利用示差扫描量热仪(DSC)研究了3种不同分子量的聚己内酯(PCL)在-20～50℃等温结晶所得晶体在不同升温速率下的熔融现象.分别讨论了PCL晶体熔点(Τm)的等温结晶温度(Τc)依赖性和升温速率依赖性,根据Τm与升温速率的关系外推得到不同Τc时形成的晶体在零升温速率下的Τm.通过Τm随Τc变化的趋势确定出PCL结晶的高温区,根据Hoffoman-Weeks方法外推得3种分子量的伸展链片晶的平衡熔点(Tm0(MW).通过PCL晶体结构参数和分子量可估算得到3种分子量的PCL伸展链片晶的厚度(lex),以1/lex与Τm0(MW)作图,可外推得PCL的平衡熔点(Τm0(∞)).利用小角X射线散射(SAXS)测定了不同Τc时形成的PCL晶体的长周期,根据广角衍射信息计算得到其体积结晶度(νc),而后分别求出不同Τc时的晶区厚度(Lc),通过Gibbs-Thomson关系式对1/Lc与Τm作图,外推至1.Lc=O,即求得PCL的平衡熔点(Τm0(∞)).用上述2种方法求得的Tm0(∞))相当接近,均为74℃左右.
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