Pub Date : 2025-11-04DOI: 10.1016/j.polymertesting.2025.109030
Qingling Meng , Haochen Duan , Sen Lu , Yuzhu Wen , Peipeng Wang , Hailiang Wang , Huayong Wu , Xiaoyu Guo , Yang Qian , Minzhuo Liang , Xin Liu
The diffusion mechanism of water vapor in cracked high-density polyethylene (HDPE) sheaths of cable-stayed bridges under alternating strain remains unclear, limiting durability assessments. Here we investigate vapor diffusion in cracked HDPE sheaths under coupled temperature–humidity and alternating strain using a custom gravimetric penetration device; cracks were introduced via alternating UV–fatigue pretreatment. Experiments show that UV degradation reduces mechanical integrity and increases microchannel density, enhancing vapor ingress; the diffusion flux J scales linearly with the inside–outside RH difference ΔRH, while the diffusion coefficient D exhibits an Arrhenius temperature dependence. Alternating strain widens crack micro-pores and raises D by 6–10 % via an influence factor f(ε). Integrating Fick's law with measurements, we formulate a diffusion-coefficient model D (T, ΔRH, ε, A) that incorporates temperature–humidity coupling, strain effects, and equivalent crack area; multivariate analysis ranks governing factors as temperature > strain magnitude > crack area > strain period > RH difference. The model predicts time-to-critical humidity from environmental conditions and A, directly informing sheath sealing/coating and maintenance decisions and bridging key gaps in environmental–load coupled degradation of cable sheaths.
{"title":"Water vapor diffusion in cracked HDPE sheaths of bridge cables under ultraviolet radiation, coupled environmental temperature-humidity and alternating strain","authors":"Qingling Meng , Haochen Duan , Sen Lu , Yuzhu Wen , Peipeng Wang , Hailiang Wang , Huayong Wu , Xiaoyu Guo , Yang Qian , Minzhuo Liang , Xin Liu","doi":"10.1016/j.polymertesting.2025.109030","DOIUrl":"10.1016/j.polymertesting.2025.109030","url":null,"abstract":"<div><div>The diffusion mechanism of water vapor in cracked high-density polyethylene (HDPE) sheaths of cable-stayed bridges under alternating strain remains unclear, limiting durability assessments. Here we investigate vapor diffusion in cracked HDPE sheaths under coupled temperature–humidity and alternating strain using a custom gravimetric penetration device; cracks were introduced via alternating UV–fatigue pretreatment. Experiments show that UV degradation reduces mechanical integrity and increases microchannel density, enhancing vapor ingress; the diffusion flux <em>J</em> scales linearly with the inside–outside RH difference Δ<em>RH</em>, while the diffusion coefficient <em>D</em> exhibits an Arrhenius temperature dependence. Alternating strain widens crack micro-pores and raises <em>D</em> by 6–10 % via an influence factor <em>f</em>(<em>ε</em>). Integrating Fick's law with measurements, we formulate a diffusion-coefficient model <em>D</em> (T, ΔRH, <em>ε</em>, <em>A</em>) that incorporates temperature–humidity coupling, strain effects, and equivalent crack area; multivariate analysis ranks governing factors as temperature > strain magnitude > crack area > strain period > RH difference. The model predicts time-to-critical humidity from environmental conditions and <em>A</em>, directly informing sheath sealing/coating and maintenance decisions and bridging key gaps in environmental–load coupled degradation of cable sheaths.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"153 ","pages":"Article 109030"},"PeriodicalIF":6.0,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145467483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The newly interesting topics about wearable electronics and smart textiles usually require a pair of flexible conductive electrodes. As far as conductivity is concerned, carbon nanomaterials are of particular interest. This study aimed to design flexible piezoelectric nanogenerators (PENGs) with carbon-based electrodes. Here, two different types of electrodes were fabricated using composites of polyvinylidene fluoride (PVDF) with single-walled carbon nanotubes (CNT) in one and reduced graphene oxide (rGO) in the other. The PENGs were structured by placing a piezo-active nanofibrous mat of PVDF and ZnO nanopowder between each pair of electrodes. The optimal PENGs were then integrated using polydimethylsiloxane (PDMS). The piezoelectric voltage constant (g33) of rGO-contained samples was approximately 5 times higher than that of samples with CNT. However, the opposite results were obtained in their tensile stress by a declining factor of 1.35. The piezoelectric sensitivity was enhanced by 5–9 % after integration. Finally, these flexible PENGs can be promising candidates for harvesting energy through textiles.
