Study of crystallization behavior of electron beam irradiated polypropylene and high-density polyethylene

The influence of e-beam irradiation on polypropylene (PP) and high-density polyethylene (HDPE) was investigated with the focus on crystallization. High temperature (200°C) creep test has revealed that HDPE gradually increases crosslinking density in the range 30-120 kGy while PP undergoes chain scission which was quantitatively evaluated by GPC. Mechanical properties were measured in the range -150 to 200°C by dynamic mechanical analysis (DMA). Small presence of C=C and C=O bonds was found in the irradiated PP by Fourier transform infrared spectroscopy (FTIR). Crystallization kinetics measured by differential scanning calorimetry (DSC) and hot-stage optical microscopy results were influenced by irradiation tremendously for HDPE and to a smaller extent for PP. Irradiation has caused a decrease in both, the number of nucleation centers and the growth rate of individual spherulites. Crystallization was analyzed in detail with the help of Hoffman-Lauritzen, Avrami and Arrhenius equations. I...

本研究针对电子束辐照对聚丙烯（PP）与高密度聚乙烯（HDPE）的影响展开探讨，重点聚焦其结晶行为。高温（200℃）蠕变试验结果显示，HDPE在30~120 kGy的辐照剂量范围内交联密度逐渐升高，而PP则发生链断裂，该过程通过凝胶渗透色谱（GPC）实现了定量表征。本研究采用动态力学分析（DMA），在-150℃至200℃的温度区间内测试了材料的力学性能。通过傅里叶变换红外光谱（FTIR）检测发现，辐照后的PP中存在少量碳碳双键与碳氧双键。差示扫描量热法（DSC）测得的结晶动力学数据以及热台光学显微镜的观测结果均表明，辐照对HDPE的结晶过程影响显著，对PP的影响则相对较弱。辐照导致晶核数量与单个球晶的生长速率均出现下降。本研究借助霍夫曼-劳里森（Hoffman-Lauritzen）、阿夫拉米（Avrami）及阿伦尼乌斯（Arrhenius）方程对结晶过程进行了详细分析。I...