Pub Date : 2024-11-13DOI: 10.1016/j.polymdegradstab.2024.111072
Jinghang Zhu , Yiqun Fang , Ruofan Yang , Yiqing Fu , Guoqing Li , Xiaoyan Bai , Weihong Wang , Yongming Song , Qingwen Wang
In this study, a fully bio-based intumescent flame retardant, phytic acid vanillin arginine salt (VR-PA), was designed and synthesized by l-arginine (AR) and vanillin (VA) via a Schiff base reaction, followed by the introduction of phytic acid (PA) using electrostatic ionic interactions. The intumescent flame retardant, VR-PA, was incorporated into wood flour polypropylene composites (WFPP) to enhance their flame retardant and smoke suppression properties. Compared to pure WF, the limiting oxygen index (LOI) of WFPP with 20 wt% VR-PA increased to 28.2 %, while the peak heat release rate and total heat release were reduced by 35.4 % and 20.6 %, respectively. Additionally, the WF with 15 wt% VR-PA exhibited the greatest reduction in total smoke production, with a significant decrease of 42.1 %. The improved flame retardant and smoke suppression performance of the WF is attributed to the free radical trapping effect of VR-PA in the gas phase during the combustion process, as well as the formation of an expanded and continuous carbon layer during in the condensed phase. This study provides a green method to enhance the flame retardancy and smoke suppression of WFPP composites.
{"title":"A fully bio-based intumescent flame retardant for enhancing the flame retardancy and smoke suppression properties of wood flour polypropylene composites","authors":"Jinghang Zhu , Yiqun Fang , Ruofan Yang , Yiqing Fu , Guoqing Li , Xiaoyan Bai , Weihong Wang , Yongming Song , Qingwen Wang","doi":"10.1016/j.polymdegradstab.2024.111072","DOIUrl":"10.1016/j.polymdegradstab.2024.111072","url":null,"abstract":"<div><div>In this study, a fully bio-based intumescent flame retardant, phytic acid vanillin arginine salt (VR-PA), was designed and synthesized by l-arginine (AR) and vanillin (VA) via a Schiff base reaction, followed by the introduction of phytic acid (PA) using electrostatic ionic interactions. The intumescent flame retardant, VR-PA, was incorporated into wood flour polypropylene composites (WFPP) to enhance their flame retardant and smoke suppression properties. Compared to pure WF, the limiting oxygen index (LOI) of WFPP with 20 wt% VR-PA increased to 28.2 %, while the peak heat release rate and total heat release were reduced by 35.4 % and 20.6 %, respectively. Additionally, the WF with 15 wt% VR-PA exhibited the greatest reduction in total smoke production, with a significant decrease of 42.1 %. The improved flame retardant and smoke suppression performance of the WF is attributed to the free radical trapping effect of VR-PA in the gas phase during the combustion process, as well as the formation of an expanded and continuous carbon layer during in the condensed phase. This study provides a green method to enhance the flame retardancy and smoke suppression of WFPP composites.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"231 ","pages":"Article 111072"},"PeriodicalIF":6.3,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653356","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}
Pub Date : 2024-11-09DOI: 10.1016/j.polymdegradstab.2024.111082
Hongqiang Zhu , Qiufei Chen , Hamza Malik , Yuhang Wang , Jian He , Bomou Ma , Xueli Wang , Hui Zhang , Yong Liu , Jianyong Yu
Understanding and regulating the oxidative stabilization behavior of polyacrylonitrile (PAN) precursor fibers are critical subjects of high-performance carbon fiber production technologies. Here, we performed continuous stabilization and carbonization of PAN fibers at industrial carbon fiber production lines in different locales (different oxygen partial pressure in atmosphere), and investigated the microstructural evolution of the fibers with a systematically analysis at different stages. Influence of oxygen partial pressure in oxidative stabilization atmosphere on tensile modulus of the obtained carbon fibers was obvious. Oxygen diffused into PAN fibers during oxidative stabilization, more homogeneous and crosslinked structures generated under higher oxygen partial pressure atmosphere, and gave the stabilized fibers lower skin-core ratio. The graphite layers gradually generated in the subsequent carbonization stages, and the gathered graphite layers transformed into graphite microcrystalline, the wide-angle x-ray diffraction (WAXD) demonstrated that higher oxygen partial pressure conditions contributed to the generation of higher crystallite preferred orientation and bigger crystallite size, Raman spectroscopy also confirmed the obtained carbon fibers with higher oxygen partial pressure conditions possessed more ordered graphite structures. Thus, relatively higher oxygen partial pressure in air gave the stabilized fibers more crosslinked structures, and contributed to the formation of high-performance carbon fibers.
