Pub Date : 2025-02-01DOI: 10.1016/j.polymertesting.2025.108719
Cheng Liu , Dongyang Zhuang , Yan Zhou , Jihua Liao , Shengping Dai , Changwang Pan , Yuntong Li , Lizong Dai , Wei Wang
The existing flame retardants are extensively utilized for epoxy resin (EP) in the field of engineering materials with good flame retardancy. Nevertheless, their introduction often brings a substantial decrease in mechanical properties of EP. To tackle this challenge, a multifunctional nano flame-retardant (PoDOH) that is designed to enhance both the flame-retardant and mechanical properties for EP simultaneously was synthesized in this study. The results demonstrate that for EP-10 %, its hardness increased by 34.8 %, and Young's modulus increased by 25.4 %, respectively, owing to the strong interfacial interaction among EP and PoDOH derived from the ring-opening reaction. Moreover, the synergistic action of the various flame retardant elements present in PoDOH imparts excellent flame retardancy to EP-10 % (V-0 rating, LOI = 32.6 % and PHRR decreased by 48.82 %). These findings indicate that PoDOH holds great potential as a versatile and efficient flame retardant for manufacturing high-performance EP.
{"title":"Mechanically reinforced and flame-retardant epoxy resin nanocomposite based on molecular engineering of POSS","authors":"Cheng Liu , Dongyang Zhuang , Yan Zhou , Jihua Liao , Shengping Dai , Changwang Pan , Yuntong Li , Lizong Dai , Wei Wang","doi":"10.1016/j.polymertesting.2025.108719","DOIUrl":"10.1016/j.polymertesting.2025.108719","url":null,"abstract":"<div><div>The existing flame retardants are extensively utilized for epoxy resin (EP) in the field of engineering materials with good flame retardancy. Nevertheless, their introduction often brings a substantial decrease in mechanical properties of EP. To tackle this challenge, a multifunctional nano flame-retardant (PoDOH) that is designed to enhance both the flame-retardant and mechanical properties for EP simultaneously was synthesized in this study. The results demonstrate that for EP-10 %, its hardness increased by 34.8 %, and Young's modulus increased by 25.4 %, respectively, owing to the strong interfacial interaction among EP and PoDOH derived from the ring-opening reaction. Moreover, the synergistic action of the various flame retardant elements present in PoDOH imparts excellent flame retardancy to EP-10 % (V-0 rating, LOI = 32.6 % and PHRR decreased by 48.82 %). These findings indicate that PoDOH holds great potential as a versatile and efficient flame retardant for manufacturing high-performance EP.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"143 ","pages":"Article 108719"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.polymertesting.2025.108687
Satya Pal, Abir Bhattacharyya
Measurement of stress-strain response under different deformation modes is important for developing constitutive models of soft polymers. However, such measurements on soft and compliant polymers are challenging using traditional techniques due to generation of unwanted stress concentrations leading to premature failure during loading. In this study, a non-contact digital image correlation (DIC) technique along with a novel experimental setup were used to accurately measure the strain field on a specimen surface subjected to finite strain. Polydimethylsiloxane (PDMS) elastomers of three different base polymer to hardener ratio were characterized under three different deformation modes— uniaxial compression, uniaxial tension, and simple shear—over strain rates ranging between 10−3/s–10−1/s. The resulting strain fields exhibited uniformity across all the deformation modes up to finite strains. While the lower strain rate experiments are minimally affected by strain acceleration and inertia effects, the specimens loaded under higher strain rate (10−1/s) are initially affected by strain acceleration during loading, which precluded reliable determination of Young's moduli and shear moduli from the initial slope of the stress-strain responses. The Poisson's ratio calculated from the ratio between measured axial and lateral strains was close to 0.5 at small strains, and exhibited a close match with that calculated from Young's modulus (E) to shear modulus (G) ratio (E/G), validating linear elasticity theory at small strains. The tangent moduli for all the compositions were found to be practically strain-rate insensitive in the region of steady strain rate.
