This study proposes a new approach to improving the properties of cast acrylic sheets (PMMA) through controlled post-processing compression. We significantly strengthened the material's thermal stability, mechanical performance, and morphological characteristics by applying compression below and beyond the glass transition temperature. Compression increased crystallinity by 1.32% and reduced crystallite size by 41.81% without altering the polymer's chemical composition. This rise in crystallinity resulted in a minor elevation of Tg for samples compressed below Tg, indicating better chain alignment. Thermogravimetric analysis (TGA) revealed enhanced thermal stability for samples compressed at 100°C, demonstrating the potential for high-temperature applications. FESEM surface morphology revealed a brittle-to-ductile transition at 120°C, accompanied by reduced surface roughness, as confirmed by AFM. Mechanically, compressed PMMA exhibited an 89.3% increase in storage modulus at 120°C, a 73.55% rise in flexural strength, along with a 17.34% improvement in tensile strength and a 25.86% boost in damping capacity. These findings underscore the method's effectiveness in optimizing PMMA for aerospace and other industries demanding superior thermal stability and mechanical performance.
{"title":"Compression Induced Molecular Orientation and Crystallization: Enhancing the Thermal and Mechanical Properties of PMMA for Aircraft Interiors","authors":"Anwar Mandali Kundu, Dibyendu Sekhar Bag, Arup Choudhury, Gautam Sarkhel","doi":"10.1016/j.polymer.2024.128009","DOIUrl":"https://doi.org/10.1016/j.polymer.2024.128009","url":null,"abstract":"This study proposes a new approach to improving the properties of cast acrylic sheets (PMMA) through controlled post-processing compression. We significantly strengthened the material's thermal stability, mechanical performance, and morphological characteristics by applying compression below and beyond the glass transition temperature. Compression increased crystallinity by 1.32% and reduced crystallite size by 41.81% without altering the polymer's chemical composition. This rise in crystallinity resulted in a minor elevation of Tg for samples compressed below Tg, indicating better chain alignment. Thermogravimetric analysis (TGA) revealed enhanced thermal stability for samples compressed at 100°C, demonstrating the potential for high-temperature applications. FESEM surface morphology revealed a brittle-to-ductile transition at 120°C, accompanied by reduced surface roughness, as confirmed by AFM. Mechanically, compressed PMMA exhibited an 89.3% increase in storage modulus at 120°C, a 73.55% rise in flexural strength, along with a 17.34% improvement in tensile strength and a 25.86% boost in damping capacity. These findings underscore the method's effectiveness in optimizing PMMA for aerospace and other industries demanding superior thermal stability and mechanical performance.","PeriodicalId":405,"journal":{"name":"Polymer","volume":"28 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929367","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}
Osmolytes are tiny organic compounds that alter the behavior of macromolecules and are ubiquitous in biological systems. The effects of osmolytes, such as urea and TMAO, and their mixture on the hydrated state and hydrophobic association behavior of the PNIPAM-b-PACMO copolymer have been thoroughly investigated by employing UV-visible spectroscopy, fluorescence spectroscopy, dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FTIR). Both urea and TMAO affect the phase transition temperature of the diblock copolymer, with urea typically lowering the LCST and TMAO producing more subtle changes depending on the concentrations of osmolytes. Later, the lower critical solution temperature (LCST) values of the block copolymer in the osmolytes and their mixtures have also obtained by temperature-dependence of DLS as the functions of the concentrations of the additives. These results reveal that the LCST values of copolymer decrease as the concentration of additives increase. The study highlights the molecular interactions, both direct and indirect, that contribute to these changes, underscoring the role of co-solutes in stabilizing the dehydrated state of the copolymer. This work could also pave the way for new approaches in the synthesis of PNIPAM-based devices and drug delivery systems.
