Pub Date : 2025-02-18DOI: 10.1016/j.polymer.2025.128150
Sujith D. Namnidi, Lambèrt C.A. van Breemen, Stan F.S.P. Looijmans
Polypropylene (PP) and high-density polyethylene (HDPE) are commonly found together in waste streams and are difficult to separate due to their similar densities, resulting in recycled polypropylene often containing some polyethylene, creating a blend. PP and HDPE form an immiscible blend whose heterophasic and crystalline morphologies that contribute to the final mechanical properties are influenced by processing conditions. Although basic thermal and rheological characterizations of these blends are somewhat addressed in the literature, the impact of controlled processing conditions on various blend compositions remains largely unexplored. This study investigates the thermal and rheological properties of these blends, and utilizes for the first time extended dilatometry to simulate a range of realistic processing conditions such as pressure (0–1200 bar) and shear rates (0–150 1/s) in such multi-component blends. The resulting mechanical properties and microstructure are evaluated through tensile testing and X-ray diffraction (XRD). Under quiescent and isobaric cooling conditions, increasing the polyethylene concentration results in reduced strength and elongation compared to the pure matrix. Conversely, when subjected to shear, the addition of polyethylene enhances the yield stress due to increased flow strength, provided the solidification of the melt happens rapidly, leading to higher oriented structures in polypropylene, as confirmed by XRD.
{"title":"Structure-property relations in PP/HDPE blends: From processing to performance","authors":"Sujith D. Namnidi, Lambèrt C.A. van Breemen, Stan F.S.P. Looijmans","doi":"10.1016/j.polymer.2025.128150","DOIUrl":"10.1016/j.polymer.2025.128150","url":null,"abstract":"<div><div>Polypropylene (PP) and high-density polyethylene (HDPE) are commonly found together in waste streams and are difficult to separate due to their similar densities, resulting in recycled polypropylene often containing some polyethylene, creating a blend. PP and HDPE form an immiscible blend whose heterophasic and crystalline morphologies that contribute to the final mechanical properties are influenced by processing conditions. Although basic thermal and rheological characterizations of these blends are somewhat addressed in the literature, the impact of controlled processing conditions on various blend compositions remains largely unexplored. This study investigates the thermal and rheological properties of these blends, and utilizes for the first time extended dilatometry to simulate a range of realistic processing conditions such as pressure (0–1200 bar) and shear rates (0–150 1/s) in such multi-component blends. The resulting mechanical properties and microstructure are evaluated through tensile testing and X-ray diffraction (XRD). Under quiescent and isobaric cooling conditions, increasing the polyethylene concentration results in reduced strength and elongation compared to the pure matrix. Conversely, when subjected to shear, the addition of polyethylene enhances the yield stress due to increased flow strength, provided the solidification of the melt happens rapidly, leading to higher oriented structures in polypropylene, as confirmed by XRD.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"323 ","pages":"Article 128150"},"PeriodicalIF":4.1,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-17DOI: 10.1016/j.polymer.2025.128169
Ruhiye Nilay Tezel , İsmet Kaya
In this work, we described the synthesis and characterization of dialdehyde monomers and poly(azomethine-ether)s based on them. In the first stage, aromatic bridged dialdehyde monomers were synthesized using 2,4-Bis(chloromethyl)-1,3,5-trimethylbenzenedihalide with three different aldehydes (4-hydroxybenzaldehyde, 3-methoxy-4-hydroxybenzaldehyde, and 3-ethoxy-4-hydroxybenzaldehyde). Subsequently, corresponding poly(azomethine-ether) derivatives were synthesized through the polycondensation reaction of synthesized dialdehyde monomers with o-toluidine and o-dianisidine diamine compounds. The structures of the obtained dialdehyde and poly(azomethine-ether)s were confirmed by FT-IR, UV–Vis and NMR measurements. The physicochemical properties of the as-prepared poly(azomethine-ether)s have been confirmed through X-ray diffraction (X-RD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX) spectroscopic techniques. In FT-IR, –CHN– peak around at 1625 cm−1 attributed to the successful conversion of dialdehydes and diamines into poly(azomethine-ether). The semicrystalline nature of the poly(azomethine-ether)s was shown through the X-RD diffractometer. The optical band gaps were found to be in the range of 2.80–2.92 eV, as measured by UV/Vis analysis. These poly(azomethine-ether)s exhibit direct band gap values in the blue/violet region of visible light, which creates opportunities for future studies related to daylight optoelectronic devices. Additionally, thermal behavior was analyzed using TGA and DSC, revealing that the materials are highly stable and rigid.