{"title":"Measurement of axial and shear mechanical response of PDMS elastomers and determination of Poisson's ratio using digital image correlation","authors":"Satya Pal, Abir Bhattacharyya","doi":"10.1016/j.polymertesting.2025.108687","DOIUrl":"10.1016/j.polymertesting.2025.108687","url":null,"abstract":"<div><div>Measurement of stress-strain response under different deformation modes is important for developing constitutive models of soft polymers. However, such measurements on soft and compliant polymers are challenging using traditional techniques due to generation of unwanted stress concentrations leading to premature failure during loading. In this study, a non-contact digital image correlation (DIC) technique along with a novel experimental setup were used to accurately measure the strain field on a specimen surface subjected to finite strain. Polydimethylsiloxane (PDMS) elastomers of three different base polymer to hardener ratio were characterized under three different deformation modes— uniaxial compression, uniaxial tension, and simple shear—over strain rates ranging between 10<sup>−3</sup>/s–10<sup>−1</sup>/s. The resulting strain fields exhibited uniformity across all the deformation modes up to finite strains. While the lower strain rate experiments are minimally affected by strain acceleration and inertia effects, the specimens loaded under higher strain rate (10<sup>−1</sup>/s) are initially affected by strain acceleration during loading, which precluded reliable determination of Young's moduli and shear moduli from the initial slope of the stress-strain responses. The Poisson's ratio calculated from the ratio between measured axial and lateral strains was close to 0.5 at small strains, and exhibited a close match with that calculated from Young's modulus (<em>E</em>) to shear modulus (<em>G</em>) ratio (<em>E/G),</em> validating linear elasticity theory at small strains. The tangent moduli for all the compositions were found to be practically strain-rate insensitive in the region of steady strain rate.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"143 ","pages":"Article 108687"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Poly(lactic acid) (PLA), a commercially fully bio-based and biodegradable polymer, stands out as a sustainable alternative to commodity plastics. Its current end-of-life management involves composting, but chemical recycling would be more appropriate for a circular economy model. Here we report two very efficient chemical recycling pathways for commercial high molar mass and highly crystalline PLA samples, both ones promoted by different imidazole[1,5-a]pyrid-3-yl)phenolate Zn(II) catalysts: (i) alcoholysis was easily achieved by simply treating the polymer samples in boiling methanol in the presence of 1 % Zn(II) catalyst, resulting in up to 99 % yield and selectivity in methyl lactate; and (ii) chemical recycling to the monomer was achieved by heating the polymer samples at 180 °C under vacuum or in a nitrogen flow in the presence of 0.1 % Zn(II) catalyst and a highly boiling alcohol, resulting in up to 99 % yield of L-lactide, having high chemical and steric purity, which could be repolymerized without any further purification.
{"title":"Efficient chemical recycling of poly(L-lactic acid) via either alcoholysis to alkyl lactate or thermal depolymerization to L-lactide promoted by Zn(II) catalysts","authors":"Maria Gentile , Licia Gaeta , Stefano Brenna , Claudio Pellecchia","doi":"10.1016/j.polymertesting.2025.108727","DOIUrl":"10.1016/j.polymertesting.2025.108727","url":null,"abstract":"<div><div>Poly(lactic acid) (PLA), a commercially fully bio-based and biodegradable polymer, stands out as a sustainable alternative to commodity plastics. Its current end-of-life management involves composting, but chemical recycling would be more appropriate for a circular economy model. Here we report two very efficient chemical recycling pathways for commercial high molar mass and highly crystalline PLA samples, both ones promoted by different imidazole[1,5-<em>a</em>]pyrid-3-yl)phenolate Zn(II) catalysts: (i) alcoholysis was easily achieved by simply treating the polymer samples in boiling methanol in the presence of 1 % Zn(II) catalyst, resulting in up to 99 % yield and selectivity in methyl lactate; and (ii) chemical recycling to the monomer was achieved by heating the polymer samples at 180 °C under vacuum or in a nitrogen flow in the presence of 0.1 % Zn(II) catalyst and a highly boiling alcohol, resulting in up to 99 % yield of L-lactide, having high chemical and steric purity, which could be repolymerized without any further purification.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"143 ","pages":"Article 108727"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143372149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.polymertesting.2025.108697
Muhammad Nafiz Hamidi, Jamaluddin Abdullah, Abdus Samad Mahmud, Muhammad Hafiz Hassan, Ahmad Yasier Zainoddin
Polylactic acid (PLA) is a polymer widely used for 3D printing process owing to its mechanical properties which are high strength and flexural modulus and environmentally friendly. However, PLA is also a brittle polymer with low impact resistance. This weakness can be compensated by combining PLA with other polymer like Thermoplastic polyurethane (TPU) that is widely used to improve mechanical properties of PLA. In polymer 3D printing process, printing parameters affect the thermo-mechanical properties of the printed products. This study investigates the influence of TPU and various printing parameters on thermal and mechanical properties of PLA/TPU polymer blends. It provides more precise understanding on how each printing parameters and different TPU ratio affect the mechanical and thermal properties. It also helps in determining the significant parameters for better PLA/TPU blend print. This exploration of parameter effects adds novel insights, enhancing applicability in practical 3D printing processes. Six different TPU ratio was used which are 10 %–50 % by weight while the parameters being tested are printing speed, raster angle, layer thickness and printing temperature. The differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were conducted to assess the thermal properties while a tensile test was conducted to evaluate the mechanical properties. ANOVA analysis was employed for the data analysis. It was found that TPU altered the thermal properties of PLA by reducing the cold crystallization temperature, Tcc, enthalpy of crystallization, ΔHc and enthalpy of melting, ΔHm. The mechanical strength reduced by 64 % but the ductility improved up to 900 %. Based on ANOVA analysis, it can be concluded that influence of printing parameters on the mechanical properties are layer thickness > printing speed > raster angle > printing temperature in descending order.
