Investigation of the properties of marble powder and chestnut shell fiber reinforced polylactic acid (PLA) biocomposites

It is very important to meet the raw material demand of human beings without disturbing the balance of the ecological system. In addition, this raw material should be available without any negative impact on the environment. Sustainability in this issue is possible by developing and using polymers obtained from sustainable sources and which are easily degradable in nature. Polylactic acid (PLA), which is a biodegradable polymer obtained from renewable sources, was determined as matrix material in this study. Chestnut trees are widely available in Bursa. Chestnut, the fruit of these trees, is mainly used in the production of chestnut sugar. After production, chestnut inner shell and pericarp part are released as industrial waste. Chestnut pericarps, which are rich in phenolic extracts and have a fibrous structure, were evaluated as organic fillers and reinforcing materials in this study. On the other hand, waste marble powders released from the marble enterprises of Afyon in our country have negative environmental impacts but it is important to evaluate them in various fields of industry. Marble powder was used as an inorganic reinforcement material in addition to chestnut fruit peel to PLA matrix. In this study, it is aimed to prepare biocomposite materials using marble powder and chestnut fruit shells and biodegradable polymer PLA and to investigate some properties of these samples. For this purpose, PLA and chestnut fruit peel, which are commercially available in granular form, are ground separately. Chestnut peel flour, marble powder and ground PLA were mixed in predetermined proportions. The mixtures were passed to the PLA at the appropriate temperature values through the extruder device and then brought to granule sizes. Biocomposite sheets were obtained by hot pressing process from granular composites. Biocomposite plates were cut to the appropriate test sample sizes with the help of laser cutter to determine the properties. In order to determine the physical properties of the biocomposite test samples, density, water uptake and thickness increase rate tests were performed. Bending and tensile strength tests were performed to determine the mechanical properties of the biocomposite. Thermogravimetric analysis was performed to determine the thermal stability and decomposition temperature of the samples. Functional groups of biocomposite samples were analyzed by FTIR analysis. In biocomposite, it was seen that the density of chestnut fruit peel increased. Marble powder decreased the thickness increase rate of the biocomposite. In the mechanical properties, tensile test yielded 120.7 mm elongation under the tensile load of 1978.1 N in the biocomposite containing % 9 chestnut fruit peel and % 0.25 marble powder. According to the results of thermogravimetric analysis, shifting of TGA curves towards higher temperatures showed that chestnut fruit peels increase the thermal stability of PLA biocomposites.