{"title":"Synthesis and characterization of fluorescent and thermally stable poly(azomethine-ether)s: Optical and morphological properties","authors":"Ruhiye Nilay Tezel , İsmet Kaya","doi":"10.1016/j.polymer.2025.128169","DOIUrl":"10.1016/j.polymer.2025.128169","url":null,"abstract":"<div><div>In this work, we described the synthesis and characterization of dialdehyde monomers and poly(azomethine-ether)s based on them. In the first stage, aromatic bridged dialdehyde monomers were synthesized using 2,4-Bis(chloromethyl)-1,3,5-trimethylbenzenedihalide with three different aldehydes (4-hydroxybenzaldehyde, 3-methoxy-4-hydroxybenzaldehyde, and 3-ethoxy-4-hydroxybenzaldehyde). Subsequently, corresponding poly(azomethine-ether) derivatives were synthesized through the polycondensation reaction of synthesized dialdehyde monomers with o-toluidine and <em>o</em>-dianisidine diamine compounds. The structures of the obtained dialdehyde and poly(azomethine-ether)s were confirmed by FT-IR, UV–Vis and NMR measurements. The physicochemical properties of the as-prepared poly(azomethine-ether)s have been confirmed through X-ray diffraction (X-RD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX) spectroscopic techniques. In FT-IR, –CH<img>N– peak around at 1625 cm<sup>−1</sup> attributed to the successful conversion of dialdehydes and diamines into poly(azomethine-ether). The semicrystalline nature of the poly(azomethine-ether)s was shown through the X-RD diffractometer. The optical band gaps were found to be in the range of 2.80–2.92 eV, as measured by UV/Vis analysis. These poly(azomethine-ether)s exhibit direct band gap values in the blue/violet region of visible light, which creates opportunities for future studies related to daylight optoelectronic devices. Additionally, thermal behavior was analyzed using TGA and DSC, revealing that the materials are highly stable and rigid.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"323 ","pages":"Article 128169"},"PeriodicalIF":4.1,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427102","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 : 2025-02-16DOI: 10.1016/j.polymer.2025.128168
Huajie Gao , Yuan Gao , Jianmin Zhang , Jianfeng Wang , Yanyu Yang , Wanjie Wang , Yanxia Cao
In this study, we synthesized ethylene-acrylic acid copolymer/recycled polyvinyl butyral (EAA/RPVB) blends using hexamethylene diisocyanate (HDI) and dicumyl peroxide (DCP) as crosslinking agents via a one-step melt blending method. This approach facilitated the formation of distinct crosslinked structures in both the RPVB and EAA phases. By adjusting the blend ratios, we engineered materials with a pseudo-interpenetrating polymer network (IPN) structure. The resulting EAA/RPVB blends exhibited a broad range of glass transition temperatures and independent crystallization/melting transitions, culminating in a remarkable triple and quadruple shape memory effects. The crosslinking reactions facilitated by HDI and DCP were systematically analyzed through torque rheological measurements, gel content assessments, and spectroscopic techniques. Our results revealed that the reactivity of HDI with the hydroxyl groups of RPVB was notably higher than that of DCP with EAA. Additionally, varying the blend compositions influenced the degree of crosslinking and network morphology, as evidenced by gel content testing, dynamic rheological analyses, and scanning electron microscopy (SEM) observations. These findings suggest that the unique structural characteristics and high crosslinking density of the blends contribute to their enhanced shape memory performance and mechanical properties.
