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Comparative Study on Properties of PBAT/PBSA Film Modified by a Multi-Functional Epoxide Chain Extender or Benzoyl Peroxide
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作者 Yanfeng Zhu Huidong Shi +3 位作者 Qing Ju Dong Zhao Yucai Shen Tingwei Wang 《Journal of Renewable Materials》 SCIE EI 2023年第3期1303-1319,共17页
Poly(butylene adipate-co-terephthalate)(PBAT)and poly(butylene succinate-co-adipate)(PBSA)blend films were prepared with different contents of a multifunctional epoxide chain extender Joncryl ADR-4468(ADR)or benzoyl p... Poly(butylene adipate-co-terephthalate)(PBAT)and poly(butylene succinate-co-adipate)(PBSA)blend films were prepared with different contents of a multifunctional epoxide chain extender Joncryl ADR-4468(ADR)or benzoyl peroxide(BPO).The long-chain-branching(LCB)introduced by ADR and branched/crosslinked entanglement induced by BPO increased melt elasticity,viscosity and compatibility,as indicated by thermal properties,rheological and morphological analyses.It was found that the elongation at break and the tensile strength were significantly improved,due to the enhancement of compatibility and the interfacial adhesion by the incorporation of ADR or BPO.The best mechanical properties were obtained in PBAT/PBSA/ADR(60/40/0.3)(A4T6A_(0.3))and PBAT/PBSA/BPO(60/40/0.9)(A4T6B_(0.9))films,respectively.With the rapid initiation of chain growth by BPO,it has significantly improved the transparency of the film.ADR and BPO can be used interchangeably in improving the comprehensive properties of PBAT/PBSA films,and it would provide more strategies for developing biodegradable materials for various applications. 展开更多
关键词 PBAT PBSA chain extend in-situ compatibilization
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Chain Extender-induced Hydrogen Bonding Organization Determines the Morphology and Properties of Thermoplastic Polycarbonate Polyurethane
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作者 Yi-Lang Qin Ping Zhu +1 位作者 Chen-Xi Ouyang Xia Dong 《Chinese Journal of Polymer Science》 SCIE EI CAS CSCD 2024年第1期87-96,I0009,共11页
Thermoplastic polycarbonate polyurethanes(PCUs) are multiblock copolymers that have been applied for medical devices for long time. Aliphatic diols are common chain extenders(CE) involved in the composition of the har... Thermoplastic polycarbonate polyurethanes(PCUs) are multiblock copolymers that have been applied for medical devices for long time. Aliphatic diols are common chain extenders(CE) involved in the composition of the hard segments of PCU. However, limited knowledge was discovered about how the chemical structure of CE affects the hydrogen bonding organization within PCUs and their mechanical properties.To investigate this problem, a group of PCUs were synthesized respectively by extending the polymer chain with 1,4-butanediol(BDO),aminoethanol(MEA), ethanediol(EO) as three kinds of chain extenders. Tiny differences in the CE chemical structure results in remarkable variations in phase separation, condensed morphologies, thermal and mechanical properties, which are characterized by Fourier transform infrared spectrometer, atomic force microscopy, small-angle X-ray scattering, differential scanning calorimetry, and tensile tests. The microstructural evolution during unilateral deformation and the different mechanism induced by the different CEs was probed and unveil by in situ wide-and small-angle X-ray diffraction. Symmetry of CE can improve the organization of the hydrogen bonding. The coherence strength of the urethane/urea group also plays a key role by comparing the two PCUs with ethanediol and aminoethanol. 展开更多
关键词 Thermoplastic polycarbonate polyurethane chain extender Hydrogen bonding Mechanical properties
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Melt Synthesis and Characterization of Poly(L-lactic Acid) Chain Linked by Multifunctional Epoxy Compound 被引量:1
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作者 王远亮 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2010年第5期774-779,共6页
