Thermoformability of Discontinuous Long Glass Fibre (LGF) reinforced polymer composites, part 1: Characterisation and Stretchability of the sheets
August 26th, 1998
Paper
S F Bush with F G Torres
Abstract
Thermoforming is a major process with a wide range of applications in several fields. One of the most interesting possibilities is the thermoforming of PP. It is well known that Long Glass Fibre (LGF) composites present better mechanical properties than unreinforced PP. In addition to that, long fibres increase the thermal stability and the melt strength of the unreinforced polymer. In this paper, the thermoformability of LGF reinforced PP is studied using dynamic mechanical analysis (DMA), hot tensile tests, sheet sag tests, and microscopical techniques for the characterisation of the fibre mat deformation process. DMA is used to characterise the anisotropy and the softening behaviour of the LGF extruded sheets. Hot tensile testing is used for assessing stretchability. Sheet sag studies under Infra-red (IR) conditions showed that LGF reinforced materials present a much lower degree of sag and a higher resistance to localised heating than the unreinforced polymers. Finally, scanning electron microscope (SEM) pictures are presented to verify the mat deformation processes occurring during thermoforming.