{"title":"Delving the osmolyte-induced modulation of the temperature-responsive behavior of PNIPAM-b-PACMO","authors":"Rashmi Prabha, Urooj Fatima, Sanjay Mor, Pannuru Venkatesu","doi":"10.1016/j.polymer.2024.127996","DOIUrl":"https://doi.org/10.1016/j.polymer.2024.127996","url":null,"abstract":"Osmolytes are tiny organic compounds that alter the behavior of macromolecules and are ubiquitous in biological systems. The effects of osmolytes, such as urea and TMAO, and their mixture on the hydrated state and hydrophobic association behavior of the PNIPAM-b-PACMO copolymer have been thoroughly investigated by employing UV-visible spectroscopy, fluorescence spectroscopy, dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FTIR). Both urea and TMAO affect the phase transition temperature of the diblock copolymer, with urea typically lowering the LCST and TMAO producing more subtle changes depending on the concentrations of osmolytes. Later, the lower critical solution temperature (LCST) values of the block copolymer in the osmolytes and their mixtures have also obtained by temperature-dependence of DLS as the functions of the concentrations of the additives. These results reveal that the LCST values of copolymer decrease as the concentration of additives increase. The study highlights the molecular interactions, both direct and indirect, that contribute to these changes, underscoring the role of co-solutes in stabilizing the dehydrated state of the copolymer. This work could also pave the way for new approaches in the synthesis of PNIPAM-based devices and drug delivery systems.","PeriodicalId":405,"journal":{"name":"Polymer","volume":"34 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924898","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}
Both stretching and adding nucleating agent can improve the mechanical properties of isotactic polypropylene (iPP), but their combined effects and mechanisms remain unclear. In this paper, α-PP and β-PP were induced by different nucleating agents and the effects of stretching on their mechanical properties and their mechanisms were studied. According to the results, stiffness and toughness of iPP can be enhanced simultaneously through stretching. After stretching, the flexural modulus, tensile strength, and impact strength of α-PP were increased by 145%, 379% and 816% while those of β-PP were increased by 208%, 486% and 1316% individually at 23 °C. Typically, the mechanical properties of iPP will significantly decrease at low temperature. The impact strengths of α-PP and β-PP were reduced by 51.0% and 75.2% at -20 °C respectively. However, after stretching, their toughness hardly decreased. Then the enhancement mechanism was investigated by differential scanning calorimeter (DSC), dynamic mechanical analysis (DMA), Raman laser spectrometer (RLS), scanning electron microscope (SEM) and micro computed tomography (micro-CT). The results indicated that the cavities were generated during stretching, which can absorb energy when fractured and improve the toughness of iPP. The increases in crystallinity, the interphase iPP content and orientation result in the improved stiffness. The amorphous phase almost disappeared, which contributes to the improvement of mechanical properties of iPP at low temperature. Additionally, stretched β-PP exhibited a higher orientation and more obvious cavitation phenomenon than stretched α-PP, leading to its superior mechanical performance. This paper not only provides a new method to improve the stiffness and toughness of iPP, especially the toughness at low temperature, but also elucidates the enhancement mechanisms.