{"title":"EAA/RPVB blends with dual crosslinked structures and multiple shape memory properties prepared by one-step melt mixing","authors":"Huajie Gao , Yuan Gao , Jianmin Zhang , Jianfeng Wang , Yanyu Yang , Wanjie Wang , Yanxia Cao","doi":"10.1016/j.polymer.2025.128168","DOIUrl":"10.1016/j.polymer.2025.128168","url":null,"abstract":"<div><div>In this study, we synthesized ethylene-acrylic acid copolymer/recycled polyvinyl butyral (EAA/RPVB) blends using hexamethylene diisocyanate (HDI) and dicumyl peroxide (DCP) as crosslinking agents via a one-step melt blending method. This approach facilitated the formation of distinct crosslinked structures in both the RPVB and EAA phases. By adjusting the blend ratios, we engineered materials with a pseudo-interpenetrating polymer network (IPN) structure. The resulting EAA/RPVB blends exhibited a broad range of glass transition temperatures and independent crystallization/melting transitions, culminating in a remarkable triple and quadruple shape memory effects. The crosslinking reactions facilitated by HDI and DCP were systematically analyzed through torque rheological measurements, gel content assessments, and spectroscopic techniques. Our results revealed that the reactivity of HDI with the hydroxyl groups of RPVB was notably higher than that of DCP with EAA. Additionally, varying the blend compositions influenced the degree of crosslinking and network morphology, as evidenced by gel content testing, dynamic rheological analyses, and scanning electron microscopy (SEM) observations. These findings suggest that the unique structural characteristics and high crosslinking density of the blends contribute to their enhanced shape memory performance and mechanical properties.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"323 ","pages":"Article 128168"},"PeriodicalIF":4.1,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417986","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 : 2025-02-16DOI: 10.1016/j.polymer.2025.128166
Jiayi Xie , Xuan Liu , Haixia Zhu , Ruijie Xu , Lei Yang , Ting Zhang , Caihong Lei
Annealing is a crucial technique for enhancing the structure and performance of polymer materials. The cooling step during annealing for polymer materials has frequently been underestimated. This study investigates how varying cooling rates during annealing impact the microstructure and properties of PBS-oriented films. Owing to the consistent annealing temperature, both two annealing processes exert similar effects on the main lamellae, which account for the majority of the crystalline fraction. Consequently, the thickness and lateral size of the main lamellae in both annealed samples are comparable, as are their lamellar orientation and crystallinity. The cooling rates during the cooling stage predominantly govern the metastable lamellae and RAF content. A slower cooling rate during annealing provides melted metastable crystals with an extended period to reorganize and form more perfect structures, thereby reducing their quantity. Furthermore, prolonged physical aging may constrain more amorphous phases, contributing to an increase in RAF content. The reduced metastable structure contributes to enhanced tensile modulus, tensile strength, and elastic recovery in AN-S samples. The increased RAF content enhances the oxygen barrier properties of the AN-S sample. This study demonstrates that selecting a slower cooling rate during annealing can significantly enhance the barrier and mechanical properties of PBS film, thereby expanding its potential applications.
{"title":"Influence of cooling rate during annealing on the microstructure and properties of Poly(butylene succinate) oriented films","authors":"Jiayi Xie , Xuan Liu , Haixia Zhu , Ruijie Xu , Lei Yang , Ting Zhang , Caihong Lei","doi":"10.1016/j.polymer.2025.128166","DOIUrl":"10.1016/j.polymer.2025.128166","url":null,"abstract":"<div><div>Annealing is a crucial technique for enhancing the structure and performance of polymer materials. The cooling step during annealing for polymer materials has frequently been underestimated. This study investigates how varying cooling rates during annealing impact the microstructure and properties of PBS-oriented films. Owing to the consistent annealing temperature, both two annealing processes exert similar effects on the main lamellae, which account for the majority of the crystalline fraction. Consequently, the thickness and lateral size of the main lamellae in both annealed samples are comparable, as are their lamellar orientation and crystallinity. The cooling rates during the cooling stage predominantly govern the metastable lamellae and RAF content. A slower cooling rate during annealing provides melted metastable crystals with an extended period to reorganize and form more perfect structures, thereby reducing their quantity. Furthermore, prolonged physical aging may constrain more amorphous phases, contributing to an increase in RAF content. The reduced metastable structure contributes to enhanced tensile modulus, tensile strength, and elastic recovery in AN-S samples. The increased RAF content enhances the oxygen barrier properties of the AN-S sample. This study demonstrates that selecting a slower cooling rate during annealing can significantly enhance the barrier and mechanical properties of PBS film, thereby expanding its potential applications.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"322 ","pages":"Article 128166"},"PeriodicalIF":4.1,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417985","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 : 2025-02-15DOI: 10.1016/j.polymer.2025.128157