了解和调节聚丙烯腈（PAN）原纤维的氧化稳定行为是高性能碳纤维生产技术的关键课题。在此，我们在不同地区（不同氧分压环境）的工业碳纤维生产线上对 PAN 纤维进行了连续稳定和碳化，并在不同阶段对纤维的微观结构演变进行了系统分析。氧化稳定气氛中的氧分压对碳纤维拉伸模量的影响非常明显。在氧化稳定过程中，氧气扩散到 PAN 纤维中，在氧分压较高的气氛中产生了更均匀的交联结构，并使稳定后的纤维具有较低的皮芯比。广角 X 射线衍射（WAXD）表明，较高的氧分压条件有助于产生更高的晶粒优选取向和更大的晶粒尺寸，拉曼光谱也证实了在较高氧分压条件下获得的碳纤维具有更有序的石墨结构。因此，空气中相对较高的氧分压使稳定纤维具有更多的交联结构，有助于形成高性能碳纤维。
{"title":"A comparison of the effect of oxygen partial pressure on microstructural evolution of PAN fibers during industrial carbon fiber production line at different altitudes","authors":"Hongqiang Zhu , Qiufei Chen , Hamza Malik , Yuhang Wang , Jian He , Bomou Ma , Xueli Wang , Hui Zhang , Yong Liu , Jianyong Yu","doi":"10.1016/j.polymdegradstab.2024.111082","DOIUrl":"10.1016/j.polymdegradstab.2024.111082","url":null,"abstract":"<div><div>Understanding and regulating the oxidative stabilization behavior of polyacrylonitrile (PAN) precursor fibers are critical subjects of high-performance carbon fiber production technologies. Here, we performed continuous stabilization and carbonization of PAN fibers at industrial carbon fiber production lines in different locales (different oxygen partial pressure in atmosphere), and investigated the microstructural evolution of the fibers with a systematically analysis at different stages. Influence of oxygen partial pressure in oxidative stabilization atmosphere on tensile modulus of the obtained carbon fibers was obvious. Oxygen diffused into PAN fibers during oxidative stabilization, more homogeneous and crosslinked structures generated under higher oxygen partial pressure atmosphere, and gave the stabilized fibers lower skin-core ratio. The graphite layers gradually generated in the subsequent carbonization stages, and the gathered graphite layers transformed into graphite microcrystalline, the wide-angle x-ray diffraction (WAXD) demonstrated that higher oxygen partial pressure conditions contributed to the generation of higher crystallite preferred orientation and bigger crystallite size, Raman spectroscopy also confirmed the obtained carbon fibers with higher oxygen partial pressure conditions possessed more ordered graphite structures. Thus, relatively higher oxygen partial pressure in air gave the stabilized fibers more crosslinked structures, and contributed to the formation of high-performance carbon fibers.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"230 ","pages":"Article 111082"},"PeriodicalIF":6.3,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654172","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}
Pub Date : 2024-11-07DOI: 10.1016/j.polymdegradstab.2024.111056
Tong-Yu Bai, Xiang-Xin Xiao, Guan-Qi Zheng, Qin Zhang, Zi-Ni Wang, Li Chen, Bo-Wen Liu, Yu-Zhong Wang
Polycarbonate is a widely used engineering plastic material, but its limited flame retardancy has restricted its application in high-end fields such as aviation and railways. In this study, we propose a novel copolymerization/macromolecular blending strategy to produce a high-performance, fire-safe polycarbonate composite. By copolymerizing with polydimethylsiloxane oligomer and blending with macromolecular polyarylate, the resulting PC-BPDMS5/PITR successfully achieved a UL-94 V-0 rating and a high limiting oxygen index value of 34.2 %. The peak heat release and total smoke release were significantly reduced by 45.2 % and 27.4 %, respectively, compared to pure PC. SEM, Raman, and XPS analyses confirmed the condensed-phase dominated flame-retardant mechanism, attributed to the char-forming ability of the polyarylate and polydimethylsiloxane segments. Polydimethylsiloxane segments can decompose to produce small molecules such as methane, and the left structure with silicon, which undergo cross-linking reactions with the substrate during combustion to promote char formation. The polyaromatic ring structure of PITR can also participate in the formation of a dense and stable char layer. The excellent compatibility between the polyarylate and the PC matrix, combined with the superior flexibility of polydimethylsiloxane, allowed the composite to maintain mechanical properties comparable to pure PC. Additionally, the increased molar volume resulted in a low dielectric constant for PC-BPDMS5/PITR. This work presents a promising approach for the development of high-performance polycarbonate composites.