{"title":"The effects of stretching on the mechanical properties of neat and nucleated isotactic polypropylene and its enhancement mechanism","authors":"Enci Zhu, Lijuan Wei, Zhilan Jin, Zhipeng Liu, Shicheng Zhao","doi":"10.1016/j.polymer.2025.128017","DOIUrl":"https://doi.org/10.1016/j.polymer.2025.128017","url":null,"abstract":"Both stretching and adding nucleating agent can improve the mechanical properties of isotactic polypropylene (iPP), but their combined effects and mechanisms remain unclear. In this paper, α-PP and β-PP were induced by different nucleating agents and the effects of stretching on their mechanical properties and their mechanisms were studied. According to the results, stiffness and toughness of iPP can be enhanced simultaneously through stretching. After stretching, the flexural modulus, tensile strength, and impact strength of α-PP were increased by 145%, 379% and 816% while those of β-PP were increased by 208%, 486% and 1316% individually at 23 °C. Typically, the mechanical properties of iPP will significantly decrease at low temperature. The impact strengths of α-PP and β-PP were reduced by 51.0% and 75.2% at -20 °C respectively. However, after stretching, their toughness hardly decreased. Then the enhancement mechanism was investigated by differential scanning calorimeter (DSC), dynamic mechanical analysis (DMA), Raman laser spectrometer (RLS), scanning electron microscope (SEM) and micro computed tomography (micro-CT). The results indicated that the cavities were generated during stretching, which can absorb energy when fractured and improve the toughness of iPP. The increases in crystallinity, the interphase iPP content and orientation result in the improved stiffness. The amorphous phase almost disappeared, which contributes to the improvement of mechanical properties of iPP at low temperature. Additionally, stretched β-PP exhibited a higher orientation and more obvious cavitation phenomenon than stretched α-PP, leading to its superior mechanical performance. This paper not only provides a new method to improve the stiffness and toughness of iPP, especially the toughness at low temperature, but also elucidates the enhancement mechanisms.","PeriodicalId":405,"journal":{"name":"Polymer","volume":"75 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924897","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}
Polyolefins and their derivatives can be modified in both phase-state and function through post-modification techniques. This study presented a novel ethylene-vinyl alcohol-acetoacetate ester copolymer (EVOH-A), synthesized via a simple post ester-exchange method. The incorporation of acetoacetic ester not only alters the polymer's phase state but also enhances its potential for further functionalization. Two-dimensional infrared spectroscopy and molecular dynamics simulations showed that the ester-exchange modification weakens hydrogen bonds in EVOH, leading to a more amorphous structure. Thermal analysis reveals that the glass transition temperature (Tg) of modified EVOH decreases from 30 oC (EVOH) to -3 oC (EVOH-A4), indicating a transformation from a glassy to a rubbery state of polymers. The tensile strength and Young's modulus of the modified EVOH-A films decrease, while tensile elongation significantly increases. Additionally, this work demonstrates the application of modified polymers in the Hantzsch reaction, endowing the photoluminescence and hydrophobicity of polymers. This study introduces a new EVOH modification method with significant potential for developing multifunctional polyolefin materials.
{"title":"Transformation of ethylene vinyl alcohol copolymer from a glassy state to a rubber state through post ester-exchange modification","authors":"Zhenjing Zhou, Yihao Meng, Jiang Wu, Jieting Zhou, Xi Yu, Ningbo Yi, Qinghua Wu, Yancheng Wu, Jialin Zhang, Longfei Fan, Juxian Zhang, Feng Gan","doi":"10.1016/j.polymer.2024.127993","DOIUrl":"https://doi.org/10.1016/j.polymer.2024.127993","url":null,"abstract":"Polyolefins and their derivatives can be modified in both phase-state and function through post-modification techniques. This study presented a novel ethylene-vinyl alcohol-acetoacetate ester copolymer (EVOH-A), synthesized via a simple post ester-exchange method. The incorporation of acetoacetic ester not only alters the polymer's phase state but also enhances its potential for further functionalization. Two-dimensional infrared spectroscopy and molecular dynamics simulations showed that the ester-exchange modification weakens hydrogen bonds in EVOH, leading to a more amorphous structure. Thermal analysis reveals that the glass transition temperature (<em>T</em><sub>g</sub>) of modified EVOH decreases from 30 <sup>o</sup>C (EVOH) to -3 <sup>o</sup>C (EVOH-A4), indicating a transformation from a glassy to a rubbery state of polymers. The tensile strength and Young's modulus of the modified EVOH-A films decrease, while tensile elongation significantly increases. Additionally, this work demonstrates the application of modified polymers in the Hantzsch reaction, endowing the photoluminescence and hydrophobicity of polymers. This study introduces a new EVOH modification method with significant potential for developing multifunctional polyolefin materials.","PeriodicalId":405,"journal":{"name":"Polymer","volume":"1 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142917528","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}
Porous polyimide films have garnered significant attention for low-dielectric applications. However, most existing porous polyimide films exhibit poor mechanical properties and high water adsorption. In this study, we propose an integrated approach that combines pore structure design with crosslinking network engineering to fabricate crosslinked porous polyimide films (CL-PFPIs). The cross-linked network structure effectively reduces the dielectric constant while simultaneously improving mechanical strength and water resistance. The performance and porosity of the CL-PFPIs can be finely tuned. Notably, the CL-PFPI-30 variant demonstrates outstanding overall performance, including a low dielectric constant of 2.08, a low dielectric loss of 0.0067, a low water adsorption of 1.03%, and a high tensile strength of 79.1 MPa, making it a promising fcandidate or low-dielectric applications.
