Prediction of mechanical properties of recycled fiberglass reinforced polyamide 66

Abstract An experimental study of the mechanical performance of in‐plant recycled fiberglass reinforced polyamide 66 is reported. The fiber length distributions were used to investigate and to predict the influence of process induced fiber shortening on the short term performance of recycled samples compared to that of virgin samples. The results indicate that fiber shortening has a strong influence on strength. Applying a modified Kelly‐Tyson model to the fiber length distribution gave excellent agreement with measured strength. There was no need to vary interface or matrix properties in the theoretical analysis. The effect of reprocessing on these factors does not appear to influence strength within the bounds of the model. The decrease in strength during a continuous in‐plant recycling process is small at a 30 wt% regrind level. Indeed, below 50 wt% regrind, the strength remains within design limits. The impact strength of dry unnotched samples indicated that the resistance is related to the reciprocal fiber length.