STUDIES ON THE THERMAL, DYNAMIC-MECHANICAL AND RHEOLOGICAL BEHAVIOR OF SHORT-GLASS-FIBER-REINFORCED COMPOSITES BASED ON POLY(BUTYLENE TEREPHTHALATE) HIGH-DENSITY POLYETHYLENE BLENDS

Blends of poly(butylene terephthalate) (PBT)/high density polyethylene (HDPE)/ionomer (IONO) polymers, at a blending ratio of 76/19/5 (by we ight), were reinforced with short glass fibres (GFs) at levels of 10-3 0 wt% in order to enhance the mechanical properties for load-bearing e ngineering applications. The melting and crystallization behaviour of the composites, studied by differential scanning calorimetery (d.s.c.) , indicate the presence of an increase in crystallinity in the presenc e of the glass fibres. Dynamic mechanical thermal analysis (d.m.t.a.) shows that the introduction of glass fibres reduces damping to a great er extent than would be expected theoretically. Incorporation of glass fibres increases the storage modulus, when compared to the unreinforc ed system, at all temperatures studied. The presence of short glass fi bres increased the melt viscosity and decreased the extrudate swell, w ith the effect being more pronounced at higher temperatures. Rheologic al data have been analysed on the basis of fibre length (or aspect rat io) and/or distribution of the fibre lengths by using the rheological model proposed by Maron and Pierce.