{"title":"Influence of thermoplastic polyurethane (TPU) and printing parameters on the thermal and mechanical performance of polylactic acid (PLA) / thermoplastic polyurethane (TPU) polymer","authors":"Muhammad Nafiz Hamidi, Jamaluddin Abdullah, Abdus Samad Mahmud, Muhammad Hafiz Hassan, Ahmad Yasier Zainoddin","doi":"10.1016/j.polymertesting.2025.108697","DOIUrl":"10.1016/j.polymertesting.2025.108697","url":null,"abstract":"<div><div>Polylactic acid (PLA) is a polymer widely used for 3D printing process owing to its mechanical properties which are high strength and flexural modulus and environmentally friendly. However, PLA is also a brittle polymer with low impact resistance. This weakness can be compensated by combining PLA with other polymer like Thermoplastic polyurethane (TPU) that is widely used to improve mechanical properties of PLA. In polymer 3D printing process, printing parameters affect the thermo-mechanical properties of the printed products. This study investigates the influence of TPU and various printing parameters on thermal and mechanical properties of PLA/TPU polymer blends. It provides more precise understanding on how each printing parameters and different TPU ratio affect the mechanical and thermal properties. It also helps in determining the significant parameters for better PLA/TPU blend print. This exploration of parameter effects adds novel insights, enhancing applicability in practical 3D printing processes. Six different TPU ratio was used which are 10 %–50 % by weight while the parameters being tested are printing speed, raster angle, layer thickness and printing temperature. The differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were conducted to assess the thermal properties while a tensile test was conducted to evaluate the mechanical properties. ANOVA analysis was employed for the data analysis. It was found that TPU altered the thermal properties of PLA by reducing the cold crystallization temperature, T<sub>cc</sub>, enthalpy of crystallization, ΔH<sub>c</sub> and enthalpy of melting, ΔH<sub>m.</sub> The mechanical strength reduced by 64 % but the ductility improved up to 900 %. Based on ANOVA analysis, it can be concluded that influence of printing parameters on the mechanical properties are layer thickness > printing speed > raster angle > printing temperature in descending order.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"143 ","pages":"Article 108697"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, the post-curing kinetic, molecular mobility and mechanical behavior of polymethylacrylimide (PMI), synthesized from methacrylic acid and methacrylonitrile, were systematically investigated. Differential scanning calorimetry results identified three distinct temperature zones during the post-curing process, which represented different types of curing reactions. Model-free kinetic methods were used to evaluate the post-curing kinetics of PMI materials. Fourier transform infrared spectroscopy demonstrated that the cyclization of anhydride groups predominantly occurred at lower post-curing temperatures, while the decomposition and transformation were observed at higher temperatures. Meanwhile, there was a progressive formation of imide rings with the increase of post-curing temperature. In addition, the molecular segment mobility of PMI materials was investigated via dielectric relaxation spectroscopy, and molecular segment mobility was gradually restricted during the post-curing process, indicated the formation of crosslinked network structure. Those changes of microstructures agreed well with the evolution of compressive properties. This study provides insights into the curing kinetics and structural evolution of PMI during post-curing process, offering guidance for optimizing post-curing conditions to achieve superior mechanical performance.
