Mechanical Properties of Polylactic Acid/ Graphene/ Chitin Nanowhisker Composite Film

Abstract

Polylactic Acid (PLA) is a thermoplastic biodegradable polyester that is widely used in various fields such as in packaging, medicine and agriculture. However, PLA has some drawbacks such as low toughness, brittleness, poor vapour barrier properties and low thermal stability that may limit its application. Properties of PLA were shown to improve when added with inorganic nanofillers such as graphene. Meanwhile organic filler such as chitin nanowhiskers (CHW) has also shown positive effect on PLA properties.  In this work the effect of CHW content (1, 2, 3 and 4 phr) on mechanical and thermal properties of PLA/graphene composite films was investigated. Tensile test and thermogravimetric analysis (TGA) were carried out to study the properties of all composites. The results showed that tensile strength of PLA/graphene composites decreased with the addition of CHW at all contents. However, the tensile strength of PLA/graphene/CHW increases up to a maximum value of 3 phr.  While elongation at break of all PLA/graphene/CHW composites decreases with addition of CHW fillers. Young’s Modulus increases at 1 phr CHW content. The results indicate that the blending of PLA/graphene with CHW did not improve its tensile strength which showed the absence of specific interactions between PLA with both fillers as shown by Fourier transform infrared (FTIR) spectroscopy.  Meanwhile TGA showed that the thermal stability of PLA did not show much improvement by addition of CHW. As a conclusion, since graphene used was at its optimum value, effect of CHW may have been more effective by using a lower graphene content.