Polymer Degradation and Stability最新文献_第10页

Effects of artificial accelerated aging on the pyrolysis and combustion properties of building external insulation materials and fire risk 人工加速老化对建筑外保温材料热解燃烧性能及火灾危险性的影响

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2025-12-15 DOI: 10.1016/j.polymdegradstab.2025.111864

Zhenxiang Tao , Xubo Huang , Bo Yang , Yisen Wang , Tong Xu , Jiansong Wu , Rui Yang

The insulation layer of external wall insulation systems undergoes progressive degradation due to prolonged exposure to ultraviolet radiation and temperature-humidity cycles Especially when the outer protective layer is damaged or peels off detached, exposing the polymer material to the external environment, the aging process accelerates significantly. In this study, three common insulation materials—expanded polystyrene (EPS), extruded polystyrene (XPS), and rigid polyurethane (RPU)—were subjected to artificial accelerated aging conditions under controlled conditions that simulated the radiation and thermal effects. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and thermogravimetric analysis were employed to elucidate the mechanisms by which aging affects the chemical structure. Cone calorimetry was used to evaluate the ignition characteristics, heat release, smoke production, and gas product toxicity of the aged insulation materials. An entropy-weighted insulation fire risk model quantified the evolving fire risk profiles of these aged insulation materials. After 150 aging cycles, the time to ignition of both EPS and XPS was significantly shortened, and the peak heat release rates increased by 25 % and 37 % respectively. Furthermore, after aging, the total heat release and total smoke production of RPU increased by 27 % and 16 %, respectively, at a radiant heat flux of 50 kW/m². Overall, RPU pronounced a significant increase in fire hazard under high level heat exposure. These findings provide valuable guidance for the aging-resistant design of external insulation systems and the management of aging fire risks.

外墙保温系统的保温层由于长时间暴露于紫外线辐射和温湿度循环下而逐渐退化，特别是当外层保护层受损或脱落，高分子材料暴露于外界环境时，老化过程明显加速。在这项研究中，三种常见的绝缘材料-膨胀聚苯乙烯（EPS），挤压聚苯乙烯（XPS）和硬质聚氨酯(RPU) -在模拟辐射和热效应的受控条件下进行人工加速老化。采用扫描电子显微镜（SEM）、傅里叶红外（FTIR）和热重分析等方法对老化影响化学结构的机理进行了研究。采用锥量热法对老化保温材料的着火特性、放热特性、产烟特性和气体产物毒性进行了评价。一个熵加权绝热材料火灾风险模型量化了这些老化绝热材料火灾风险的演变特征。经过150次老化循环后，EPS和XPS的点火时间均显著缩短，峰值放热率分别提高了25%和37%。老化后，在辐射热通量为50 kW/m²时，RPU的总放热量和总产烟量分别增加了27%和16%。总的来说，RPU宣布在高水平的热暴露下火灾危险显著增加。研究结果为建筑外保温系统的耐老化设计和老化火灾风险管理提供了有价值的指导。

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引用次数: 0

X-ray irradiation-induced real-time conductivity evolution and cumulative damage effects of epoxy-based shape memory polymers x射线辐照诱导环氧基形状记忆聚合物的实时电导率演化和累积损伤效应

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2025-12-15 DOI: 10.1016/j.polymdegradstab.2025.111863

Jiale Mao , Chenyang Li , Likang Zhou , Min Li , Jing Li , Shuang Wang , Yu Chen , Zicai Shen

Shape memory polymers (SMPs) for space deployable structures, as a new type of smart material, whose adaptivity to space environments plays a crucial role in ensuring the long-term stable operation of next-generation spacecraft. This study systematically investigates the real-time photoconductive response and cumulative damage effects of SMPs with varying crosslinking network architectures under X-ray irradiation. By tailoring the curing agent functionality and mass ratios, a series of SMPs are synthesized and evaluated through shape memory behavior, thermodynamic and dielectric properties, and conductivity characteristics with and without X-ray irradiation. The research emphasizes the effects of X-ray irradiation on their dielectric properties, not only examining damage effects but also closely monitoring the real-time evolution of charge transport properties during irradiation, with the influence of temperature on these properties simultaneously considered. The results demonstrate that X-ray exposure induces a sharp increase in conductivity, with an effect significantly greater than that of temperature, accompanied by a phenomenon resembling current saturation. And at high doses accumulation, leads to partial chain scission and the formation of new functional groups, indicating a simultaneous process of degradation and re-crosslinking. This work provides a foundational understanding of radiation effects on epoxy SMPs and practical guidance for their use in high-radiation environments.