聚碳酸酯是一种广泛使用的工程塑料材料，但其有限的阻燃性限制了它在航空和铁路等高端领域的应用。在本研究中，我们提出了一种新型共聚/大分子共混策略，以生产高性能、防火安全的聚碳酸酯复合材料。通过与聚二甲基硅氧烷低聚物共聚并与高分子聚芳酸酯共混，制得的 PC-BPDMS5/PITR 成功达到了 UL-94 V-0 等级，极限氧指数值高达 34.2%。与纯 PC 相比，峰值热释放量和总烟雾释放量分别显著降低了 45.2% 和 27.4%。扫描电子显微镜、拉曼和 XPS 分析证实了聚芳酸酯和聚二甲基硅氧烷片段的成炭能力主导了凝聚相阻燃机制。聚二甲基硅氧烷段可分解产生甲烷等小分子，左侧结构中含有硅，在燃烧过程中会与基质发生交联反应，促进炭的形成。PITR 的多芳香族环结构还能参与形成致密稳定的炭层。聚芳酸酯与 PC 基体之间出色的兼容性，再加上聚二甲基硅氧烷优越的柔韧性，使复合材料能够保持与纯 PC 相当的机械性能。此外，摩尔体积的增加使 PC-BPDMS5/PITR 的介电常数降低。这项研究为开发高性能聚碳酸酯复合材料提供了一种前景广阔的方法。
{"title":"Fire-safe and mechanically robust polycarbonate composite enabled by novel copolymerization/macromolecular blending strategy","authors":"Tong-Yu Bai, Xiang-Xin Xiao, Guan-Qi Zheng, Qin Zhang, Zi-Ni Wang, Li Chen, Bo-Wen Liu, Yu-Zhong Wang","doi":"10.1016/j.polymdegradstab.2024.111056","DOIUrl":"10.1016/j.polymdegradstab.2024.111056","url":null,"abstract":"<div><div>Polycarbonate is a widely used engineering plastic material, but its limited flame retardancy has restricted its application in high-end fields such as aviation and railways. In this study, we propose a novel copolymerization/macromolecular blending strategy to produce a high-performance, fire-safe polycarbonate composite. By copolymerizing with polydimethylsiloxane oligomer and blending with macromolecular polyarylate, the resulting PC-BPDMS<sub>5</sub>/PITR successfully achieved a UL-94 V-0 rating and a high limiting oxygen index value of 34.2 %. The peak heat release and total smoke release were significantly reduced by 45.2 % and 27.4 %, respectively, compared to pure PC. SEM, Raman, and XPS analyses confirmed the condensed-phase dominated flame-retardant mechanism, attributed to the char-forming ability of the polyarylate and polydimethylsiloxane segments. Polydimethylsiloxane segments can decompose to produce small molecules such as methane, and the left structure with silicon, which undergo cross-linking reactions with the substrate during combustion to promote char formation. The polyaromatic ring structure of PITR can also participate in the formation of a dense and stable char layer. The excellent compatibility between the polyarylate and the PC matrix, combined with the superior flexibility of polydimethylsiloxane, allowed the composite to maintain mechanical properties comparable to pure PC. Additionally, the increased molar volume resulted in a low dielectric constant for PC-BPDMS<sub>5</sub>/PITR. This work presents a promising approach for the development of high-performance polycarbonate composites.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"230 ","pages":"Article 111056"},"PeriodicalIF":6.3,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654171","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}
Pub Date : 2024-11-06DOI: 10.1016/j.polymdegradstab.2024.111079
Yuqing Dai , Rongjia Wen , Chunyan Zhao , Ahmed Al-Mansour , Chengji Xu , Le Li , Qiang Zeng , Kefei Li , Qinghua Li , Shilang Xu
Epoxy-based coatings are widely used in engineering but are prone to degrade under aggressive environmental actions, especially in hygrothermal environments. However, the degradation mechanisms of a coating-substrate system under coupled UV irradiation and bulk water remain insufficiently explored. Herein, we designed three parallel accelerated aging tests, including UV irradiation only, UV/flush, and UV/submerged, on a waterborne epoxy resin (WER) coating on cement mortar substrate. The chemical structure, micro-morphology, and hydrophilicity over aging time were comprehensively characterized by the tests of attenuated total reflectance Fourier transformation infrared spectrometer (ATR-FTIR), scanning electron microscopy (SEM), image analysis, water contact angle (WCA). Results show that the UV/flush environments induced more micro-pinholes on the WER outer surface than the neat UV photooxidation. The UV/ submerged environment led to a blistering rate over 24% after 60 d's exposure owing to the significant osmotic pressure built between the inner and outer surfaces of the WER coating. Additionally, the physicochemical and microstructure changes to the outer surface of WER also caused the changes of WCA. The osmotic, hydrolysis, and thermal stresses were evaluated to clarify the water-accelerated photooxidation and interface degradation mechanisms. These findings contribute to a deeper understanding of epoxy coating degradation mechanisms in response to environmental stressors, and offer insights for enhancing coating performance under varying conditions.
