聚乳酸/羟基磷灰石复合材料的研究 Ⅲ.聚(D,L-乳酸)/羟基磷灰石复合材料的体外降解行为

Studies of Polylactide/Hydroxylapatite Composites Ⅲ. The in vitro Degradation Behavior of Poly(D,L-lactide)/Hydroxylapatite Composites

将取向模压增强的聚（Ｄ，Ｌ－乳酸）／羟基磷灰石（ＰＤＬＬＡ／ＨＡ）复合物圆棒（φ＝３．２ｍｍ）在３７℃的生理盐水中进行降解试验，考察了ＰＤＬＬＡ的相对分子质量、水解液的ｐＨ值和棒材的力学性能随降解时间的变化，结果显示ＨＡ对ＰＤＬＬＡ的降解有较大抑制作用，圆棒的力学强度保持时间比纯ＰＤＬＬＡ棒长．ＳＥＭ观察表明，纯ＰＬＡ材料的“双态降解”（ｂｉｍｏｄｅｌｄｅｇｒａｄａｔｉｏｎ）现象在 ＰＤＬＬＡ／ＨＡ复合材料中同样出现．复合物中ＰＤＬＬＡ的降解符合一级反应动力学，但它们的降解速率常数明显小于纯ＰＤＬＬＡ．

The in vitro degradation behavior of poly (D, L-lactide)/hydroxylapatite (PDLLA/HA) composite rods with φ 3.2 mm, prepared by oriented compression molding, was tested in physiological saline at 37℃. The changes in relative molecular mass of PDLLA, pH value of the physiological saline and mechanical properties of the composite rods with degradation time were observed. Results showed that HA has significant inhibition on the degra- dation of PDLLA and thus the composite rods have longer strength-maintaining periods than the pure PDLLA materi- al. SEM observations revealed that bimodal degradation occured in pure PDLLA also appeared in PDLLA/HA com- posites. The in vitro degradation kinetics off PDLLA in composites was in agreement with the first-order reaction,but the rate constants of degradation were obviously less than that of the pure PDLLA.