Mechanical and thermal properties of polylactic acid/ polypropylene composites reinforced with natural fiber

Wood-plastic based composite products are being commonly used in many areas in the industry nowadays such as sidings, chairs, tables, banks, items of furniture, automotive, construction, etc. Wood-plastic based composites need to meet the high strength and low production cost. Turkey produces a significance amount of agricaltural wastes each year. Agricultural wastes should be used in wood-plastic composites in order to contribute to the country's economy. In this thesis study, our aim is to produce Polylactic Acid (PLA)/Polypropylene (PP)/Rice stem based biocomposite materials. With the help of its certain features, PLA is being used as a substitute for petroleum-based polymers. Rice stems which supplied from Trakya Agricultural Research Institute were used as natural fiber. Maleic anhydrit infused Polypropylene (MAPP) was used in order to strengthen the bond between wood flour and Polypropylene. PLA / PP mixture was consolidated with 4% MAPP and 30% rice stem. PLA/PP was prepared with 3 different variations in the following rates: 75%-25%, 50%-50%, 25%, 75%. Neat PLA and PP specimens were produced as control samples. The effects of a variety of PLA/PP rates on thermal and mechanical features of biocomposite materials was investigated. The materials were pulverized using a grinder to obtain a homogeneous mixture. After mechanical stirring, the mixtures were granulated with a twin screw extruder. With doing so, first biocomposite midproducts was obtained. Granular shaped biocomposite transformed into 200x200x3,5 mm plates by hot press. Finally control samples obtained with laser cut machine from those plates. The mechanical properties of the test samples were determined by tensile-bending, thermal properties by TGA and chemical structures by FTIR. Results compared with and between non-reinforced PP and PLA. As a result of thermal tests, it was observed that residual amount increased and initial decomposition temperatures decreased in biocomposite materials. Along with mechanical analysis, composite materials showed lower performance than pure samples. PLA25 has the highest mechanical properties with tensile strength of 18.74 MPa and flexural strength of 42.92 MPa. PLA75 shows the lowest performance. The produced biocomposite materials can be a preferable alternative in terms of cost and performance.