环氧基涂料广泛应用于工程领域，但在侵蚀性环境作用下，尤其是在湿热环境中，容易发生降解。然而，涂层-基底系统在紫外线辐照和散水耦合作用下的降解机理仍未得到充分探索。在此，我们对水泥砂浆基材上的水性环氧树脂（WER）涂层设计了三种平行加速老化试验，包括仅紫外线照射、紫外线/冲洗和紫外线/浸泡。通过衰减全反射傅立叶变换红外光谱仪（ATR-FTIR）、扫描电子显微镜（SEM）、图像分析、水接触角（WCA）等测试，对老化时间内的化学结构、微观形态和亲水性进行了综合表征。结果表明，与纯紫外光氧化相比，紫外/冲洗环境在 WER 外表面诱发了更多的微针孔。由于 WER 涂层内外表面之间形成了巨大的渗透压，紫外线/浸没环境在暴露 60 天后导致起泡率超过 24%。此外，WER 外表面的物理化学和微观结构变化也导致了 WCA 的变化。通过对渗透、水解和热应力的评估，阐明了水加速光氧化和界面降解的机理。这些发现有助于加深对环氧涂层在环境应力作用下降解机理的理解，并为在不同条件下提高涂层性能提供了启示。
{"title":"Distinct photooxidation and interface degradation of waterborne epoxy resin coatings on mortar substrate affected by bulk water","authors":"Yuqing Dai , Rongjia Wen , Chunyan Zhao , Ahmed Al-Mansour , Chengji Xu , Le Li , Qiang Zeng , Kefei Li , Qinghua Li , Shilang Xu","doi":"10.1016/j.polymdegradstab.2024.111079","DOIUrl":"10.1016/j.polymdegradstab.2024.111079","url":null,"abstract":"<div><div>Epoxy-based coatings are widely used in engineering but are prone to degrade under aggressive environmental actions, especially in hygrothermal environments. However, the degradation mechanisms of a coating-substrate system under coupled UV irradiation and bulk water remain insufficiently explored. Herein, we designed three parallel accelerated aging tests, including UV irradiation only, UV/flush, and UV/submerged, on a waterborne epoxy resin (WER) coating on cement mortar substrate. The chemical structure, micro-morphology, and hydrophilicity over aging time were comprehensively characterized by the tests of attenuated total reflectance Fourier transformation infrared spectrometer (ATR-FTIR), scanning electron microscopy (SEM), image analysis, water contact angle (WCA). Results show that the UV/flush environments induced more micro-pinholes on the WER outer surface than the neat UV photooxidation. The UV/ submerged environment led to a blistering rate over 24% after 60 d's exposure owing to the significant osmotic pressure built between the inner and outer surfaces of the WER coating. Additionally, the physicochemical and microstructure changes to the outer surface of WER also caused the changes of WCA. The osmotic, hydrolysis, and thermal stresses were evaluated to clarify the water-accelerated photooxidation and interface degradation mechanisms. These findings contribute to a deeper understanding of epoxy coating degradation mechanisms in response to environmental stressors, and offer insights for enhancing coating performance under varying conditions.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"230 ","pages":"Article 111079"},"PeriodicalIF":6.3,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654169","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}
Pub Date : 2024-11-06DOI: 10.1016/j.polymdegradstab.2024.111078
Yangwen Mao , Wenbo Wang , Wanyu Huang , Haopeng Cai
For the purpose of investigating the modified flame-retardant epoxy resin (FREP) with the low smoke density release during combustion, the flame retardant containing P/N/B elements named DBT was synthesized with the raw materials of 4-Acetylphenylboronic acid, 3,5-diaminotriazole and DOPO. The DBT was added as a co-curing agent to an amine-cured epoxy resin system, and based on the DSC results of the resin, it was revealed that -NH- in the structure of the DBT was capable of facilitating EP curing. With the introduction of DBT, the transparency of FREP samples was slightly affected. On account of the excellent flame retardancy exerted by the DBT in the FREP system, the FREP samples reached the V-0 grade in UL-94 testing with an LOI of 35.9% at 5 wt% DBT addition. Meanwhile, the results of the cone calorimetry test demonstrated that in comparison with the epoxy resin, the PHRR, THR and av-EHC of the EP/DBT7.5 sample decreased by 34.0%, 35.4% and 18.68%, respectively. The DBT was effective in reducing the smoke density of EP, and the EP/DBT7.5 sample attained the HL1 level for DS (4) and VOF4. The chemical analyses for residual char revealed that DBT was mainly employed for flame retardancy and smoke suppression by forming P/B-containing chars in the condensed phase. There was no loss of mechanical properties of the FREP samples as the rigid groups were present in the DBT structure. Furthermore, it was noted that the FREP samples exhibited a decrease in dielectric loss and dielectric constant as the content increased.