{"title":"Understanding the post-curing behaviors of polymethylacrylimide: Curing kinetics and molecular mobility","authors":"Yuan Chen , Xiaolian Qiang , Yaping Zhang , Ningning Song , Lixian Guo , Siyuan Zhang , Chunrong Tian , Keping Chen","doi":"10.1016/j.polymertesting.2025.108720","DOIUrl":"10.1016/j.polymertesting.2025.108720","url":null,"abstract":"<div><div>In this study, the post-curing kinetic, molecular mobility and mechanical behavior of polymethylacrylimide (PMI), synthesized from methacrylic acid and methacrylonitrile, were systematically investigated. Differential scanning calorimetry results identified three distinct temperature zones during the post-curing process, which represented different types of curing reactions. Model-free kinetic methods were used to evaluate the post-curing kinetics of PMI materials. Fourier transform infrared spectroscopy demonstrated that the cyclization of anhydride groups predominantly occurred at lower post-curing temperatures, while the decomposition and transformation were observed at higher temperatures. Meanwhile, there was a progressive formation of imide rings with the increase of post-curing temperature. In addition, the molecular segment mobility of PMI materials was investigated via dielectric relaxation spectroscopy, and molecular segment mobility was gradually restricted during the post-curing process, indicated the formation of crosslinked network structure. Those changes of microstructures agreed well with the evolution of compressive properties. This study provides insights into the curing kinetics and structural evolution of PMI during post-curing process, offering guidance for optimizing post-curing conditions to achieve superior mechanical performance.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"143 ","pages":"Article 108720"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.polymertesting.2024.108669
Sergio Fuentes del Toro , Jorge Crespo-Sanchez , Jorge Ayllón , Alvaro Rodríguez-Prieto , Ana María Camacho
The emergence of metamaterials and layered structures obtained through additive manufacturing (AM) techniques opens a new paradigm of mechanical properties for advanced applications that need to be explored. This study investigates the mechanical behavior of 3D-printed auxetic structures, fabricated from thermoplastic polyurethane (TPU), under tensile and compressive loads. Utilizing fused deposition modeling (MEX), we examined the influence of printing direction on the anisotropic mechanical properties of TPU, with a particular focus on energy absorption, stress–strain responses, and damping capabilities. The research employs the Ogden model for hyperelastic characterization, demonstrating excellent correlation with experimental data. Thus, the novelty of this work relies on an approach that – with a focus in the precision and accuracy of the mechanical performance assessment – through a robust novel methodology combining the Ogden’s analytical model with numerical simulation provided by Ansys® and experimental tests of tensile and compression allows to comprehensively understand the mechanical performance of novel auxetic structures intended to energy absorption and impact resistance applications. Our findings reveal significant variations in mechanical performance based on printing orientation, with the 0°direction offering superior ductility and strength. These results suggest that optimizing the printing direction is crucial for enhancing the performance of TPU auxetic structures, particularly in applications requiring high impact resistance, energy absorption, and damping. This study contributes to the advancement of 3D printing technology for the development of next-generation materials with potential applications in protective gear, medical devices or damping devices, among others.
