等温退火对PLLGA85/15结晶度、力学性能和降解性能的影响

摘要

研究了等温退火对左旋乳酸乙醇酸无规共聚物(PLLGA85/15)结晶度、力学性能和降解性能的影响.在最佳退火温度130℃时对材料进行退火操作.采用X射线衍射仪(XRD)考察了退火后材料的结晶情况,同时用万能力学试验机测试了材料的力学性能,并且研究了不同的退火时间对材料结晶度和力学性能的影响.对不同退火时间的PLLGA85/15材料进行降解实验,考察了材料降解过程中样品吸水率、失重率和降解液pH的变化.用凝胶渗透色谱仪(GPC)考察了降解后样品的分子量变化,用差示扫描量热分析仪(DSC)考察了材料降解后热力学性能的变化,用扫描电镜(SEM)观察了降解后样品的微观形貌变化.实验结果表明,随退火时间延长,材料结晶度和强度提高,至最大值后结晶度和强度保持不变;长时间的等温退火过程会导致材料的热降解,使分子量降低,从而导致材料的降解速率加快;而短时间的退火使材料结晶度提高,同时降解速率减缓.%The effect of isothermal annealing on the degree of crystallinity,mechanical properties and degradation behavior of a random copolymer poly(L-lactic-co-glycolic acid) with monomer molar ratios of 85/15 (PLLGA85/15) was investigated.The polymer was annealed at the optimal annealing temperature of 130 ℃.Its crystallization behavior after annealing was observed by X-ray diffraction (XRD),and the mechanical properties were tested by universal mechanical experimental machine.The degradation experiments of PLLGA85/15 with different annealing times were performed,and the changes of water adsorption rate,weight loss rate and pH of solution after degradation were observed.The change of polymer molecular weight after degradation was determined by gel chromatography (GPC),change of mechanical properties was measured by differential scanning calorimetry (DSC),and the change of micromorphology of samples was observed by scanning electron microscopy (SEM).As shown by the experimental results,the degrees of crystallinity and mechanical properties were increased with the increasing of annealing time,while kept constant when reached the maximum data.Long time annealing led to accelerated thermal degradation and reduced molecular weight,while short time annealing resulted in increase of the degree of crystallinity and reduction of degradation rate.