WELDING OF THERMOPLASTICS REINFORCED WITH RANDOM GLASS MAT

Thermoplastics reinforced with random glass mat have high strength and stiffness; the fibers dominate the mechanical behavior of these compo sites. The results of this investigation have shown that fibers are in effective for reinforcing hot-tool and vibration welded butt welds. Th e maximum weld strengths attained with GMT are comparable to the stren gths of good welds of the unfilled material. The optimum hot-tool weld ing parameters;for the reinforced materials are different from those f or the unfilled material. Unfilled polypropylene is easier to weld tha n unfilled polyamide. This characteristic is also true of the reinforc ed materials. In vibration welding, high welding pressures and high am plitudes result in lower mechanical properties. The optimum penetratio n depends on the fiber content of the bulk material. This penetration dependence is different from that for unfilled thermoplastic, for whic h the mechanical properties are independent of the penetration once a steady state has been attained.