玻璃纤维毡增强聚丙烯在压缩模塑流动过程中的纤维分布

Fiber Distribution During Compression Molding of Glass Mat Reinforced Polypropylene

通过测定玻璃纤维毡增强聚丙烯经挤压流动后不同区域的纤维含量 ,研究了基体树脂、增强材料的结构与性质、坯料设计、模具温度及坯料的预热温度等对玻璃纤维毡增强聚丙烯在压缩模塑流动过程中纤维分布的影响。结果表明 ,适当提高基体的粘度及采用多层坯料叠层的坯料设计方法 ,有利于制品内纤维的均匀分布 ;针刺密度适当的连续针刺毡及由短切纤维组成的复合针刺毡与聚丙烯形成的复合材料 (GMT) ,在压缩模塑的流动过程中纤维分布的均匀性较好 ,随着针刺密度的增加 ,纤维分布的均匀性下降 ;用粘结剂粘结而成的连续原丝毡与聚丙烯复合得到的GMT材料 ,纤维分布的均匀性较差 ,经适当针刺以后 ,纤维分布的均匀性得到一定程度的改善 ;过低的模具温度及坯料预热温度 ,会引起材料充模流动能力下降 ,但模具温度及坯料预热温度过高时 ,流动前沿区域的树脂富集现象将加剧。

The effect of matrix resin,architecture and property of reinforcement,blank design,mold temperature and blank preheat temperature on the fiber distribution during compression molding of glass mat reinforced polypropylene(GMT-PP)was investigated by measuring the fiber content in various areas of GMT-PP after squeezing flow.It was found that the fiber distribution was uniform when using stacked blank design and increasing the viscosity of matrix resin.The needling operation of random continuous fiber mat was advantageous to the fiber distribution,however excessive needle punching would decrease the uniformity of fiber distribution.The fiber distribution was also better when using chopped fiber kept together in a mat by needling operation.Moreover,the fiber distribution was improved to some extent if the continuous fiber mat kept together by a binder was treated with needling.Excessive low mold temperature and blank preheat temperature leaded to the decrease in the ability of composites flowing to fill mold,whereas the resin enrichment occurred at the flow front of composites when using excessive high mold temperature and blank preheat temperature.