{"title":"Porous polyimide films with low dielectric constant prepared by integrated strategy containing construction of pore structure and crosslinking network engineering","authors":"Haidan Lin, Hang Fan, Chenyuan Yang, Shiyang Zhu, Tiantian Xie, Chao Xiang, Hongyan Yao, Shaowei Guan","doi":"10.1016/j.polymer.2024.128000","DOIUrl":"https://doi.org/10.1016/j.polymer.2024.128000","url":null,"abstract":"Porous polyimide films have garnered significant attention for low-dielectric applications. However, most existing porous polyimide films exhibit poor mechanical properties and high water adsorption. In this study, we propose an integrated approach that combines pore structure design with crosslinking network engineering to fabricate crosslinked porous polyimide films (CL-PFPIs). The cross-linked network structure effectively reduces the dielectric constant while simultaneously improving mechanical strength and water resistance. The performance and porosity of the CL-PFPIs can be finely tuned. Notably, the CL-PFPI-30 variant demonstrates outstanding overall performance, including a low dielectric constant of 2.08, a low dielectric loss of 0.0067, a low water adsorption of 1.03%, and a high tensile strength of 79.1 MPa, making it a promising fcandidate or low-dielectric applications.","PeriodicalId":405,"journal":{"name":"Polymer","volume":"6 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924899","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}
Pressurization-induced crystallization (PIC) of isotactic polypropylene (iPP) with the β-nucleating agent (β-NA) was investigated by wide-angle X-ray diffraction, polarizing microscopy and differential scanning calorimetry measurement. A competitive formation process between the mesophase and γ-iPP was found in the PIC process. Specifically, increasing the pressurization rate can significantly suppress the formation of γ-phase and induce the formation of mesophase with the range between the critical pressurization rate from R1 to R2, however, when the temperature exceeds a critical value of about 280 °C, only mesophase forms despite any pressurization rate. Moreover, instead of β-iPP, β-NA serves as an effective nucleating agent and promotes the formation of γ-iPP under PIC treatment, and its self-assembly morphology can also be controlled by verifying pressurization rates and/or temperatures. As a result, a reasonable mechanism was proposed to show how to tune the crystalline polymorphism and morphology of iPP materials by using the “pressurization” method, and a pressure-temperature crystallization structural diagram was established to analyze the synergistic effect of pressurization rate and temperature on the crystallization polymorphism of iPP. It demonstrates that pressurization is likely to be a universal method for tailoring polymer crystallization within an appropriate temperature range.
