Optimization of microcrystalline cellulose (MCC) isolated from rice husk (RH) as reinforcement filler in polylactic acid (PLA) biocomposite / Nur Hanani Abu Seman

• Main Author: Abu Seman, Nur Hanani
• Format: Thesis
• Language: English
• Published: 2020
• Subjects: Polymers and polymer manufacture
• Online Access: https://ir.uitm.edu.my/id/eprint/55743/1/55743.pdf; https://ir.uitm.edu.my/id/eprint/55743/

In this study, microcrystalline cellulose (MCC) was isolated from rice husk (RH) cellulose via acid hydrolysis process using nitric acid (HNO3) in comparison with sulphuric acid (H2SO4) and hydrochloric acid (HCl). The parameters used to isolate MCC from RH were extensively studied by using 0.5M and 1.0M of different acid concentration at 30 min, 60 min and 120 min reaction time. The optimum condition of acid hydrolysis process was undergone with 0.5M of HNO3 and 30 min reaction time successfully produced the highest percentage yield of MCC-RH at 83.5% as compared to H2SO4 and HCl at 80.6% and 81.8% respectively. Besides, the analysis of Fourier Transform Infrared (FTIR) spectroscopy affirmed the successive elimination of non- cellulosic material from RH cellulose resulting highly purified MCC-RH. X-ray Diffraction (XRD) analysis showed MCC-RH treated with HCl produced the highest crystallinity index value of 54.2% while HNO3 and H2SO4 produced comparable results of 52.4% and 49.7% respectively. TGA analysis showed the thermal stability of the MCC-RH treated with 0.5M HNO3 was enhanced as the degradation temperature at Ton, T20 and T50 increased compared with the untreated RH. The highest MCC-RH yielded by 0.5M of HNO3 was further analyzed as reinforcement filler in polylactic acid (PLA) biocomposite preparation through solvent casting technique. The incorporation of 1%, 3%, 5%, 7% and 9% of MCC-RH filler in the prepared PLA/MCC-RH biocomposite were successfully enhanced the physical and mechanical properties of PLA. Thermogravimetric analysis (TGA) has proved 3% MCC loading has the highest thermal stability as it degraded at higher temperature, 380 °C compared with pure PLA and 9% MCC loading which degraded at 365 °C and 350 °C respectively due to good interaction of MCC filler and PLA matrix. The good incorporation of 3% MCC loading with PLA matrix of the prepared PLA/MCC-RH biocomposite was further proved by SEM analysis with no agglomeration, filler pulled-out and void observed. In addition, PLA/MCC-RH biocomposite with 3% MCC loading has the highest tensile strength at 25.08 MPa with 56.6% increment compared with pure PLA which only produced tensile strength at 16.02 MPa due to good dispersion between MCC filler and PLA matrix that produced a good filler and matrix interaction. Whilst the addition of 5%, 7% and 9% of MCC loading caused declination in tensile strength and Young’s modulus due to agglomeration of MCC, filler pull-out and voids observed during SEM analysis. PLA/MCC-RH biocomposite with minimal water absorption properties is favorable to prolong the lifetime of the prepared PLA/MCC-RH biocomposite. Hence, water immersion test was done on the prepared biocomposites to determine its water absorption properties. PLA/MCC-RH bioomposite with 3% MCC loading was observed with minimal water absorption and thickness swelling recorded at 1.59% and 5.65% respectively compared with 9% MCC loading resulted 5.28% water absorption and 7.40% thickness swelling.