空间可展开结构的形状记忆聚合物（SMPs）作为一种新型智能材料，其对空间环境的适应性对保证下一代航天器的长期稳定运行起着至关重要的作用。本研究系统地研究了具有不同交联网络结构的SMPs在x射线照射下的实时光导响应和累积损伤效应。通过调整固化剂的功能和质量比，合成了一系列smp，并通过形状记忆行为、热力学和介电性能以及在x射线照射和不照射下的电导率特性来评估smp。本研究着重研究了x射线辐照对其介电性能的影响，不仅考察了损伤效应，还密切监测了辐照过程中电荷输运性质的实时演变，同时考虑了温度对这些性质的影响。结果表明，x射线暴露诱导电导率急剧增加，其影响明显大于温度，并伴有类似电流饱和的现象。并且在高剂量积累时，导致部分链断裂并形成新的官能团，表明降解和重新交联的同时过程。这项工作为环氧树脂SMPs的辐射效应提供了基础认识，并为其在高辐射环境中的使用提供了实用指导。

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引用次数: 0

Inspired by the catalytic properties of biological enzymes: Design of bifunctional catalytic flame retardants for enhanced polyurethane flame retardancy 受生物酶催化特性的启发：设计双功能催化阻燃剂增强聚氨酯阻燃性

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2025-12-13 DOI: 10.1016/j.polymdegradstab.2025.111860

Xingyao Li, Kangcheng Xu, Lin Wang, Yulu Zhang, Zhishuai Geng, Xangmei Li, Jiyu He, Rongjie Yang

The flammability of polymers limits their use, and traditional flame-retardant approaches no longer meet modern performance needs. To address issues with metal-based flame retardants—such as poor char-forming efficiency and mismatched decomposition—we designed a metal–ligand coordination system that mimics enzymatic catalysis to regulate polyurethane degradation. Under heat, the metal centers selectively cleave weak bonds, suppressing flammable small-molecule formation and promoting the generation of high-molecular-weight, carbon-rich intermediates. These intermediates rapidly crosslink and carbonize, forming a dense char layer that shifts degradation from gasification to carbonization. As a result, (Co-ATMP)₁-co-PU reduces HRR by 69.9%, SPR by 33%, and CO₂ release by 73.4%, while increasing char yield. This catalytic strategy significantly enhances flame retardancy and improves char stability at high temperature, offering a promising route to intrinsically flame-retardant polymers.

聚合物的可燃性限制了它们的使用，传统的阻燃方法不再满足现代性能的需要。为了解决金属基阻燃剂的问题，如低成炭效率和不匹配分解，我们设计了一个金属配体配位系统，模拟酶催化来调节聚氨酯降解。在高温下，金属中心选择性地切割弱键，抑制可燃小分子的形成，促进高分子量、富碳中间体的生成。这些中间体迅速交联并碳化，形成致密的炭层，将降解从气化转变为碳化。结果表明，（CO - atmp） 1 -co-PU可使HRR降低69.9%，SPR降低33%，CO₂释放量降低73.4%，同时提高炭产率。这种催化策略显著提高了阻燃性，改善了高温下炭的稳定性，为本质阻燃聚合物提供了一条有前途的途径。

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引用次数: 0

Integrated electromagnetic shielding and flame retardancy in coated fabrics through synergistic NiZnFe2O4@MnO2/graphene aerogel and APP 通过协同NiZnFe2O4@MnO2/石墨烯气凝胶和APP在涂层织物中集成电磁屏蔽和阻燃性

