Performance improvements of a short glass fiber-reinforced PA66 composite

Abstract

Abstract A plate used in a medium voltage switch, made by a 25 wt% glass fiber-reinforced polyamide 66 composite filled with flame-retardant red phosphorus (RP) (PA66-GF25 FR (RP)), was injection molded. To satisfy the relatively high dimensional accuracy requirement, a “supporting mold” was used to compensate for the difference between the transverse and longitudinal linear shrinkage of the PA66-GF25 FR (RP). To reduce the internal residual stress caused by the “supporting mold,” hygrothermal conditioning treatments, including boiling water bath at 90–100°C and re-drying at 110°C, were used. To determine the effects of boiling water bath and re-drying on the dimensional accuracy and mechanical properties of the product, three treatment routes were applied. It was found that the route in which the boiling water bath is applied after the “supporting mold” is preferred to ensure the dimensional accuracies and the mechanical properties as a whole. Using a boiling water bath as a hygrothermal conditioning treatment can improve the mechanical properties and increase the dimensional accuracy of the product. In addition, by using the preferred route, re-drying can further improve the tensile, bending, and even impact strength.