尼龙6反应注射成型厚度效应的数值模拟

Numerical Simulation of Thickness Effect in Reaction Injection Molding Process of Nylon 6

对尼龙6反应注射成型加工进行了数值模拟,考察了三维模腔的厚度对加工过程中体系温度、转化率及结晶度的影响。结果表明,体系的温度、转化率及结晶度存在厚度效应。入模初期表层温度较高,约24s后呈现由表面层向中心层的逐渐递增分布;体系各层温升高至极值后呈现由表面层向中心层转化率递增、结晶度递减分布。片材厚度增大会使体系的极值温度升高、升至峰值温度的时间延迟、峰温变宽甚至出现高温平台期;厚度变化不影响单体聚合完全所需时间,但中心层的转化率最大上升速率出现的时间相应地延迟,由2mm时的约40s增至10mm时的约72s。表面层的结晶度不受厚度影响,但中心层结晶时间随厚度增大而显著延长,由2mm时的约238s延长至10mm时的约491s。

The numerical investigations of reaction injection molding of nylon 6 were presented.The effects of thickness in three-dimension mold cavity on the system temperature,monomer conversion and polymer crystallization were studied,and the thickness effect was revealed.The results show that the system temperature appears the distribution of increasing from surface layer to middle layer thereafter about 24 seconds injection with higher surface temperature in the initial stage.The distribution takes on increasing for conversion and decreasing for crystallinity from surface layer to middle layer after the temperature experiences the maximum.The increasing of sheet thickness causes the maximum temperature elevation,time lag for the maximum upcoming with widen peaks and even engendering a high temperature platform.Although the thickness variation has little effect on the totally time of monomer converting to polymer,the emerging time of middle layer maximum conversion rising rate delays,from about 40 seconds of 2 mm thickness to about 72 seconds of 10 mm thickness.There is no effect of thickness on surface layer crystallinity,but remarkably prolongs the crystallization time for the middle layer,from about 238 seconds of 2 mm thickness to about 491 seconds of 10 mm thickness.