聚己内酯和酚氧树脂共混物的结晶行为和熔融转变

通过采用不同变温程序对溶液铸膜PCL与酚氧共混物进行了热分析。实验结果显示,在准平衡状态下,对PCL含量大于30％的共混对,PCL均可从混合物熔体中降温结晶出来。进一步研究发现熔融温度随PCL含量减少而下降,此现象可籍结晶、非晶聚合物之间的热力学混容解释,并应用由Scott方程推导出的关系式计算,发现对该聚合物对,相互作用参数在320K时为-0.155。从熔融态等速降温,对PCL含量大于50％的共混对均观察到结晶转变,转变温度强烈依赖于组成和降温速率,主要原因在于对这种“动力学”实验,熔体中PCL链段向晶体表面的扩散过程控制结晶,任何使PCL链段扩散能力减弱的因素,都将降低结晶温度。在等速降低温度过程中还发现,共混物产生双结晶峰。

CRYSTALLIZATION BEHAVIOUR AND MELTING TRANSITION IN POLY (s-CAPROLACTONE) AND POLY (HYDROXY ETHER OF BISPHENOL A) MIXTURES

Thermal analysis of solution cast mixtures of PCL and phenoxy has been carried out with various programmed temperature profiles. Results from experiments conducted in a quasi-equi-librium state show that PCL crystallizes in the mixtures upon cooling. Furthermore, depressions were observed in melting and crystallization temperatures. The melting point depression pheonomenon is found to be explicable in terms of thermodynamic mixing of a crystalli-ne polymer with an amorphous polymer. To this end, an analytical expression appropriate to the crystalline-amorphous polymer pair derived from Scott's equation for thermodynamic mixing of two polymers was used. From this expression the interaction parameter for this polymer pair is calculated to be -0.155 at 320 K, indicating that the system is well compatible. The crystallization temperature which depends strongly on both the composition and the cooling rate is attributed to the migrate of the PCL segments. Any factor which retards the migration will depress the crystallization temperature. Double crystallization peaks were also observed in the process of cooling.