{"title":"Pressurization induced crystallization of iPP containing self-assembly β-nucleating agents: role of pressurization rate and temperature","authors":"Yaxin Liu, Cong Wei, Zipei Ding, Huashen Zhang, Jian Xu, Baobao Chang, Zhen Wang, Chuntai Liu, Changyu Shen, Chunguang Shao","doi":"10.1016/j.polymer.2025.128026","DOIUrl":"https://doi.org/10.1016/j.polymer.2025.128026","url":null,"abstract":"Pressurization-induced crystallization (PIC) of isotactic polypropylene (iPP) with the β-nucleating agent (β-NA) was investigated by wide-angle X-ray diffraction, polarizing microscopy and differential scanning calorimetry measurement. A competitive formation process between the mesophase and γ-iPP was found in the PIC process. Specifically, increasing the pressurization rate can significantly suppress the formation of γ-phase and induce the formation of mesophase with the range between the critical pressurization rate from <strong>R</strong><sub><strong>1</strong></sub> to <strong>R</strong><sub><strong>2</strong></sub>, however, when the temperature exceeds a critical value of about 280 °C, only mesophase forms despite any pressurization rate. Moreover, instead of β-iPP, β-NA serves as an effective nucleating agent and promotes the formation of γ-iPP under PIC treatment, and its self-assembly morphology can also be controlled by verifying pressurization rates and/or temperatures. As a result, a reasonable mechanism was proposed to show how to tune the crystalline polymorphism and morphology of iPP materials by using the “pressurization” method, and a pressure-temperature crystallization structural diagram was established to analyze the synergistic effect of pressurization rate and temperature on the crystallization polymorphism of iPP. It demonstrates that pressurization is likely to be a universal method for tailoring polymer crystallization within an appropriate temperature range.","PeriodicalId":405,"journal":{"name":"Polymer","volume":"5 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924902","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 : 2025-01-03DOI: 10.1016/j.polymer.2025.128018
Yu Zhang, Guang-ming Yan, Jie Yang, Gang Zhang
Low dielectric polymers are urgently needed in wireless communication. Compared with porous structure, the introduction of free volume can reduce the dielectric constant without damage the mechanical properties. Therefore, a new kind of low dielectric constant polyarylates with furan as the reactive pendent groups (PAFRs) were innovatively designed and synthesized based on furfural. The introduction of pendent furan groups was found to increase the free volume and molecular chain space that further affect the dielectric properties. The dielectric constant and dielectric loss of PAFRs decreased down to 2.57 - 2.92 and 0.005 - 0.0091 at 1 MHz, respectively, with excellent thermal (Tg > 209 oC) and mechanical properties (Tensile strength > 73 MPa). Furthermore, reversible crosslinked low dielectric constant polyarylates (C-PAFR) were designed and prepared by dynamic covalent based on pendent furan groups. The crosslinked structure further reduced the dielectric constant as the dielectric constant of crosslinked PAFR films (C-PAFR23) could even decrease down to 2.17. In addition, the dynamic crosslinked structure endowed C-PAFRs with excellent solvent resistance and good re-processability with the on/off Diels-Alder reaction. We believe such recyclable dynamic crosslinked low dielectric materials are interesting and would be applicable in the field of wireless communication.
{"title":"Synthesis and Properties of Novel Polyarylates Containing Furan Pendent Groups and Reversibly Crosslinked structure","authors":"Yu Zhang, Guang-ming Yan, Jie Yang, Gang Zhang","doi":"10.1016/j.polymer.2025.128018","DOIUrl":"https://doi.org/10.1016/j.polymer.2025.128018","url":null,"abstract":"Low dielectric polymers are urgently needed in wireless communication. Compared with porous structure, the introduction of free volume can reduce the dielectric constant without damage the mechanical properties. Therefore, a new kind of low dielectric constant polyarylates with furan as the reactive pendent groups (PAFRs) were innovatively designed and synthesized based on furfural. The introduction of pendent furan groups was found to increase the free volume and molecular chain space that further affect the dielectric properties. The dielectric constant and dielectric loss of PAFRs decreased down to 2.57 - 2.92 and 0.005 - 0.0091 at 1 MHz, respectively, with excellent thermal (T<sub>g</sub> > 209 <sup>o</sup>C) and mechanical properties (Tensile