Perbaikan Sifat Termal dan Mekanik Komposit Poliasam Laktat- Nanoselulosa melalui Asetilasi

Abstract

Microfibrillated cellulose (MFC) has nano-sized dimension, high molecular weight, and high crystallinity that can be used as reinforcement and filler in polylactic acid (PLA) composites. Property differences between hydrophobic PLA and hydrophilic MFC cause low compatibility and dispersibility will decrease the thermal and mechanical properties of the PLA composites. Therefore, improvement of these properties should be done by modifying the MFC to MFCacetate. Degree of substitution (DS) of the MFC-acetate tested in the PLA composites were 0.2, 0.5, and 0.8. The success of acetylation was evidenced by infrared spectrophotometer: reduced absorption of -OH group at 3300 cm-1, existence of C=O stretching at 1770 cm-1 and C-O acetyl at 1235 cm-1. Compatibility and dispersibility in the composite was achieved by increasing the DS of acetyl. The best thermal and mechanical properties was achieved by DS 0.5 with high heat resistance, low crystalization temperature (Tcc), and melting temperature (Tm), namely 88 °C and 166 °C, respectively. Mechanical properties of the resulting DS 0.5 showed higher maximum strain, tensile strength, and modulus of elasticity as compared to the pure PLA and PLA/MFC composite by 1.6%, 31.3 MPa, and 2.7 GPa, respectively.