Production of cellulose based reinforced green composite

Polymer matrix composites have begun to replace metals in areas such as automotive, aerospace, biomedical, marine and sporting goods, electronics and packaging applications quickly. Lightness, good mechanical and thermal properties widen the application areas of these materials day by day. Polymer composite materials have disadvantages due to recyclability problems at their production and end of service life despite their increasing use. As a result of increased production activities in recent years, non-renewable and non-recylable composite material components cause uncontrolled pollution. Increasing environmental concerns due to pollution, limited petroleum reserves and the difficulty of recycling petroleum derived polymers, led to the need to move towards the production of new materials with the potential to replace these materials. Materials such as green polymers and composites have been designed to join the natural cycle, to be able to produce with minimum energy consumption and high efficiency in order to provide solutions to the environmental problems. Biodegradable green composites consisting of matrix and reinforcements obtained from fully natural sources are economical and light, as well as having mechanical, thermal etc. properties. Polylactic acid (PLA) is used in many basic industrial applications (packaging, medical, etc.) due to its high molecular weight and different structural properties (such as semi-crystalline and amorphous). PLA, which is the most popular biopolymer alternative to traditional petroleum based polymers with high strength and hardness, as well as having recyclability and compostability, has begun to be used in durable products, including automotive applications. Nanocrystalline cellulose (NCC) is used to tolarate weak impact and thermal properties of PLA. NCC, which can be used as a reinforcement in polymer matrix due to its high crystallinity and specific surface area, is obtained from various primitive and highly organized plants and bacteria. Because it is available from sustainable and renewable sources, due to its light weight and strength it is a unique reinforcement option for ''new generation green composite'' materials. In this thesis study, it is aimed to produce completely green polymer composite material suitable for industrial applications with improved mechanical and thermal properties by using PLA as matrix and NCC as reinforcement. First stage of the study, the effect of NCC content to be added into PLA and at the second stage, effect of maleic anhydride compatibilzer on PLA-NCC interface interaction were investigated. In the production of composite granules, melt mixing method with a twin screw extruder is used and injection molding method is used for forming of test samples. Fourier Transform İnfrared Spectroscopy (FTIR) and X-Ray Diffraction Analysis (XRD) were performed to characterize the structural properties of the composites. Morphological properties of the composites and matrix-reinforcement interactions were studied by Scanning Electron Microscopy (SEM). Thermal properties are characterized with thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC), mechanical properties are also characterized by tensile, bend and impact tests. Experimental results show that the increases in NCC content, decreases in tensile strength and elongation at break, increases in tensile modulus. It has been determined that the maleic anhydride (MA) compatibilizer, increases the tensile modulus and decreases tensile strength and elongation at break. From the results of the bending test, highest flexural modulus and strength were observed in PLA-g-MA/NCC5. NCC content was increased the flexural modulus usually. The highest flexural strength was found in PLA-g-MA (102 MPa) and PLA-g-MA/NCC5 (100 MPa) composites. It was determined that the highest impact strength of the Izod impact test made at -30°C belongs to PLA/NCC3 (5,10 kJ/m2) and PLA-g-MA/NCC3 (5,10 kJ/m2) composites. It was determined that the PLA-g-MA/NCC3 with the highest impact strength (4,71 kJ/m2) was also obtained as a result from the Izod impact test made at + 23°C. MFI values are reduced in all composites compared to pure PLA. It can be said that this reduction also changed the processability properties of the material. Moisture determination analyzes revealed that moisture content of 5 wt% NCC composites were higher than the others. In addition, DSC analysis has shown that the use of NCC does not cause significant changes in PLA's thermal conversion temperatures. As a result of TGA analysis, it was determined that the thermal stability was decreased. While there is no notable increase in the heat deflection and Vicat softening temperature, especially MA affects the Vicat softening temperatures negatively. From the results of SEM analysis, it was seen that the uniform dispersion was in 3 wt% NCC composites. Agglomeration was observed in 5 wt% NCC composites without MA effect.