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2025-12-11 DOI: 10.1016/j.polymdegradstab.2025.111859

Peiyong Ren , Xiaori Yang , Ziyu Wang , Jinwei Yang , Xiaoping Gao , Xin Jiang

With the rapid development of communication technologies, the demand for multifunctional textiles with both electromagnetic interference (EMI) shielding and flame retardancy has intensified. In this study, a graphene-based composite aerogel doped with NiZnFe₂O₄@MnO₂ core-shell microspheres (NiZnFe₂O₄@MnO₂/GA) was synthesized via hydrothermal reduction and subsequently integrated with ammonium polyphosphate (APP) into a waterborne polyurethane (WPU) matrix, which was coated onto aramid/stainless-steel textiles to produce a multifunctional fabric. Interfacial bonding was strengthened through chemical crosslinking, providing a structural basis for the integrated electromagnetic and thermal functions. The EMI shielding and flame-retardant performances of the coated fabrics were systematically evaluated to clarify their synergistic enhancement mechanisms. The three-dimensional (3D) conductive-magnetic network of the NiZnFe₂O₄@MnO₂/GA heterostructure induced strong interfacial polarization losses, achieving a total shielding effectiveness (SE_T) of 44.5 dB at only 2 wt% loading with a 77 % absorption contribution. Meanwhile, the synergy between NiZnFe₂O₄@MnO₂/GA and APP produced a dual flame-retardant mechanism by stabilizing the char layer and diluting flammable gases. The peak heat release rate (pHRR), total heat release (THR), total smoke production (TSP), and peak CO production (pCO) were reduced by 45.9 %, 53.9 %, 48.1 %, and 85.2 %, respectively, compared with pure WPU-coated fabrics. These findings provide a viable strategy for designing lightweight, flexible fabrics with integrated electromagnetic and thermal protection.

随着通信技术的飞速发展，对兼具屏蔽电磁干扰和阻燃功能的多功能纺织品的需求日益增加。在本研究中，通过水热还原合成了掺杂NiZnFe2O4@MnO2核壳微球（NiZnFe2O4@MnO2/GA）的石墨烯基复合气凝胶，随后与聚磷酸铵（APP）集成到水性聚氨酯（WPU）基体中，并将其涂覆在芳纶/不锈钢纺织品上，制成多功能织物。通过化学交联增强了界面键合，为集成电磁和热功能提供了结构基础。系统评价了涂层织物的电磁干扰屏蔽性能和阻燃性能，阐明了其协同增强机理。NiZnFe2O4@MnO2/GA异质结构的三维（3D）导磁网络诱导了强的界面极化损失，在仅2 wt%的负载下实现了44.5 dB的总屏蔽效率（SET），吸收贡献为77%。同时，NiZnFe2O4@MnO2/GA与APP协同作用产生稳定炭层和稀释可燃气体的双重阻燃机理。与纯wpu涂层织物相比，峰值放热率（pHRR）、总放热率（THR）、总产烟率（TSP）和峰值CO产量（pCO）分别降低了45.9%、53.9%、48.1%和85.2%。这些发现为设计具有集成电磁和热保护的轻质柔性织物提供了可行的策略。

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引用次数: 0

Flame retarded recycled PET foams: Comparative analysis of gas-phase and solid-phase additive performance and feasibility 阻燃再生PET泡沫：气相和固相添加剂性能和可行性的比较分析

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2025-12-11 DOI: 10.1016/j.polymdegradstab.2025.111858

Kata Enikő Decsov , Emese Győry-Slezák , Dániel Gere , Ferenc Ronkay , Béla Botond Marosfői , Sándor Lenk , Katalin Bocz

This study evaluates flame retardant formulations in recycled poly(ethylene terephthalate) (rPET) foams, focusing on processability, performance, and structure-property relationships. Microcellular foams were produced from post-industrial rPET using a CO₂-assisted batch foaming process, incorporating aluminium-tris-(diethylphosphinate) (AlPi), melamine polyphosphate (MPP), and their combination at 5 wt% loading. Morphological, thermal, flammability, mechanical, and optical properties were comprehensively assessed.

