COMPOSITES FROM NATURAL FIBRES

Abstract

Composites are widely used in our day to day life. Due to their low weight and ability to be tailored for specific end use they have gained a considerable ground in the high performance applications, such as aerospace and automobile industry. However, the use of polymers that can be recycled when used with carbon and other niche fibers renders the composite non-recyclable. This has become a major issue as the landfills are filling up at a faster pace along with the need for going green due to global warming. To tackle these issues research in recent years has been focused on substituting olefin (polypropylene, polyethylene, etc.) based composites with biodegradable ones. In order to achieve the goal of recyclable composites, natural fibers surfaced as the fiber of choice for reinforcing composites. The overhead for using natural fibers is their cleaning and processing needs. The current project uses hemp, a natural fiber, as a reinforcing media for producing a biodegradable polymer. The novel aspect is in terms of processing, in the elimination of carding, a cost and time intensive process. The web coming from the opening and cleaning line are needle-punched to provide integrity before being used as reinforcement. After considering various materials for use in a matrix, a soy protein isolate and poly lactic acid (PLA) were selected, because the soy protein isolate used as matrix material can be dissolved in water. In order to form composites the water has to be completely evaporated from the hemp and soy protein isolate mixture. The cost for evaporating water became a hindering factor, along with poor composite properties such as porosity and brittleness. Thus poly lactic acid (PLA) was selected as material of choice for using as matrix. PLA in fiber form was blended with hemp fibers during processing. The hemp-PLA webs produced were hot pressed in order to form composites. Various parameters studied to derive performance metrics were blend ratio of fibers and processing temperatures. The composites were analyzed for various mechanical properties like tensile and flexural properties. Composites were fabricated from epoxy vinyl ester based resin reinforced with hemp fiber webs in order to compare their properties with the biodegradable composites formed from hemp-PLA. The hemp-PLA composites though not as superior as the hemp-epoxy vinyl ester composite are made from renewable resources and can be used for non-structural applications and may provide superior thermal and acoustic insulation.