strength > 73 MPa). Furthermore, reversible crosslinked low dielectric constant polyarylates (C-PAFR) were designed and prepared by dynamic covalent based on pendent furan groups. The crosslinked structure further reduced the dielectric constant as the dielectric constant of crosslinked PAFR films (C-PAFR23) could even decrease down to 2.17. In addition, the dynamic crosslinked structure endowed C-PAFRs with excellent solvent resistance and good re-processability with the on/off Diels-Alder reaction. We believe such recyclable dynamic crosslinked low dielectric materials are interesting and would be applicable in the field of wireless communication.","PeriodicalId":405,"journal":{"name":"Polymer","volume":"27 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142917530","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}
A series of thermoset imide oligomers have been prepared by the thermal polycondensation of pyromellitic dianhydride (PMDA) with two different aromatic diamines, bis(4‐amino‐2‐trifluoromethylphenyl)ether (TFODA) and 2,2'-bis(trifluoromethyl)benzidine (TFDB) in the presence of 4-phenylethynylphthalic anhydride (4-PEPA) as an end-capping reagent. The effects of different diamine ratios and different molecular weights on the solubility and melt viscosity of imide oligomers, as well as on the thermal and mechanical properties of cured polyimide sheets were investigated. The experimental results showed that the imide oligomers PI-1, PI-2, PI-3, and PI-4 exhibited good solubility (≥33 wt%) in common solvents. Among them, PI-2 showed the best processing properties with a minimum melt viscosity of 4.8 Pa·s. After thermally curing at 371 °C for 2.5 h, the cured polyimide sheets showed glass transition temperatures (Tgs) of 413-472 °C, 5% weight loss temperatures (Td5%s) of 560-578 °C in both air and N2 atmosphere, and good toughness with elongation of 8.6-19.1%.
{"title":"Highly heat-resistant and soluble phenylethynyl-terminated thermoset imide oligomers based on pyromellitic dianhydride","authors":"Minghui Bai, Chunshan Lu, Guofei Chen, Xingzhong Fang","doi":"10.1016/j.polymer.2025.128024","DOIUrl":"https://doi.org/10.1016/j.polymer.2025.128024","url":null,"abstract":"A series of thermoset imide oligomers have been prepared by the thermal polycondensation of pyromellitic dianhydride (PMDA) with two different aromatic diamines, bis(4‐amino‐2‐trifluoromethylphenyl)ether (TFODA) and 2,2'-bis(trifluoromethyl)benzidine (TFDB) in the presence of 4-phenylethynylphthalic anhydride (4-PEPA) as an end-capping reagent. The effects of different diamine ratios and different molecular weights on the solubility and melt viscosity of imide oligomers, as well as on the thermal and mechanical properties of cured polyimide sheets were investigated. The experimental results showed that the imide oligomers PI-1, PI-2, PI-3, and PI-4 exhibited good solubility (≥33 wt%) in common solvents. Among them, PI-2 showed the best processing properties with a minimum melt viscosity of 4.8 Pa·s. After thermally curing at 371 °C for 2.5 h, the cured polyimide sheets showed glass transition temperatures (<em>T</em><sub>g</sub>s) of 413-472 °C, 5% weight loss temperatures (<em>T</em><sub>d5%</sub>s) of 560-578 °C in both air and N<sub>2</sub> atmosphere, and good toughness with elongation of 8.6-19.1%.","PeriodicalId":405,"journal":{"name":"Polymer","volume":"73 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924900","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 : 2025-01-03DOI: 10.1016/j.polymer.2025.128023
Yusuke Momonoi, Koh-hei Nitta, Yusuke Hiejima
Perylene was doped into high- and low-density polyethylene (HDPE and LDPE, respectively) as an aggregation-induced emission (AIE) dye. Emission spectra were monitored in situ during tensile tests and analyzed using nonnegative matrix factorization (NMF). The components of the second score, s2, corresponding to the AIE fraction showed a significant increase beyond the elastic limit because of further aggregation induced by the compressive stress exerted on the amorphous phase. The s2 components decreased drastically at the second yield point because plastic flow caused the perylene aggregates to collapse. The results of step-cycle tests revealed the difference in the yielding mechanisms between HDPE and LDPE. Deformation in HDPE was hindered by the compressive stress exerted on the densely-packed bulky units. The present study demonstrated that AIE is a sensitive probe of amorphous deformation and that the proposed method can be used to quantitatively evaluate material failure even before yielding occurs.
