Polymer Degradation and Stability最新文献_第7页

On the resistance of PEKK to degradation during multiple recycling cycles for additive manufacturing 增材制造中PEKK在多次循环中的抗降解性能研究

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2026-04-01 Epub Date: 2026-01-20 DOI: 10.1016/j.polymdegradstab.2026.111951

F. Malekpour , M. Hojjati

The recyclability of high-performance poly(ether ketone) (PEKK) is critical for sustainable additive manufacturing and future in-space resource utilization. This study systematically evaluates the thermal, mechanical, and chemical stability of PEKK subjected to multiple recycling loops to elucidate potential degradation mechanisms. Thermogravimetric analysis revealed negligible (<1%) mass loss after 5 h of isothermal exposure below 450 °C, confirming the polymer’s excellent thermal resistance under extrusion and printing conditions. Cyclic differential scanning calorimetry (DSC) demonstrated stable melting and cold-crystallization behavior across six thermal cycles, indicating preserved crystallization kinetics. Tensile testing showed that the amorphous strength remained within 83–91 MPa across all cycles, while annealed samples maintained strengths of 102–116 MPa. Flexural strength similarly remained consistent, ranging from 112 to 127 MPa (amorphous) and 147–160 MPa (annealed), and dynamic mechanical analysis (DMA) results indicated minimal changes in viscoelastic properties. Together, these mechanical and thermomechanical analyses confirm that PEKK retains its structural integrity after three complete recycling sequences involving shredding, pulverization, extrusion, and reprinting. Fourier transform infrared spectroscopy detected no new carbonyl or hydroxyl bands, excluding oxidative chain scission, while X-ray fluorescence (XRF) revealed only trace (<0.5 wt%) metallic contamination. Scanning electron microscopy (SEM) of fracture surfaces further confirmed well-fused interlayer morphology and minimal porosity evolution. Collectively, these results demonstrate that PEKK maintains its molecular and microstructural integrity during repeated thermal–mechanical cycles, highlighting its exceptional thermal-oxidative stability and its suitability for circular, high-performance, and extended-lifetime polymer applications.

高性能聚醚酮（PEKK）的可回收性对于可持续增材制造和未来空间资源利用至关重要。本研究系统地评估了PEKK在多次循环下的热、力学和化学稳定性，以阐明潜在的降解机制。热重分析显示，在低于450°C的等温暴露5小时后，质量损失可以忽略不计（<1%），证实了该聚合物在挤压和印刷条件下具有优异的耐热性。循环差示扫描量热法（DSC）在6个热循环中显示出稳定的熔融和冷结晶行为，表明结晶动力学保持不变。拉伸试验表明，在所有循环过程中，非晶态强度保持在83 ~ 91 MPa之间，而退火后的非晶态强度保持在102 ~ 116 MPa之间。弯曲强度同样保持一致，范围从112到127兆帕（非晶）和147-160兆帕（退火），动态力学分析（DMA）结果表明粘弹性性能变化很小。总之，这些机械和热机械分析证实，PEKK在粉碎、粉碎、挤压和重印三个完整的回收过程后，仍保持其结构完整性。傅里叶变换红外光谱未检测到新的羰基或羟基带，不包括氧化链断裂，而x射线荧光（XRF）仅显示微量（<0.5 wt%）金属污染。断口表面的扫描电镜进一步证实了层间形态融合良好，孔隙度演化最小。总的来说，这些结果表明，PEKK在重复的热机械循环中保持了其分子和微观结构的完整性，突出了其卓越的热氧化稳定性，以及其适用于圆形、高性能和延长寿命的聚合物应用。

{"title":"On the resistance of PEKK to degradation during multiple recycling cycles for additive manufacturing","authors":"F. Malekpour , M. Hojjati","doi":"10.1016/j.polymdegradstab.2026.111951","DOIUrl":"10.1016/j.polymdegradstab.2026.111951","url":null,"abstract":"<div><div>The recyclability of high-performance poly(ether ketone) (PEKK) is critical for sustainable additive manufacturing and future in-space resource utilization. This study systematically evaluates the thermal, mechanical, and chemical stability of PEKK subjected to multiple recycling loops to elucidate potential degradation mechanisms. Thermogravimetric analysis revealed negligible (<1%) mass loss after 5 h of isothermal exposure below 450 °C, confirming the polymer’s excellent thermal resistance under extrusion and printing conditions. Cyclic differential scanning calorimetry (DSC) demonstrated stable melting and cold-crystallization behavior across six thermal cycles, indicating preserved crystallization kinetics. Tensile testing showed that the amorphous strength remained within 83–91 MPa across all cycles, while annealed samples maintained strengths of 102–116 MPa. Flexural strength similarly remained consistent, ranging from 112 to 127 MPa (amorphous) and 147–160 MPa (annealed), and dynamic mechanical analysis (DMA) results indicated minimal changes in viscoelastic properties. Together, these mechanical and thermomechanical analyses confirm that PEKK retains its structural integrity after three complete recycling sequences involving shredding, pulverization, extrusion, and reprinting. Fourier transform infrared spectroscopy detected no new carbonyl or hydroxyl bands, excluding oxidative chain scission, while X-ray fluorescence (XRF) revealed only trace (<0.5 wt%) metallic contamination. Scanning electron microscopy (SEM) of fracture surfaces further confirmed well-fused interlayer morphology and minimal porosity evolution. Collectively, these results demonstrate that PEKK maintains its molecular and microstructural integrity during repeated thermal–mechanical cycles, highlighting its exceptional thermal-oxidative stability and its suitability for circular, high-performance, and extended-lifetime polymer applications.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"246 ","pages":"Article 111951"},"PeriodicalIF":7.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035632","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

Effect of isocyanate structure on bio-based poly(diethylene furanoate)-b- poly(caprolactone) thermoplastic polyurethanes 异氰酸酯结构对生物基聚呋喃二酯-b-聚己内酯热塑性聚氨酯的影响

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2026-04-01 Epub Date: 2026-01-06 DOI: 10.1016/j.polymdegradstab.2026.111929