The CO₂-assisted process enabled the preparation of highly porous foams (void fraction >70 %) with fine cellular structures (average cell size ∼ 2 µm). AlPi showed superior flame retardant performance, achieving a limiting oxygen index (LOI) of 25.0 %, delayed ignition, and a 23 % reduction in peak heat release rate during cone calorimetry. Enhanced char formation containing thermally stable aluminium phosphates was confirmed via energy dispersive spectroscopy (EDS) and attenuated total reflectance infrared spectroscopy (ATR-IR) analyses. In contrast, MPP alone provided limited flame retardancy, and its combination with AlPi offered no synergistic benefit.

Mechanical performance was primarily determined by foam density, with negligible influence of flame retardant additives. The foams exhibited high crystallinity (χ > 31 %) due to strain-induced crystallisation during cell growth, contributing to enhanced thermomechanical stability. Additionally, the microcellular structure enabled excellent optical reflectivity (>90 %) in the visible spectrum, which was retained even in flame-retarded formulations.

本研究评估了再生聚对苯二甲酸乙酯（rPET）泡沫的阻燃配方，重点是可加工性、性能和结构-性能关系。以工业后的rPET为原料，采用CO₂辅助间歇发泡工艺制备微孔泡沫，其中加入三磷酸二乙基膦酸铝（AlPi），三聚氰胺聚磷酸（MPP）及其混合物，负载为5 wt%。形态，热，可燃性，机械和光学性能进行了全面评估。CO₂辅助工艺能够制备具有精细细胞结构（平均细胞尺寸~ 2 μ m）的高多孔泡沫（孔隙率>； 70%）。AlPi表现出优异的阻燃性能，达到了25.0%的极限氧指数（LOI），延迟了点火，在锥量热法中峰值放热率降低了23%。通过能量色散光谱（EDS）和衰减全反射红外光谱（ATR-IR）分析，证实了热稳定磷酸铝的增焦作用。相比之下，MPP单独提供有限的阻燃性，其与AlPi的组合没有协同效益。机械性能主要由泡沫密度决定，阻燃剂添加剂的影响可以忽略不计。由于在细胞生长过程中应变诱导的结晶，泡沫表现出高结晶度（χ > 31%），有助于增强热机械稳定性。此外，微蜂窝结构在可见光谱中具有优异的光学反射率（> 90%），即使在阻燃配方中也能保持这种反射率。

{"title":"Flame retarded recycled PET foams: Comparative analysis of gas-phase and solid-phase additive performance and feasibility","authors":"Kata Enikő Decsov , Emese Győry-Slezák , Dániel Gere , Ferenc Ronkay , Béla Botond Marosfői , Sándor Lenk , Katalin Bocz","doi":"10.1016/j.polymdegradstab.2025.111858","DOIUrl":"10.1016/j.polymdegradstab.2025.111858","url":null,"abstract":"<div><div>This study evaluates flame retardant formulations in recycled poly(ethylene terephthalate) (rPET) foams, focusing on processability, performance, and structure-property relationships. Microcellular foams were produced from post-industrial rPET using a CO₂-assisted batch foaming process, incorporating aluminium-tris-(diethylphosphinate) (AlPi), melamine polyphosphate (MPP), and their combination at 5 wt% loading. Morphological, thermal, flammability, mechanical, and optical properties were comprehensively assessed.</div><div>The CO₂-assisted process enabled the preparation of highly porous foams (void fraction >70 %) with fine cellular structures (average cell size ∼ 2 µm). AlPi showed superior flame retardant performance, achieving a limiting oxygen index (LOI) of 25.0 %, delayed ignition, and a 23 % reduction in peak heat release rate during cone calorimetry. Enhanced char formation containing thermally stable aluminium phosphates was confirmed via energy dispersive spectroscopy (EDS) and attenuated total reflectance infrared spectroscopy (ATR-IR) analyses. In contrast, MPP alone provided limited flame retardancy, and its combination with AlPi offered no synergistic benefit.</div><div>Mechanical performance was primarily determined by foam density, with negligible influence of flame retardant additives. The foams exhibited high crystallinity (χ > 31 %) due to strain-induced crystallisation during cell growth, contributing to enhanced thermomechanical stability. Additionally, the microcellular structure enabled excellent optical reflectivity (>90 %) in the visible spectrum, which was retained even in flame-retarded formulations.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"245 ","pages":"Article 111858"},"PeriodicalIF":7.4,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145760747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A P-N-B flame retardant synergistically improving fire safety and mechanical properties of ramie fabric/epoxy composites 一种协同提高苎麻/环氧复合材料防火安全性和力学性能的P-N-B阻燃剂