{"title":"Mechanical performance of 3D-printed TPU auxetic structures for energy absorption applications","authors":"Sergio Fuentes del Toro , Jorge Crespo-Sanchez , Jorge Ayllón , Alvaro Rodríguez-Prieto , Ana María Camacho","doi":"10.1016/j.polymertesting.2024.108669","DOIUrl":"10.1016/j.polymertesting.2024.108669","url":null,"abstract":"<div><div>The emergence of metamaterials and layered structures obtained through additive manufacturing (AM) techniques opens a new paradigm of mechanical properties for advanced applications that need to be explored. This study investigates the mechanical behavior of 3D-printed auxetic structures, fabricated from thermoplastic polyurethane (TPU), under tensile and compressive loads. Utilizing fused deposition modeling (MEX), we examined the influence of printing direction on the anisotropic mechanical properties of TPU, with a particular focus on energy absorption, stress–strain responses, and damping capabilities. The research employs the Ogden model for hyperelastic characterization, demonstrating excellent correlation with experimental data. Thus, the novelty of this work relies on an approach that – with a focus in the precision and accuracy of the mechanical performance assessment – through a robust novel methodology combining the Ogden’s analytical model with numerical simulation provided by Ansys® and experimental tests of tensile and compression allows to comprehensively understand the mechanical performance of novel auxetic structures intended to energy absorption and impact resistance applications. Our findings reveal significant variations in mechanical performance based on printing orientation, with the 0°direction offering superior ductility and strength. These results suggest that optimizing the printing direction is crucial for enhancing the performance of TPU auxetic structures, particularly in applications requiring high impact resistance, energy absorption, and damping. This study contributes to the advancement of 3D printing technology for the development of next-generation materials with potential applications in protective gear, medical devices or damping devices, among others.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"143 ","pages":"Article 108669"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.polymertesting.2025.108698
Yaoming Wang , Guihao Liu , Yuqing Liu , Yiqing Zhang , Guangtao Chang , Ruoxin Li
Carbon black (CB) offers valuable properties, but its tendency to agglomerate hinders its full potential in polymer applications. This study presents a novel and straightforward graft modification method to overcome this limitation. By covalently bonding organic functional groups to the CB surface, the surface energy of carbon black was significantly reduced and enhanced its compatibility with organic PP polymers. Characterization techniques (FTIR, XPS, Raman, TGA, etc.) confirm successful grafting and demonstrate excellent dispersion stability of modified CB in organic media. The modified CB exhibits uniform dispersion and reduced particle size within polypropylene (PP) fibers, leading to tensile strength increased dramatically from 103 MPa (unmodified) to 517 MPa (modified). Moreover, the strain reached 1086 %, exceeding both unmodified CB or commercial CB concentrate modified polypropylene (PP) fibers by 31 % and 11 %, respectively. This method represents a significant advancement over existing techniques by providing a straightforward and efficient approach to developing high-strength polypropylene fibers with exceptional tensile and strain characteristics for coloring synthetic fiber applications.
{"title":"Facile grafting method achieves Unprecedented dispersion stability of carbon black in PP fiber","authors":"Yaoming Wang , Guihao Liu , Yuqing Liu , Yiqing Zhang , Guangtao Chang , Ruoxin Li","doi":"10.1016/j.polymertesting.2025.108698","DOIUrl":"10.1016/j.polymertesting.2025.108698","url":null,"abstract":"<div><div>Carbon black (CB) offers valuable properties, but its tendency to agglomerate hinders its full potential in polymer applications. This study presents a novel and straightforward graft modification method to overcome this limitation. By covalently bonding organic functional groups to the CB surface, the surface energy of carbon black was significantly reduced and enhanced its compatibility with organic PP polymers. Characterization techniques (FTIR, XPS, Raman, TGA, etc.) confirm successful grafting and demonstrate excellent dispersion stability of modified CB in organic media. The modified CB exhibits uniform dispersion and reduced particle size within polypropylene (PP) fibers, leading to tensile strength increased dramatically from 103 MPa (unmodified) to 517 MPa (modified). Moreover, the strain reached 1086 %, exceeding both unmodified CB or commercial CB concentrate modified polypropylene (PP) fibers by 31 % and 11 %, respectively. This method represents a significant advancement over existing techniques by providing a straightforward and efficient approach to developing high-strength polypropylene fibers with exceptional tensile and strain characteristics for coloring synthetic fiber applications.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"143 ","pages":"Article 108698"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.polymertesting.2025.108701
Yingying Zhang, Yanpeng Hao, Zikui Shen, Dongyuan Du, Hongru Mi
Excessive residual strain generated by curing shrinkage of epoxy/Al2O3 composite insulation materials can reduce the mechanical properties of gas-insulated metal-enclosed switchgear (GIS) insulators. The process and formula optimization of insulators lack effective detection methods. A thermocouple-compensated fiber Bragg grating in-situ detection method for seven high-temperature curing characteristics is proposed. The curing shrinkage characteristics and residual strain generation mechanism of this material cured at 114 °C are studied. The cured residual strain is calculated by the total central wavelength shift of the grating and the thermocouple temperature change inside the sample at the end of the curing process. The curing degree, curing initiation time, and curing completion time are calculated by the temperature inside the sample and the surface temperature of the mold based on the law of thermal equilibrium. Gel time, gel temperature, and glass transition temperature are detected by linear fitting and differential analysis of the strain variation with temperature inside the sample based on the thermal expansion coefficient. Differential scanning calorimetry and SB(m, n) autocatalytic reaction model are used to calculate the curing kinetic equation and to comparatively verify the glass transition temperature and curing degree. The differences between the two test results of the glass transition temperature, curing initiation time, and curing completion time are 0.39 %, 11.2 %, and 17.6 %, respectively. The proposed method can be used for detecting and evaluating the processes and formulations of GIS insulators in the same batch of production samples and optimizing the processes and formulations.
