液晶共聚酯高级工程塑料的链结构分析

本文揭示了液晶共聚酯的红外光谱、直接裂解质谱、裂解气相色谱、核磁共振谱和凝胶渗透色谱的主要特征，并讨论了它们的大分子链组成、序列结构和分子量分布，同时给出了其链结构分布的普适规律。     

聚酯扩链的新途径

1 前言聚酯是目前世界上最重要的已商业化的高聚物之一,聚酯的性能优越用途很广,可以纺成纤维(涤纶),可以制成薄膜,可以吹成中空容器,可以作工程塑料。聚酯的结构式为:     

液晶聚酯链结构与热性能的关系

液晶聚酯具有高强度，高模量，耐高温，耐腐蚀，自阻燃和尺寸稳定性等优点，使其无论在工业技术领域还是在学术理论域都获得了很大的发展。这些优异性能主要来自于液晶聚酯大分子链的高度刚性。本文介绍了与液晶聚酯的加工工艺和使用性能密切相关的玻璃化转变，冷结晶现象，软化温度，熔融行为和热稳定性及其与链结构之间的关系，提出了改善液晶聚酯热性能的一些可行途径。     

软段分子链结构对PUF性能的影响

通过将聚乙二醇(PEG)、聚己内酯(PCL)、聚乳酸(PLA)和聚四氢呋喃醚(PTMG)等不同特性的聚合物链段引入聚氨酯(PU)基体,制备了具有不同软段结构的聚氨酯泡沫塑料(PUF)。考察了不同软段分子链结构对PUF力学性能、热性能及在土壤中降解性能的影响。结果表明,随着软段中PEG或PLA含量的增加,PUF的拉伸强度下降;不同软段结构PUF的玻璃化转变温度顺序为:PTMG1000相似文献   

聚酯醚液晶弹性纤维的结晶性与力学性能

利用广角X一射线衍射仪和单纤维电子强力仪对聚酯醚液晶弹性体及其纤维的结晶性和力学性能进行了研究.讨论了聚酯醚液晶弹性体的结构与力学性能的关系.结果表明,共聚物的结晶度随聚酯硬段含量的增加而增加,而其力学性能则受聚酯硬段含量和聚醚分子量的影响.     

磷酸三甲酯对聚酯热性能的影响

研究了磷酸三甲酯对PET热性能的影响 ,结果表明磷酸三甲酯不仅提高了PET热稳定性 ,而且改变了PET的熔融和结晶行为     

热塑性聚酯弹性体的研究

通过缩聚反应,合成了具有一定软、硬段比例的热塑性聚酯弹性体。应用凝胶渗透色谱、红外光谱以及差示扫描量热法对该热塑性聚酯弹怀体结构进行了研究,并测定出其主要的力学性能基本达到进口同类产品Ｄ６３５６的水平。     

长链二元酸和二元醇合成聚酯的研究

以长链二元酸和二无醇为反应单体,采用熔融缩聚的方法合成了聚酯,对合成产物进行了红外吸收光谱（FTIR）、核磁共振氢谱（＇H NMR）和凝胶色谱（GPC）等表征。研究了醇酸比、反应单体、催化剂种类、催化剂用量、抽真空时间等因素对合成产物结构的影响。     

扩链剂对基于聚酯/MDI聚氨酯弹性体力学性能的影响

用聚酯多元醇(PBA、PEA、PEPA、PCL)、4,4'-二苯基甲烷二异氰酸酯(MDI)和混合扩链剂等原料合成了浇注型聚氨酯弹性体(PUE)。考察了聚酯多元醇种类、预聚体-NCO质量分数、扩链剂和扩链系数(R)等对PUE力学性能的影响,并比较了MDI/混醇体系与2,4-甲苯二异氰酸酯(TDI)/MOCA体系的性能。结果表明,PUE的硬度、模量和撕裂强度随预聚体-NCO含量增加而增加,随交联密度提高,撕裂强度和扯断伸长率下降,R>1.05时,PUE的力学性能急剧变化,MDI/混醇体系比TDI/MOCA体系的冲击弹性好。     

Synthesis and enzymatic degradation of high molecular weight aliphatic polyesters