High molecular weight(Mw) poly(L-lactic acid)s(PLLAs) were synthesized using multifunctional epoxy compound(Joncryl-ADR4370) as chain extender. The products were characterized by gel permeation chromatography... High molecular weight(Mw) poly(L-lactic acid)s(PLLAs) were synthesized using multifunctional epoxy compound(Joncryl-ADR4370) as chain extender. The products were characterized by gel permeation chromatography(GPC) and spectroscopy(1HNMR and FTIR). The results indicated that the Mw of PLLA increased with the increasing of the ratio of epoxy compound and the extending of reaction time. The highest Mw of PLLA reached 360 000 g/mol when the ratio of epoxy compound was 1.5 wt%. However, the reactants turned to cross-linking when the ratio of epoxy compound was over 1.5 wt%. Differential scanning calorimetry(DSC) measurements demonstrated that the glass transition(Tg) and melting temperatures(Tm) of products increased slightly as the increase of the molecular weight. Analysis of the hydrolytic degradation in vitro showed that the branched PLLA possessed the quicker degradability than that of the linear PLLA. 展开更多
关键词 melt synthesis poly(lactic acid) epoxy compound chain extender
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Testing and Evaluation for Web Usability Based on Extended Markov Chain Model 被引量:2
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作者 MAOCheng-ying LUYan-sheng 《Wuhan University Journal of Natural Sciences》 EI CAS 2004年第5期687-693,共7页
As the increasing popularity and complexity of Web applications and the emergence of their new characteristics, the testing and maintenance of large, complex Web applications are becoming more complex and difficult. W... As the increasing popularity and complexity of Web applications and the emergence of their new characteristics, the testing and maintenance of large, complex Web applications are becoming more complex and difficult. Web applications generally contain lots of pages and are used by enormous users. Statistical testing is an effective way of ensuring their quality. Web usage can be accurately described by Markov chain which has been proved to be an ideal model for software statistical testing. The results of unit testing can be utilized in the latter stages, which is an important strategy for bottom-to-top integration testing, and the other improvement of extended Markov chain model (EMM) is to present the error type vector which is treated as a part of page node. this paper also proposes the algorithm for generating test cases of usage paths. Finally, optional usage reliability evaluation methods and an incremental usability regression testing model for testing and evaluation are presented. Key words statistical testing - evaluation for Web usability - extended Markov chain model (EMM) - Web log mining - reliability evaluation CLC number TP311. 5 Foundation item: Supported by the National Defence Research Project (No. 41315. 9. 2) and National Science and Technology Plan (2001BA102A04-02-03)Biography: MAO Cheng-ying (1978-), male, Ph.D. candidate, research direction: software testing. Research direction: advanced database system, software testing, component technology and data mining. 展开更多
关键词 statistical testing evaluation for Web usability extended Markov chain model (EMM) Web log mining reliability evaluation
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MORPHOLOGY EVOLUTION IN PTFE AS A FUNCTION OF MELT TIME AND TEMPERATURE——Ⅱ.LOW MOLECULAR WEIGHT FOLDED CHAIN SINGLE CRYSTALS AND BAND STRUCTURES
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作者 J.YangandP.H.Geil T.C.LongandP.Xu 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2005年第2期137-145,共9页
The effect of sintering dispersed and bulk,low molecular weight(M_n=50,000 Da),nano-emulsionpolytetrafluoroethylene(PTFE)particles near their melting point is described.With the nascent particles consisting of ca.75 n... The effect of sintering dispersed and bulk,low molecular weight(M_n=50,000 Da),nano-emulsionpolytetrafluoroethylene(PTFE)particles near their melting point is described.With the nascent particles consisting of ca.75 nm diameter,hexagonal,single crystals,sintering at,e.g.,350℃,results,initially,in merger of neighboring particles,followed by individual molecular motion on the substrate and the formation of folded chain,lamellar single crystals andspherulites,and on-edge ribbons.It is suggested these structures develop,with time,in the mesomorphic“melt”.Sintering ofthe bulk resin yields extended chain,band structures,as well as folded chain lamellae;end-surface to end-surface merger,possibly by end-to-end polymerization,occurs with increasing time. 展开更多
关键词 Polytetrafluoroethylene NANO-EMULSION Single crystals SPHERULITES Banded structures Extended chain crystals Sintering.
