Hygrothermal ageing and its effects on the flexural properties and failure modes of plant oil based composites for maritime applications

摘要

This research looks at moisture uptake and its effects on the flexural properties of glass reinforced epoxy, linseed oil and castor oil composites. Water uptake damages the material through chemical, physical and mechanical ageing. At the same time there is a need to reduce the environmental effects of the maritime industry and using composites from renewable resources could be a viable solution. While the conventional composites like glass/epoxy are trusted as a structural material in harsh humid conditions, there is very little known about more sustainable composite materials. As resins have a greater environmental impact when manufactured, and no information on their long term performance is available, this research looks at the flexural performance of glass reinforced castor and linseed oil resins over 2 years of ageing in comparison with glass/epoxy.As a result of accelerated ageing it has been shown that the degradation of all three composites is significant, ranging between 18{87% over the 2 year testing period. The moisture equilibrium content in glass/epoxy was 2.11%, glass/castor oil 3.62% and glass/linseed oil 2.87%. While the moisture uptake of glass/epoxy follows an expected trend, the moisture uptake of plant oil based resin composites does not and differs from conventional models. After 2 years of ageing the properties of glass/castor oil are comparable with glass/epoxy. The degradation of properties in glass/linseed oil is the greatest.MicroCT and AE techniques were used to look at the failure modes in glass/epoxy and glass/linseed oil specimens showing changes in the failure mode of glass/linseed oil only after 3 days of ageing. The failure modes of glass/epoxy were found to be mainly fibre dominated and most of the damage occurred on the tensile side of the specimens while the failure in glass/linseed oil was largely dominated by compressive damage. For the first time the failure mechanisms of glass/linseed oil have been proposed.