Keran Zhu , Wei Jiang , Yuting Wang , Huasheng Yuan , Li Xia , Yesheng Zhu , Liang Chen
Pyrolysis carbon black (CBp) from waste tires not only has significant economic benefits but also addresses the urgent environmental problem of waste tire disposal. To date, many studies have been conducted to improve the properties of CBp in order to enhance its reinforcing effects. However, due to the structural complexity of CBp, it is crucial to quantitatively evaluate its structural discrepancies and identify the subtle distinctions between CBp and commercial carbon black (CB) in order to guide the improvement of CBp's properties. In this study, synchrotron radiation X-ray Nano-CT, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) were employed to carefully investigate the spatial and chemical structures of CBp before and after nitric acid (HNO3) treatment. We believe the main reasons for the low structurer (fractal dimension: 2.162 for CBp, lower than 2.307 for commercial CB), inhomogeneous size distributions, and inert chemical surface properties of CBp are the presence of rubber residues (volume ratio: 3.6 %) and other oxides remaining on the surface. These substances block pores, cover the active sites for chemical groups, and cause smaller particles to adhere to larger ones. After the residues were removed through HNO3 treatment, the spatial and chemical structures of CBp were significantly improved (pore volume ratio increased from 2.7 % to 6.5 %), bringing its properties closer to those of commercial CB. The aim of this study is to identify subtle microstructural changes that can guide the optimization of conditions for producing CBp with the potential to replace commercial CB in tire fabrication.
{"title":"The studies of structural characteristic improvement of pyrolysis carbon black by synchrotron radiation X-ray nano-computed tomography","authors":"Keran Zhu , Wei Jiang , Yuting Wang , Huasheng Yuan , Li Xia , Yesheng Zhu , Liang Chen","doi":"10.1016/j.polymer.2025.128157","DOIUrl":"10.1016/j.polymer.2025.128157","url":null,"abstract":"<div><div>Pyrolysis carbon black (CBp) from waste tires not only has significant economic benefits but also addresses the urgent environmental problem of waste tire disposal. To date, many studies have been conducted to improve the properties of CBp in order to enhance its reinforcing effects. However, due to the structural complexity of CBp, it is crucial to quantitatively evaluate its structural discrepancies and identify the subtle distinctions between CBp and commercial carbon black (CB) in order to guide the improvement of CBp's properties. In this study, synchrotron radiation X-ray Nano-CT, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) were employed to carefully investigate the spatial and chemical structures of CBp before and after nitric acid (HNO<sub>3</sub>) treatment. We believe the main reasons for the low structurer (fractal dimension: 2.162 for CBp, lower than 2.307 for commercial CB), inhomogeneous size distributions, and inert chemical surface properties of CBp are the presence of rubber residues (volume ratio: 3.6 %) and other oxides remaining on the surface. These substances block pores, cover the active sites for chemical groups, and cause smaller particles to adhere to larger ones. After the residues were removed through HNO<sub>3</sub> treatment, the spatial and chemical structures of CBp were significantly improved (pore volume ratio increased from 2.7 % to 6.5 %), bringing its properties closer to those of commercial CB. The aim of this study is to identify subtle microstructural changes that can guide the optimization of conditions for producing CBp with the potential to replace commercial CB in tire fabrication.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"323 ","pages":"Article 128157"},"PeriodicalIF":4.1,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417988","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 : 2025-02-15DOI: 10.1016/j.polymer.2025.128161
Artur Rozanski
In this work, the influence of temperature and molecular orientation on the elastic modulus of the amorphous regions (Ea) of semicrystalline polymers was determined using high-density polyethylene (HDPE) as an example. The decrease in Ea with increasing temperature was observed due to the gradual increase in the mobility of polymer chains, stimulated by the α relaxation processes within the crystalline regions. Thus, with the temperature increase, a gradual minimization of the “stiffening” influence of the crystals on the interlamellar layers was observed. Then, the influence of both the orientation and the undisturbed length of crystallites, as well as the orientation of the amorphous component, on the Ea value was demonstrated using materials deformed in a channel die with different compression ratios. At low compression ratios, a significant decrease in Ea was observed, stimulated by the fragmentation of lamellar crystals in the absence of measurable molecular orientation. At higher compression ratios, although the processes of crystal fragmentation remain active, a gradual increase in the orientation of chains in both the crystalline and amorphous components along the Ea measurement direction stimulated a significant increase in the Ea value. Consequently, Ea for the material with the highest compression ratio was six times higher compared to the reference material. The observed changes in Ea were also correlated with changes in the macroscopic Young's modulus.
