Recycling effect on mechanical behavior of HDPE/glass fibers at low concentrations

The present article investigates the recycling effect on properties of dilute suspension of HDPE reinforced by SGF without coupling agents. This dilute suspension at different proportions of SGF loading was produced by melt compounding cycles with a single screw extruder. The differential scanning calorimetry results have shown an increase in the crystallinity of HDPE with SGF proportion and the number of extrusions. The increase varies from 8.2% for neat HDPE 5 extrusions to 13.3% for HDPE 10% SGF 3 extrusions. Besides, rheological measurements have shown a decrease in the viscosity of neat matrix from 33,800 Pa.s to 24,500 Pa.s after 5 extrusions for 0.01 s(-1), while the opposite is observed for composites for which the highest viscosity is obtained with five cycles of extrusion. These results suggest a decrease in the molecular weight of the HDPE during reprocessing, but for composites a good dispersion of SGF matrix was obtained, increasing with the extrusion number. As for the mechanical properties, a substantial enhancement in ductility was observed, compared to neat recycled matrix, by adding small SGF concentrations. Thus, for 1.6% and 2.6% SGF the best enhancement of ductility was obtained with conservation of the fiber length and a good dispersion of fibers.