The aliphatic polyesters with high molecular weight have been prepared according to two methods. First is the synthesis of the polyesters by polycondensation of dimethyl succinate (DMS) with 1,4‐butanediol (BD) using various metal alkoxides as a catalyst. Among the metal alkoxides used, titanium tetraisopropoxide [Ti(OiPr)₄] gave the best results (highest molecular weight and yield). Thus, we have prepared aliphatic polyesters using a variety combinations of diesters [MeOOC—(CH₂)_x—COOMe, x = 2–8] with BD by the catalysis of Ti(OiPr)₄. The polyesters with high number‐average molecular weight (M_n > 35,000), except dimethyl adipate (DMA, x = 4)/BD polyester (M_n = 26,900), were obtained in high yield. The melting temperatures (T_m) of polyesters were relatively low (43.4–66.8°C) except that (115.6°C) of the DMS/BD polyester. Second is the synthesis of high molecular weight polyesters by chain extension reaction of lower molecular weight (M_n = 15,900–26,000) polyesters using hexamethylene diisocyanate (HDI) as a chain extender. The M_n values of chain‐extended polyesters consequently increased more than two times (M_n = 34,700–56,000). The thermal properties of polyesters hardly changed before and after chain extension. Enzymatic degradations of the polyesters were performed using three different enzymes (cholesterol esterase, lipase B, and Rhizopus delemar lipase) before chain extension. The enzymatic degradability varied depending on both thermal properties of polyesters [melting temperature and heat of fusion (crystallinity)] and the substrate specificity of enzymes, but it was the following order: cholesterol esterase > lipase B > R. delemar lipase. The ¹H‐NMR spectrum of water‐soluble degraded products of the polyester indicated that the polyester was degraded into a condensation product of diol with diester in a monomer form. The enzymatic degradation of chain extended polyesters was slightly smaller than that before chain extension, but proceeded steadily. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 340–347, 2001     

Photopolymerization and the related properties of dendritic methacrylated polyesters

Three kinds of photopolymerizable dendritic polyesters have been synthesized based on 1,1,1‐trishydroxymethyl‐propanol, pentaerythritol, and dipentaerythritol as polyols and polycarboxylic acid anhydride, modified with glycidyl methacrylate and then esterified by acetic anhydride, which contain a maximum of 6, 8, and 12 methacrylic groups at the molecular chains, respectively. Their dynamic viscosity and UV‐cure speed have been measured by a spinning viscometer and the tack‐free time of the product, and the mechanical properties have been investigated by pendulum hardness and tensile strength of the UV‐cured films. It is found by comparison with traditional linear epoxy (meth)acrylate oligomers with lower molecular weights that the dynamic viscosity of the dendritic methacrylated polyesters is only half of that for the linear oligomers. However, the UV‐cure speed is about five times of that for the latter. The tensile strength of the cured films increases with the functionality of the polyester and a small amount of comonomer addition. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 499–504, 2001     

生物降解聚酯降解性能调控研究进展

综述了聚合物分子结构设计、聚合物共混改性以及复合材料配方设计等生物降解聚酯降解速率调控方法,分析了生物降解聚酯降解性能调控面临的问题并展望其前景,以期为制备具有高性能、时控性和完全降解性的生物降解聚合物材料提供理论基础。     

超声波降解对丙烯基塑性体性能的影响

利用自制的超声波辐照装置,对一种新型丙烯基塑性体(简称DP)熔体进行超声波降解,研究了超声波降解对DP结晶性能、力学性能和流变性能的影响。与等规聚丙烯相比,DP的结晶性能差,屈服拉伸强度低,但断裂伸长率明显提高。在超声波辐照下,DP熔体发生力化学降解,无规断链主要集中在高相对分子质量部分,相对分子质量分布变宽,大分子结构中出现羰基。超声波降解产生的低相对分子质量链段活动能力和极性增强,可在较高温度下结晶。另外,超声波降解也会导致DP的屈服拉伸强度下降,表观黏度降低。     

硬段对热塑性聚氨酯弹性体结构及性能的影响

以实验室自制聚己二酸乙二醇酯二醇PEA为软段,二苯基甲烷-4,4’二异氰酸酯(MDI)为硬段,分别采用乙二醇(EG、1,4-丁二醇)、BOD和1,6-己二醇、HG为扩链剂,经预聚体法合成了硬段不同的聚氨酯弹性体。研究了硬段结构和硬段含量对弹性体硬度及力学性能的影响。采用旋转流变仪研究了弹性体在降温条件下的非等温结晶过程。结果表明,当硬段含量相同时,BDO-TPU结晶性能最好,拉伸强度最大;HG-TPU断裂伸长率最好。在BDO-TPU体系中,随硬段含量增加,材料硬度和强度增加,伸长率减小;结晶起始温度逐渐增大,结晶性能增强。     

两种羧酸盐成核剂的制备及其对聚丙烯的成核效果研究

合成了两种具有相似化学结构的聚丙烯（iPP）α晶型成核剂二环［2.2.1］庚⁃5⁃烯⁃2,3⁃二羧酸钠（NA₁）和二环［2.2.1］庚烷⁃2,3⁃二羧酸钠（NA₂）,研究了其在iPP中的成核效果。首先,利用差示扫描量热仪（DSC）和偏光显微镜（PLM）分别考察了两种成核剂对iPP结晶行为的影响。结果表明,当NA₁和NA₂的含量为0.3 %（质量分数,下同）时,iPP的结晶峰值温度分别提升了14.5 ℃和16.0 ℃。同时,两种成核剂都能够明显细化iPP球晶尺寸。其次,利用广角X射线衍射仪（WXAD）对成核iPP进行了表征,两种成核剂都诱导iPP产生了α晶型,说明均为α晶型成核剂。然后,对成核iPP的力学性能进行了表征。结果表明,随着两种成核剂用量的增加,iPP的拉伸强度和弯曲模量呈现先升高后平稳的趋势。当NA₁和NA₂含量为0.05 %时,成核iPP的拉伸强度较纯iPP分别提升了4.6 %和8.6 %,弯曲模量分别提升了8.2 %和21.7 %;冲击强度基本保持不变。     