{"title":"Amorphous deformation in high- and low-density polyethylene probed by aggregation-induced emission","authors":"Yusuke Momonoi, Koh-hei Nitta, Yusuke Hiejima","doi":"10.1016/j.polymer.2025.128023","DOIUrl":"https://doi.org/10.1016/j.polymer.2025.128023","url":null,"abstract":"Perylene was doped into high- and low-density polyethylene (HDPE and LDPE, respectively) as an aggregation-induced emission (AIE) dye. Emission spectra were monitored <em>in situ</em> during tensile tests and analyzed using nonnegative matrix factorization (NMF). The components of the second score, <strong><em>s</em></strong><sub>2</sub>, corresponding to the AIE fraction showed a significant increase beyond the elastic limit because of further aggregation induced by the compressive stress exerted on the amorphous phase. The <strong><em>s</em></strong><sub>2</sub> components decreased drastically at the second yield point because plastic flow caused the perylene aggregates to collapse. The results of step-cycle tests revealed the difference in the yielding mechanisms between HDPE and LDPE. Deformation in HDPE was hindered by the compressive stress exerted on the densely-packed bulky units. The present study demonstrated that AIE is a sensitive probe of amorphous deformation and that the proposed method can be used to quantitatively evaluate material failure even before yielding occurs.","PeriodicalId":405,"journal":{"name":"Polymer","volume":"11 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924903","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 : 2025-01-03DOI: 10.1016/j.polymer.2025.128020
Mayankkumar L. Chaudhary, Rutu Patel, Ram K. Gupta
Bio-based elastomers are emerging as sustainable alternatives to conventional elastomers, driven by advancements in self-healing, three-dimensional (3D) printability, and processability. Derived from renewable resources, these materials align with global sustainability goals while offering unique functionalities that extend their lifespan and enable the precise fabrication of complex structures. Recent research has focused on intrinsic and extrinsic self-healing mechanisms, significantly enhancing the autonomous repair capabilities of these materials. Additionally, progress in 3D printing technologies has transformed the design and manufacturing of bio-based elastomers, opening new avenues for smart applications across various industries. This comprehensive review highlights and integrates the interplay between self-healing, 3D printability, and processability in bio-based elastomers. It addresses this gap by providing critical insights into their environmental and economic implications. Furthermore, it identifies unresolved challenges, such as scalability and performance optimization, and proposes future research directions to advance the field. By bridging these aspects, this review offers a fresh perspective on developing bio-based self-healing elastomers and their transformative potential for 3D printing applications.
{"title":"Advances in Self-Healable and 3D Printable Biobased Elastomers","authors":"Mayankkumar L. Chaudhary, Rutu Patel, Ram K. Gupta","doi":"10.1016/j.polymer.2025.128020","DOIUrl":"https://doi.org/10.1016/j.polymer.2025.128020","url":null,"abstract":"Bio-based elastomers are emerging as sustainable alternatives to conventional elastomers, driven by advancements in self-healing, three-dimensional (3D) printability, and processability. Derived from renewable resources, these materials align with global sustainability goals while offering unique functionalities that extend their lifespan and enable the precise fabrication of complex structures. Recent research has focused on intrinsic and extrinsic self-healing mechanisms, significantly enhancing the autonomous repair capabilities of these materials. Additionally, progress in 3D printing technologies has transformed the design and manufacturing of bio-based elastomers, opening new avenues for smart applications across various industries. This comprehensive review highlights and integrates the interplay between self-healing, 3D printability, and processability in bio-based elastomers. It addresses this gap by providing critical insights into their environmental and economic implications. Furthermore, it identifies unresolved challenges, such as scalability and performance optimization, and proposes future research directions to advance the field. By bridging these aspects, this review offers a fresh perspective on developing bio-based self-healing elastomers and their transformative potential for 3D printing applications.","PeriodicalId":405,"journal":{"name":"Polymer","volume":"24 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924901","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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