中文摘要：

利用凝胶渗透色谱（GPC）、傅里叶变换红外光谱（FTIR）和示差扫描量热（DSC）等手段对不同剂量γ射线辐照后等规聚丙烯（iPP）的分子链结构及结晶行为的变化进行了研究.结果表明,γ射线辐照使iPP的分子量下降,并在其分子链中产生羟基和羰基等极性基团,从而影响其结晶行为.在非等温结晶过程中,当辐照剂量≤50 kGy时,iPP的热结晶温度略有升高;增大辐照剂量,iPP的热结晶温度明显降低.iPP的熔融温度则随辐照剂量的增大而降低,且分裂成双峰.利用Avrami方程研究了辐照前后iPP的等温结晶动力学,发现辐照前后样品的Avrami指数n都在3左右,表明iPP的结晶遵循异相成核机理,且不受辐照剂量和等温结晶温度的影响,但总结晶速率随等温结晶温度和辐照剂量的升高而逐渐减小.探讨了iPP经过γ射线辐照后,分子链断裂、链结构变化和结晶速率之间的关系.

英文摘要：

The structure and crystallization behavior of isotactic polypropylene（iPP） irradiated by γ-ray,were investigated by a combination of gel permeation chromatography（GPC）,Fourier transform infrared spectroscopy（FTIR） and differential scanning calorimetry（DSC）.The results indicated that γ-ray irradiation led to the formation of hydroxyl and carbonyl groups on iPP main chains as well as the degradation of iPP macromolecules.As the irradiation dose was lower than 50 kGy,the crystallization temperature（Tc） of irradiated iPP increased slightly with the increase of irradiation dose.However,the Tc of irradiated iPP decreased obviously,when the irradiation dose is above 50 kGy,and the melting peak of iPP moved to lower temperature and split into two peaks.The overall isothermal crystallization kinetics of unirradiated and irradiated iPP were analyzed by the Avrami equation.The values of Avrami exponent n are close to 3,indicating that iPP nucleates in the heterogeneous manner regardless of the crystallization temperature and the irradiation dose.The DSC data indicated that the overall crystallization rates decrease with the increase of crystallization temperature and radiation dose.The relationship between chain structure change and crystallization rate was discussed.