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首页> 外文期刊>Polimery >Microstructure transformation due to hydrolytic degradation of ethylene terephthalate/lactic acid copolyesters
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Microstructure transformation due to hydrolytic degradation of ethylene terephthalate/lactic acid copolyesters

机译：对苯二甲酸乙二酯/乳酸共聚酯的水解降解引起的微观结构转变

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摘要

Wide-angle (WAXS) and small-angle (SAXS) X-ray scattering methods have been used to study the supermolecular structure of ethylene terephthalate and lactic acid copolyesters having different chemical structure of macromolecules. The effect of copolymers chemical structure on their microstructure was investigated using crystallized (annealed) polymer samples. It has been found that the crystalline phase in the copolyesters contains mainly PET segments (ET sequences). The degree of crystallinity decreases with lowering the length of (ET)_x sequences (X values). The crystallized copolymers of sufficiently long ET sequences showed lamellar structure (long period reflex) in SAXS studies. Copolyester specimens in form of monofilaments ("as spun" as well as annealed) were subjected to hydrolytic degradationh at pH 7.35 and temp. 60 deg C over a time period of up to 9 weeks. Intensity of degradation changes (eta_(red) and weight of the specimens) as well as intensity and nature of microstructure changes (WAXS and SAXS data) were highly dependent on chemical structure of the copolymers. Microstructure changes, especially SAXS characteristics, were also highly dependent on the initial morphology of the specimens, i.e. on whether they were crystallized or not before degradation.
机译：广角（WAXS）和小角（SAXS）X射线散射方法已用于研究具有不同大分子化学结构的对苯二甲酸乙二酯和乳酸共聚酯的超分子结构。使用结晶的（退火的）聚合物样品研究了共聚物化学结构对其微观结构的影响。已经发现，共聚酯中的结晶相主要包含PET链段（ET序列）。结晶度随着（ET）_x序列（X值）的长度的减小而降低。 ET序列足够长的结晶共聚物在SAXS研究中显示出层状结构（长时间反射）。将单丝形式的共聚酯样品（“纺丝”并退火）在pH 7.35和温度下进行水解降解。 60摄氏度，长达9周的时间。降解变化的强度（样品的红色和重量）以及微结构变化的强度和性质（WAXS和SAXS数据）高度依赖于共聚物的化学结构。微观结构的变化，特别是SAXS特性，也高度取决于样品的初始形态，即它们在降解前是否结晶。

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