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2025-12-11 DOI: 10.1016/j.polymdegradstab.2025.111856

Jia-Xiang Yang, Ying-Jun Xu, Ya-Wei Zheng, Wan-Meng Song, Yun Liu

Ramie fiber-reinforced epoxy composites have high mechanical strength and outstanding corrosion resistance, and are widely used in many fields. However, ramie fiber and epoxy resin are inherently flammable, and there is an increasing focus on the flame-retardant improvement of Ramie fiber-reinforced epoxy (EP/RF) composites. In this study, an eco-friendly and higher efficient P-N-B flame retardant (denoted as DBC) was synthesized and subsequently applied to ramie fabric to impart flame retardancy of EP/RF composites. When the weight gain on ramie fabric was about 10 wt%, the limiting oxygen index of EP/RF-DBC is 32.6 %, and EP/RF-DBC has been upgraded from UL-94 No rating to UL-94 V-0 rating. Compared with EP/RF, the peak heat release rate and total heat release of EP/RF-DBC reduced by 31.9 % and 32.0 %, respectively, indicating that the introduction of DBC reduces the fire hazard of EP/RF. The presence of DBC promotes the dehydration of EP/RF into residual chars, which act as a barrier to block the exchange of heat and gas, releasing more noncombustible gases and diluting the concentration of combustible gases. In terms of mechanical properties, due to the low acidity of DBC and the presence of many amino groups in chitosan oligosaccharide, the adhesion between RF and EP is improved. The flexural strength and modulus of EP/RF-DBC are increased by 15.3 % and 32.1 %, respectively, compared with EP/RF.

苎麻纤维增强环氧复合材料具有较高的机械强度和优异的耐腐蚀性，在许多领域得到了广泛的应用。然而，苎麻纤维和环氧树脂本身具有可燃性，因此苎麻纤维增强环氧树脂（EP/RF）复合材料的阻燃性改进日益受到关注。在本研究中，合成了一种环保高效的P-N-B阻燃剂（DBC），并将其应用于苎麻织物，以增强EP/RF复合材料的阻燃性。苎麻织物增重约10 wt%时，EP/RF-DBC的极限氧指数为32.6%，EP/RF-DBC已由UL-94 No级提升至UL-94 V-0级。与EP/RF相比，EP/RF-DBC的峰值放热率和总放热率分别降低了31.9%和32.0%，表明DBC的引入降低了EP/RF的火灾危险性。DBC的存在促进EP/RF脱水成残炭，残炭作为阻挡热和气体交换的屏障，释放出更多的不燃气体，稀释了可燃气体的浓度。在力学性能方面，由于DBC的低酸度和壳聚糖中存在许多氨基，RF与EP之间的附着力得到了改善。与EP/RF相比，EP/RF- dbc的抗弯强度和模量分别提高了15.3%和32.1%。

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引用次数: 0

Breaking the strength-degradability trade-off in PET-based copolyesters via enhanced intermolecular interactions and embedding easily hydrolysable sites 通过增强分子间相互作用和嵌入易水解位点，打破pet基共聚酯的强度-降解性权衡

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2025-12-08 DOI: 10.1016/j.polymdegradstab.2025.111855

Tian Y. Liu , Wei J. Zhang , Tian C. Shi , Ze Y. Zhang , Zhi C. Zhen , Ping L. Wang , Xiu B. Yang , Dan Huang , Jun H. Ji , Ge X. Wang

