锌
聚合
材料科学
聚合物
锡
水解
降级(电信)
压缩成型
高分子化学
金属
摩尔质量分布
丙交酯
化学工程
核化学
化学
有机化学
冶金
复合材料
电信
模具
计算机科学
工程类
作者
Grégoire Schwach,Jean Coudane,Robert Engel,Michel Vert
出处
期刊:Biomaterials
[Elsevier]
日期:2002-02-01
卷期号:23 (4): 993-1002
被引量:71
标识
DOI:10.1016/s0142-9612(01)00209-5
摘要
Laboratory- and pilot-scale racemic polylactides (PLA50) were synthesized in the presence of stannous octoate (SnOct2) or zinc-metal as initiators in the absence of alcohol. The resulting polymers were processed by compression molding or injection molding depending on the batch scale. The hydrolytic degradation of compression-molded samples selected to be comparable was investigated first in order to show the influence of the initiator system. Differences in water uptake were found between PLA50-Zn (zinc-metal initiation) and PLA50-Sn (SnOct2 initiation). PLA50-Zn being much more hydrophilic. PLA50-Sn exhibited a slower molecular weight decrease and delayed onsets of weight loss, release of acidity and stereocomplex formation, with respect to PLA-Zn. The concentration in residual tin in PLA50-Sn increased from 306 to 795 ppm during aging. In the case of PLA50-Zn the residual metal remains constant at ca. 40 ppm. In a second series of experiments, high molecular weight PLA50 different in characteristics and in initiator, synthesized under pilot-scale, were compared. The effects of the initiator on the degradation of the polymers well agreed with laboratory-scale findings, differences in hydrophobicity being enlarged by the up scaling. PLA50-Sn polymers appeared much more degradation resistant than PLA50-Zn ones. Contributions of the other characteristics (e.g. molecular weight, purity, stereoregularity, processing) were shown to be important as well.
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