{"title":"Fiber Bragg grating in-situ detection method for curing characteristics of GIS epoxy/Al2O3 composite insulation materials","authors":"Yingying Zhang, Yanpeng Hao, Zikui Shen, Dongyuan Du, Hongru Mi","doi":"10.1016/j.polymertesting.2025.108701","DOIUrl":"10.1016/j.polymertesting.2025.108701","url":null,"abstract":"<div><div>Excessive residual strain generated by curing shrinkage of epoxy/Al<sub>2</sub>O<sub>3</sub> composite insulation materials can reduce the mechanical properties of gas-insulated metal-enclosed switchgear (GIS) insulators. The process and formula optimization of insulators lack effective detection methods. A thermocouple-compensated fiber Bragg grating in-situ detection method for seven high-temperature curing characteristics is proposed. The curing shrinkage characteristics and residual strain generation mechanism of this material cured at 114 °C are studied. The cured residual strain is calculated by the total central wavelength shift of the grating and the thermocouple temperature change inside the sample at the end of the curing process. The curing degree, curing initiation time, and curing completion time are calculated by the temperature inside the sample and the surface temperature of the mold based on the law of thermal equilibrium. Gel time, gel temperature, and glass transition temperature are detected by linear fitting and differential analysis of the strain variation with temperature inside the sample based on the thermal expansion coefficient. Differential scanning calorimetry and SB(<em>m</em>, <em>n</em>) autocatalytic reaction model are used to calculate the curing kinetic equation and to comparatively verify the glass transition temperature and curing degree. The differences between the two test results of the glass transition temperature, curing initiation time, and curing completion time are 0.39 %, 11.2 %, and 17.6 %, respectively. The proposed method can be used for detecting and evaluating the processes and formulations of GIS insulators in the same batch of production samples and optimizing the processes and formulations.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"143 ","pages":"Article 108701"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.polymertesting.2025.108723
Qingwen Li , Mengjiao Xu , Wenxia Li , Chuangchuang Pan , Mengmeng Yu
To reveal the improvement effects of Carbon fiber reinforced polymer (CFRP) jackets on the strength and deformation characteristics of coal samples, and the energy transformation mechanism during the failure process of coal samples under different loading rates. In this study, uniaxial compression tests were conduct on 28 coal samples, the results indicated that both the loading rate and the number of CFRP layers significantly influenced the energy evolution process of the coal samples. The total energy growth ratio of coal samples confined by single and double layer of CFRP jackets ranging from 11.86 to 23.46 and 32.002–56.066, respectively, with the total energy at failure of the double layer samples being 1.8 times that of the single layer ones. The number of CFRP layers significantly enhances the total energy at the peak point and its growth ratio of the coal samples. At the minimum (maximum) loading rate, the growth ratio of the dissipation energy rate at the peak point decreases with the increase of CFRP layers. Additionally, the value at the maximum rate is approximately 6.03–8.87 times greater than that at the minimum rate. The elastic energy consumption ratio exhibited a ‘fishhook-shaped’ trend as axial deformation increased. The use of CFRP jackets can effectively improve the energy storage mechanism of coal samples. Therefore, studying the energy dissipation and failure behavior of CFRP confined coal samples subjected to different loading rates is crucial for reducing the risk of accidents caused by coal pillar instability.