{"title":"Flame retardant, transparent, low dielectric and low smoke density EP composites implemented with reactive flame retardants containing P/N/B","authors":"Yangwen Mao , Wenbo Wang , Wanyu Huang , Haopeng Cai","doi":"10.1016/j.polymdegradstab.2024.111078","DOIUrl":"10.1016/j.polymdegradstab.2024.111078","url":null,"abstract":"<div><div>For the purpose of investigating the modified flame-retardant epoxy resin (FREP) with the low smoke density release during combustion, the flame retardant containing P/N/B elements named DBT was synthesized with the raw materials of 4-Acetylphenylboronic acid, 3,5-diaminotriazole and DOPO. The DBT was added as a co-curing agent to an amine-cured epoxy resin system, and based on the DSC results of the resin, it was revealed that -NH- in the structure of the DBT was capable of facilitating EP curing. With the introduction of DBT, the transparency of FREP samples was slightly affected. On account of the excellent flame retardancy exerted by the DBT in the FREP system, the FREP samples reached the V-0 grade in UL-94 testing with an LOI of 35.9% at 5 wt% DBT addition. Meanwhile, the results of the cone calorimetry test demonstrated that in comparison with the epoxy resin, the PHRR, THR and av-EHC of the EP/DBT7.5 sample decreased by 34.0%, 35.4% and 18.68%, respectively. The DBT was effective in reducing the smoke density of EP, and the EP/DBT7.5 sample attained the HL1 level for D<sub>S</sub> (4) and VOF<sub>4</sub>. The chemical analyses for residual char revealed that DBT was mainly employed for flame retardancy and smoke suppression by forming P/B-containing chars in the condensed phase. There was no loss of mechanical properties of the FREP samples as the rigid groups were present in the DBT structure. Furthermore, it was noted that the FREP samples exhibited a decrease in dielectric loss and dielectric constant as the content increased.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"230 ","pages":"Article 111078"},"PeriodicalIF":6.3,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654261","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}
Pub Date : 2024-11-06DOI: 10.1016/j.polymdegradstab.2024.111077
Kai Dong, Shasha Tang, Di Zhao, Yang Pang, Chengji Zhao
Incorporating reversible covalent bonds into the crosslinked matrix of bio-based epoxy resins can address the challenges of difficult degradation and sustainable development associated with petroleum-based epoxy resins. However, the dynamic capability conferred by a single dynamic chemical bond proves relatively insufficient in thermosetting polymers. Therefore, we propose a strategy to introduce proportionally adjustable dual dynamic covalent bonds in the bio-based epoxy resin system to leverage the advantages of different dynamic bonds and improve the dynamic properties of the resulting epoxy vitrimers in this study. First, a bio-based epoxy monomer (BVF-EP) derived from vanillin was prepared and cured with a diamine hardener (AFD). Subsequently, vanillin-derived epoxy vitrimers were prepared by varying the stoichiometric ratio of AFD to BVF-EP (R = 0.5, 1.0, and 1.5) without catalysts. Some of the vitrimers showed good thermal stability and excellent reprocessability and degradability. Notably, BVF-EP/AFD (R = 1.5) containing both dynamic reversible covalent bonds of S-S and C=N with the highest crosslink density, exhibited the highest thermal decomposition temperature, highest tensile modulus (7175 MPa), and the shortest stress relaxation time (6 s at 200 ℃). Simultaneously, BVF-EP/AFD (R = 1.5) demonstrated good multiple reprocessing capacity under a pressure of 5 MPa at 140 ℃. It can be completely degraded in two distinct mixed solutions (50 % DMF/50 % β-ME and 50 % 1 M HCl/50 % DMF), offering great potential in recovering high-value carbon fibers from its carbon fiber-reinforced composites. This work advances the development of bio-based epoxy resins with dual dynamic crosslinked networks, providing new insights for the degradation and reprocessing of thermoset polymers.