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Effect of Chain Extender on Hydrogen Bond and Microphase Structure of Biodegradable Thermoplastic Polyurethanes 被引量:4
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作者 Wen-Kai Liu Yun Zhao +4 位作者 Rong Wang Feng Luo Jian-Shu Li Jie-Hua Li Hong Tan 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2018年第4期514-520,共7页
Thermomechanical properties of polyurethanes(PUs) strongly depend on the molecular interactions and microphase structure. In this work, two chain extenders with different ratios, flexile 1,4-butanediol(BDO) and br... Thermomechanical properties of polyurethanes(PUs) strongly depend on the molecular interactions and microphase structure. In this work, two chain extenders with different ratios, flexile 1,4-butanediol(BDO) and branched trimethylolpropane mono allyl ether(TMPAE), are used to tune the molecular interactions and microphase structures of a series of biodegradable thermoplastic polyurethanes(TPUs). In TPUs, the biodegradable polycaprolactone(PCL, M_n of 2000) is used as soft segment while 1,6-diisocyanatohexane(HDI) and chain extenders are used as hard segment. Fourier transform infrared spectroscopy(FTIR), proton nuclear magnetic resonance spectroscppy(~1 H-NMR), gel permeation chromatography(GPC), differential scanning calorimetry(DSC), dynamic mechanical analysis(DMA) and mechanical tests were performed to characterize the bulk structure and properties of TPUs. Compared with BDO, the steric bulk of TMPAE is larger. The increment of TMPAE can help to increase the hydrogen bond content, microphase separation, and the elastic modulus ratio(R), which would strongly affect the thermomechanical property of the TPUs. The results of this work verify the importance of the structure of chain extender on the properties of TPUs. It provides valuable information for further understanding the structure-property relationships of these polyurethanes. 展开更多
关键词 chain extender Hydrogen bond CRYSTALLINITY POLYURETHANE
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Synthesis and characterization of N,N-(pyromellitoyl)-bis-L-phenylalanine diacid ester butynediol
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作者 唐启恒 艾青松 +2 位作者 何吉宇 李晓东 杨荣杰 《Journal of Beijing Institute of Technology》 EI CAS 2014年第2期279-284,共6页
N,N-(pyromellitoyl)-bis-L-phenylalanine diacid ester butynediol(PBDCB)from pyromellitic dianhydride(PMDA),butynediol(2-butyne-1,4-diol)and DL-phenylalanine(DLP)was synthesized.The PBDCB can be used as chain ... N,N-(pyromellitoyl)-bis-L-phenylalanine diacid ester butynediol(PBDCB)from pyromellitic dianhydride(PMDA),butynediol(2-butyne-1,4-diol)and DL-phenylalanine(DLP)was synthesized.The PBDCB can be used as chain extender for thermoplastic polyurethane.The starting material of N,N-(pyromellitoyl)-bis-L-phenylalanine diacid(PBD)was synthesized through addition reaction between PMDA and DLP.Then,PBD was esterified using triethylamine as catalyst and attached antacids as well as dimethylacetamide(DMAc)as solvent.The obtained PBDCB was characterized using Fourier transformed infrared spectroscopy(FTIR),nuclear magnetic resonance(1 H NMR)spectroscopy,mass spectrometry(MS),thermal gravimetric(TG),and differential scanning calorimetry(DSC).The results showed that the PBDCB was highly thermal stable. 展开更多
关键词 polyurethane chain extender imide alkynyl
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A Defective Linear Pentachromium Complex for the Enhanced Catalysis of the Cycloaddition of CO2 with Propylene Oxide
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作者 王文珍 蔺伟 +4 位作者 李磊磊 刘双 拉亚特伊斯梅洛夫 李锦祥 彭旭明 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2018年第8期1305-1312,共8页
Based on the ligand(2,7-bis(α-pyrimidylamino)-1,8-naphthyridine(H2 bpmany)), a linear pentachromium complex [Cr5(μ5-bpmany)4Cl2]PF6(1, μ5-bpmany = 2,7-bis(a-pyrimidylamino)-1,8-naphthyridine) was synthe... Based on the ligand(2,7-bis(α-pyrimidylamino)-1,8-naphthyridine(H2 bpmany)), a linear pentachromium complex [Cr5(μ5-bpmany)4Cl2]PF6(1, μ5-bpmany = 2,7-bis(a-pyrimidylamino)-1,8-naphthyridine) was synthesized. The crystal structure of compound 1 has been characterized by X-ray crystallography. Interestingly, one metal atom in the center is missing in this linear chain, leading to the defective pentachromium metal string structure which is similar with the reported complex [Cr5(μ5-dpznda)4Cl2](2, dpznda = N^2,N^7-di(pyrazin-2-yl)-1,8-naphthyridine-2,7-diamine). The central Cr(Ⅲ) ion of 1 is eight-coordinated and is also rare in the chromium complex. The reaction of carbon dioxide with propylene oxide that generates propylene carbonate(PC) when catalyzed by [Cr5(μ5-bpmany)4Cl2]PF6 was investigated. Different reaction conditions including temperature and pressure were studied to optimize the reaction conditions. 展开更多
关键词 metal string complex pentachromium(Ⅲ) complex extended metal atomic chain
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Silicone Elastomer with High Elongation at Break Used in Digital Light Processing 3D Printing 被引量:1
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作者 Tian-Xin Yu Ya-Yuan Liu +3 位作者 Fu-Yue Tian Nan-Ying Ning Bing Yu Ming Tian 《Chinese Journal of Polymer Science》 SCIE EI CAS CSCD 2023年第11期1786-1795,I0010,共11页
