Huttunen Mikko, Kellomäki Minna
BioMediTech; Tampere, Finland; Department of Electronics and Communications Engineering; Tampere University of Technology; Tampere, Finland.
Biomatter. 2013 Oct-Dec;3(4). doi: 10.4161/biom.26395. Epub 2013 Sep 11.
The strength retention characteristics of oriented semicrystalline polylactides were monitored during hydrolytic degradation in vitro. The effects of the polymer type, the material's initial inherent viscosity (iv), the sample diameter and the residual monomer content on strength retention were analyzed. The analyzed polylactides had similar, but not identical, strength retention characteristics. It was concluded that a higher degree of initial crystallinity was a major variable determining the earlier and more profound strength loss of PLLA than 96L/4D PLA and 80L/20 D,L PLA. Samples with a higher initial iv were found to have a longer strength retention time than lower iv samples. Size-dependency was observed, as the strength retention time was shorter for the smaller diameter samples. This size-dependency was caused by faster iv decay. The amount of residual monomer content had a remarkable impact on strength retention. Neither the sample diameter, initial iv or residual monomer content were found to have an effect on the iv range in which there was a rapid decline in strength properties. Therefore, it was concluded that the inherent viscosity and/or molecular weight of oriented PLLA, 96L/4D PLA and 80L/20 D,L PLA is a major variable determining the strength retention of these materials.
在体外水解降解过程中监测了取向半结晶聚乳酸的强度保持特性。分析了聚合物类型、材料的初始特性粘度（iv）、样品直径和残留单体含量对强度保持的影响。所分析的聚乳酸具有相似但不完全相同的强度保持特性。得出的结论是，较高的初始结晶度是决定聚左旋乳酸（PLLA）比96L/4D聚乳酸和80L/20 D,L聚乳酸更早、更显著强度损失的主要变量。发现初始特性粘度较高的样品比特性粘度较低的样品具有更长的强度保持时间。观察到尺寸依赖性，因为较小直径的样品强度保持时间较短。这种尺寸依赖性是由特性粘度更快的衰减引起的。残留单体含量对强度保持有显著影响。未发现样品直径、初始特性粘度或残留单体含量对强度性能快速下降的特性粘度范围有影响。因此，得出结论，取向PLLA、96L/4D聚乳酸和80L/20 D,L聚乳酸的特性粘度和/或分子量是决定这些材料强度保持的主要变量。