{"title":"Flexible PVDF/ZnO/rGO and PVDF/ZnO/CNT electrodes designed for piezoelectric nanogenerators","authors":"Zohreh Moarref , Majid Montazer , Roohollah Bagherzadeh (.) , Nahid Hemmatinejad , Sara Ziaee","doi":"10.1016/j.polymertesting.2025.109023","DOIUrl":"10.1016/j.polymertesting.2025.109023","url":null,"abstract":"<div><div>The newly interesting topics about wearable electronics and smart textiles usually require a pair of flexible conductive electrodes. As far as conductivity is concerned, carbon nanomaterials are of particular interest. This study aimed to design flexible piezoelectric nanogenerators (PENGs) with carbon-based electrodes. Here, two different types of electrodes were fabricated using composites of polyvinylidene fluoride (PVDF) with single-walled carbon nanotubes (CNT) in one and reduced graphene oxide (rGO) in the other. The PENGs were structured by placing a piezo-active nanofibrous mat of PVDF and ZnO nanopowder between each pair of electrodes. The optimal PENGs were then integrated using polydimethylsiloxane (PDMS). The piezoelectric voltage constant (g<sub>33</sub>) of rGO-contained samples was approximately 5 times higher than that of samples with CNT. However, the opposite results were obtained in their tensile stress by a declining factor of 1.35. The piezoelectric sensitivity was enhanced by 5–9 % after integration. Finally, these flexible PENGs can be promising candidates for harvesting energy through textiles.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"153 ","pages":"Article 109023"},"PeriodicalIF":6.0,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145467484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-03DOI: 10.1016/j.polymertesting.2025.109017
Yiwei Long , Jieke Jiang , Wilko Rohlfs , Wim Brilman , Claas Willem Visser
Amine-based hydrogel sorbents are gaining increasing attention for CO2 capture application due to their long-term stability, simple fabrication, and compatibility with humid environments. These hydrogels are solidified with crosslinkers, which have a potentially large but unstudied influence on both the production process and the CO2 uptake of the sorbent. Therefore, in this study, we systematically investigate how different crosslinkers influence the performance of polyethylenimine (PEI)-based hydrogel sorbents. Six crosslinkers representing acids, epoxides, and vinyl-based agents are initially screened based on crosslinking time, toxicity, and material cost. Subsequently, epichlorohydrin (ECH)-, trimethylolpropane triglycidyl ether (TTE)-, and 3-glycidyloxypropyltrimethoxysilane (GPTMS)-crosslinked particles are selected for detailed investigation on their CO2 uptake and mechanical strength. Among the three, TTE-crosslinked particles show the highest CO2 uptake, closely followed by GPTMS, with ECH significantly lower. All three crosslinkers result in sorbents with excellent cycling stability when using steam regeneration. GPTMS particles offer higher CO2 uptake under low-humidity conditions and exhibit the best mechanical strength, which makes GPTMS as superior for the selected crosslinkers. Overall, the presented evaluation method provides practical guidelines for design and evaluation of durable, high-performance hydrogel sorbents for CO2 capture.
{"title":"Optimization of amine-based hydrogel sorbents for CO2 capture: The role of crosslinkers","authors":"Yiwei Long , Jieke Jiang , Wilko Rohlfs , Wim Brilman , Claas Willem Visser","doi":"10.1016/j.polymertesting.2025.109017","DOIUrl":"10.1016/j.polymertesting.2025.109017","url":null,"abstract":"<div><div>Amine-based hydrogel sorbents are gaining increasing attention for CO<sub>2</sub> capture application due to their long-term stability, simple fabrication, and compatibility with humid environments. These hydrogels are solidified with crosslinkers, which have a potentially large but unstudied influence on both the production process and the CO<sub>2</sub> uptake of the sorbent. Therefore, in this study, we systematically investigate how different crosslinkers influence the performance of polyethylenimine (PEI)-based hydrogel sorbents. Six crosslinkers representing acids, epoxides, and vinyl-based agents are initially screened based on crosslinking time, toxicity, and material cost. Subsequently, epichlorohydrin (ECH)-, trimethylolpropane triglycidyl ether (TTE)-, and 3-glycidyloxypropyltrimethoxysilane (GPTMS)-crosslinked particles are selected for detailed investigation on their CO<sub>2</sub> uptake and mechanical strength. Among the three, TTE-crosslinked particles show the highest CO<sub>2</sub> uptake, closely followed by GPTMS, with ECH significantly lower. All three crosslinkers result in sorbents with excellent cycling stability when using steam regeneration. GPTMS particles offer higher CO<sub>2</sub> uptake under low-humidity conditions and exhibit the best mechanical strength, which makes GPTMS as superior for the selected crosslinkers. Overall, the presented evaluation method provides practical guidelines for design and evaluation of durable, high-performance hydrogel sorbents for CO<sub>2</sub> capture.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"153 ","pages":"Article 109017"},"PeriodicalIF":6.0,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145467486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-31DOI: 10.1016/j.polymertesting.2025.109025
