聚乙烯辐射交联与结晶结构的变化

RADIATION-INDUCED EFFECT ON THE MORPHOLOGY OF MELT-CRYSTALLIZED POLYETHYLENE

通过傅里叶变换红外光谱、激光拉曼光谱、小角激光散射以及凝胶渗透色谱等,研究了室温辐照聚乙烯的结晶结构变化。辐照交联聚乙烯的红外光谱表明,作为聚乙烯晶区特征吸收的730cm(-1)吸收峰,1463cm^(-1)和1474cm^(-1)劈裂吸收峰均随辐照剂量而变化。拉曼光谱的峰位不随剂量而改变,但其强度却随之减小。经硝酸腐蚀的试样,其凝胶渗透色谱测得的数均分子量,随着辐照剂量的增加而增加,表明晶区内分子数减少。由DSC所得熔点变化估算晶区的辐射化学产额为3.5,而激光小角散射的结果却表明,辐射交联后,在高于熔点测得的光散射强度仍然相当高。结果表明,聚乙烯辐照后,结晶结构的内部被破坏。

Radiation effect on the morphology of melt-crystallized polyethylene is studied with infrared spec-troscopy, laser light Raman longitudinal acoustic mode (LAM) spectr'oscopy, light scattering, wide angle X-ray diffraction and differential scanning calorimetry. The intensity of the band 730cm from C-H bending vibration in crystalline phase is found to decrease with radiation dose. The position of LAM peak does not change with radiation dose, but its intensity decreases. It indicates that the damage or amorpho-tization takes place-within crystalline lamellae rather on their surface. After radiation-crosslinking of polyethylene, its four clover-leaf Hv light scattering pattern keeps its pattern after melting, though its intensity decreases. The residue of the intensity after melting increases with radiation dose. From the depression of melting point with radiation dose, the G value of damage of the units in crystalline region is estimated to be 3. 5.