Judit Rebeka Molnár, Yu-I Hsu, Hiroshi Uyama

Thermoplastic polyurethane elastomers combine the durability and toughness of thermoplastics with the elasticity of rubber. Since most conventional polyurethanes are fossil-based, the development of sustainable alternatives is essential. While the composition and phase separation have been explored extensively, only a few reports have systematically examined the effect of isocyanate type on polyurethanes. In this work, bio-based poly(diethylene furanoate)-b-poly(caprolactone) (PDEF-b-PCL) copolymers were synthesized, where diisocyanates with three different structures were used as a chain-extender: methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and dicyclohexylmethane 4,4′-diisocyanate (H12MDI) to systematically evaluate how their structure affects the structure–property relationships of the resulting copolymers. DSC and DMA confirmed that the copolymers exhibited dual-phase transitions, indicating that they consisted of a crystalline phase formed by PCL and an amorphous phase comprising PCL and PDEF. Structural analysis revealed that crystallinity was governed by PCL content and was highest in HDI-based samples, which was the most mobile among the isocyanates. For PDEF, due to its amorphous structure, the tensile properties were mainly influenced by the structure of the isocyanate. The copolymers exhibited enhanced elongation at break compared to the homopolymers, reaching up to 2372 ± 340%, attributed to strain hardening of the PCL crystalline domains and the amorphous PDEF segments acting as physical crosslinks that distributed stress. Some of the copolymers achieved superior toughness up to 233 MJ/m³, compared to both PCL and PDEF homopolymers. The incorporation of PDEF significantly improved thermal stability with higher T_d,max values, and all copolymers showed higher T_d,5% compared to their homopolymer counterparts.

热塑性聚氨酯弹性体结合了热塑性塑料的耐用性和韧性与橡胶的弹性。由于大多数传统聚氨酯是基于化石的，因此开发可持续的替代品至关重要。虽然组成和相分离已被广泛探讨，只有少数报告系统地研究了异氰酸酯类型对聚氨酯的影响。在本研究中，合成了生物基聚（二乙烯呋喃酸酯）-b-聚己内酯（pdefb - pcl）共聚物，其中使用三种不同结构的二异氰酸酯作为扩链剂：亚甲基二苯基二异氰酸酯（MDI）、六亚乙烯二异氰酸酯（HDI）和二环己基甲烷4,4 ' -二异氰酸酯（H12MDI），系统地评价了它们的结构如何影响所得共聚物的结构-性能关系。DSC和DMA证实共聚物表现出双相转变，表明它们由PCL形成的结晶相和由PCL和PDEF组成的非晶相组成。结构分析表明，结晶度受PCL含量的影响，在hdi基样品中结晶度最高，在异氰酸酯中流动性最强。对于PDEF，由于其无定形结构，其拉伸性能主要受异氰酸酯结构的影响。与均聚物相比，共聚物的断裂伸长率更高，达到2372±340%，这是由于PCL晶体域的应变硬化和无定形PDEF片段作为物理交联来分布应力。与PCL和PDEF均聚物相比，一些共聚物的韧性高达233 MJ/m3。PDEF的加入显著提高了热稳定性，具有更高的Td，max值，所有共聚物的Td值都比均聚物高5%。

{"title":"Effect of isocyanate structure on bio-based poly(diethylene furanoate)-b- poly(caprolactone) thermoplastic polyurethanes","authors":"Judit Rebeka Molnár, Yu-I Hsu, Hiroshi Uyama","doi":"10.1016/j.polymdegradstab.2026.111929","DOIUrl":"10.1016/j.polymdegradstab.2026.111929","url":null,"abstract":"<div><div>Thermoplastic polyurethane elastomers combine the durability and toughness of thermoplastics with the elasticity of rubber. Since most conventional polyurethanes are fossil-based, the development of sustainable alternatives is essential. While the composition and phase separation have been explored extensively, only a few reports have systematically examined the effect of isocyanate type on polyurethanes. In this work, bio-based poly(diethylene furanoate)-b-poly(caprolactone) (PDEF-b-PCL) copolymers were synthesized, where diisocyanates with three different structures were used as a chain-extender: methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and dicyclohexylmethane 4,4′-diisocyanate (H12MDI) to systematically evaluate how their structure affects the structure–property relationships of the resulting copolymers. DSC and DMA confirmed that the copolymers exhibited dual-phase transitions, indicating that they consisted of a crystalline phase formed by PCL and an amorphous phase comprising PCL and PDEF. Structural analysis revealed that crystallinity was governed by PCL content and was highest in HDI-based samples, which was the most mobile among the isocyanates. For PDEF, due to its amorphous structure, the tensile properties were mainly influenced by the structure of the isocyanate. The copolymers exhibited enhanced elongation at break compared to the homopolymers, reaching up to 2372 ± 340%, attributed to strain hardening of the PCL crystalline domains and the amorphous PDEF segments acting as physical crosslinks that distributed stress. Some of the copolymers achieved superior toughness up to 233 MJ/m<sup>3</sup>, compared to both PCL and PDEF homopolymers. The incorporation of PDEF significantly improved thermal stability with higher T<sub>d,max</sub> values, and all copolymers showed higher T<sub>d,5%</sub> compared to their homopolymer counterparts.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"246 ","pages":"Article 111929"},"PeriodicalIF":7.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974645","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

Oxygen vacancy–driven redox mechanisms for enhanced thermo-oxidative stability of silicone rubber with Fe2O3, CeO2, and CeZrO2 Fe2O3、CeO2和CeZrO2增强硅橡胶热氧化稳定性的氧空位驱动氧化还原机制

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2026-04-01 Epub Date: 2026-01-07 DOI: 10.1016/j.polymdegradstab.2026.111927

Hyeon Woo Jeong, Hye In Kang, Jaewon Lee, Sang Eun Shim

The thermal degradation of silicone rubber in high-temperature oxidative environments remains a critical challenge, yet the mechanistic role of oxygen vacancy engineering in cerium-based stabilizers has not been systematically explored. This study demonstrates that CeO₂ and CeZrO₂ (HRA-01) achieve superior stabilization through oxygen vacancy–mediated Ce³⁺/Ce⁴⁺ redox cycling that couples radical scavenging with dynamic oxygen buffering, with zirconium incorporation further enhancing oxygen vacancy density and mobility. Consequently, under harsh aging at 250 °C for 200 h, whereas pristine PDMS exhibited catastrophic toughness loss (∼98.5 %) and Fe₂O₃ composites offered only partial mitigation (81–98.5 % loss), CeO₂-filled and HRA-01 composites retained markedly higher toughness, limiting losses to 42–54 % and 40–50 %, respectively. Thermogravimetric analysis showed nearly constant residues for CeO₂ and HRA-01 (31–32 %), in sharp contrast to the substantial increases in pristine and Fe₂O₃ systems. Beyond performance metrics, we elucidate the oxygen-vacancy-mediated stabilization mechanism: vacancy-enabled Ce³⁺/Ce⁴⁺ redox cycling couples rapid radical scavenging with dynamic oxygen buffering, additionally, Zr incorporation increases vacancy density and mobility to suppress thermo-oxidative chain scission and uncontrolled crosslinking. These findings establish CeZrO₂ as a next-generation stabilizer that will contribute to enhanced durability and extended service lifetimes of silicone rubbers in demanding industrial applications.

