PET-PEN共聚酯的合成研究

以2,6-萘二甲酸(NDA)、对苯二甲酸或2,6-萘二甲酸二甲酯(NDC)、对苯二甲酸二甲酯与乙二醇为原料,在2 L聚合反应装置上,采用直接酯化法或酯交换法合成聚对苯二甲酸乙二酯(PET)-聚2,6-萘二甲酸乙二酯(PEN)共聚酯(PETN),探讨了PETN的合成反应条件。结果表明:直接酯化法较酯交换法更加可行易控;直接酯化法反应条件:酸/醇摩尔比为1:(1.3～1.5),NDA摩尔分数(相对于酸的总量)为28%,酯化阶段无需催化剂,酯化反应温度220～250℃,缩聚反应温度280～295℃,合成的PETN特性黏数达0.65～0.85 dL/g;钛系催化剂的催化活性优于锑系催化剂,且添加比例小,添加量为8～50μg/g时,即可得到高特性黏数的PETN。     

聚丁二酸乙二醇酯及其共聚酯的生物降解性能

通过降解过程的质量损失率、相对分子质量及其分布、热性能、表面形貌等评价手段,重点考察了Aspergillus niger脂肪酶对聚丁二酸乙二醇酯(PES)和聚(丁二酸乙二醇-共-对苯二甲酸乙二醇酯)(PEST)的降解性能。结果表明:PES在脂肪酶溶液中具有较好的生物降解性能,随着对苯二甲酸摩尔含量的增加,PEST的质量损失率呈现先增加后逐渐减少的趋势;随着酶解时间的延长,残留部分的PES、PEST的相对分子质量均呈下降趋势;残留部分的PES、PEST的熔点随降解时间的延长变化不大,熔融热焓有所增加;聚酯薄膜表面产生了不同程度的沟槽、孔洞和裂纹。可以推测,PES及PEST的生物降解首先发生在无定形区,并且大分子链段发生的是随机断裂。     

草酸酯合成研究进展

简述草酸及草酸酯合成的传统方法。着重介绍一氧化碳催化氧化偶联制草酸酯的发展历史、技术原理及工艺研究的进展情况。     

共聚酯的合成与性能表征

以对苯二甲酸、乙二醇为主要原料,添加共聚单体新戊二醇(NPG)、5-叔丁基间苯二甲酸(tBI),通过熔融缩聚合成了一系列不同组成比例的共聚酯,分析了共聚酯的化学结构与组成、特性黏度、热性能、结晶性能和动态热力学性能。结果表明:随着tBI和NPG含量的增加,共聚酯的熔点降低,结晶能力逐渐减弱;当tBI和NPG物质的量分数总和达到13%及以上时,共聚酯为完全无定形态;tBI单元的加入使共聚酯的玻璃化转变温度升高,弥补了PENT共聚酯玻璃化转变温度低于PET的缺点;共聚酯的初始分解温度高于PET,初始储能模量大于PET,而随着测试温度的升高,共聚酯的柔韧性大于PET材料。     

PET与PTT共聚酯的合成及其性能研究

采用直接酯化法合成了不同比例的PET与PTT共聚酯,研究了所得共聚酯的热性能、力学性能及染色性等与不同组成比之间关系。     

耐温共聚酯的合成及其性能研究

本文提供了一种耐温的改性共聚酯,采用不同的二元醇合成改性PET。研究酯化温度、催化剂及不同量的功能性单体合成耐温聚酯材料的影响。结果表明：酯化温度在255℃,催化剂的量在300×10^-6,异山梨醇与1,4-环己烷二甲醇的复合含量为30%其综合性能最好。该共聚酯的玻璃化转变温度(Tg)比一般的聚对苯二甲酸乙二醇酯更高,且具有更优异的综合性能。     

PBS基共聚酯降解性能的研究概述

简要分析了结晶能力、链段柔顺性和化学组成等对聚丁二酸丁二醇酯(PBS)基共聚酯降解性能的影响。结果表明,柔软的链结构易于被生物降解,有规晶态结构阻碍生物降解,脂肪族聚酯比芳香族聚酯易于生物降解,并指出提高PBS基共聚酯的降解性能仍然是一项具有挑战性的工作。     

PET-PTT共聚酯的流变性能

利用毛细管流变仪研究了聚对苯二甲酸乙二酯(PET)-聚对苯二甲酸丙二酯(PTT)共聚酯(简称PETT)熔体的剪切流动性能,且与对应纯组分的流变性能进行了比较.结果表明:PETT熔体属于非牛顿流体,在相同温度下,PETT的剪切速率和黏度均小于纯PTT的值,且均随PTT链段含量的增加而减小.PETT的非牛顿指数和结构黏度指数均小于纯PTT.在相同剪切速率下,PETT的黏流活化能介于纯PET和纯PTT之间,且随PTT链段含量的增加而减小.     