Existing biodegradable plastics encounter performance limitations and degrade slowly in natural environments, especially seawater. Incorporating degradation-promoting monomers can accelerate breakdown but often weakens polymer backbone bonds and reduces crystallinity, sacrificing strength. Consequently, materials with both high strength and rapid degradability are currently missing. This study addresses this issue by enhancing intermolecular interactions in polymers to compensate for reduced mechanical strength. First, adipic acid, a long-chain aliphatic monomer, is introduced into non-degradable PET as a molecular chain flexibility regulator. Using fluorescence screening, polyethylene adipate-co-terephthalate (PEAT) with an optimal A/T ratio of 30/70, demonstrating the strongest intermolecular interactions, is selected as the base material. Glycolic (GA) and lactic (LA) acid are then incorporated as easily hydrolysable sites to synthesis PEATG and PEATL copolyesters. Despite being amorphous, these copolyesters maintain high mechanical strength (up to 70 MPa). Hydroxy acid incorporation accelerates hydrolysis, enabling rapid degradation in seawater and compost environments, especially in PEATG copolyesters. For example, after 238 days in seawater, the molecular weight of PEATG120 (69.9 MPa) drops below 10³ g mol⁻¹. After 122 days of composting, PEATG80 (58.5 MPa) and PEATL80 (61.3 MPa) achieve mineralization rates of 43.6 % and 19.1 %, respectively. This approach enables high-strength, fast-degrading materials for natural environments.

现有的可生物降解塑料在自然环境特别是海水中存在性能限制和降解缓慢的问题。加入促进降解的单体可以加速分解，但往往会削弱聚合物的主键，降低结晶度，从而牺牲强度。因此，目前缺乏具有高强度和快速降解性的材料。本研究通过增强聚合物中的分子间相互作用来弥补机械强度的降低，从而解决了这一问题。首先，将长链脂肪族单体己二酸作为分子链柔韧性调节剂引入不可降解PET中。通过荧光筛选，选择具有最强分子间相互作用的最佳A/T比为30/70的聚己二甲酸乙二醇酯（PEAT）作为基础材料。然后将乙醇酸（GA）和乳酸（LA）作为易水解位点掺入合成PEATG和PEATL共聚酯。尽管是无定形的，这些共聚酯保持高机械强度（高达70兆帕）。羟基酸的掺入加速了水解，使其能够在海水和堆肥环境中快速降解，特别是在PEATG共聚酯中。例如，在海水中浸泡238天后，PEATG120的分子量（69.9 MPa）降至103 g mol−1以下。经过122 d的堆肥处理，PEATG80 （58.5 MPa）和peat80 （61.3 MPa）的矿化率分别达到43.6%和19.1%。这种方法使高强度、快速降解的材料适用于自然环境。

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引用次数: 0

Comparative evaluation of bio-based films made of commercial PHB(V) and laboratory PHB(V) polymers produced from sugar beet pulp hydrosol 商业PHB(V)和实验室用甜菜浆纯溶胶制备PHB(V)聚合物生物基薄膜的比较评价

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2025-12-08 DOI: 10.1016/j.polymdegradstab.2025.111844

Ioanna-Georgia Athanasoulia, Philippos Tserotas, Demetres Briassoulis

Poly-(hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) fully biobased and biodegradable in various environments aliphatic polyesters, are produced by a wide range of microorganisms and renewable raw materials. The synthesis of PHB with co-polymers poly-(3-hydroxyvalerate) (HV) allows for a decrease of the glass transition and melting temperatures towards a broadened thermal processing window. Mechanical tensile properties monitoring natural ageing behaviour of either melt blending and compression moulding (MB) or solvent casting (SC) formed PHB and PHBV, with variable content of HV molar composition and molecular weight (Mw) films, of both commercial and laboratory grade (produced from sugar-beet pulp (SBP) and simulated SBP hydrosols), revealed some characteristic differences and their dependence on Mw. These macroscopic results were interpreted via Fourier transform infrared spectroscopy/attenuated total reflection (FTIR/ATR), differential scanning calorimetry (DSC) and polarised optical microscopy (POM). The variation of the ratio of absorbance in the crystalline and amorphous characteristic bands laid the basis for the quantitively determination of crystallinity index ratio (CI) dependence on the HV content and Mw, was consistent with the DSC crystallinity degree (X_c(%)). The crystallisation and melting behaviour of the laboratory and commercial PHB(V) grades, as expressed via POM, revealed the secondary crystallisation pattern predecessors. The goal was to associate the characteristics of polyhydroxyalkanoates (PHAs) with their response under industrial processing conditions.