{"title":"Vanillin-derived bio-based epoxy resins containing dual dynamic Schiff base and disulfide bonds with reprocessability and degradability","authors":"Kai Dong, Shasha Tang, Di Zhao, Yang Pang, Chengji Zhao","doi":"10.1016/j.polymdegradstab.2024.111077","DOIUrl":"10.1016/j.polymdegradstab.2024.111077","url":null,"abstract":"<div><div>Incorporating reversible covalent bonds into the crosslinked matrix of bio-based epoxy resins can address the challenges of difficult degradation and sustainable development associated with petroleum-based epoxy resins. However, the dynamic capability conferred by a single dynamic chemical bond proves relatively insufficient in thermosetting polymers. Therefore, we propose a strategy to introduce proportionally adjustable dual dynamic covalent bonds in the bio-based epoxy resin system to leverage the advantages of different dynamic bonds and improve the dynamic properties of the resulting epoxy vitrimers in this study. First, a bio-based epoxy monomer (BVF-EP) derived from vanillin was prepared and cured with a diamine hardener (AFD). Subsequently, vanillin-derived epoxy vitrimers were prepared by varying the stoichiometric ratio of AFD to BVF-EP (<em>R</em> = 0.5, 1.0, and 1.5) without catalysts. Some of the vitrimers showed good thermal stability and excellent reprocessability and degradability. Notably, BVF-EP/AFD (<em>R</em> = 1.5) containing both dynamic reversible covalent bonds of S-S and C=N with the highest crosslink density, exhibited the highest thermal decomposition temperature, highest tensile modulus (7175 MPa), and the shortest stress relaxation time (6 s at 200 ℃). Simultaneously, BVF-EP/AFD (<em>R</em> = 1.5) demonstrated good multiple reprocessing capacity under a pressure of 5 MPa at 140 ℃. It can be completely degraded in two distinct mixed solutions (50 % DMF/50 % <em>β</em>-ME and 50 % 1 M HCl/50 % DMF), offering great potential in recovering high-value carbon fibers from its carbon fiber-reinforced composites. This work advances the development of bio-based epoxy resins with dual dynamic crosslinked networks, providing new insights for the degradation and reprocessing of thermoset polymers.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"230 ","pages":"Article 111077"},"PeriodicalIF":6.3,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654268","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}
Pub Date : 2024-11-05DOI: 10.1016/j.polymdegradstab.2024.111074
Xiaorong He, Zhou Zhang, Teng Ren, Xinyan Yue, Shifeng Wang
Thermo-oxidative degradation of tire rubber has been demonstrated as a green method for upcycling waste tire rubber. However, the complicated tire compositions present challenges to achieving the homogeneity and efficiency of the reclaimed products, which restricts their widespread industrial adoption. To address this challenge, natural rubber(NR)and natural rubber/butadiene rubber(NR/BR)were innovatively designed to simulate complex tire compositions and investigate the influence of oxygen diffusion on thermo-oxidative degradation at 150–240 °C. The evolution of chemical structural changes and mechanical properties during degradation was traced by FTIR, UV–vis, and nanoindentation test. A basic reactive-diffusion model based on Fickian oxygen diffusion was used to simulate the diffusion profiles. It was found that recrosslinking decreases the oxygen permeability coefficient during NR/BR degradation as the temperature increases, making it difficult for oxygen to diffuse into the inner layer, and therefore tire rubber degrades unevenly. Lower temperatures and prolonged treatment times were recommended to enhance degradation. These findings provide substantial guidance for optimizing the recycling process of tire rubber and its sustainable utilization.
轮胎橡胶的热氧化降解已被证明是废旧轮胎橡胶升级再利用的一种绿色方法。然而，复杂的轮胎成分给实现再生产品的均匀性和效率带来了挑战，限制了其在工业中的广泛应用。为应对这一挑战，研究人员创新性地设计了天然橡胶（NR）和天然橡胶/丁二烯橡胶（NR/BR），模拟复杂的轮胎成分，并研究了氧气扩散对 150-240 °C 下热氧化降解的影响。通过傅立叶变换红外光谱（FTIR）、紫外可见光谱（UV-vis）和纳米压痕测试，对降解过程中化学结构变化和机械性能的演变进行了追踪。采用基于费克氧扩散的基本反应扩散模型模拟了扩散曲线。研究发现，随着温度的升高，再交联会降低 NR/BR 降解过程中的氧气渗透系数，使氧气难以扩散到内层，因此轮胎橡胶的降解不均匀。建议降低温度并延长处理时间，以促进降解。这些发现为优化轮胎橡胶的回收过程及其可持续利用提供了重要指导。
{"title":"Oxygen diffusion effects in thermo-oxidative degradation of typical tire rubber","authors":"Xiaorong He, Zhou Zhang, Teng Ren, Xinyan Yue, Shifeng Wang","doi":"10.1016/j.polymdegradstab.2024.111074","DOIUrl":"10.1016/j.polymdegradstab.2024.111074","url":null,"abstract":"<div><div>Thermo-oxidative degradation of tire rubber has been demonstrated as a green method for upcycling waste tire rubber. However, the complicated tire compositions present challenges to achieving the homogeneity and efficiency of the reclaimed products, which restricts their widespread industrial adoption. To address this challenge, natural rubber(NR)and natural rubber/butadiene rubber(NR/BR)were innovatively designed to simulate complex tire compositions and investigate the influence of oxygen diffusion on thermo-oxidative degradation at 150–240 °C. The evolution of chemical structural changes and mechanical properties during degradation was traced by FTIR, UV–vis, and nanoindentation test. A basic reactive-diffusion model based on Fickian oxygen diffusion was used to simulate the diffusion profiles. It was found that recrosslinking decreases the oxygen permeability coefficient during NR/BR degradation as the temperature increases, making it difficult for oxygen to diffuse into the inner layer, and therefore tire rubber degrades unevenly. Lower temperatures and prolonged treatment times were recommended to enhance degradation. These findings provide substantial guidance for optimizing the recycling process of tire rubber and its sustainable utilization.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"230 ","pages":"Article 111074"},"PeriodicalIF":6.3,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654170","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}
Pub Date : 2024-11-05DOI: 10.1016/j.polymdegradstab.2024.111076
Marc Vermeulen , Samuel P. Johns , Gwen dePolo , Pedro Maximo Rocha , Matthew J. Collins , Lora Angelova , Mélanie Roffet-Salque
To assess the short and long-term effect of a newly developed minimally invasive lipid extraction method on parchment, sacrificial pieces of parchments were subjected to artificial ageing and investigated using various analytical methods. Lipids were extracted using our novel vacuum-aided extraction method and characterised by high-temperature gas chromatography (HTGC-FID). Lipids were identified as arising from degraded animal fats. The physical, molecular, and mechanical properties of the parchment samples before/after lipid extraction, and before/after ageing were assessed using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and pure shear single notch fracture testing. SEM imaging allowed for an assessment of potential structural changes of the collagen fibres while FTIR was used to investigate the possible molecular changes indicated by changes in amide I and II bands. Mechanical tests were used to record the changes in brittleness and stiffness occurring in the materials through lipid extraction and ageing. The multimodal investigation did not highlight measurable changes in the structural, molecular, and mechanical properties of the lipid-extracted parchment, thus indicating the suitability for the minimally invasive lipid extraction method to be applied to historical parchments.
