Flexural testing of sustainable and alternative materials for surfboard construction, in comparison to current industry standard materials

Abstract

The objective of the project was to test if natural materials were a viable and sustainable alternative to current surfboard materials. The testing was comparative, comparing differing natural fibre laminates (2 differing hemp cloths), an environmentally friendly Bio-Foam and epoxy resin against the industry standard materials of glass fibre, polyurethane foam and polyester resin. The materials were laid up in sandwich construction (dimensions: l=240mm, w=50mm, d=10.3-11.6mm) and tested in three point flexural testing. Four test specimens for each material selection were tested, with the mean result taken.

All the samples failed in indentation, with the core crushing beneath the top skin, underneath the load beam. In comparison to the standard materials, the thin hemp cloth showed decreased flexural strength (-0.055 GPa) and flexural stiffness (-30.9%). The thick hemp cloth showed further decreased flexural strength (-0.0183GPa) and flexural stiffness (-63.2%) in comparison to industry standard materials. The hemp cloths also showed high levels of deviation from the mean (Thin: 23.8 N and Thick: 21.1).

The Bio-Foam sample expressed lower compressive core shear strength in comparison to polyurethane foam, and therefore lower flexural strength and stiffness in comparison to the standard (Flex strength: -0.27 GPa, Stiffness: -39.1%). The epoxy sample was the only specimen to show increased mechanical properties in comparison, with an increase in flexural strength of 0.046 GPa and an increase of 5.2% in flexural stiffness.

The results showed that natural alternatives do not show comparable properties to currently used materials, although by using an epoxy matrix the strength and stiffness of the specimen is increased. This would therefore increase the longevity of a surfboard, leading to decreased waste.