低熔点聚酯的合成与性能研究

通过共聚反应在PET大分子链中引入第三组分、第四组分合成低熔点聚酯,对合成的低熔点聚酯 的结晶性能、热稳定性和流变性能进行了研究。结果表明:引入第三组分(间苯二甲酸)、第四组分(丁二醇) 可以降低聚酯的熔点,当第三组分的添加量为20％(占所有二元酸的摩尔分数),第四组分的添加量为35％ (占所有二元醇的摩尔分数)时,可以得到熔点为110℃的低熔点聚酯,而且所得的低熔点聚酯结晶性能、热 稳定性较好,其流体属于非牛顿型假塑性流体。     

染色改性共聚酯的热性能研究

在聚对苯二甲酸乙二醇酯(PET)分子链上分别引入聚醚、间苯二甲酸乙二醇酯-5-磺酸钠(SIPE)、脂肪链酯类,得到染色改性共聚酯,考察了改性组分对改性共聚酯热性能及热稳定性的影响。结果表明:改性共聚酯的玻璃化转变温度(T_g)均低于常规PET,醚改性共聚酯结晶性能稍好于常规PET,加入SIPE、醚型/酯型单体制备的共聚酯(ECDP)结晶性能弱于常规PET,其中酯型ECDP结晶能力最弱;在空气氛围下,改性共聚酯的非等温降解可分为三个阶段,第一阶段的降解活化能(△E)均小于常规PET,第二、第三阶段的△E大于常规PET;醚改性共聚酯的等温降解过程接近二级反应,ECDP的等温降解过程为一级反应。     

Hydrolytic Degradation of Aliphatic Polyesters Copolymerized with Poly(ethylene glycol)s

Poly(1,4-butanediol succinate) copolymers were prepared by melt polycondensation of succinic acid and 1,4-butanediol with 10–50mol% (in feed) of poly(ethylene glycol) (PEG), where molecular weight (MW) of PEG is 200–2000. The reduced specific viscosity of the copolymers increased with incorporation of the PEG component, but a higher PEG content in the copolymers reduced it. The temperature of melting (T_m) and crystallinity decreased with increasing PEG content. T_m depression of the copolymers followed approximately Flory’s equation, suggesting that these are random type copolymers. Tensile strength and elongation decreased with increasing MW and content of PEG. The weight loss of copolymer films in a buffer solution with or without lipase at 37°C, as well as water absorption, increased with increasing PEG content, implying that higher water absorption contributes to hydrolytic degradation of the films. However, the weight loss of copolymers with PEG of lower MW increased greatly in spite of lower water absorption, demonstrating that hydrolytic degradation is influenced by the concentration of degradable ester linkages between succinic acid and PEG segments rather than water absorption. © of SCI.     

支化聚酯的合成及热性能研究

通过直接酯化-缩聚工艺,在聚对苯二甲酸乙二醇酯(PET)聚合的缩聚过程中分别引入第三组分——3-羟甲基丙烷(TMP)、季戊四醇(PER)或双季戊四醇(DPT)合成了一系列不同的支化PET,并采用氢核磁共振波谱仪(1H-NMR)、差示扫描量热仪(DSC)和热重分析(TG)表征了产物的结构和性能。结果表明:与纯PET相比,经TMP、PER或DPT改性后的支化PET的玻璃化转变温度(Tg)均下降,含摩尔分数0.3%DPT改性的支化PET的Tg最低;除TMP1-PET外,各支化PET的冷结晶温度(Tc)都增大;各支化PET的熔点(Tm)也都呈现下降趋势;除PER3-PET外,各支化PET的结晶焓ΔHc都有所下降,而各支化PET的熔融焓ΔHm却变化不大;所得到的各支化PET具有较好的热稳定性能。     

Blends of Poly(hydroxybutyrate) and Poly(ethylene succinate) Prepared in the Presence of Samarium

Blends of the commercial biodegradable polymer poly(hydroxybutyrate) (PHB) with the oligomeric polyester poly(ethylene succinate) (PES) were prepared by melt processing in the presence of Sm(acac)₃. The occurrence of transesterification reactions during blend processing using the samarium catalyst was investigated. ¹H NMR analyses showed no evidence of transreactions, even using high content of catalyst (4 wt%), long reaction times and high temperatures (200°C). Under the drastic reaction conditions employed, chain degradation characterized by a significant decrease in the molecular weight (MW) of PHB has taken place. PHB/PES blends form immiscible systems in which the PHB crystallizes as large spherulites, but its crystallization is significantly influenced by the presence of PES, which does not crystallize at conditions in which the poly(hydroxyalkanoate) is crystallized.     