Yingying Zhang , Cancan Yang , Chongyue Bai , Xuanye Wang , Chao Feng , Huige Wei
Polyacrylamide (PAM) based hydrogels are promising for soft strain sensor applications, while the incorporation of vinylimidazole (VI) endows the hydrogels with unique ion responsiveness and good biocompatibility. In this study, a high-performance PAM-co-VI/Ni/Co hydrogel was successfully fabricated through copolymerization of PAM with VI followed by modification with bimetallic nickel-cobalt ions. Experimental results demonstrate that when the VI content is 30 % with a Ni/Co ion ratio of 3:1, the hydrogel exhibits remarkable comprehensive properties, with a tensile fracture strength of 0.46 MPa, an ultrahigh fracture strain of 1800 %, a tensile sensitivity of 4.62, and long-term durability exceeding 1000 cycles. Furthermore, the hydrogel shows high pressure sensitivity (0.059 kPa−1 in the 0–5 kPa range), enabling precise detection of various mechanical signals from acoustic vibrations to complex human motions. Owing to its superior conductivity and biocompatibility, the PAM-co-VI/Ni/Co hydrogel also functions as a flexible electrode for electrocardiogram (ECG) monitoring, achieving conformal skin contact while stably acquiring high signal-to-noise ratio ECG waveforms with accurate identification of P-waves, Q, R, and S waves (QRS complexes), and other key features, demonstrating great potential for wearable health monitoring applications.
聚丙烯酰胺（PAM）为基础的水凝胶在软应变传感器领域具有广阔的应用前景，而乙烯酰咪唑（VI）的掺入使水凝胶具有独特的离子响应性和良好的生物相容性。在本研究中，通过PAM与VI的共聚，再用双金属镍钴离子改性，成功制备了高性能PAM- Co -VI/Ni/Co水凝胶。实验结果表明，当VI含量为30%，Ni/Co离子比为3:1时，水凝胶具有优异的综合性能，拉伸断裂强度为0.46 MPa，超高断裂应变为1800%，拉伸灵敏度为4.62，长期耐久性超过1000次。此外，水凝胶具有很高的压力敏感性（在0-5 kPa范围内为0.059 kPa−1），能够精确检测从声音振动到复杂人体运动的各种机械信号。PAM-co-VI/Ni/Co水凝胶由于其优异的导电性和生物相容性，还可作为心电图监测的柔性电极，在实现适形皮肤接触的同时，稳定地获得高信噪比的心电波形，准确识别p波、Q波、R波和S波（QRS复合物），以及其他关键特性，显示出可穿戴健康监测应用的巨大潜力。
{"title":"PAM-co-VI-based bimetallic-doped single-network conductive hydrogel for stress sensing and ECG signal monitoring applications","authors":"Yingying Zhang , Cancan Yang , Chongyue Bai , Xuanye Wang , Chao Feng , Huige Wei","doi":"10.1016/j.polymertesting.2025.109025","DOIUrl":"10.1016/j.polymertesting.2025.109025","url":null,"abstract":"<div><div>Polyacrylamide (PAM) based hydrogels are promising for soft strain sensor applications, while the incorporation of vinylimidazole (VI) endows the hydrogels with unique ion responsiveness and good biocompatibility. In this study, a high-performance PAM-co-VI/Ni/Co hydrogel was successfully fabricated through copolymerization of PAM with VI followed by modification with bimetallic nickel-cobalt ions. Experimental results demonstrate that when the VI content is 30 % with a Ni/Co ion ratio of 3:1, the hydrogel exhibits remarkable comprehensive properties, with a tensile fracture strength of 0.46 MPa, an ultrahigh fracture strain of 1800 %, a tensile sensitivity of 4.62, and long-term durability exceeding 1000 cycles. Furthermore, the hydrogel shows high pressure sensitivity (0.059 kPa<sup>−1</sup> in the 0–5 kPa range), enabling precise detection of various mechanical signals from acoustic vibrations to complex human motions. Owing to its superior conductivity and biocompatibility, the PAM-co-VI/Ni/Co hydrogel also functions as a flexible electrode for electrocardiogram (ECG) monitoring, achieving conformal skin contact while stably acquiring high signal-to-noise ratio ECG waveforms with accurate identification of P-waves, Q, R, and S waves (QRS complexes), and other key features, demonstrating great potential for wearable health monitoring applications.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"153 ","pages":"Article 109025"},"PeriodicalIF":6.0,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145467487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-31DOI: 10.1016/j.polymertesting.2025.109026
Antonio Minopoli , Davide Evangelista , Matteo Marras , Giordano Perini , Valentina Palmieri , Marco De Spirito , Massimiliano Papi
