Bio-based composites produced by conventional techniques using recycled polymer matrix

In the recent years, the use of renewable resources for the preparation of polymer-based materials has attracted a growing attention because of the increasing demand of environmental friendly materials. Among biodegradable plastics, poly(lactic acid) (PLA) is a very interesting material. It is a degradable thermoplastic polymer with excellent mechanical properties and is produced on a large scale by fermentation of corn starch to lactic acid which is subsequently chemically polymerized. In our previous studies it has been shown that composites based оn PLA and kenaf fibers have good mechanical properties, acceptable for the preparation of materials applicable in various areas of construction [1,2,3]. In this paper we have investigated the mechanical and thermal properties of composite materials manufactured from recycled PLA matrix reinforced with kenaf fibers using the conventional techniques, compression and extrusion. For comparison, the composite material manufactured from recycled polypropylene (PP) reinforced with kenaf fibers with identical fiber/ matrix ratio, using the same techniques, was tested. Also, the properties of the composites with recycled matrix were compared to the composites with virgin matrix. Contrary to the recycled PP based composites, recycled PLA based composites have shown significant deterioration in mechanical properties compared to virgin PLA based composites but there isn’t significant change in their thermal properties. Further research will be targeted at evaluation of the possibility for recycling of the PLA under the conditions that will not cause major changes in the molecular weight of the polymer