Impact of Injection Parameters on Gloss Properties of Grained Polypropylene Parts

This paper deals with the optical and colorometric properties of the recycled polymer during numerous internal reprocess. The effects of the number of grinding-injection cycles, three process parameters (material temperature, mold temperature, and injection rate) were investigated. One most limit for this kind of study is the large number of experiments that requires long time and significant investments. The idea is to vary five injection parameters (Tmaterial, Tmold, injection rate for five injection cycles using statistical approach. The five variables were investigated at three industrial used levels. The number of recycling varies from cycle 0 to cycle 4 at five levels. The complete matrix for screening was designed using D-optimal quadratic design. The experimental design was generated with the statistical software MODDE 10.1-Umetrics. A set of 42 experiments was carried out to determine the influence of injection parameters, polluant and recycling on the appearance properties of smooth and grained surfaces. The statistical software package Nemrodw® version 2007, LPRAI (Marseille, France) was used to analyze the experimental design.