Precise characterization of biomechanical properties at the micro- and nanoscale is essential for developing biomaterials for tissue engineering, regenerative medicine, and drug delivery. Traditional bulk techniques fail to capture the local mechanical heterogeneities of soft materials such as hydrogels, polymers, and biological tissues. Atomic force microscopy (AFM) nanoindentation enables high-resolution stiffness mapping under near-physiological conditions; however, the standard Hertz model assumes purely elastic behavior, overlooking the viscoelastic nature of most biological systems. This study relies on established viscoelastic models to better interpret rate-dependent mechanical responses in AFM nanoindentation experiments. Force-displacement curves were analyzed to separate elastic and viscous contributions and account for the effect of indentation speed. Experiments on four hydrogels (alginate, Cellink-RGD, GelMA, GelMA A) revealed nonlinear stiffening trends with increasing indentation rate, associated with polymer network dynamics and crosslinking density. Additional analyses on erythrocytes and zona pellucida confirmed their complex viscoelastic responses, highlighting physiological and pathological differences in cells and species-specific behavior in reproductive structures. Our approach provides a simple and effective method to predict nanoscale stiffness as a function of indentation rate, improving accuracy in nanomechanical characterization and supporting the design of advanced bioengineered constructs.
{"title":"Viscoelastic interpretation of AFM nanoindentation for predicting nanoscale stiffness in soft biomaterials","authors":"Antonio Minopoli , Davide Evangelista , Matteo Marras , Giordano Perini , Valentina Palmieri , Marco De Spirito , Massimiliano Papi","doi":"10.1016/j.polymertesting.2025.109026","DOIUrl":"10.1016/j.polymertesting.2025.109026","url":null,"abstract":"<div><div>Precise characterization of biomechanical properties at the micro- and nanoscale is essential for developing biomaterials for tissue engineering, regenerative medicine, and drug delivery. Traditional bulk techniques fail to capture the local mechanical heterogeneities of soft materials such as hydrogels, polymers, and biological tissues. Atomic force microscopy (AFM) nanoindentation enables high-resolution stiffness mapping under near-physiological conditions; however, the standard Hertz model assumes purely elastic behavior, overlooking the viscoelastic nature of most biological systems. This study relies on established viscoelastic models to better interpret rate-dependent mechanical responses in AFM nanoindentation experiments. Force-displacement curves were analyzed to separate elastic and viscous contributions and account for the effect of indentation speed. Experiments on four hydrogels (alginate, Cellink-RGD, GelMA, GelMA A) revealed nonlinear stiffening trends with increasing indentation rate, associated with polymer network dynamics and crosslinking density. Additional analyses on erythrocytes and zona pellucida confirmed their complex viscoelastic responses, highlighting physiological and pathological differences in cells and species-specific behavior in reproductive structures. Our approach provides a simple and effective method to predict nanoscale stiffness as a function of indentation rate, improving accuracy in nanomechanical characterization and supporting the design of advanced bioengineered constructs.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"153 ","pages":"Article 109026"},"PeriodicalIF":6.0,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145467482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-31DOI: 10.1016/j.polymertesting.2025.109027
Salah Sabeeh , Sameer Algburi , Q. Alkhawlani , Feryal Ibrahim Jabbar , Mohammed El-Meligy , Haitham A. Mahmoud
Global plastic waste streams motivate routes that convert polyethylene terephthalate into durable, repairable parts through additive manufacturing. The central question addressed is whether a continuous reactive-extrusion process can transform polyethylene terephthalate flakes into vitrimer filaments that deliver high strength, heat resistance, and repairability with practical energy and cost. Developed a twin-screw reactive-extrusion route that couples grafting and vacuum devolatilization with in-line drawing to 1.75 mm filament, and verified transesterification and imine exchange using infrared spectroscopy, solid-state carbon nuclear magnetic resonance, gel fraction, and Flory–Rehner analysis. Rheology and stress-relaxation defined a topology-freezing window of 120–145 °C and activation energies of 148–190 kJ mol−1, guiding print settings and post-print repair schedules. Printing at 252–255 °C nozzle, 85 °C bed, and 0.20 mm layers produced consistent deposition; mechanical testing reached tensile strength up to 63 MPa, interlayer shear 28–30 MPa, and heat-deflection temperature of 120–125 °C. Weld repair at 150–180 °C restored about 80 % tensile strength, and five melt reprocessings retained about 95 % heat-deflection temperature with modest viscosity drift. Microscopy showed wider inter-bead necks and about 1.6 % porosity with nano-silica, consistent with tougher interfaces. Process energy use totaled 1.70 kWh kg−1 and modeled cost was $1.69 kg−1 with major contributions from feed at $0.752 and electricity at $0.345. The study demonstrates a scalable pathway to high-strength, heat-resistant, and repairable vitrimer parts from waste polyethylene terephthalate with quantified performance, energy, and cost.