本研究以高密度聚乙烯（HDPE）为例，测定了温度和分子取向对半结晶聚合物无定形区弹性模量（Ea）的影响。观察到 Ea 随温度升高而降低，这是由于聚合物链的流动性在结晶区内的 α 松弛过程的刺激下逐渐增加。因此，随着温度的升高，晶体对层间层的 "硬化 "影响逐渐减小。然后，使用在具有不同压缩比的槽模中变形的材料，证明了晶体的取向和未扰动长度以及无定形成分的取向对 Ea 值的影响。在低压缩比情况下，Ea 值会显著降低，这是由于在没有可测量的分子取向的情况下，片状晶体碎裂造成的。在较高的压缩比下，虽然晶体破碎过程仍然活跃，但沿 Ea 测量方向晶体和无定形成分链的取向逐渐增加，促使 Ea 值显著增加。因此，压缩比最高的材料的 Ea 值是参考材料的六倍。观察到的 Ea 变化也与宏观杨氏模量的变化相关。
{"title":"Influence of temperature and orientation on the mechanical properties of amorphous regions on the example of polyethylene","authors":"Artur Rozanski","doi":"10.1016/j.polymer.2025.128161","DOIUrl":"10.1016/j.polymer.2025.128161","url":null,"abstract":"<div><div>In this work, the influence of temperature and molecular orientation on the elastic modulus of the amorphous regions (<em>E</em><sub><em>a</em></sub><em>)</em> of semicrystalline polymers was determined using high-density polyethylene (HDPE) as an example. The decrease in <em>E</em><sub><em>a</em></sub> with increasing temperature was observed due to the gradual increase in the mobility of polymer chains, stimulated by the α relaxation processes within the crystalline regions. Thus, with the temperature increase, a gradual minimization of the “stiffening” influence of the crystals on the interlamellar layers was observed. Then, the influence of both the orientation and the undisturbed length of crystallites, as well as the orientation of the amorphous component, on the <em>E</em><sub><em>a</em></sub> value was demonstrated using materials deformed in a channel die with different compression ratios. At low compression ratios, a significant decrease in <em>E</em><sub><em>a</em></sub> was observed, stimulated by the fragmentation of lamellar crystals in the absence of measurable molecular orientation. At higher compression ratios, although the processes of crystal fragmentation remain active, a gradual increase in the orientation of chains in both the crystalline and amorphous components along the <em>E</em><sub><em>a</em></sub> measurement direction stimulated a significant increase in the E<sub>a</sub> value. Consequently, <em>E</em><sub><em>a</em></sub> for the material with the highest compression ratio was six times higher compared to the reference material. The observed changes in <em>E</em><sub><em>a</em></sub> were also correlated with changes in the macroscopic Young's modulus.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"323 ","pages":"Article 128161"},"PeriodicalIF":4.1,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417987","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 : 2025-02-14DOI: 10.1016/j.polymer.2025.128164
Zhenyuan Li , Xing Liu , Ying Sun , Lili Gong , Chunfa Liao , Shuangjiang Luo
Industrial gas separation processes demand membranes with superior separation performance under high feed pressures. Herein, we fabricate defect-free hollow fiber membranes (HFMs) using 6FDA-mPDA0.9-TFMB0.1 copolyimide, achieving both exceptional pressure resistance and excellent gas separation performance. Through a dry-jet/wet-quench spinning approach, we systematically optimize the microstructure of the HFMs by adjusting the dope composition and spinning conditions. The results reveal that polymer concentration, dope-to-bore fluid ratio, and take-up rate have a significant impact on the pressure resistance of HFMs. Under optimized conditions, the fabricated HFMs exhibit a high burst pressure of 10.5 MPa, along with excellent gas separation performance, including a He permeance of 72.1 GPU and a He/CH4 selectivity of 178. Additionally, mixed-gas permeation experiments conducted at feed pressures up to 750 PSIA demonstrate excellent resistance to heavy hydrocarbons. These ultra-strong, high-performance HFMs show great potential for efficient helium separation from natural gas under high-pressure conditions.
