 was incorporated into the PPM coating via ionic bonds, with a phosphorus atomic content of 0.9 %. Homogeneous and continuous coatings were formed on the surface of fabrics because of good film-forming ability of PPM. When the PPM loading was 15.3 %, the coated fabric showed a limiting oxygen index value of 64.9 % and quickly self-extinguished during the vertical flammability test with a damage length of 63 mm. In the cone calorimetry test, the PPM-coated fabric presented a 50 % reduction in peak heat release rate and a 52 % decrease in total smoke production. The PPM coating exhibited flame-retardant activities in both condensed and gaseous phases.
      原文链接:
    • NETL
    • NSTL
    • Elsevier

    Simultaneous enhancement of fire retardancy and ceramifiable properties in polyolefm-based composites using melamine cyanurate and layered tri-metallic hydroxide

    Hui HeRui QiQing ZhaoCong Deng...
    111375.1-111375.17页
    查看更多>>摘要：Ceramifiable cables develop a robust ceramic layer under high-temperature conditions, preventing internal conductor meltdown while maintaining electrical transmission integrity during fire events. Nevertheless, these materials often fail to satisfy applicable cable industry standards owing to inadequate ceramification characteristics or flame retardancy. In this work, a two-dimensional layered tri-metal hydroxide was synthesized through a simple hydrothermal method and combined with melamine cyanurate to create a synergistic flame retardant system. This formulation was integrated into an ethylene vinyl acetate (EVA)-based composite formulated with hollow glass microspheres, glass powder, and montmorillonite as ceramic-forming fillers (CF), yielding a lightweight, flame-retardant ceramifiable composite. Fire resistance evaluations revealed that the material formed a dense protective ceramic layer, enabling uninterrupted circuit functionality following 90-min-ute butane flame exposure. The ceramic layer demonstrated 15.2 MPa flexural strength, significantly exceeding the 10 MPa threshold required for splash resistance. The composite exhibits a limiting oxygen index of 24.7 % and achieves a UL-94 V-0 rating. Relative to pure EVA, peak heat release rate, total heat release, and total smoke production were reduced by 85.7 %, 28.4 %, and 87.1 %, respectively. This research establishes an enhanced foundation for developing cable materials with dual flame-retardant and ceramifiable functionalities, thereby expanding potential applications of ceramifiable cable systems.
      原文链接:
    • NETL
    • NSTL
    • Elsevier

    Novel Si-MXene/PAPP hybrid system for high-performance flame-retardant polypropylene composites

    Qinling LiuJunhan ChuYuhui XieZhaoyu Li...
    111376.1-111376.14页
    查看更多>>摘要：The development of high-performance flame-retardant polypropylene (PP) composites is essential for enhancing fire safety across various industries. However, conventional intumescent flame retardant systems often suffer from poor char stability, weak condensed-phase protection, and insufficient gas-phase flame inhibition. To address these challenges, this study introduces a synergistic system combining Si-modified MXene (Si-MXene) and piperazine-modified ammonium polyphosphate (PAPP) to enhance the flame retardancy of PP composites. The piperazine modification of PAPP improves its compatibility with PP, facilitating uniform dispersion and enhancing its catalytic charring capability. Simultaneously, Si-modified MXene reinforces the char layer by promoting the formation of a highly graphitized and compact carbon structure, effectively blocking heat and oxygen transfer. As a result, the Si-MXene/PAPP system significantly reduces the peak heat release rate (PHRR) of PP by 52.6 % and total heat release (THR) by 35.4 %, while substantially improving thermal stability and char quality. Moreover, gas-phase analysis confirms that phosphorus radicals (P-, PO) and non-flammable gases (NH_3, H_2O) scavenge combustion free radicals and dilute flammable volatiles, effectively suppressing flame propagation. This study provides a novel approach to developing high-efficiency flame-retardant PP composites, offering new insights into the synergistic mechanisms of MXene-based hybrid flame retardants and advancing the design of eco-friendly, high-performance polymeric materials for safety-critical applications.
      原文链接:
    • NETL
    • NSTL
    • Elsevier

    Novel reactive rejuvenation strategy for aged SBS modified bitumen based on molecular structure modulation