3D printing silicone elastomer has demonstrated great potential in diverse areas such as medical devices,flexible electronics and soft robotics.It is of great value to investigate how to improve the mechanical propert... 3D printing silicone elastomer has demonstrated great potential in diverse areas such as medical devices,flexible electronics and soft robotics.It is of great value to investigate how to improve the mechanical properties,including tensile strength and elongation at break of printed parts.In this work,a light curing system that can be applied in silicone elastomer 3D printing is explored,which is composed of vinyl terminated polysiloxane as the macromer and thiol containing polysiloxane as the crosslinking agent,and a chain extension reaction is also introduced into this light curing system via the addition of the chain extender dithiol molecules,and a light curing system accompanied with chain extension is designed and realized based on the thiol-ene click reaction mechanism.After reinforced with silica fillers,the obtained light curing system can endow the light curing silicone elastomer with better mechanical properties under the condition of a lower viscosity of the precursor,the tensile strength and elongation at break can reach 525.5 k Pa and 601%,respectively.This light curing system provides a feasible method to solve the contradiction between the viscosity of the precursor and the mechanical properties of the light curing elastomer in the digital light processing(DLP)3D printing field. 展开更多
关键词 Silicone elastomer Thiol-ene click chemistry Light curing 3D-printing chain extender
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HIGH SPEED INJECTION MOLDING OF HIGH DENSITY POLYETHYLENE—EFFECTS OF INJECTION SPEED ON STRUCTURE AND PROPERTIES 被引量:5
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作者 邓华 傅强 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2011年第4期456-464,共9页
Thin wall samples of high density polyethylene (HDPE) were prepared via injection molding with different injection speeds ranging from 100 mm/s to 1200 mm/s. A significant decrease in the tensile strength and Young... Thin wall samples of high density polyethylene (HDPE) were prepared via injection molding with different injection speeds ranging from 100 mm/s to 1200 mm/s. A significant decrease in the tensile strength and Young's modulus was observed with increasing injection speed. In order to investigate the mechanism behind this decrease, the orientation, molecular weight, molecular weight distribution, melt flow rate, crystallinity and crystal morphology of HDPE were characterized using two-dimensional wide-angle X-ray diffraction (2D-WAXD), gel permeation chromatography (GPC), capillary rheometry and differential scanning calorimetry (DSC), respectively. It is demonstrated that the orientation, molecular weight, molecular weight distribution, melt flow rate and crystallinity have no obvious change with increasing injection speed. Nevertheless, the content of extended chain crystals or large folded chain crystals was found to decrease with increasing injection speed. Therefore, it is concluded that the decrease in tensile properties is mainly contributed by the reduced content of extended chain crystals or large folded chain crystals. This study provides industry with valuable information for the application of high speed injection molding. 展开更多
关键词 High speed injection molding High density polyethylene Tensile properties Extended chain crystals structure Large folded chain crystals.
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Synthesis and characterization of poly(p-dioxanone)-based degradable copolymers with enhanced thermal and hydrolytic stabilities
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作者 Yi-Teng Yan Gang Wu +1 位作者 Si-Chong Chen Yu-Zhong Wang 《Chinese Chemical Letters》 SCIE CAS CSCD 2022年第4期2151-2154,共4页
Herein, we presented a novel biodegradable copolymer via the chain extending reaction of poly(pdioxanone)-co-poly(2-(2-hydroxyethoxy) benzoate)(PPDO-co-PDHB) prepolymer with hexamethylene diisocyanate(HDI) as a chain ... Herein, we presented a novel biodegradable copolymer via the chain extending reaction of poly(pdioxanone)-co-poly(2-(2-hydroxyethoxy) benzoate)(PPDO-co-PDHB) prepolymer with hexamethylene diisocyanate(HDI) as a chain extender. The structures and molecular weight of PPDO-co-PDHB prepolymer and PPDO-co-PDHB-PU chain-extended copolymer are characterized via hydrogen nuclear magnetic resonance spectroscopy(1 H NMR) and viscosity test. The relationship between the molecular structures and properties of the chain-extended copolymers is established. The PPDO-co-PDHB-PU copolymers possess a better thermal stability comparing with the PPDO homopolymer. The study of mechanical properties shows that the elongation-at-break of PPDO-co-PDHB-PU is much higher than that of PPDO. The investigation of hydrolytic degradation behaviors indicates the degradation rate of PPDO can be controlled by adjusting the PDHB compositions, and proves that chain-extended copolymers exhibit an excellent hydrolytic stability being better than that of PPDO. 展开更多
关键词 Poly(p-dioxanone) Poly(2-(2-hydroxyethoxy)benzoate) Tunable properties chain extending Controlled degradation
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