Polypropylene/low density polyethylene blend matrices and short glass fibers based composites. I. Mechanical degradation of fibers as a function of processing method

Abstract The fiber length degradation during compounding (two‐roll milling and twin‐screw extrusion) of glass fiber and polypropylene (PP)/low density polyethylene (LDPE) blend matrices based composites was investigated. The effect of LDPE percentage and fiber content on fiber length were studied using a semiautomatic image analysis system. Two‐roll milling causes a more severe attrition of the fibers than twin‐screw extrusion. In the first case, the higher the LDPE percentage in the polymer matrix, the larger the final fiber length. Both methods lead to a broader fiber length distribution as LDPE percentage increases. The effect of fiber content is opposite to that of the LDPE percentage, but in the case of twin‐screw extrusion it is less noticeable, During the injection molding of the composites a slight decrease of the final fiber length takes place. This decrease depends on the initial fiber length, the effect being more pronounced for longer fibers.