硅橡胶在高温氧化环境下的热降解仍然是一个严峻的挑战，但氧空位工程在铈基稳定剂中的作用机理尚未得到系统的探讨。该研究表明，CeO 2和CeZrO 2 （HRA-01）通过氧空位介导的Ce + /Ce⁴+氧化还原循环实现了优异的稳定性，该循环将自由基清除与动态氧缓冲结合在一起，锆的掺入进一步增强了氧空位密度和迁移率。因此，在250°C 200 h的苛刻时效下，原始PDMS表现出灾难性的韧性损失（~ 98.5%），Fe₂O₃复合材料只提供部分缓解（81 - 98.5%），而填充CeO₂和HRA-01复合材料保留了明显更高的韧性，分别将损失限制在42 - 54%和40 - 50%。热重分析显示，CeO₂和HRA-01的残留量几乎不变（31 - 32%），与原始和Fe₂O₃系统的大量增加形成鲜明对比。除了性能指标之外，我们阐明了氧空位介导的稳定机制：空位激活的Ce + /Ce⁴氧化还原循环对动态氧缓冲的快速自由基清除，此外，Zr掺入增加了空位密度和迁移率，以抑制热氧化链断裂和不受控制的交联。这些发现确定了CeZrO₂作为下一代稳定剂，将有助于提高硅橡胶在苛刻的工业应用中的耐用性和延长使用寿命。

{"title":"Oxygen vacancy–driven redox mechanisms for enhanced thermo-oxidative stability of silicone rubber with Fe2O3, CeO2, and CeZrO2","authors":"Hyeon Woo Jeong, Hye In Kang, Jaewon Lee, Sang Eun Shim","doi":"10.1016/j.polymdegradstab.2026.111927","DOIUrl":"10.1016/j.polymdegradstab.2026.111927","url":null,"abstract":"<div><div>The thermal degradation of silicone rubber in high-temperature oxidative environments remains a critical challenge, yet the mechanistic role of oxygen vacancy engineering in cerium-based stabilizers has not been systematically explored. This study demonstrates that CeO₂ and CeZrO₂ (HRA-01) achieve superior stabilization through oxygen vacancy–mediated Ce³⁺/Ce⁴⁺ redox cycling that couples radical scavenging with dynamic oxygen buffering, with zirconium incorporation further enhancing oxygen vacancy density and mobility. Consequently, under harsh aging at 250 °C for 200 h, whereas pristine PDMS exhibited catastrophic toughness loss (∼98.5 %) and Fe₂O₃ composites offered only partial mitigation (81–98.5 % loss), CeO₂-filled and HRA-01 composites retained markedly higher toughness, limiting losses to 42–54 % and 40–50 %, respectively. Thermogravimetric analysis showed nearly constant residues for CeO₂ and HRA-01 (31–32 %), in sharp contrast to the substantial increases in pristine and Fe₂O₃ systems. Beyond performance metrics, we elucidate the oxygen-vacancy-mediated stabilization mechanism: vacancy-enabled Ce³⁺/Ce⁴⁺ redox cycling couples rapid radical scavenging with dynamic oxygen buffering, additionally, Zr incorporation increases vacancy density and mobility to suppress thermo-oxidative chain scission and uncontrolled crosslinking. These findings establish CeZrO₂ as a next-generation stabilizer that will contribute to enhanced durability and extended service lifetimes of silicone rubbers in demanding industrial applications.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"246 ","pages":"Article 111927"},"PeriodicalIF":7.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974647","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

Tough and biodegradable lactate (LA)-based polyester (LAHB) hyperproduced by reinforcing LA-polymerizing enzyme gene expression 通过增强乳酸聚合酶基因表达而产生的坚韧可生物降解乳酸基聚酯（LAHB）

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2026-04-01 Epub Date: 2025-12-31 DOI: 10.1016/j.polymdegradstab.2025.111910

Sangho Koh , Furutate Sho , Yusuke Imai , Shunsuke Sato , Seiichi Taguchi

Poly[(d-lactate)-co-(R)-3-hydroxybutyrate] (LAHB) is a microbial copolyester that exhibits excellent environmental biodegradability. LAHB also functions as a multifunctional modifier that markedly improves both the mechanical properties and biodegradability of non-biodegradable poly(l-lactide) (PLLA). The lactate (LA) fraction is a key determinant governing the material properties of LAHB as well as its d-LA-l-LA-mediated interactions with PLLA. Then, in this study, we attempted to reinforce the gene expression of lactate-polymerizing enzyme (LPE) in the recombinant strain of Cupriavidus necator that was plausibly to be a rate-limiting factor for LA-unit incorporation. Expectedly, with the improved LA fraction, high-cell-density cultivation of the engineered strain GSXd147 synergistically achieved 97 g L⁻¹ dry cell weight and 70 wt% LAHB within 48 h from glucose—the highest LAHB titer and productivity reported to date. It should be noted that the resulting LA-enriched LAHB retained a high-molecular weight (15 mol% LA, M_w 30 × 10⁴) and consequently exhibited a well-balanced combination of strength and elongation, yielding overall toughness comparable to the petroleum-based polyethylene.

