Effect of glass fiber loading and reprocessing cycles on the mechanical, thermal, and morphological properties of isotactic polypropylene composites

In this study, a preliminary finding is carried out to obtain the optimum E-glass fiber content in polypropylene (PP) plastic products using loadings of 5, 10, 20, 30, and 40 wt%. The formulation with the optimum loading of 10 wt% glass fiber was reprocessed 10 times via extrusion and compression molding techniques to simulate actual recycling and impacts on service life properties such as mechanical, toughness, chemical, thermal, composition, and morphology. In the result, mechanical properties were lost after each reprocessing without effect on the chemical properties and elemental compositions. The thermal studies showed a decrease in degradation temperatures with the onset degradation temperature (T-Onset) for the one-time reprocessed PP recorded at 336.93?degrees C with a maximum rate of weight loss (T-Max) at 427.68?degrees C which further reduced to 259.90(?)degrees C (T-Max of 388.47?degrees C) after 10 extrusion run showing one-step decomposition patterns. This work provides that glass fiber-reinforced plastics should not be reprocessed beyond 3 times except when refreshed with the addition of virgin PP to make up for the lost property. This will be very useful for manufacturers who want to simultaneously save costs (retain profit margin) and maintain the environment.

Automated summary

A preliminary study was conducted to determine the optimal E-glass fiber content in polypropylene (PP) plastic products. Mechanical properties were lost after each reprocessing, but the chemical properties and elemental compositions remained unchanged. Thermal studies showed a decrease in degradation temperatures and a change in decomposition patterns after multiple reprocessing.