THE EFFECT OF FIBRE CONTENT ON THE THERMAL AND FIRE PERFORMANCE OF POLYPROPYLENE-GLASS COMPOSITES

摘要

Thermoplastic composites demand constant improvements in fire retardant and mechanical properties to fulfil their full market potential, especially in demanding sectors such as rail, aerospace and infrastructure where fire performance is critical. The aim of this work is to understand the effect of reinforcing fibres on flammability of polypropylene-glass (P-G) composites and means of improving their fire performance in a cost effective manner. A number of polypropylene – glass composites with 0, 10 and 20% (w/w) glass fibre have been prepared by co-extruding polypropylene and short length glass fibres and then hot-melt-pressing the pellets into plaques/laminates. The effect of fibre content on the thermal stability, flammability and mechanical performance of the polypropylene-glass without and in presence of conventional fire retardants, has been studied. It has been observed that while the presence of glass fibre lowers down the limiting oxygen index (LOI) value of the composite, the rate of flame spread in a UL-94 equivalent test is also lowered. The reduction in LOI is due to the fact that glass fibre reduces the melt dripping behavior of polypropylene (PP) and does not let the polymer (PP) move away from flame, which then burns. Cone calorimetric study indicated that the glass fibre act as a thermal insulator, reducing the overall flammability of the composite laminate.