聚[（d-乳酸）-co-(R)-3-羟基丁酸酯]（LAHB）是一种微生物共聚聚酯，具有良好的环境生物降解性。LAHB还可以作为多功能改性剂，显著改善非生物降解聚l-丙交酯（PLLA）的力学性能和生物降解性。乳酸（LA）部分是控制LAHB材料性能以及其与PLLA介导的相互作用的关键决定因素。然后，在本研究中，我们试图加强乳酸聚合酶（LPE）基因在重组菌株Cupriavidus necator中的表达，这可能是LA-unit掺入的限速因素。预料中，随着LA分数的提高，高密度培养的工程菌株GSXd147在48小时内协同达到97 g L - 1干细胞重和70 wt%的LAHB，这是迄今为止报道的最高的LAHB滴度和生产力。值得注意的是，最终得到的富含LA的LAHB保持了高分子量（15 mol% LA, Mw 30 × 104），因此表现出良好的强度和伸长率组合，其整体韧性可与石油基聚乙烯相媲美。

{"title":"Tough and biodegradable lactate (LA)-based polyester (LAHB) hyperproduced by reinforcing LA-polymerizing enzyme gene expression","authors":"Sangho Koh , Furutate Sho , Yusuke Imai , Shunsuke Sato , Seiichi Taguchi","doi":"10.1016/j.polymdegradstab.2025.111910","DOIUrl":"10.1016/j.polymdegradstab.2025.111910","url":null,"abstract":"<div><div>Poly[(<span>d</span>-lactate)-<em>co</em>-(<em>R</em>)-3-hydroxybutyrate] (LAHB) is a microbial copolyester that exhibits excellent environmental biodegradability. LAHB also functions as a multifunctional modifier that markedly improves both the mechanical properties and biodegradability of non-biodegradable poly(<span>l</span>-lactide) (PLLA). The lactate (LA) fraction is a key determinant governing the material properties of LAHB as well as its <span>d</span>-LA-<span>l</span>-LA-mediated interactions with PLLA. Then, in this study, we attempted to reinforce the gene expression of lactate-polymerizing enzyme (LPE) in the recombinant strain of <em>Cupriavidus necator</em> that was plausibly to be a rate-limiting factor for LA-unit incorporation. Expectedly, with the improved LA fraction, high-cell-density cultivation of the engineered strain GSXd147 synergistically achieved 97 g L⁻¹ dry cell weight and 70 wt% LAHB within 48 h from glucose—the highest LAHB titer and productivity reported to date. It should be noted that the resulting LA-enriched LAHB retained a high-molecular weight (15 mol% LA, <em>M</em><sub>w</sub> 30 × 10<sup>4</sup>) and consequently exhibited a well-balanced combination of strength and elongation, yielding overall toughness comparable to the petroleum-based polyethylene.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"246 ","pages":"Article 111910"},"PeriodicalIF":7.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974651","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

Unveiling the role of localized secondary crystallization in poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) aging and its effective reversal via annealing 揭示了局部二次结晶在聚（3-羟基丁酸-co-3-羟基己酸）时效过程中的作用及其退火过程的有效逆转

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2026-04-01 Epub Date: 2026-01-20 DOI: 10.1016/j.polymdegradstab.2026.111950

Pengwu Xu , Yongchun Mo , Jiale Liu , Weijun Yang , Yunsheng Xu , Deyu Niu , Piming Ma

Polyhydroxyalkanoates (PHAs) represent promising biodegradable and biocompatible materials for packaging and biomedical applications, yet their practical implementation is hindered by mechanical deterioration during storage. This study elucidates the aging mechanism of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) through systematic investigation of its room-temperature structural evolution. We demonstrate that localized secondary crystallization in amorphous regions, while minimally increasing overall crystallinity (<1%), fundamentally limits chain mobility by elevating the rigid amorphous fraction and glass transition temperature (T_g), ultimately inducing embrittlement. Crucially, we provide the first direct evidence of this structural ordering through decreased small-angle X-ray scattering invariant (Q) values, confirming low-density secondary crystal formation. Remarkably, annealing above T_g effectively reverses aging by eliminating secondary crystals while promoting lamellar thickening and amorphous region homogenization. The consequent narrowing of long-period distribution facilitates uniform stress transfer, enabling simultaneous recovery of strength and toughness: elongation at break recovers from 2.9% to 10.3% alongside tensile strength improvement from 21.9 MPa to 37.8 MPa. These findings establish both a fundamental understanding of PHBH aging and a practical recovery strategy, advancing its potential for sustainable applications.

聚羟基烷酸酯（PHAs）代表了包装和生物医学应用中有前途的可生物降解和生物相容性材料，但它们的实际实施受到储存过程中机械变质的阻碍。本研究通过对聚（3-羟基丁酸酯-co-3-羟基己酸酯）（PHBH）室温结构演变的系统研究，阐明了其老化机理。我们证明，在非晶态区域的局部二次结晶，虽然最低限度地增加了整体结晶度（<1%），但通过提高刚性非晶态分数和玻璃化转变温度（Tg），从根本上限制了链迁移率，最终导致脆化。至关重要的是，我们通过减小的小角度x射线散射不变量(Q)值提供了这种结构有序的第一个直接证据，证实了低密度二次晶体的形成。值得注意的是，Tg以上的退火通过消除二次晶体而有效地逆转了时效，同时促进了片层增厚和非晶区均匀化。由此产生的长周期分布的收窄有利于均匀的应力传递，使强度和韧性同时恢复：断裂伸长率从2.9%恢复到10.3%，抗拉强度从21.9 MPa提高到37.8 MPa。这些发现建立了对PHBH老化的基本理解和实际的回收策略，提高了其可持续应用的潜力。

{"title":"Unveiling the role of localized secondary crystallization in poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) aging and its effective reversal via annealing","authors":"Pengwu Xu , Yongchun Mo , Jiale Liu , Weijun Yang , Yunsheng Xu , Deyu Niu , Piming Ma","doi":"10.1016/j.polymdegradstab.2026.111950","DOIUrl":"10.1016/j.polymdegradstab.2026.111950","url":null,"abstract":"<div><div>Polyhydroxyalkanoates (PHAs) represent promising biodegradable and biocompatible materials for packaging and biomedical applications, yet their practical implementation is hindered by mechanical deterioration during storage. This study elucidates the aging mechanism of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) through systematic investigation of its room-temperature structural evolution. We demonstrate that localized secondary crystallization in amorphous regions, while minimally increasing overall crystallinity (<1%), fundamentally limits chain mobility by elevating the rigid amorphous fraction and glass transition temperature (<em>T</em><sub>g</sub>), ultimately inducing embrittlement. Crucially, we provide the first direct evidence of this structural ordering through decreased small-angle X-ray scattering invariant (<em>Q</em>) values, confirming low-density secondary crystal formation. Remarkably, annealing above <em>T</em><sub>g</sub> effectively reverses aging by eliminating secondary crystals while promoting lamellar thickening and amorphous region homogenization. The consequent narrowing of long-period distribution facilitates uniform stress transfer, enabling simultaneous recovery of strength and toughness: elongation at break recovers from 2.9% to 10.3% alongside tensile strength improvement from 21.9 MPa to 37.8 MPa. These findings establish both a fundamental understanding of PHBH aging and a practical recovery strategy, advancing its potential for sustainable applications.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"246 ","pages":"Article 111950"},"PeriodicalIF":7.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073696","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