{"title":"Energy evolution characteristics and failure mechanism of coal confined by CFRP jackets subjected to different loading rates","authors":"Qingwen Li , Mengjiao Xu , Wenxia Li , Chuangchuang Pan , Mengmeng Yu","doi":"10.1016/j.polymertesting.2025.108723","DOIUrl":"10.1016/j.polymertesting.2025.108723","url":null,"abstract":"<div><div>To reveal the improvement effects of Carbon fiber reinforced polymer (CFRP) jackets on the strength and deformation characteristics of coal samples, and the energy transformation mechanism during the failure process of coal samples under different loading rates. In this study, uniaxial compression tests were conduct on 28 coal samples, the results indicated that both the loading rate and the number of CFRP layers significantly influenced the energy evolution process of the coal samples. The total energy growth ratio of coal samples confined by single and double layer of CFRP jackets ranging from 11.86 to 23.46 and 32.002–56.066, respectively, with the total energy at failure of the double layer samples being 1.8 times that of the single layer ones. The number of CFRP layers significantly enhances the total energy at the peak point and its growth ratio of the coal samples. At the minimum (maximum) loading rate, the growth ratio of the dissipation energy rate at the peak point decreases with the increase of CFRP layers. Additionally, the value at the maximum rate is approximately 6.03–8.87 times greater than that at the minimum rate. The elastic energy consumption ratio exhibited a ‘fishhook-shaped’ trend as axial deformation increased. The use of CFRP jackets can effectively improve the energy storage mechanism of coal samples. Therefore, studying the energy dissipation and failure behavior of CFRP confined coal samples subjected to different loading rates is crucial for reducing the risk of accidents caused by coal pillar instability.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"143 ","pages":"Article 108723"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.polymertesting.2025.108724
Louis O. Vaught , Jacob L. Meyer , Omar El Arwadi , Tanaya Mandal , Ahmad Amiri , Mohammad Naraghi , Andreas A. Polycarpou
Thermogravimetric Analysis (TGA) is a valuable tool for studying chemical reactions that release volatile compounds. Constant-temperature TGA can be particularly useful for polymer cure reactions with complex, time-evolving phenomenology, by ensuring time and temperature effects remain separable. In this work, a compound isothermal TGA methodology is developed to study the cure process of high-performance vitrimers known as Aromatic Thermosetting coPolyesters (ATSP). By fitting observed mass loss to a nondimensional phenomenological model with generalized terms and introducing additional nonphysical terms to account both known and suspected non-cure behaviors, changes in cure kinetics were evaluated across a wide range of temperatures (210°C–380 °C). The activation of the added nonphysical terms was used to differentiate between expected cure behavior (240°C–340 °C), and cures involving precursor decomposition (>340 °C). An unexpected cure-like reaction below cure temperature (<240 °C) was hypothesized to correspond to self-healing bond exchange, which is well-understood to cause changes in molecular weight in thermoplastic polyesters. This was directly validated via evolved gas analysis, and activation energies were calculated for the cure-dominant region of the reaction. These activation energies were found to be similar across different polymer formulations. When combined with significant observed mass loss below the expected cure temperature and findings in prior work, this indicates that the apparent cure process may be driven by thermodynamically-favorable bond exchange reactions.
{"title":"Complex cure kinetics of self-healing copolyester vitrimers via isothermal thermogravimetric analysis","authors":"Louis O. Vaught , Jacob L. Meyer , Omar El Arwadi , Tanaya Mandal , Ahmad Amiri , Mohammad Naraghi , Andreas A. Polycarpou","doi":"10.1016/j.polymertesting.2025.108724","DOIUrl":"10.1016/j.polymertesting.2025.108724","url":null,"abstract":"<div><div>Thermogravimetric Analysis (TGA) is a valuable tool for studying chemical reactions that release volatile compounds. Constant-temperature TGA can be particularly useful for polymer cure reactions with complex, time-evolving phenomenology, by ensuring time and temperature effects remain separable. In this work, a compound isothermal TGA methodology is developed to study the cure process of high-performance vitrimers known as Aromatic Thermosetting coPolyesters (ATSP). By fitting observed mass loss to a nondimensional phenomenological model with generalized terms and introducing additional nonphysical terms to account both known and suspected non-cure behaviors, changes in cure kinetics were evaluated across a wide range of temperatures (210°C–380 °C). The activation of the added nonphysical terms was used to differentiate between expected cure behavior (240°C–340 °C), and cures involving precursor decomposition (>340 °C). An unexpected cure-like reaction below cure temperature (<240 °C) was hypothesized to correspond to self-healing bond exchange, which is well-understood to cause changes in molecular weight in thermoplastic polyesters. This was directly validated via evolved gas analysis, and activation energies were calculated for the cure-dominant region of the reaction. These activation energies were found to be similar across different polymer formulations. When combined with significant observed mass loss below the expected cure temperature and findings in prior work, this indicates that the apparent cure process may be driven by thermodynamically-favorable bond exchange reactions.</div></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"143 ","pages":"Article 108724"},"PeriodicalIF":5.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143313090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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