Effect of Fillers and Processing Parameters on the Shrinkage of Injected Molding Polyamide 66

摘要

The in-flow and cross-flow shrinkage of injected molding polyamide 66 (PA66) could be effectively reduced by optimizing glass fiber content and molding condition. The chosen molding conditions were melt temperature, cooling time and cooling temperature. The filler effect between glass fiber and clay on PA66 shrinkage also being compared. The result showed that glass fiber can effectively reduce the in-flow and cross-flow shrinkage by giving 54% to 86% reduction of shrinkage percentage. The optimum shrinkage was predicted sequentially at glass fiber content, melting temperature, cooling time and cooling temperature for in-flow are 45%; 285 °C; 45 seconds; 90 °C and for cross-flow are 45%; 285 °C; 35 seconds; 60 °C. The verification for cross-flow shrinkage was 0.41%, while the predicted value was 0.39%. The optimum cross-flow molding condition was applied to PA66/clay composite giving 28% to 51% reduction for 1% to 5% clay and 23% to 77% reduction for 15 % to 45 % clay. The shrinkage reduction by clay was lower than glass fiber, however, the addition of clay giving isotropic shrinkage that leads to less warpage.