Effect of Weld Lines on Injection Moulded Fibreglass Reinforced Structural Foams. 1 - Morphology, Shear and Tensile Properties

Abstract

In this work, the effect of weld lines and density reduction on the morphology and mechanical properties of injection moulded fibreglass reinforced polypropylene structural foams is reported. In this first part, cell size, cell density, skin thickness as well as tensile and shear mechanical properties are reported. As expected, all mechanical properties decreased with density reduction. On the other hand, the presence of a weld line produced a more complex behaviour: lower tensile properties with higher torsion modulus. These results are shown to be related to a change in fibre orientation along the sample length which is the main factor controlling the mechanical response of these composite foams.

Effect of Weld Lines on Injection Moulded Fibreglass Reinforced Structural Foams. 2 - Impact and Flexural Properties

“…The materials used were reported in the fi rst part of this study (3) . Glass fi bre (GF) reinforced polypropylene (PP) Hostacom PC072-3 natural from Basell Polyolefi ns was used as the matrix.…”

“…As described in the fi rst part of this work, the samples were produced on a Nissei PS-E injection moulding machine (60 tons of clamping force) equipped with a spring-type shut-off nozzle (3) . The injection parameters were selected based on an earlier work (21) : a temperature profi le of 177, 185, 210 and 230 °C with a mould temperature of 60 °C.…”

“…To produce a weld line (WL), a second channel in the mould was open which divided the main stream of polymer in two melt fronts ( Figure 1b) producing a cold weld line in the part's centre. Further details on the injection moulding process can be found elsewhere (3,21) .…”

“…As reviewed in the fi rst part of this work, several studies are available on the effect of a weld line on tensile and shear (torsion) properties of polymer *Corresponding author: Denis.Rodrigue@gch.ulaval.ca composites and foams (3) . Unfortunately, much less work has been done on the effect of weld lines on the fl exural properties of foams (4,5) , composites based on natural fi bres (6,7) or glass fi bres (8)(9)(10)(11)(12) , and composite foams (13) .…”

“…In the fi rst part of this investigation (3) , the morphology of glass fi bre/polypropylene (GF/PP) composite foams was reported with their tensile and torsion properties. In this second part of the study, the impact and fl exural properties of these structural composite foams are reported as a function of density reduction and mould temperature.…”