Ionic liquid functionalized h-BN enhanced polyurethane power battery sealants 离子液体功能化h-BN增强聚氨酯动力电池密封胶

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2026-04-01 Epub Date: 2026-01-15 DOI: 10.1016/j.polymdegradstab.2026.111944

Xiongzhuang Gao, Xingyuan Ma, Xinyuan Xue, Lu Lin

With the continuous development of battery technology for new energy vehicles (NEVs), the comprehensive performance requirements for power battery sealants are growing increasingly demanding. This study proposes an innovative strategy for preparing high-performance polyurethane power battery sealants (PUSs) by introducing ionic liquid functionalized boron nitride nanosheets (IL-fhBNNS) as a multifunctional filler. [BMIM]PF₆ was used to exfoliate and functionalize h-BN via heating and stirring method, successfully yielding IL-fhBNNS with an average lateral size of 1.59 μm and a thickness of 3.77 nm. Based on polyurethane prepolymer (PUP) and IL-fhBNNS, a series of PUSs samples were successfully synthesized via the prepolymer method combined with casting molding method. The effects of the addition of IL-fhBNNS on the thermal conductivity (TC), flame retardancy, mechanical properties, adhesion and solvent resistance of sealants were investigated. Based on the comprehensive experimental results, the PUS-4 demonstrated optimal comprehensive properties. Thanks to the dense three-dimensional heat conduction network formed by IL-fhBNNS in the PU matrix, the TC of PUS-4 reached 2.701 W m^-1 K^-1, representing an increase of 963.39 % over pure PU. Meanwhile, PUS-4 exhibited excellent thermal stability and flame retardancy, significantly reducing the PHRR (265.69 kW/m²) and THR (59.09 MJ/m²) by 44.19 % and 35.70 %, respectively, and reaching the flame retardant rating of V-0 compared with pure PU. Besides, PUS-4 exhibited excellent mechanical properties, with stress and strain reaching 43.98 MPa and 550.16 %, respectively. PUS-4 also showed satisfactory adhesive performance solvent resistance. The lap shear force of PUS-4 on steel substrates reached 3382.56 N. Therefore, PUSs demonstrate great application potential in addressing the challenges of thermal management and sealing in power batteries.

随着新能源汽车电池技术的不断发展，对动力电池密封胶的综合性能要求越来越高。本研究通过引入离子液体功能化氮化硼纳米片（IL-fhBNNS）作为多功能填料，提出了制备高性能聚氨酯动力电池密封胶（PUSs）的创新策略。[BMIM]PF6通过加热搅拌的方法对h-BN进行剥离和功能化，成功制备出平均横向尺寸为1.59 μm、厚度为3.77 nm的IL-fhBNNS。以聚氨酯预聚体（PUP）和IL-fhBNNS为基础，通过预聚体法和浇铸成型法相结合，成功合成了一系列PUSs样品。研究了IL-fhBNNS的加入对密封胶导热性、阻燃性、力学性能、附着力和耐溶剂性的影响。综合实验结果表明，pu -4具有最佳的综合性能。由于IL-fhBNNS在PU基体中形成致密的三维热传导网络，PU -4的TC达到2.701 W m-1 K-1，比纯PU提高了963.39%。同时，PU -4表现出优异的热稳定性和阻燃性，与纯PU相比，其PHRR （265.69 kW/m2）和THR （59.09 MJ/m2）分别显著降低44.19%和35.70%，阻燃等级达到V-0。此外，pu -4具有优异的力学性能，应力和应变分别达到43.98 MPa和550.16%。pus4也表现出良好的粘接性能。PUSs -4在钢基板上的剪切力达到3382.56 N.因此，PUSs在解决动力电池的热管理和密封挑战方面显示出巨大的应用潜力。

{"title":"Ionic liquid functionalized h-BN enhanced polyurethane power battery sealants","authors":"Xiongzhuang Gao, Xingyuan Ma, Xinyuan Xue, Lu Lin","doi":"10.1016/j.polymdegradstab.2026.111944","DOIUrl":"10.1016/j.polymdegradstab.2026.111944","url":null,"abstract":"<div><div>With the continuous development of battery technology for new energy vehicles (NEVs), the comprehensive performance requirements for power battery sealants are growing increasingly demanding. This study proposes an innovative strategy for preparing high-performance polyurethane power battery sealants (PUSs) by introducing ionic liquid functionalized boron nitride nanosheets (IL-fhBNNS) as a multifunctional filler. [BMIM]PF<sub>6</sub> was used to exfoliate and functionalize h-BN via heating and stirring method, successfully yielding IL-fhBNNS with an average lateral size of 1.59 μm and a thickness of 3.77 nm. Based on polyurethane prepolymer (PUP) and IL-fhBNNS, a series of PUSs samples were successfully synthesized via the prepolymer method combined with casting molding method. The effects of the addition of IL-fhBNNS on the thermal conductivity (TC), flame retardancy, mechanical properties, adhesion and solvent resistance of sealants were investigated. Based on the comprehensive experimental results, the PUS-4 demonstrated optimal comprehensive properties. Thanks to the dense three-dimensional heat conduction network formed by IL-fhBNNS in the PU matrix, the TC of PUS-4 reached 2.701 W m<sup>-1</sup> K<sup>-1</sup>, representing an increase of 963.39 % over pure PU. Meanwhile, PUS-4 exhibited excellent thermal stability and flame retardancy, significantly reducing the PHRR (265.69 kW/m<sup>2</sup>) and THR (59.09 MJ/m<sup>2</sup>) by 44.19 % and 35.70 %, respectively, and reaching the flame retardant rating of V-0 compared with pure PU. Besides, PUS-4 exhibited excellent mechanical properties, with stress and strain reaching 43.98 MPa and 550.16 %, respectively. PUS-4 also showed satisfactory adhesive performance solvent resistance. The lap shear force of PUS-4 on steel substrates reached 3382.56 N. Therefore, PUSs demonstrate great application potential in addressing the challenges of thermal management and sealing in power batteries.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"246 ","pages":"Article 111944"},"PeriodicalIF":7.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035625","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