{"title":"Pressure-resistant polyimide hollow fiber membranes for high-performance helium recovery from natural gas","authors":"Zhenyuan Li , Xing Liu , Ying Sun , Lili Gong , Chunfa Liao , Shuangjiang Luo","doi":"10.1016/j.polymer.2025.128164","DOIUrl":"10.1016/j.polymer.2025.128164","url":null,"abstract":"<div><div>Industrial gas separation processes demand membranes with superior separation performance under high feed pressures. Herein, we fabricate defect-free hollow fiber membranes (HFMs) using 6FDA-mPDA<sub>0.9</sub>-TFMB<sub>0.1</sub> copolyimide, achieving both exceptional pressure resistance and excellent gas separation performance. Through a dry-jet/wet-quench spinning approach, we systematically optimize the microstructure of the HFMs by adjusting the dope composition and spinning conditions. The results reveal that polymer concentration, dope-to-bore fluid ratio, and take-up rate have a significant impact on the pressure resistance of HFMs. Under optimized conditions, the fabricated HFMs exhibit a high burst pressure of 10.5 MPa, along with excellent gas separation performance, including a He permeance of 72.1 GPU and a He/CH<sub>4</sub> selectivity of 178. Additionally, mixed-gas permeation experiments conducted at feed pressures up to 750 PSIA demonstrate excellent resistance to heavy hydrocarbons. These ultra-strong, high-performance HFMs show great potential for efficient helium separation from natural gas under high-pressure conditions.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"323 ","pages":"Article 128164"},"PeriodicalIF":4.1,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417989","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 : 2025-02-13DOI: 10.1016/j.polymer.2025.128163
Naifan Dong , Jintang Duan , Cailiang Zhang , Xueping Gu , Lianfang Feng , Liu Liu
Polysiloxanes with amino functional groups exhibit remarkable backbone flexibility, lubricity, and softness, positioning them a promising class of polymer materials. The phosphazene base (Bu-t-P4) serves as an effective catalyst for the ring-opening copolymerization (ROCP) of octamethylcyclotetrasiloxane (D4) and N-β-(aminoethyl)-γ-aminopropylmethyldiethoxysilane (KH-602). Under catalysis by 100 ppm of Bu-t-P4 at 110 °C for 1 h, high yield of 93.59 % was achieved, resulting in amino silicone oil with a number-average molecular weight of 4.3 × 103 g/mol, and a narrow molecular weight distribution (2.00). Fourier-transform infrared spectroscopy and nuclear magnetic resonance (NMR) confirmed that the product's structure corresponds to expected chemical shifts. In situ Raman spectroscopy monitoring and NMR analysis was employed to propose and validate the polymerization mechanism within the Bu-t-P4-catalyzed system involving both cyclic and linear monomers. This study demonstrates an effective strategy, affirming that Bu-t-P4 can be used as an efficient organic catalyst for the modified polysiloxanes.