为了评估新开发的微创脂质提取方法对羊皮纸的短期和长期影响，我们对羊皮纸牺牲品进行了人工老化，并使用各种分析方法对其进行了研究。我们采用新颖的真空辅助提取法提取脂质，并通过高温气相色谱法（HTGC-FID）进行表征。经鉴定，脂质来自降解的动物脂肪。使用扫描电子显微镜 (SEM)、傅立叶变换红外光谱 (FTIR) 和纯剪切单缺口断裂测试评估了羊皮纸样品在脂质提取前后和老化前后的物理、分子和机械性能。扫描电子显微镜成像可评估胶原纤维的潜在结构变化，而傅立叶变换红外光谱则用于研究酰胺 I 和 II 波段变化所显示的可能的分子变化。机械测试用于记录材料在脂质提取和老化过程中发生的脆性和硬度变化。多模态调查并未突出显示提取脂质的羊皮纸在结构、分子和机械性能方面发生了可测量的变化，从而表明微创脂质提取方法适用于历史悠久的羊皮纸。
{"title":"Assessing the effect of minimally invasive lipid extraction on parchment integrity by artificial ageing and integrated analytical techniques","authors":"Marc Vermeulen , Samuel P. Johns , Gwen dePolo , Pedro Maximo Rocha , Matthew J. Collins , Lora Angelova , Mélanie Roffet-Salque","doi":"10.1016/j.polymdegradstab.2024.111076","DOIUrl":"10.1016/j.polymdegradstab.2024.111076","url":null,"abstract":"<div><div>To assess the short and long-term effect of a newly developed minimally invasive lipid extraction method on parchment, sacrificial pieces of parchments were subjected to artificial ageing and investigated using various analytical methods. Lipids were extracted using our novel vacuum-aided extraction method and characterised by high-temperature gas chromatography (HTGC-FID). Lipids were identified as arising from degraded animal fats. The physical, molecular, and mechanical properties of the parchment samples before/after lipid extraction, and before/after ageing were assessed using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and pure shear single notch fracture testing. SEM imaging allowed for an assessment of potential structural changes of the collagen fibres while FTIR was used to investigate the possible molecular changes indicated by changes in amide I and II bands. Mechanical tests were used to record the changes in brittleness and stiffness occurring in the materials through lipid extraction and ageing. The multimodal investigation did not highlight measurable changes in the structural, molecular, and mechanical properties of the lipid-extracted parchment, thus indicating the suitability for the minimally invasive lipid extraction method to be applied to historical parchments.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"230 ","pages":"Article 111076"},"PeriodicalIF":6.3,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-05DOI: 10.1016/j.polymdegradstab.2024.111058
Kazem Sabet-Bokati, Kevin Plucknett
Among the various strategies implemented to improve the integrity of metallic structures, polymer coatings have emerged as a compelling choice due to their capacity to offer cost-effective and enduring protection. However, humidity is a critical environmental factor that poses a risk to the integrity of polymer coatings, manifesting in dimensional alterations, induced internal stresses, diminished adhesion strength between coating and substrate, microstructural changes, and hydrolytic degradation. Many of these detrimental changes remain concealed until the advanced stages of coating failure. Comprehending the water-induced degradation mechanisms in polymer coatings is crucial for improving their protective effectiveness, ensuring safety and dependability, minimizing economic and environmental impacts, and promoting innovation and regulatory compliance. This study rigorously explores the water-induced failure mechanisms in polymeric coatings, highlighting both visible signs of degradation, such as corrosion, cathodic delamination, and blistering, and less apparent phenomena like hydrolysis, swelling, and plasticization. From the initial stages of water diffusion to the eventual delamination of the coating, diffusion mechanisms and the interaction between water molecules and coating constituents are scrutinized. Moreover, this review explores the distinctive and interrelated impacts of each phenomenon on the integrity of the coating, along with potential mitigation strategies. The review culminates with practical recommendations aimed at bolstering the integrity of coated structures.