Enhanced dispersion stability of gold nanoparticles with injectable thermoresponsive poly(l-lactide-co-ε-caprolactone)-b-poly(ethylene glycol)-b-poly(l-lactide-co-ε-caprolactone) hydrogels 热响应型聚（l-丙交酯-co-ε-己内酯）-b-聚乙二醇-b-聚（l-丙交酯-co-ε-己内酯）水凝胶增强金纳米颗粒的分散稳定性

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2026-04-01 Epub Date: 2026-01-08 DOI: 10.1016/j.polymdegradstab.2026.111933

Jiahui Dong, Yu-I Hsu, Hiroshi Uyama

Amphiphilic block copolymers are widely used to construct thermoresponsive micellar systems with injectable sol-gel transition behavior, making them promising candidates for biomedical applications. In this study, poly(l-lactide-co-ε-caprolactone)-b-poly(ethylene glycol)-b-poly(l-lactide-co-ε-caprolactone) (PLCL-PEG-PLCL) triblock copolymers were employed to fabricate micelles and micelle-AuNP hybrids. AuNPs were incorporated through two distinct strategies, direct aqueous mixing and THF-induced micellization, resulting in different spatial distributions. Spectroscopic and rheological analyses revealed that corona-associated AuNPs hindered micelle association and delayed gelation, whereas core-encapsulated AuNPs preserved the intrinsic thermo-responsive behavior. In addition, micelle formation significantly enhanced the stability of AuNPs under freezing, lyophilization, and heating conditions. These results demonstrate that controlling AuNPs localization within PLCL-PEG-PLCL micelles offers an effective strategy to tune optical response, rheology, and stability, providing a versatile platform for photothermally active injectable hydrogels.

两亲嵌段共聚物被广泛用于构建具有可注射溶胶-凝胶过渡行为的热响应胶束体系，使其成为生物医学应用的有希望的候选者。本研究采用聚（l-丙交酯-co-ε-己内酯）-b-聚乙二醇-b-聚（l-丙交酯-co-ε-己内酯）（PLCL-PEG-PLCL）三嵌段共聚物制备胶束和胶束- aunp杂化物。通过两种不同的策略，直接水混合和thf诱导胶束，AuNPs被纳入，导致不同的空间分布。光谱和流变学分析表明，冠状相关的AuNPs阻碍了胶束结合和延迟凝胶化，而核包裹的AuNPs保留了固有的热响应行为。此外，胶束的形成显著增强了AuNPs在冷冻、冻干和加热条件下的稳定性。这些结果表明，在PLCL-PEG-PLCL胶束中控制AuNPs的定位提供了一种有效的策略来调节光学响应、流变学和稳定性，为光热活性可注射水凝胶提供了一个通用的平台。

{"title":"Enhanced dispersion stability of gold nanoparticles with injectable thermoresponsive poly(l-lactide-co-ε-caprolactone)-b-poly(ethylene glycol)-b-poly(l-lactide-co-ε-caprolactone) hydrogels","authors":"Jiahui Dong, Yu-I Hsu, Hiroshi Uyama","doi":"10.1016/j.polymdegradstab.2026.111933","DOIUrl":"10.1016/j.polymdegradstab.2026.111933","url":null,"abstract":"<div><div>Amphiphilic block copolymers are widely used to construct thermoresponsive micellar systems with injectable sol-gel transition behavior, making them promising candidates for biomedical applications. In this study, poly(l-lactide-co-ε-caprolactone)-b-poly(ethylene glycol)-b-poly(l-lactide-co-ε-caprolactone) (PLCL-PEG-PLCL) triblock copolymers were employed to fabricate micelles and micelle-AuNP hybrids. AuNPs were incorporated through two distinct strategies, direct aqueous mixing and THF-induced micellization, resulting in different spatial distributions. Spectroscopic and rheological analyses revealed that corona-associated AuNPs hindered micelle association and delayed gelation, whereas core-encapsulated AuNPs preserved the intrinsic thermo-responsive behavior. In addition, micelle formation significantly enhanced the stability of AuNPs under freezing, lyophilization, and heating conditions. These results demonstrate that controlling AuNPs localization within PLCL-PEG-PLCL micelles offers an effective strategy to tune optical response, rheology, and stability, providing a versatile platform for photothermally active injectable hydrogels.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"246 ","pages":"Article 111933"},"PeriodicalIF":7.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035626","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

Molecularly engineered PBS/FDCA copolymers: Balancing strength, degradability, and osteoinductivity for sustainable bone scaffolds 分子工程PBS/FDCA共聚物：平衡强度，可降解性和可持续骨支架的骨诱导性

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2026-04-01 Epub Date: 2026-01-05 DOI: 10.1016/j.polymdegradstab.2026.111922

Zheng Li , Zhixuan Li , Sichao Yu , Xuan Yao , Guosheng Wang , Dayin Sun , Jie Zhang , Na Wang

Polybutylene succinate (PBS) is a biodegradable polyester with good biocompatibility and processability, yet its relatively low mechanical strength, slow degradation, and limited bioactivity hinder its use in osteogenic scaffolds. To address these limitations, and inspired by the nacreous “brick-and-mortar” structure of marine shells, this study incorporated bio-based 2,5-furandicarboxylic acid (FDCA) into the PBS backbone via a stepwise, temperature-controlled polycondensation, generating a series of PBSF copolymers. Experimental results showed that moderate FDCA incorporation at 15 mol% (PBSF15) markedly improved mechanical performance, with tensile strength and elongation at break increasing by 30.63% and 467.59%, respectively, compared with pure PBS. Notably, PBSF15 exhibited the optimal compressive performance, achieving a compressive strength of 115.41 MPa and a compressive modulus of 283.97 MPa. It also exhibited the highest flexural modulus (586.48 MPa) and flexural strength (33.28 MPa), while maintaining good processability and hydrophilicity. Moreover, enzymatic degradation tests revealed accelerated mass loss (≈ 89.89% within 12 days), and in vitro studies using MC3T3-E1 cells confirmed excellent cytocompatibility, sustained proliferation, and significant upregulation of osteogenic markers, including Col I and TGF-β. Collectively, this work presents a sustainable molecular design strategy that simultaneously enhances mechanical performance, accelerates degradation, and promotes osteoinductive activity, providing a promising platform for bone defect repair and regenerative medicine.

