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

In the second part of this investigation, the effects of weld lines on impact strength and flexural properties of injection moulded glass fibre reinforced structural polypropylene foams are reported. The results show that Charpy impact strength decreases with density and presence of a weld line. For three-point bending tests, a linear decrease of the flexural modulus and flexural strength as density decreases was found, the latter being more important. There is also a significant decrease of flexural properties for samples with a weld line compared to samples without one of the same density. Also, to evaluate the weakness of the weld line region, off-centre flexural tests were performed to determine the minimum distance at which load should be applied for the failure to no longer occur at the weld line. The results obtained indicate that this distance decreases as density decreases.