聚对苯二甲酸乙二醇酯合成催化剂研究进展

探讨了各类锑系催化剂、钛系催化剂(包括乙二醇钛)等不同类型的催化剂在聚酯缩聚反应中的催化性能研究的最新成果,指出在各种类型催化剂中,由于具有作为催化剂时不会带入多余的杂质进入反应体系等优点,乙二醇锑和乙二醇钛的应用前景较为广阔。     

生物可降解聚丁二酸乙二醇酯的合成与降解性能研究

以丁二酸和乙二醇为原料,直接熔融聚合,合成了高相对分子量的聚丁二酸乙二醇酯(PES),用FTIR,1H-NMR表征其结构;考察了不同聚酯反应催化剂对其聚合反应的影响,结果表明:三氧化二锑的催化效果是最佳的。同时,利用酶降解和体外水解的方法,对聚合物降解性能进行研究,结果表明:PES是一种可生物降解的聚合物,且在体外具有一定的降解性。     

聚乙二醇中共轭烯炔化合物的合成

发展了一种在聚乙二醇介质中末端炔烃与缺电子炔烃选择性生成共轭烯炔化合物的方法。在三苯基膦氯化钯(2mol%)、溴化亚铜(4mol%)、PEG-400(1.0g)和氮气的作用下,1mmol末端炔烃与0.5mmol缺电子炔烃可以顺利地发生交叉偶联反应选择性生成相应的共轭烯炔化合物,该反应产率较高,对环境友好,且催化体系可以适当地重复使用。     

Hydrolytic degradation of poly(ethylene terephthalate)

Molecular weight is an important factor in the processing of polymer materials, and it should be well controlled to obtain desired physical properties in final products for end‐use applications. Degradation processes of all kinds, including hydrolytic, thermal, and oxidative degradations, cause chain scission in macromolecules and a reduction in molecular weight. The main purpose of this research is to illustrate the importance of degradation in the drying of poly(ethylene terephthalate) (PET) before processing and the loss of weight and mechanical properties in textile materials during washing. Several techniques were used to investigate the hydrolytic degradation of PET and its effect on changes in molecular weight. Hydrolytic conditions were used to expose fiber‐grade PET chips in water at 85°C for different periods of time. Solution viscometry and end‐group analysis were used as the main methods for determining the extent of degradation. The experimental results show that PET is susceptible to hydrolysis. Also, we that as the time of retention in hydrolytic condition increased, the molecular weight decreases, but the rate of chain cleavage decreased to some extent, at which point there was no more sensible degradation. The obtained moisture content data confirmed the end‐group analysis and viscometry results. Predictive analytical relationships for the estimation of the extent of degradation based on solution viscosity and end‐group analysis are presented. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2304–2309, 2007     

Studies of temperature influence on volatile thermal degradation products of poly(ethylene terephthalate)

The temperature influence on the thermal degradation products evolved from poly(ethylene terephthalate) (PET) was investigated. The experiments were carried out within the temperature range of 200–700°C in air. The main volatile toxic products and weight losses during thermal degradation of PET were determined. The results are presented on plots as a function of the degradation temperature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2377–2381, 1998     

不同熔融混炼条件下PET的降解行为和结晶行为

采用不同预处理条件对聚对苯二甲酸乙二醇酯（PET）切片进行熔融混炼,考察了不同熔融混炼条件下PET的降解行为和结晶行为。结果表明,不同条件的熔融混炼过程均导致PET降解,而降解速率和样品含水率密切相关;PET的降解不仅导致其结晶速率提高,也将导致其球晶晶片厚度增加和结晶度增大;PET的结晶峰值温度（Tcp）、结晶起始温度（Tonset）和结晶结束温度（Tendset）与其特性黏度\[η\]之间存在相关关系,表现为\[η\]越小,Tcp越高,结晶速率越快。