聚丁内酰胺的热性能改性

Thermal Properties Modification of Polybutyrolactam

聚丁内酰胺的熔点与热分解温度较接近,不利于熔融加工。文中采用溶液共混法制备支化聚丁内酰胺(B-PA4)及线型聚丁内酰胺(L-PA4)共混物,并通过差示扫描量热分析、X射线衍射和热重分析表征共混物的结晶性能及热性能,通过拉伸测试研究了共混膜的力学性能。结果表明,B-PA4的加入使得共混物的结晶度、熔点、热稳定性均发生降低。当相对分子质量为2000的B-PA4与L-PA4质量比大于1∶1时,共混物熔点(T_(m))降至258℃,最大降解速率对应温度(T_(p))保持不变,两者间温度差与L-PA4相比提高了10℃。当相对分子质量为5000的B-PA4与L-PA4共混质量比为2∶1时,T_(m)与T_(p)的温度差提高了5℃。相对分子质量为8000的B-PA4与L-PA4共混后,T_(m)和T_(p)温度差无显著变化。共混物膜的拉伸强度均提高至40 MPa以上,但断裂伸长率明显下降,高分子量B-PA4有助于提高其强度,减小断裂伸长率的降低幅度。

Due to its melting point(T_(m))nearing to the thermal decomposition temperature,polybutyrolactam(PA 4)was not suitable for melting process.In this work,branched polybutyrolactam(B-PA4)and linear polybutyrolactam(L-PA4)were mixed to investigate the property dependence on blending.The crystallization and thermal properties of blends were characterized by DSC,XRD and TG,and the mechanical properties were measured by tensile test.The results show that the addition of B-PA4 reduces the crystallinity,melting point(T_(m))and thermal stability.When the mass ratio of B-PA4(2000)to L-PA4 is no less than 1∶1,T_(m) decreases to 258℃,while the temperature at the maximum decomposition rate(T_(p))remains unchanged,and the interval between them is increased by 10℃compared with that of L-PA4.With increasing the mass ratio of B-PA4(5000)larger than 2∶1,the interval between T_(m) and T_(p) is 5℃.As for B-PA4(8000),such interval is the same as that of L-PA4.The tensile strength of the blend increases to more than 40 MPa,but the elongation at break decreases significantly.B-PA4 with higher molecular weight is contributed to improve the tensile strength and reduce the decreasing extent of elongation at break.