Investigation of cork as filler for fiber-reinforced composite material in kayaks

Abstract

This project is a continuation in the investigation of ways in which cork can be incorporated into composite material for boats and kayaks without significant performance losses. Fiberglass lay-ups (cloth, mat, and epoxy) and cork-epoxy samples are prepared by vacuum bagging. Samples undergo a three-point bending test (ASTM D79o) and a Charpy impact test (ASTM D611o) to investigate maximum flexural stress, effective elastic modulus, and impact resistance. Fiberglass-epoxy samples serve as the control for comparing the results of the cork composite samples. The average flexural strength of the fiberglass ranged from 191-234 MPa with the different configurations of fiberglass cloth. The effective elastic modulus ranged from 8.4-10 MPa. These values fall in the lower range of other composites when compared to general Ashby charts. Its impact resistance, taken with respect to cross-sectional area to account for variations in the thickness from sample to sample in the formation process, ranged from 54.9 to 64.5 kJ/m2. The cork composite samples were at least four times weaker than their fiberglass counterparts in all investigated respects. However, the cork samples were up to three times lighter and needed less than half of the epoxy the fiberglass samples required. The inclusion of fiberglass cloth helped increase its strength significantly without sacrifice to weight, indicating the likely need to incorporate chopped fiberglass strands in future testing.