Estimation of injection parameters of a bio-based composite material from the rheological characterization

This research work presents an analysis of the injection molding process of a natural fiber-reinforced composite, from the characterization of its rheological properties by the technique of capillary rheometry. Two of the main parameters of injection molding were estimated: the injection pressure and the clamping force. The rheological coefficients obtained were used as inputs in analytical and finite element models, for the prediction of the injection parameters. The results were compared, and it was observed that there is good agreement between them. The percentage errors between the two estimation methods were less than 5% for injection pressure and less than 10% for the clamping force. Also, the behavior of the material using different natural reinforcing contents (compositions of 20%, 30% and 40% fiber with a coupling agent at 4% and 8%) and the effect of its rheological properties on both the injection pressure and clamping force were evaluated. The study is of particular interest given that from the rheological characterization, the experimental values were adjusted to the Cross-WLF viscosity model and the adjustment coefficients, which contain both the reinforcing and coupling agent effects, were fed into the two methods of estimation of the injection parameters. The methodology used and the results obtained allow the prediction of the main parameters of injection molding of new bio-based composites, facilitating their use on an industrial scale.