{"title":"Cyclo-linear synthesis of amino silicone oil and study on the catalytic polymerization mechanism of phosphazene base","authors":"Naifan Dong , Jintang Duan , Cailiang Zhang , Xueping Gu , Lianfang Feng , Liu Liu","doi":"10.1016/j.polymer.2025.128163","DOIUrl":"10.1016/j.polymer.2025.128163","url":null,"abstract":"<div><div>Polysiloxanes with amino functional groups exhibit remarkable backbone flexibility, lubricity, and softness, positioning them a promising class of polymer materials. The phosphazene base (Bu-t-P<sub>4</sub>) serves as an effective catalyst for the ring-opening copolymerization (ROCP) of octamethylcyclotetrasiloxane (D<sub>4</sub>) and N-β-(aminoethyl)-γ-aminopropylmethyldiethoxysilane (KH-602). Under catalysis by 100 ppm of Bu-t-P<sub>4</sub> at 110 °C for 1 h, high yield of 93.59 % was achieved, resulting in amino silicone oil with a number-average molecular weight of 4.3 × 10<sup>3</sup> g/mol, and a narrow molecular weight distribution (2.00). Fourier-transform infrared spectroscopy and nuclear magnetic resonance (NMR) confirmed that the product's structure corresponds to expected chemical shifts. In situ Raman spectroscopy monitoring and NMR analysis was employed to propose and validate the polymerization mechanism within the Bu-t-P<sub>4</sub>-catalyzed system involving both cyclic and linear monomers. This study demonstrates an effective strategy, affirming that Bu-t-P<sub>4</sub> can be used as an efficient organic catalyst for the modified polysiloxanes.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"323 ","pages":"Article 128163"},"PeriodicalIF":4.1,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143418038","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 : 2025-02-12DOI: 10.1016/j.polymer.2025.128159
Yingliang Zhang , Chenjun Liu , Kang Chen , Jiake Fan , Zhongli Zhang , Bohao Li , Yunsheng Xu , Xianming Zhang
Polyethylene terephthalate (PET) monofilament is extensively utilized in various industries due to its exceptional properties. However, PET monofilament is apt to hydrolysis when exposed to moisture and heat, and the corresponding steam-aging mechanism is not clearly, which severely affects its properties and service life. Hence, the pure PET and modified anti-hydrolysis PET monofilament by introducing hydrolysis stabilizers (polycarbodiimide, PCDI) were subjected to the pressure cooker test, and the resultant changes in mechanical properties were studied. Additionally, the varying length scales structural changes were compared to assess the effectiveness of the hydrolysis stabilizers and to reveal the steam-aging mechanisms of PET monofilaments. The results indicated that both PET monofilaments underwent three distinct aging processes, including pre-aging, steady-aging stage, and rapid failure aging stage. The disorientation of the molecular chain within the oriented amorphous region occurred in the pre-aging stage, giving rise to a subtle increment in breaking strain. Competitive recrystallization and hydrolysis reactions then took place simultaneously in the amorphous region, with the generation of small crystals acting as cross-linking points during the steady-aging stage, forming a more stable lamellar structure that delayed mechanical property loss due to hydrolysis-induced molecular chain breakage. The hydrolysis degradation reaction predominates in the rapid failure aging stage, resulting in a significant decrease in intrinsic viscosity, breaking stress and strain, and causing macroscopic defects. The degradation of molecular chains and the morphology damage induced by steam-aging are the main reasons for the decline of mechanical properties. Moreover, the addition of hydrolysis stabilizers (PCDI) predominantly influenced the molecular chain arrangement in the amorphous region, effectively prolonging the duration of the steady-aging stage and enhancing resistance to hydrolytic degradation conversely.
{"title":"Comprehensive study of the steam-aging degradation behaviors and its correspondence to aging mechanism of PET monofilaments under artificially accelerated environment","authors":"Yingliang Zhang , Chenjun Liu , Kang Chen , Jiake Fan , Zhongli Zhang , Bohao Li , Yunsheng Xu , Xianming Zhang","doi":"10.1016/j.polymer.2025.128159","DOIUrl":"10.1016/j.polymer.2025.128159","url":null,"abstract":"<div><div>Polyethylene terephthalate (PET) monofilament is extensively utilized in various industries due to its exceptional properties. However, PET monofilament is apt to hydrolysis when exposed to moisture and heat, and the corresponding steam-aging mechanism is not clearly, which severely affects its properties and service life. Hence, the pure PET and modified anti-hydrolysis PET monofilament by introducing hydrolysis stabilizers (polycarbodiimide, PCDI) were subjected to the pressure cooker test, and the resultant changes in mechanical properties were studied. Additionally, the varying length scales structural changes were compared to assess the effectiveness of the hydrolysis stabilizers and to reveal the steam-aging mechanisms of PET monofilaments. The results indicated that both PET monofilaments underwent three distinct aging processes, including pre-aging, steady-aging stage, and rapid failure aging stage. The disorientation of the molecular chain within the oriented amorphous region occurred in