Influence of monomeric and polymeric structure on the physical properties of thermoplastic polyesters derived from hydroxy fatty acids

The physical properties of three vegetable oil derived medium and long chain poly(ω‐hydroxy fatty ester)s (P(Me‐ω‐OHFA)s), namely poly(ω‐hydroxynonanoate) [P(Me‐ω‐OHC9)], poly(ω‐hydroxytridecanoate) [P(Me‐ω‐OHC13)] and poly(ω‐hydroxyoctadecanoate) [P(Me‐ω‐OHC18)] (n = 8, 12 and 17, respectively), of the [?(CH₂)_n?COO–]_x polyester homologous series are presented. The effect of M_n (M_n 10–40 kg mol^?1) and n on the crystal structure and thermal and mechanical properties of the P(Me‐ω‐OHFA)s were investigated by wide‐angle X‐ray diffraction (WAXD), TGA, DSC, dynamic mechanical analysis (DMA) and tensile analysis and are discussed in the context of the [?(CH₂)_n?COO–]_x polyester homologous series, contrasted with linear polyethylene (PE). For all P(Me‐ω‐OHFA)s the WAXD data indicated an orthorhombic crystal phase reminiscent of linear PE with crystallinity (X_c = 50%?80%) depending strongly on M_n. The glass transition temperature and Young's modulus for P(Me‐ω‐OHFA)s increased with X_c. The DSC, DMA and TGA studies for P(Me‐ω‐OHFA)s (n = 8, 12 and 17) indicated strong correlations between the melting, glass transition and thermal degradation behavior and n. The established predictive structure relationships can be used for the custom engineering of polyester materials suitable for specialty and commodity applications. © 2014 Society of Chemical Industry     

Crystallization kinetics,mechanical properties,and hydrolytic degradation of novel eco‐friendly poly(butylene diglycolate) containing ether linkages

The basic thermal properties, isothermal melt crystallization kinetics, spherulitic morphology, mechanical properties, and hydrolytic degradation behavior of a novel eco‐friendly polyester poly(butylene diglycolate) (PBDG) containing ether linkages were systematically studied with several techniques in this research. PBDG is an aliphatic polyester with high thermal stability. It had a glass transition temperature (T_g) of ?25.7 °C, a melting point temperature of 65.1 °C, and an equilibrium melting point of 73.2 °C. During the isothermal melt crystallization, PBDG crystallized slowly with increasing crystallization temperature, but the crystallization mechanism did not change. Negative spherulites were observed for PBDG. The mechanical properties of PBDG were investigated from the tensile testing. As a ductile polyester, PBDG possessed good mechanical properties. PBDG also showed a fast hydrolytic degradation rate. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44186.     

Effect of microwave irradiation on the physical properties and structures of wool fabric

Microwaves are high frequency radio waves which are capable of penetrating many materials and causing heat to be generated in the process. To investigate the effect of microwave irradiation on the physical property, chemical structure, surface morphological structure, and fine structure of wool fabric, wool fabric was treated with microwave irradiation under variety of conditions in terms of the power and the time of microwave treatment. The breaking strength, breaking elongation, and whiteness of the treated wool fabric in different humid state were investigated. The structures of the untreated and treated wool were investigated with Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), and Laser Raman spectroscopy (LRS). The results show that the physical properties of the treated wool fabrics were changed with microwave irradiation time and power. The chemical structure had not significant change. The surface morphological structure, the concentration of cystine S S bonds and crystallinity of the treated wool were changed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Evaluation of disulfide chain extender effect on the mechanical properties of unsaturated polyurethane‐urea networks

4‐Aminophenyl disulfide and bis(4‐aminophenyl)methane chain extenders containing hydroxyl‐terminated polybutadiene‐based polyurethane‐ureas are prepared one‐shot to explore the effect of the chain extender structure on the elastomers mechanical properties. However, the results revealed that the participation of the disulfide chain extender in side reactions like thiol‐ene and proton abstraction prevented disulfide metathesis reaction due to decomposing chain extender in the polyurethane‐urea matrix. Also, these side reactions improved the phase mixing via chemical crosslinking between polyurethane‐ureas soft and hard segments, too. Tensile test results showed higher stress strength of the elastomers in the presence of the disulfide chain extender in comparison with the nondisulfide bond containing elastomers. This result was in agreement with the observed result in dynamical mechanical analysis. Dynamic mechanical analysis results established that the absence of the disulfide bond in the polyurethane‐urea matrix led to the higher viscous modulus. The swelling test revealed chemical crosslinking increased in the presence of the disulfide bond. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46309.