    Song XuXiangjie NiuShilong PanBingtao Xu...
    111377.1-111377.16页
    查看更多>>摘要：The aging of SBS modified bitumen (SMB) involves bitumen aging and SBS degradation. Traditional rejuvenators restore bitumen properties by rebalancing its chemical composition but fail to repair damaged SBS. Some reactive rejuvenators can repair damaged SBS, improving low temperature performance of rejuvenated SMB but compromising high temperature stability. In order to achieve rejuvenated SMB with excellent high and low temperature performance, an aliphatic epoxy compound (1,6-hexanediol diglycidyl ether, HDE), aromatic epoxy compounds (resorcinol diglycidyl ether, RDGE; 2,2-bis (4-glycidyloxyphenyl) propane, DGEBA; N, N, N', N'-tetraglycidyl-4,4'-diaminodiphenylmethane, MBDA), a catalyst (Pentaethylenehexamine, PEHA) as well as bio-oil were utilized to develop a novel composite reactive rejuvenation system. The optimal composition of rejuvenation system was determined through physical properties test, followed by rheological test to evaluate rheological properties of rejuvenated SMB. The rejuvenation effect of the composite system was demonstrated using FTIR and FM tests, and the molecular dynamics simulation was conducted to explore the composite reaction rejuvenation mechanism of aged SMB. Results show that the combination of HDE and DGEBA presents superior effectiveness compared to others. SBS repaired with HDE exhibits enhanced flexibility, allowing for greater molecular chain rearrangement, which leads to a looser molecular structure and increased free volume fraction, enabling rejuvenated SMB to maintain better deformability at low temperatures. The incorporation of DGEBA introduces rigid groups that constrain molecular chain conformation and slippage, rotation, or stretching between chain segments, which reduces the free volume fraction and improves deformation resistance. Besides, SBS repaired with DGEBA shows stronger interactions with asphaltenes, better restricting their mobility and enhancing the rigidity of bitumen. At an HDE: DGEBA ratio of 1:1, with a total dosage of 5 wt % by weight of bitumen, the composite reactive rejuvenation system restores crosslinking network of SBS in bitumen and achieves rejuvenated SMB with excellent high and low temperature performance.
      原文链接:
    • NETL
    • NSTL
    • Elsevier

    Biodegradation of cellulose-based water-soluble polymers through interactions with wastewater bacteria

    Praneetha PulyalaMeng JingWenshiue YoungKathleen Michels...
    111378.1-111378.13页
    查看更多>>摘要：Water-soluble cellulose derivatives are widely used across personal care, agriculture and manufacturing applications. Despite their extensive usage, the environmental fate of the cellulose-based water-soluble polymers (WSPs) is not fully understood. Understanding how these polymers interact with bacterial communities in wastewater is crucial to assessing their end-of-life impact on the environment. This study examines the bidirectional influences of three high molecular weight cellulose-based WSPs, containing cationic, non-ionic and anionic modifications, with the microbial consortium PolySeed, which is made up of microorganisms representative of activated sewage. Specifically, we investigated polymer sorption on bacterial cells, cell responses such as growth and cellulase enzyme secretion, and the resulting polymer degradation. Our results reveal a strong correlation between the function of secreted enzyme and degree of WSP degradation. Notably, the cationic polymer exhibited strong sorption on bacterial cells, leading to aggregate formation, reduced enzyme activity, and hindered degradation. In contrast, non-ionic and anionic polymers demonstrated moderate sorption on bacterial cells, resulting in higher enzyme activity and enhanced degradation. This research highlights the need to investigate bi-directional interactions between WSPs and bacterial cells to gain critical insights into their fates in wastewater and natural water environments. These findings may inform targeted strategies for reducing the environmental impact of WSPs and enhancing remediation of WSP waste.
      原文链接:
    • NETL
    • NSTL
    • Elsevier

    Sustainable, degradable and malleable low-dielectric-constant thermosets derived from biomass for recyclable green electronics

    Ka Hyun LimSoo Jeong JeongJi Won JooChurl Seung Lee...
    111379.1-111379.11页
    查看更多>>摘要：In view of their excellent thermal and chemical resistance, favorable adhesion properties, high tensile strength, and other advantages, epoxy thermosets have numerous industrial applications such as coating, adhesive, and composite material production. However, bisphenol A (BPA)-based resins, which account for a significant fraction of the above thermosets, adversely affect human health by interfering with the normal functioning of the endocrine system and cannot be easily decomposed and recycled. Herein, degradable and sustainable bio-based epoxy thermosets with crosslinked network structures are prepared by the epoxidation of isosorbide with epichlorohydrin and the curing of the produced isosorbide diglycidyl ether (ISDGE) with cyclic lactones through a cationic ring-opening reaction. The ISDGE thermosets fully decompose into soluble and recyclable products under mildly basic conditions within three days, which is ascribed to the presence of ester moieties within the polymer network structure. Compared to a representative BPA-based epoxy, ISDGE-based thermosets exhibit lower dielectric constants and are more flexible. Moreover, the glass fibers in ISDGE-based prepregs can be fully recovered after on-demand degradation. Thus, our work provides promising eco-friendly alternatives to conventional epoxy thermosets and paves the way for the reduction of plastic waste generation and the development of recyclable green electronics.
      原文链接:
    • NETL
    • NSTL
    • Elsevier