聚（羟基丁酸酯）（PHB）和聚（3-羟基丁酸酯-co-3-羟基戊酸酯）（PHBV）是完全生物基和在各种环境下可生物降解的脂肪族聚酯，是由多种微生物和可再生原料生产的。用共聚物聚-（3-羟戊酸酯）（HV）合成PHB可以降低玻璃化转变和熔化温度，从而扩大热加工窗口。对熔融混合和压缩成型（MB）或溶剂铸造（SC）形成的PHB和PHBV的机械拉伸性能进行监测，发现商业级和实验室级（由甜菜浆（SBP）和模拟SBP水溶胶生产）的HV摩尔组成和分子量（Mw）含量不同的PHB和PHBV薄膜的一些特征差异及其对Mw的依赖。这些宏观结果通过傅里叶变换红外光谱/衰减全反射（FTIR/ATR）、差示扫描量热（DSC）和偏振光学显微镜（POM）进行了解释。晶体和非晶态特征带吸光度比值的变化为定量测定结晶度指数比值（CI）与HV含量和Mw的关系奠定了基础，与DSC结晶度（Xc(%)）相一致。实验室和商业PHB(V)等级的结晶和熔化行为，通过POM表示，揭示了二次结晶模式的前身。目的是将聚羟基烷酸酯（pha）的特性与其在工业加工条件下的反应联系起来。

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引用次数: 0

Non-destructive evaluation of thermo-oxidative aging in PP-g-MAH cable insulation using terahertz dielectric spectroscopy 使用太赫兹介电光谱无损评价PP-g-MAH电缆绝缘热氧化老化

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2025-12-08 DOI: 10.1016/j.polymdegradstab.2025.111853

Fan Yang , Xing Li , Pengbo Wang , Yanzhi Wu , Xinheng Li , Yuxin Fang , Shaohua Wang

Understanding the aging mechanisms of polypropylene (PP) cable insulation under thermal and oxidative stress is crucial for ensuring the reliable operation of power systems. Although PP insulation holds promise as an alternative to cross-linked polyethylene (XLPE), its development is still ongoing, and its long-term aging process is not yet fully understood. In this work, the thermo-oxidative aging behavior of PP cable insulation was investigated using terahertz time-domain spectroscopy (THz-TDS). Optical and dielectric responses of the aged materials were extracted from the measured time-domain spectra. The thermal, chemical, and crystallization properties of the samples were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The results show a clear decoupling between chemical oxidation and structural changes. The carbonyl index (CI) increased continuously with aging time, while crystallinity first increased and then decreased, reaching a peak at approximately 288 h. This behavior originates from a dynamic competition between recrystallization induced by chain scission and the degradation of existing crystalline regions. Both the real (ε′) and imaginary (ε″) components of the terahertz dielectric response closely followed the changes in crystallinity, rather than the steady increase in CI. A strong linear relationship (R² = 0.85) was established between ε′ and the crystallinity measured by XRD. These results suggest that the terahertz dielectric response of PP-g-MAH during aging is mainly influenced by structural changes rather than changes in chemical polarity. This finding not only provides new insights into the interaction mechanisms between terahertz waves and polymers but also offers a solid theoretical basis for developing non-destructive terahertz methods to assess the insulation performance of polymer materials.

