Introduction – Composite materials do offer freedom to design a material fitting best to the requirements of a given application. In case of fiber reinforced polymers especially the low weight in combination with other favourable properties, e.g. high mechanical performance, are the driving force for their application. Materials from renewable resources are of high interest if sustainability is aimed. In a holistic approach a green composite based on hemp fiber reinforcement embedded in hemp seed oil based thermoset resin system is aimed to be used in a rotor blade for wind energy production.
The challenging topic for this approach is to identify a possibility to gain a thermoset resin being really green, i.e. based on renewable resources and being not critical, e.g. toxic, at any stage of the whole processing chain. For this purpose several different approaches are studied and compared with other solutions based on green resin systems from other resources and conventional petrochemical based resin systems.
Experimental – Hemp seed oil based epoxy resin with different curing agents and catalyst, epoxy resin systems partly based on renewable resources, i.e. GREENPOXY 56 (Sicomin Epoxy Systems) and SUPER SAP® CPM (Entropy Resins Inc.), and a standard epoxy resin system, i.e. EPIKOTETM RIMR 135 (Hexion Inc.) were used. A vacuum infusion and compression moulding process were used to process flat plates of hemp fiber reinforcement and epoxy resin. Processability of the resin and resulting part properties, e.g. void content, impregnation and mechanical properties, were characterised.
Results and Discussion – Best results for the hemp seed oil based epoxy resin was received using a curing agent, which is not based on renewable resources, and resulting in relatively long curing times. Compared with the petrochemical based system none of the other resin systems performed better.
Conclusions – Fully green composites are challenging. A good performance level can be reached, but high performance is still a topic of development.