{"title":"Water-induced failure in polymer coatings: Mechanisms, impacts and mitigation strategies—A comprehensive review","authors":"Kazem Sabet-Bokati, Kevin Plucknett","doi":"10.1016/j.polymdegradstab.2024.111058","DOIUrl":"10.1016/j.polymdegradstab.2024.111058","url":null,"abstract":"<div><div>Among the various strategies implemented to improve the integrity of metallic structures, polymer coatings have emerged as a compelling choice due to their capacity to offer cost-effective and enduring protection. However, humidity is a critical environmental factor that poses a risk to the integrity of polymer coatings, manifesting in dimensional alterations, induced internal stresses, diminished adhesion strength between coating and substrate, microstructural changes, and hydrolytic degradation. Many of these detrimental changes remain concealed until the advanced stages of coating failure. Comprehending the water-induced degradation mechanisms in polymer coatings is crucial for improving their protective effectiveness, ensuring safety and dependability, minimizing economic and environmental impacts, and promoting innovation and regulatory compliance. This study rigorously explores the water-induced failure mechanisms in polymeric coatings, highlighting both visible signs of degradation, such as corrosion, cathodic delamination, and blistering, and less apparent phenomena like hydrolysis, swelling, and plasticization. From the initial stages of water diffusion to the eventual delamination of the coating, diffusion mechanisms and the interaction between water molecules and coating constituents are scrutinized. Moreover, this review explores the distinctive and interrelated impacts of each phenomenon on the integrity of the coating, along with potential mitigation strategies. The review culminates with practical recommendations aimed at bolstering the integrity of coated structures.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"230 ","pages":"Article 111058"},"PeriodicalIF":6.3,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-02DOI: 10.1016/j.polymdegradstab.2024.111070
Hung-Anh Tran Vu , Minh Nguyen Ngoc , Anh Tuan Pham , Viet Huong Nguyen
Polymers are widely used in various industries, however, their sensitivity to environmental factors such as moisture, UV radiation, heat, and some organic solvents limits their application. Atomic layer deposition (ALD) and vapor phase infiltration (VPI) are cutting-edge technologies to enhance the protective performance of polymers. ALD is concerned with depositing uniform, pinhole-free thin films with thickness control down to sub-nanometer level, while VPI creates organic-inorganic hybrid structures, further improving polymer stability. This review aims to evaluate the effectiveness of ALD and VPI for protecting polymers in outdoor applications or advanced technological fields such as lithium-ion batteries (LIBs), organic light-emitting diodes (OLEDs), and biomedical applications. The mechanisms governing ALD and VPI processes on polymers are discussed, alongside with challenges such as deposition on inert polymers, controllability, and scalability. The potential of various metal oxides by ALD/VPI technologies to expand the use of polymers in harsh environments is particularly highlighted, with an emphasis on future research directions and industrial applications.
{"title":"Vapor-phase protective coatings for polymers: Advances and challenges in ALD and VPI technologies","authors":"Hung-Anh Tran Vu , Minh Nguyen Ngoc , Anh Tuan Pham , Viet Huong Nguyen","doi":"10.1016/j.polymdegradstab.2024.111070","DOIUrl":"10.1016/j.polymdegradstab.2024.111070","url":null,"abstract":"<div><div>Polymers are widely used in various industries, however, their sensitivity to environmental factors such as moisture, UV radiation, heat, and some organic solvents limits their application. Atomic layer deposition (ALD) and vapor phase infiltration (VPI) are cutting-edge technologies to enhance the protective performance of polymers. ALD is concerned with depositing uniform, pinhole-free thin films with thickness control down to sub-nanometer level, while VPI creates organic-inorganic hybrid structures, further improving polymer stability. This review aims to evaluate the effectiveness of ALD and VPI for protecting polymers in outdoor applications or advanced technological fields such as lithium-ion batteries (LIBs), organic light-emitting diodes (OLEDs), and biomedical applications. The mechanisms governing ALD and VPI processes on polymers are discussed, alongside with challenges such as deposition on inert polymers, controllability, and scalability. The potential of various metal oxides by ALD/VPI technologies to expand the use of polymers in harsh environments is particularly highlighted, with an emphasis on future research directions and industrial applications.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"230 ","pages":"Article 111070"},"PeriodicalIF":6.3,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654173","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}
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