全球塑料废物流激发了通过增材制造将聚对苯二甲酸乙二醇酯转化为耐用、可修复部件的路线。研究的核心问题是，连续反应挤出工艺是否可以将聚对苯二甲酸乙二醇酯薄片转化为具有高强度、耐热性和可修复性的玻璃钢长丝，并且具有实际的能源和成本。开发了一种双螺杆反应挤出路线，将接枝和真空脱挥发结合在一起，直列拉伸至1.75 mm长丝，并通过红外光谱、固体碳核磁共振、凝胶分数和Flory-Rehner分析验证了酯交换和亚胺交换。流变学和应力松弛定义了120-145°C的拓扑冻结窗口和148-190 kJ mol−1的活化能，指导打印设置和打印后修复计划。打印在252-255°C喷嘴，85°C床，0.20 mm层产生一致的沉积；力学测试达到抗拉强度63 MPa，层间剪切28 ~ 30 MPa，热挠曲温度120 ~ 125℃。150-180°C的焊缝修复恢复了约80%的抗拉强度，五种熔体再处理保留了约95%的热挠曲温度，并具有适度的粘度漂移。显微镜观察显示，纳米二氧化硅的孔隙率约为1.6%，与较硬的界面相一致。过程能耗总计为1.70 kWh kg - 1，模型成本为1.69 kg - 1，主要来自饲料的贡献为0.752美元，电费为0.345美元。该研究展示了一种可扩展的途径，可以从废弃的聚对苯二甲酸乙二醇酯中获得高强度、耐热和可修复的玻璃体部件，并具有量化的性能、能源和成本。
{"title":"Upcycled PET vitrimer filaments via reactive extrusion for high strength heat resistant and repairable FDM parts","authors":"Salah Sabeeh , Sameer Algburi , Q. Alkhawlani , Feryal Ibrahim Jabbar , Mohammed El-Meligy , Haitham A. Mahmoud","doi":"10.1016/j.polymertesting.2025.109027","DOIUrl":"10.1016/j.polymertesting.2025.109027","url":null,"abstract":"<div><div>Global plastic waste streams motivate routes that convert polyethylene terephthalate into durable, repairable parts through additive manufacturing. The central question addressed is whether a continuous reactive-extrusion process can transform polyethylene terephthalate flakes into vitrimer filaments that deliver high strength, heat resistance, and repairability with practical energy and cost. Developed a twin-screw reactive-extrusion route that couples grafting and vacuum devolatilization with in-line drawing to 1.75 mm filament, and verified transesterification and imine exchange using infrared spectroscopy, solid-state carbon nuclear magnetic resonance, gel fraction, and Flory–Rehner analysis. Rheology and stress-relaxation defined a topology-freezing window of 120–145 °C and activation energies of 148–190 kJ mol<sup>−1</sup>, guiding print settings and post-print repair schedules. Printing at 252–255 °C nozzle, 85 °C bed, and 0.20 mm layers produced consistent deposition; mechanical testing reached tensile strength up to 63 MPa, interlayer shear 28–30 MPa, and heat-deflection temperature of 120–125 °C. Weld repair at 150–180 °C restored about 80 % tensile strength, and five melt reprocessings retained about 95 % heat-deflection temperature with modest viscosity drift. Microscopy showed wider inter-bead necks and about 1.6 % porosity with nano-silica, consistent with tougher interfaces. Process energy use totaled 1.70 kWh kg<sup>−1</sup> and modeled cost was $1.69 kg<sup>−1</sup> with major contributions from feed at $0.752 and electricity at $0.345. The study demonstrates a scalable pathway to high-strength, heat-resistant, and repairable vitrimer parts from waste polyethylene terephthalate with quantified performance, energy, and cost.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"153 ","pages":"Article 109027"},"PeriodicalIF":6.0,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145467485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-31DOI: 10.1016/j.polymertesting.2025.109029
Taleeha Roheen , Shagufta Kamal , Saima Rehman , Ismat Bibi , Tanvir Ahmed , Osama A. Mohammed , Fatimah M. Alzahrani , Munawar Iqbal
The utilization of Sphingomonas-MT for the isolation of methane monooxygenases (MMO) has garnered significant attention due to the growing focus on selective activation of methane under moderate conditions, particularly for utilizing new sources of natural gas pollution, for controlling its emission in the environment. This study explores the immobilization of soluble methane monooxygenase (sMMO) within polyvinyl alcohol (PVA) hydrogel matrices, evaluating its catalytic performance, stability, and reusability to optimize the conversion of methane to methanol. Methane concentration less than 2 ± 0.5 g/L was found to be suitable for a higher methanotrophic growth rate (0.075 ± 0.5 h−1) and sMMO production (2.5 ± 0.25 U) after 48 h. The polyvinyl alcohol immobilized soluble methane monooxygenase (PVA-sMMO) displayed the highest immobilization yield and immobilization efficiency of 78.20 ± 1.10 %, and 86.40 ± 1.25 %, respectively, under optimum conditions. The PVA-sMMO exhibits the highest activity (610 ± 1.15 Ug−1 of PVA) and RSM analysis identified the optimal conditions for maximum enzyme activity as follows: temperature 38 °C, pH 7.72, inoculum size 3.8 mL, and a carbon-to-nitrogen (C: N) ratio 0.58, ensuring the robustness of PVA-sMMO in industrial processes. A high value of (1.44 mM) for PVA-sMMO and superior reusability of about 70 % after ten cycles, highlight the potential for sustained methanol production. EDX spectra confirmed the successful covalent immobilization of sMMO on the gel. The study also tracked methanol production over time, revealing consistent yields and highlighting the potential of PVA-immobilized sMMO for continuous, sustainable enzymatic processes. The improved stability and reusability of the PVA-sMMO system enhance its suitability for large-scale applications, meeting the rising demand for eco-friendly and efficient methane conversion technologies.
