注射成型塑化过程对聚碳酸酯性能的影响

Effect of Injection Molding Plasticizing Process on the Properties of Polycarbonate

采用双因素多水平试验方法考察了注射成型塑化过程的塑化温度和塑化停留时间对聚碳酸酯(PC)黄色指数、拉伸性能和残余应力的影响。结果表明,PC分子链基团和分子键发生高温断裂,引发PC产生黄化,且黄化程度与塑化停留时间呈线性增加关系。塑化温度升高,塑化停留时间延长,PC的拉伸强度和断裂标称应变快速降低,PC由韧性断裂向脆性断裂转变;在塑化温度300℃,310℃和320℃下,PC临界塑化停留时间分别为126.1 min,77.1 min和38.7min。残余应力结果表明,在充填方向上,PC应力呈对称分布;塑化停留时间延长,PC光程差增大,应力分布逐步均匀。

The influences of injection molding plasticizing processing parameters such as plasticizing temperature and plasticizing residence time on the yellowness index, tensile properties and residual stress of polycarbonate（PC） were investigated through two factors and multiple levels test method. The results show the yellowness index of yellowing PC caused by the thermal rupture of radical group and molecule bond increases linearly with increase of the plasticizing residence time. While increasing the plasticizing temperature and plasticizing residence time, the tensile strength and nominal tensile strain at break decrease rapidly and the fracture model of PC converts from toughness rupture to brittle rupture. In addition, the results also indicate that the critical residence time under the plasticizing temperature of 300℃, 310℃ and 320℃ is 126.1 min, 77.1 rain and 38.7 min respectively. Besides, the results of residual stress show that stress of PC is symmetric distribution along the melt filling transverse and longitudinal direction. With increasing the plasticizing residence time, the optical path difference increases and the stress distribution is more and more uniform.