Surface quality and mechanical properties of epoxy-glass fibre laminates manufactured by VARI method with use of gelcoat
Mateusz Kozioł, Bartosz Hekner, Jakub Wieczorek
Quarterly No. 3, 2016 pages 167-173
DOI:
keywords: laminate, gelcoat, vacuum assisted resin infusion (VARI)
abstract The aim of the study is a preliminary evaluation of the possibility and purposefulness of applying a gelcoat covering on GFRP (glass fibre reinforced polymer) laminates manufactured by the VARI (vacuum assisted resin infusion) method. A set of panels was manufactured on the basis of three types of glass fibre reinforcements: plain-woven fabric, chopped strand mat and 3D non-crimp fabric, while the composite matrix was epoxy resin. Alternatively, panels with and without the gelcoat layer were manufactured. The polyester gelcoat was laid on the mould by hand. Profilographometric tests were applied as the main method of evaluating the laminate surfaces. To evaluate the border area between the gelcoat layer and the laminate, microscopic visualization was performed with use of a scanning electron microscope (SEM) and - for chosen specimens - with use of a light microscope in Nomarski’s contrast conditions. In order to evaluate the influence of the gelcot layer presence on the laminate mechanical properties, tests of static bending were conducted on the laminates with and without the layer. The obtained profilographometric results showed that application of the gelcoat resulted in improvement of surface quality (a decrease in the maximum and average profile height as well) practically in all the tested specimens. Micrographs made of the gelcoat-laminate border area confirm very good coupling between these two elements. The obtained results of the bending tests showed that the presence of the gelcoat layer does not significantly affect the mechanical performance of the laminates. The registered differences in flexural strength between the specimens with the gelcoat covering and those without it are not big - and in most cases they are in favor of the latter ones. The obtained results allow the authors to conclude that VARI technology is very well suited to manufacturing products with a gelcoat layer. The results and conclusions obtained within the study may be useful for manufacturers in planning and optimization of manufacturing processes for elements made of composite laminates.