{"title":"Immobilization of methane monooxygenase in polyvinyl alcohol hydrogels for enhanced methanol production: Insights into catalytic efficiency and industrial applicability","authors":"Taleeha Roheen , Shagufta Kamal , Saima Rehman , Ismat Bibi , Tanvir Ahmed , Osama A. Mohammed , Fatimah M. Alzahrani , Munawar Iqbal","doi":"10.1016/j.polymertesting.2025.109029","DOIUrl":"10.1016/j.polymertesting.2025.109029","url":null,"abstract":"<div><div>The utilization of <em>Sphingomonas</em>-MT for the isolation of methane monooxygenases (MMO) has garnered significant attention due to the growing focus on selective activation of methane under moderate conditions, particularly for utilizing new sources of natural gas pollution, for controlling its emission in the environment. This study explores the immobilization of soluble methane monooxygenase (sMMO) within polyvinyl alcohol (PVA) hydrogel matrices, evaluating its catalytic performance, stability, and reusability to optimize the conversion of methane to methanol. Methane concentration less than 2 ± 0.5 g/L was found to be suitable for a higher methanotrophic growth rate (0.075 ± 0.5 <span><math><mrow><msub><mi>μ</mi><mi>max</mi></msub></mrow></math></span> h<sup>−1</sup>) and sMMO production (2.5 ± 0.25 U) after 48 h. The polyvinyl alcohol immobilized soluble methane monooxygenase (PVA-sMMO) displayed the highest immobilization yield and immobilization efficiency of 78.20 ± 1.10 %, and 86.40 ± 1.25 %, respectively, under optimum conditions. The PVA-sMMO exhibits the highest activity (610 ± 1.15 Ug<sup>−1</sup> of PVA) and RSM analysis identified the optimal conditions for maximum enzyme activity as follows: temperature 38 °C, pH 7.72, inoculum size 3.8 mL, and a carbon-to-nitrogen (C: N) ratio 0.58, ensuring the robustness of PVA-sMMO in industrial processes. A high value of <span><math><mrow><msub><mi>K</mi><mi>m</mi></msub></mrow></math></span> (1.44 mM) for PVA-sMMO and superior reusability of about 70 % after ten cycles, highlight the potential for sustained methanol production. EDX spectra confirmed the successful covalent immobilization of sMMO on the gel. The study also tracked methanol production over time, revealing consistent yields and highlighting the potential of PVA-immobilized sMMO for continuous, sustainable enzymatic processes. The improved stability and reusability of the PVA-sMMO system enhance its suitability for large-scale applications, meeting the rising demand for eco-friendly and efficient methane conversion technologies.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"153 ","pages":"Article 109029"},"PeriodicalIF":6.0,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145517638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-29DOI: 10.1016/j.polymertesting.2025.109019
Aurélien Doriat , Marco Gigliotti , Marianne Beringhier , Gildas Lalizel , Eva Dorignac , Patrick Berterretche , Matteo Minervino
The objective of this study is to investigate the effect of the airflow on the thermo-oxidative aging of polymer matrix composites (PMCs). Understanding how airflow affects the aging process is crucial for designing composite parts subjected to airflow conditions, such as in aeronautics. We conducted tests in an oven at 150 °C and in wind tunnel at Mach 0.85 to compare static and dynamic aging conditions. The airflow conditions are determined using a Reynolds Averaged Navier–Stokes (RANS) Computational Fluid Dynamic (CFD) simulation to estimate the pressure and temperature conditions at any point of the air-polymer interface. The oxidation is characterized by colorimetric and roughness testing. Based on our experimental data and simulation results, we show that the compressibility effect of the airflow affects the pressure field at the interface and the thermal boundary layer affects the temperature of the samples. The samples aged in the wind tunnel are always more oxidized than those aged under oven conditions. The airflow accelerates the thermo-oxidation by mainly increasing the static pressure.