the pre-aging stage, giving rise to a subtle increment in breaking strain. Competitive recrystallization and hydrolysis reactions then took place simultaneously in the amorphous region, with the generation of small crystals acting as cross-linking points during the steady-aging stage, forming a more stable lamellar structure that delayed mechanical property loss due to hydrolysis-induced molecular chain breakage. The hydrolysis degradation reaction predominates in the rapid failure aging stage, resulting in a significant decrease in intrinsic viscosity, breaking stress and strain, and causing macroscopic defects. The degradation of molecular chains and the morphology damage induced by steam-aging are the main reasons for the decline of mechanical properties. Moreover, the addition of hydrolysis stabilizers (PCDI) predominantly influenced the molecular chain arrangement in the amorphous region, effectively prolonging the duration of the steady-aging stage and enhancing resistance to hydrolytic degradation conversely.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"322 ","pages":"Article 128159"},"PeriodicalIF":4.1,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143393541","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 : 2025-02-12DOI: 10.1016/j.polymer.2025.128148
Omar El Arwadi , Ajinkya Raut , Jacob L. Meyer , Andreas Polycarpou , Mohammad Naraghi
This study investigates the formation of exchangeable bonds and recovery of load bearing in bulk vitrimers. The critical load required to fracture compact tension samples in bulk aromatic thermosetting co-polyester (ATSP) and the ability of the material to heal the crack was studied as a function of duration and temperature of healing, and number of cycles. We established a marked improvement in healing efficiency at higher temperature especially in the first healing cycle, as the thermal energy reduces the energy barriers for bond re-formation. However, the healing efficiency progressively dropped in four healing cycles, and the drop was more significant at higher temperatures. We analyzed the cure kinetics of the ATSP by means of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and gel fraction tests. The results showed a particularly good thermal stability below 300 °C. The material loss from gel fraction tests was bound to 0.7 %. While not significant by mass, this mass will turn into volatile species and gas form, occupying a much larger volume, leading to formation of voids which serve as physical barrier to curing (material degredation). This is also evidenced in the increase in the fracture surface roughness, as improper bond exchange lead to the formation of volatile species. The formation of volatile species leads to surface asperities, reducing the contact area between the two faces of the crack, and results in a reduction in healing efficiency. The study concludes by outlining the differences between the intrinsic healing in vitrimers with high vitrification temperature and thermoplastics, highlighting the differences between the molecular mechanisms at play.
{"title":"Time and temperature-dependent fracture mechanics of self-healing vitrimers","authors":"Omar El Arwadi , Ajinkya Raut , Jacob L. Meyer , Andreas Polycarpou , Mohammad Naraghi","doi":"10.1016/j.polymer.2025.128148","DOIUrl":"10.1016/j.polymer.2025.128148","url":null,"abstract":"<div><div>This study investigates the formation of exchangeable bonds and recovery of load bearing in bulk vitrimers. The critical load required to fracture compact tension samples in bulk aromatic thermosetting co-polyester (ATSP) and the ability of the material to heal the crack was studied as a function of duration and temperature of healing, and number of cycles. We established a marked improvement in healing efficiency at higher temperature especially in the first healing cycle, as the thermal energy reduces the energy barriers for bond re-formation. However, the healing efficiency progressively dropped in four healing cycles, and the drop was more significant at higher temperatures. We analyzed the cure kinetics of the ATSP by means of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and gel fraction tests. The results showed a particularly good thermal stability below 300 °C. The material loss from gel fraction tests was bound to 0.7 %. While not significant by mass, this mass will turn into volatile species and gas form, occupying a much larger volume, leading to formation of voids which serve as physical barrier to curing (material degredation). This is also evidenced in the increase in the fracture surface roughness, as improper bond exchange lead to the formation of volatile species. The formation of volatile species leads to surface asperities, reducing the contact area between the two faces of the crack, and results in a reduction in healing efficiency. The study concludes by outlining the differences between the intrinsic healing in vitrimers with high vitrification temperature and thermoplastics, highlighting the differences between the molecular mechanisms at play.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"322 ","pages":"Article 128148"},"PeriodicalIF":4.1,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143393542","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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