了解聚丙烯（PP）电缆绝缘在热氧化应力作用下的老化机理对保证电力系统的可靠运行至关重要。尽管PP绝缘材料有望成为交联聚乙烯（XLPE）的替代品，但其开发仍在进行中，其长期老化过程尚未完全了解。本文利用太赫兹时域光谱（THz-TDS）研究了PP电缆绝缘的热氧化老化行为。从测量的时域光谱中提取了老化材料的光学和介电响应。采用傅里叶变换红外光谱（FTIR）、x射线衍射（XRD）和差示扫描量热法（DSC）对样品的热、化学和结晶性能进行了表征。结果表明化学氧化与结构变化之间存在明显的解耦关系。随着时效时间的延长，羰基指数（CI）不断增加，结晶度先升高后降低，在288h左右达到峰值。这种行为源于链断裂引起的再结晶与现有晶区的降解之间的动态竞争。太赫兹介电响应的实（ε′）和虚（ε″）分量都密切跟随结晶度的变化，而不是CI的稳定增加。ε′与XRD测得的结晶度呈明显的线性关系（R²= 0.85）。这些结果表明，老化过程中PP-g-MAH的太赫兹介电响应主要受结构变化而不是化学极性变化的影响。这一发现不仅为太赫兹波与聚合物之间的相互作用机制提供了新的见解，而且为开发非破坏性太赫兹方法来评估聚合物材料的绝缘性能提供了坚实的理论基础。

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引用次数: 0

Chemical upcycling of complex PET waste: Upcycling of milder reaction conditions and use for polyurethane as added-value product 复杂PET废弃物的化学升级利用：温和反应条件的升级利用和聚氨酯的增值产品利用

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2025-12-08 DOI: 10.1016/j.polymdegradstab.2025.111852

Miriam Paola Barrera Nava , María Dolores de Dios Caputto , Rodrigo Navarro , Alberto Fernández Torres , Antonio Martínez-Richa , Ángel Marcos-Fernández

This study presents an efficient chemical upcycling route for complex poly(ethylene terephthalate) (PET) waste, including post-consumer bottles, thermoform PET, and the glycolysed monomer bis(2-hydroxyethyl) terephthalate (BHET), transforming them into liquid polyols for the synthesis of polyurethanes. The strategy is based on a catalysed solvolysis using ethylene carbonate (EC) as both a reagent and solvent, operating under mild conditions and at atmospheric pressure. A systematic screening demonstrated that caesium carbonate (Cs₂CO₃) is more efficient catalyst than KOH, as it minimises the hydrolysis of carbonate groups, thereby yielding polyols with a higher content of these valuable units. Kinetic studies revealed the critical importance of reaction time and the transition from a heterogeneous to a solvated and highly swollen polymer state.

The resulting polyols, with controlled molecular weights in the range of 1000–2500 g/mol —appropriate for use as soft segments— were successfully employed in the synthesis of polyurethanes. The final materials exhibited high molecular weights and thermal properties that correlate with the chemical composition of the precursor polyol, validating this methodology as a versatile and sustainable alternative to advance towards a circular economy.

本研究为复杂的聚对苯二甲酸乙酯（PET）废物提供了一种有效的化学升级回收途径，包括消费后的瓶子，热成型PET和糖水解单体双（2-羟乙基）对苯二甲酸乙酯（bet），将它们转化为用于合成聚氨酯的液体多元醇。该策略基于催化溶剂分解，使用碳酸乙烯（EC）作为试剂和溶剂，在温和条件下和常压下操作。系统筛选表明，碳酸铯（Cs2CO3）是比KOH更有效的催化剂，因为它可以最大限度地减少碳酸基的水解，从而产生具有更高含量这些有价值单位的多元醇。动力学研究揭示了反应时间的重要性，以及从非均相到溶剂化和高度膨胀的聚合物状态的转变。所得到的多元醇，其分子量控制在1000 - 2500g /mol范围内，适合用作软段，成功地用于聚氨酯的合成。最终材料表现出与前体多元醇的化学成分相关的高分子量和热性能，验证了这种方法作为一种多功能和可持续的替代方案，可以推进循环经济。

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引用次数: 0