{"title":"Effect of high-temperature high-speed airflow on the thermo-oxidative aging of epoxy polymer and composite: An experimental study","authors":"Aurélien Doriat , Marco Gigliotti , Marianne Beringhier , Gildas Lalizel , Eva Dorignac , Patrick Berterretche , Matteo Minervino","doi":"10.1016/j.polymertesting.2025.109019","DOIUrl":"10.1016/j.polymertesting.2025.109019","url":null,"abstract":"<div><div>The objective of this study is to investigate the effect of the airflow on the thermo-oxidative aging of polymer matrix composites (PMCs). Understanding how airflow affects the aging process is crucial for designing composite parts subjected to airflow conditions, such as in aeronautics. We conducted tests in an oven at 150<!--> <!-->°C and in wind tunnel at Mach 0.85 to compare static and dynamic aging conditions. The airflow conditions are determined using a Reynolds Averaged Navier–Stokes (RANS) Computational Fluid Dynamic (CFD) simulation to estimate the pressure and temperature conditions at any point of the air-polymer interface. The oxidation is characterized by colorimetric and roughness testing. Based on our experimental data and simulation results, we show that the compressibility effect of the airflow affects the pressure field at the interface and the thermal boundary layer affects the temperature of the samples. The samples aged in the wind tunnel are always more oxidized than those aged under oven conditions. The airflow accelerates the thermo-oxidation by mainly increasing the static pressure.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"153 ","pages":"Article 109019"},"PeriodicalIF":6.0,"publicationDate":"2025-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145419607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-28DOI: 10.1016/j.polymertesting.2025.109020
Kateřina Hamalová , Viktorie Neubertová , Adéla Jagerová , Anna Kutová , Jan Novotný , Zdeňka Kolská
Developing antimicrobial coatings is an important challenge nowadays, significant for managing microbial contamination across various applications, including medical devices, food packaging, and waste management. This study examines the preparation, modification and characterization of specific polystyrene-block-polyisoprene-block-polystyrene (SIS) and polystyrene-block-polybutadiene-block-polystyrene (SBS) thin polymer films modified by selected cationic biocides (CB), namely chlorhexidine (CHX) and dodecyltrimethylammonium bromide (DTAB). Two approaches were used to prepare and modify polymer films. First, CBs were added directly to the polymer solution. Second, pristine samples were exposed to plasma or UV radiation and afterwards immersed in an ethanol solution of CBs. Morphology, chemical structure and surface properties of the samples were characterized. Furthermore, their stability was evaluated, with a focus on their antibacterial activity and adhesion to selected substrates. The antibacterial activity of films improved when modified with CHX, as demonstrated by testing against Escherichia coli and Staphylococcus aureus. Specifically, one of the CHX-modified samples resulted in a bacterial survival rate of only 0.2 % in comparison with the control, less than the survival rates observed in DTAB-modified samples. Surface characterization revealed that lower zeta potential and contact angle values exhibited a correlation with higher hydrophilicity and antimicrobial activity, especially for CHX-modified films. Particularly the effect of surface charge is significant and plays a vital role. This work demonstrates several positive results of incorporating antibacterial agents into a polymer matrix. It also provides new insights into these materials as potential antibacterial coatings for a wide range of applications.
