HDPE微注射成型条件下非等温静态结晶

HDPE static non-isothermal crystallization in micro-injection molding process

利用差示扫描量热仪(DSC),物理模拟HDPE微注射成型模腔中心层的静态非等温结晶过程,将样品从80℃以10℃/min升温速率升至180℃,并保温2 min。然后在液氮冷却作用下分别以5,10,15,20℃/min的恒降温速率,将温度降至80℃,得到静态非等温结晶DSC热流曲线,并利用Eopoxobeku方法对HDPE非等温结晶动力学参数进行解析。研究结果表明:当降温速率从5℃/min增大到20℃/min时,HDPE结晶起始温度从121.81℃下降到118.93℃,结晶度由86.19%增大到90.34%,非等温结晶动力学曲线在结晶初期基本上呈线性关系,而在后期不呈线性关系;结晶初期降温速率对晶体成核和生长机理的影响比较大,而结晶后期晶体成核和生长机理受降温速率的影响较小。

Difference scanning calorimeter （DSC） was utilized to physically simulate the static non-isothermal crystallization in the center layer of micro-injection mold cavity, and the temperature of HDPE sample was raised from 80 ℃ to 180 ℃ with the speed of 10 ℃/min and held for 2 min. Afterward decrease the temperature to 80 ℃ with the invariable speed of 5, 10, 15, 20 ℃/min, respectively, when liquid nitrogen is cooled, and gain non-isothermal crystallization DSC curves, and HDPE non-isothermal crystallization kinetics parameters were resolved by Eopoxobeku method. The results show that the crystallization starting temperature decreases from 121.81 ℃ to 118.93 ℃ when the speed of decreasing temperature rises from 5 ℃/min to 20 ℃/min, and the degree of crystallization rises from 86.19% to 90.34%. The cooling speed strongly influences crystal nuclei forming and growing mechanism in initial stages of crystallization, but weakly in later stages.