聚丁二酸丁二酯（PBS）是一种生物可降解聚酯，具有良好的生物相容性和加工性，但其机械强度较低，降解速度慢，生物活性有限，阻碍了其在成骨支架中的应用。为了解决这些限制，并受到海洋贝壳“砖瓦”结构的启发，本研究通过逐步控制温度的缩聚，将生物基2,5-呋喃二羧酸（FDCA）加入PBS骨架中，生成了一系列PBSF共聚物。实验结果表明，适量添加15 mol% （PBSF15）的FDCA显著改善了材料的力学性能，拉伸强度和断裂伸长率分别比纯PBS提高了30.63%和467.59%。其中，PBSF15的抗压性能最佳，抗压强度为115.41 MPa，抗压模量为283.97 MPa。具有最高的抗弯模量（586.48 MPa）和抗弯强度（33.28 MPa），同时保持良好的加工性和亲水性。此外，酶降解测试显示加速质量损失（12天内≈89.89%），使用MC3T3-E1细胞的体外研究证实了良好的细胞相容性，持续增殖，并显著上调成骨标志物，包括Col I和TGF-β。总的来说，这项工作提出了一种可持续的分子设计策略，同时提高了机械性能，加速了降解，促进了骨诱导活性，为骨缺损修复和再生医学提供了一个有希望的平台。

{"title":"Molecularly engineered PBS/FDCA copolymers: Balancing strength, degradability, and osteoinductivity for sustainable bone scaffolds","authors":"Zheng Li , Zhixuan Li , Sichao Yu , Xuan Yao , Guosheng Wang , Dayin Sun , Jie Zhang , Na Wang","doi":"10.1016/j.polymdegradstab.2026.111922","DOIUrl":"10.1016/j.polymdegradstab.2026.111922","url":null,"abstract":"<div><div>Polybutylene succinate (PBS) is a biodegradable polyester with good biocompatibility and processability, yet its relatively low mechanical strength, slow degradation, and limited bioactivity hinder its use in osteogenic scaffolds. To address these limitations, and inspired by the nacreous “brick-and-mortar” structure of marine shells, this study incorporated bio-based 2,5-furandicarboxylic acid (FDCA) into the PBS backbone via a stepwise, temperature-controlled polycondensation, generating a series of PBSF copolymers. Experimental results showed that moderate FDCA incorporation at 15 mol% (PBSF15) markedly improved mechanical performance, with tensile strength and elongation at break increasing by 30.63% and 467.59%, respectively, compared with pure PBS. Notably, PBSF15 exhibited the optimal compressive performance, achieving a compressive strength of 115.41 MPa and a compressive modulus of 283.97 MPa. It also exhibited the highest flexural modulus (586.48 MPa) and flexural strength (33.28 MPa), while maintaining good processability and hydrophilicity. Moreover, enzymatic degradation tests revealed accelerated mass loss (≈ 89.89% within 12 days), and in vitro studies using MC3T3-E1 cells confirmed excellent cytocompatibility, sustained proliferation, and significant upregulation of osteogenic markers, including Col I and TGF-β. Collectively, this work presents a sustainable molecular design strategy that simultaneously enhances mechanical performance, accelerates degradation, and promotes osteoinductive activity, providing a promising platform for bone defect repair and regenerative medicine.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"246 ","pages":"Article 111922"},"PeriodicalIF":7.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145941235","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

High temperature performance of polyimide under accelerated thermal aging: linking chemical modifications to electrical properties 加速热老化下聚酰亚胺的高温性能：化学改性与电性能的联系

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2026-04-01 Epub Date: 2026-01-11 DOI: 10.1016/j.polymdegradstab.2026.111939

Jizhu Jin, Davide Fabiani, Simone Vincenzo Suraci

Polyimide (PI) films are widely employed as high-temperature insulation in aerospace and electrical systems, where long-term reliability strongly depends on their thermo-oxidative stability. To evaluate their aging behavior, PMDA-ODA PI films were thermally aged in air at 280°C up to 60 days. Materials were tested by nondestructive techniques: Field Emission Scanning Electron Microscope (FE-SEM), Fourier Transform Infra‐Red (FTIR) (using both ATR and transmission modes), dielectric spectroscopy, DC conductivity and thermally stimulated depolarization current (TSDC) measurements. The results reveal that the material remains stable during the first 10 days with limited oxidation. From 10 to 40 days, FTIR shows that oxidation gradually extends from the surface into the bulk, increasing the amount of carbonyl dipoles. This leads to stronger dipolar polarization, while microstructural rearrangements caused by chain scission enhance interfacial polarization and conductivity. In the later stage, both interfacial polarization and conductivity reach a stable plateau. DC conductivity and TSDC measurements jointly revealed a two-stage trap evolution: a pronounced reduction of activation energy and trap depth up to 30 days, followed by a slower stabilization phase. These findings deepen the understanding of polyimide aging and support the development of more reliable high-temperature insulation.

聚酰亚胺（PI）薄膜广泛用于航空航天和电气系统的高温绝缘，其长期可靠性很大程度上取决于其热氧化稳定性。为了评估其老化行为，PMDA-ODA PI薄膜在280°C的空气中热老化60天。材料通过非破坏性技术进行测试：场发射扫描电子显微镜（FE-SEM），傅里叶变换红外（FTIR）（使用ATR和透射模式），介电光谱，直流电导率和热激退极化电流（TSDC）测量。结果表明，材料在前10天内保持稳定，氧化程度有限。从10天到40天，FTIR显示氧化逐渐从表面延伸到主体，增加了羰基偶极子的数量。这导致了更强的偶极极化，而链断裂引起的微观结构重排增强了界面极化和电导率。在后期，界面极化和电导率都达到稳定的平台。直流电导率和TSDC测量共同揭示了两个阶段的圈闭演化：活化能和圈闭深度显著降低，持续时间长达30天，随后是一个较慢的稳定阶段。这些发现加深了对聚酰亚胺老化的理解，并为开发更可靠的高温绝缘材料提供了支持。