{"title":"Antibacterial coating of substrates based on cationic biocides-enhanced thin films of selected polystyrene-based copolymers","authors":"Kateřina Hamalová , Viktorie Neubertová , Adéla Jagerová , Anna Kutová , Jan Novotný , Zdeňka Kolská","doi":"10.1016/j.polymertesting.2025.109020","DOIUrl":"10.1016/j.polymertesting.2025.109020","url":null,"abstract":"<div><div>Developing antimicrobial coatings is an important challenge nowadays, significant for managing microbial contamination across various applications, including medical devices, food packaging, and waste management. This study examines the preparation, modification and characterization of specific polystyrene-block-polyisoprene-block-polystyrene (SIS) and polystyrene-block-polybutadiene-block-polystyrene (SBS) thin polymer films modified by selected cationic biocides (CB), namely chlorhexidine (CHX) and dodecyltrimethylammonium bromide (DTAB). Two approaches were used to prepare and modify polymer films. First, CBs were added directly to the polymer solution. Second, pristine samples were exposed to plasma or UV radiation and afterwards immersed in an ethanol solution of CBs. Morphology, chemical structure and surface properties of the samples were characterized. Furthermore, their stability was evaluated, with a focus on their antibacterial activity and adhesion to selected substrates. The antibacterial activity of films improved when modified with CHX, as demonstrated by testing against <em>Escherichia coli</em> and <em>Staphylococcus aureus</em>. Specifically, one of the CHX-modified samples resulted in a bacterial survival rate of only 0.2 % in comparison with the control, less than the survival rates observed in DTAB-modified samples. Surface characterization revealed that lower zeta potential and contact angle values exhibited a correlation with higher hydrophilicity and antimicrobial activity, especially for CHX-modified films. Particularly the effect of surface charge is significant and plays a vital role. This work demonstrates several positive results of incorporating antibacterial agents into a polymer matrix. It also provides new insights into these materials as potential antibacterial coatings for a wide range of applications.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"153 ","pages":"Article 109020"},"PeriodicalIF":6.0,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145419608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-28DOI: 10.1016/j.polymertesting.2025.109022
Florian Feyne , Eric Le Bourhis , Florian Lacroix , Laurence Autissier , Julie Pepin , Olga Smerdova
This study highlights the formation of a skin-core effect inside a filled silicone rubber exposed to air for durations up to 600 days at temperatures between 30 °C and 70 °C. Coupling mechanical and physico-chemical characterisations reveal that the volatile components, such as crosslinking by-products and oligomers, evaporate from the elastomeric network during the exposure, resulting in the shrinkage of the sample. This phenomenon gives rise to the formation of a composition gradient from the sample's surface towards its core. All the samples become more brittle with ageing, but the tensile modulus increase only slightly at the longest durations and highest temperatures. More fillers are found on the outer surface while the infrared spectra in the core of the sample remain unaffected by neither the temperature nor the duration. The nanoindentation highlights gradients of elastic modulus on the cross-section and provides an estimation of the skin thickness. By wrapping the samples in aluminum foil, the evaporation of volatile components is prevented. The measured properties remain constant with the duration of thermal exposure even at the highest temperature.
{"title":"Formation of skin-core structure in filled room-temperature vulcanized polydimethylsiloxane after long exposure to moderate temperatures","authors":"Florian Feyne , Eric Le Bourhis , Florian Lacroix , Laurence Autissier , Julie Pepin , Olga Smerdova","doi":"10.1016/j.polymertesting.2025.109022","DOIUrl":"10.1016/j.polymertesting.2025.109022","url":null,"abstract":"<div><div>This study highlights the formation of a skin-core effect inside a filled silicone rubber exposed to air for durations up to 600 days at temperatures between 30 °C and 70 °C. Coupling mechanical and physico-chemical characterisations reveal that the volatile components, such as crosslinking by-products and oligomers, evaporate from the elastomeric network during the exposure, resulting in the shrinkage of the sample. This phenomenon gives rise to the formation of a composition gradient from the sample's surface towards its core. All the samples become more brittle with ageing, but the tensile modulus increase only slightly at the longest durations and highest temperatures. More fillers are found on the outer surface while the infrared spectra in the core of the sample remain unaffected by neither the temperature nor the duration. The nanoindentation highlights gradients of elastic modulus on the cross-section and provides an estimation of the skin thickness. By wrapping the samples in aluminum foil, the evaporation of volatile components is prevented. The measured properties remain constant with the duration of thermal exposure even at the highest temperature.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"153 ","pages":"Article 109022"},"PeriodicalIF":6.0,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145419610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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