{"title":"High temperature performance of polyimide under accelerated thermal aging: linking chemical modifications to electrical properties","authors":"Jizhu Jin, Davide Fabiani, Simone Vincenzo Suraci","doi":"10.1016/j.polymdegradstab.2026.111939","DOIUrl":"10.1016/j.polymdegradstab.2026.111939","url":null,"abstract":"<div><div>Polyimide (PI) films are widely employed as high-temperature insulation in aerospace and electrical systems, where long-term reliability strongly depends on their thermo-oxidative stability. To evaluate their aging behavior, PMDA-ODA PI films were thermally aged in air at 280°C up to 60 days. Materials were tested by nondestructive techniques: Field Emission Scanning Electron Microscope (FE-SEM), Fourier Transform Infra‐Red (FTIR) (using both ATR and transmission modes), dielectric spectroscopy, DC conductivity and thermally stimulated depolarization current (TSDC) measurements. The results reveal that the material remains stable during the first 10 days with limited oxidation. From 10 to 40 days, FTIR shows that oxidation gradually extends from the surface into the bulk, increasing the amount of carbonyl dipoles. This leads to stronger dipolar polarization, while microstructural rearrangements caused by chain scission enhance interfacial polarization and conductivity. In the later stage, both interfacial polarization and conductivity reach a stable plateau. DC conductivity and TSDC measurements jointly revealed a two-stage trap evolution: a pronounced reduction of activation energy and trap depth up to 30 days, followed by a slower stabilization phase. These findings deepen the understanding of polyimide aging and support the development of more reliable high-temperature insulation.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"246 ","pages":"Article 111939"},"PeriodicalIF":7.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145975012","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

Boosting the flame retardancy of vinyl ester resins via a DE@DMMP hybrid: Reducing migration and improving fire performance 通过DE@DMMP混合物提高乙烯基酯树脂的阻燃性：减少迁移和提高防火性能

IF 7.4 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability

Pub Date : 2026-04-01 Epub Date: 2026-01-27 DOI: 10.1016/j.polymdegradstab.2026.111963

Jinxin Xie , Akhmetova Marzhan , Zhanturina Nurgul , Yanbei Hou , Bekeshev Amirbek , Weizhao Hu , Xin Wang , Yuan Hu , Fukai Chu

Vinyl ester resins (VER) require flame-retardant modification for safe application, but conventional additives face limitations. To overcome the high volatility and migration tendency of the effective liquid phosphorus flame retardant dimethyl methylphosphonate (DMMP), this study develops a novel composite by confining DMMP within the micro-nano porous structure of diatomite (DE) to form a DE@DMMP hybrid. This hybrid was incorporated into VER to create flame-retardant composites. Successful DMMP adsorption onto DE was confirmed through FTIR and SEM analysis. Compared with the physically mixed DE/DMMP system, the VER composite containing 25 wt% DE@DMMP exhibited better thermal stability and more char residues. It achieved superior flame retardancy, with a limiting oxygen index of 26% and a UL-94 V-0 rating. Cone calorimetry tests revealed a remarkable 50.54% reduction in the peak heat release rate and a 58.30% decrease in total heat release versus pure VER, alongside suppressed total smoke production. The enhanced performance is attributed to a synergistic phosphorus-silicon effect. The immobilized DMMP provides efficient gas-phase radical quenching, whereas the silica framework of DE promotes the formation of a compact, thermally stable char layer enriched with Si-O-P crosslinking structures, as evidenced by XPS analysis. This work presents an effective strategy to mitigate additive migration and develop high-performance, halogen-free, flame-retardant VER with balanced fire safety.

乙烯基酯树脂（VER）需要阻燃改性才能安全应用，但传统添加剂存在局限性。为了克服有效液态磷阻燃剂甲基膦酸二甲酯（DMMP）的高挥发性和迁移倾向，本研究通过将DMMP限制在硅藻土（DE）的微纳多孔结构中形成DE@DMMP杂化物，开发了一种新型复合材料。这种混合物被加入到VER中以制造阻燃复合材料。通过FTIR和SEM分析证实了DMMP在DE上的成功吸附。与物理混合DE/DMMP体系相比，含有25 wt% DE@DMMP的VER复合材料具有更好的热稳定性和更多的炭残。它达到了优异的阻燃性，具有26%的极限氧指数和UL-94 V-0等级。锥形量热测试显示，与纯VER相比，峰值热释放率降低了50.54%，总热释放率降低了58.30%，同时总烟产量受到抑制。性能的增强是由于磷硅的协同效应。固定化的DMMP提供了有效的气相自由基猝灭，而DE的二氧化硅框架促进形成致密、热稳定的富含Si-O-P交联结构的炭层，这一点得到了XPS分析的证实。这项工作提出了一个有效的策略，以减轻添加剂迁移和开发高性能，无卤，阻燃VER与平衡的防火安全。

{"title":"Boosting the flame retardancy of vinyl ester resins via a DE@DMMP hybrid: Reducing migration and improving fire performance","authors":"Jinxin Xie , Akhmetova Marzhan , Zhanturina Nurgul , Yanbei Hou , Bekeshev Amirbek , Weizhao Hu , Xin Wang , Yuan Hu , Fukai Chu","doi":"10.1016/j.polymdegradstab.2026.111963","DOIUrl":"10.1016/j.polymdegradstab.2026.111963","url":null,"abstract":"<div><div>Vinyl ester resins (VER) require flame-retardant modification for safe application, but conventional additives face limitations. To overcome the high volatility and migration tendency of the effective liquid phosphorus flame retardant dimethyl methylphosphonate (DMMP), this study develops a novel composite by confining DMMP within the micro-nano porous structure of diatomite (DE) to form a DE@DMMP hybrid. This hybrid was incorporated into VER to create flame-retardant composites. Successful DMMP adsorption onto DE was confirmed through FTIR and SEM analysis. Compared with the physically mixed DE/DMMP system, the VER composite containing 25 wt% DE@DMMP exhibited better thermal stability and more char residues. It achieved superior flame retardancy, with a limiting oxygen index of 26% and a UL-94 V-0 rating. Cone calorimetry tests revealed a remarkable 50.54% reduction in the peak heat release rate and a 58.30% decrease in total heat release versus pure VER, alongside suppressed total smoke production. The enhanced performance is attributed to a synergistic phosphorus-silicon effect. The immobilized DMMP provides efficient gas-phase radical quenching, whereas the silica framework of DE promotes the formation of a compact, thermally stable char layer enriched with Si-O-P crosslinking structures, as evidenced by XPS analysis. This work presents an effective strategy to mitigate additive migration and develop high-performance, halogen-free, flame-retardant VER with balanced fire safety.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"246 ","pages":"Article 111963"},"PeriodicalIF":7.4,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074292","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