Determination of glass transition temperature and modulus of PLA films using dynamic mechanical analysis at 50oc and amplitude of 10

Abstract

Polylactic acid (PLA) is an environment friendly biodegradable thermoplastic produced by microorganism synthesis through the fermentation of starch. It can be used in the manufacture of thermoplastic films used to produce packaging material in place of those produced from fossil fuels. It may reduce consumption of petroleum, which releases Carbon IV Oxide, a greenhouse emission, unburned carbon fragments and other compounds that give rise to smog and air pollution on burning. It is also compostable, aiding solid waste management. In this study, the mechanical properties of PLA were determined over a temperature and amplitude range to establish whether it can be used in production of packaging material for single use purposes and disposable items. The storage ( ) and loss ( ) moduli as well as the Loss Tangent ( ) and glass transition temperature (Tg) of PLA films were determined using the Dynamic Mechanical Analyzer (DMA) model 2980, used in the Multistrain mode. At 50oC and amplitude of 10 the storage modulus of PLA was 2220.00 MPa, while loss modulus was 112.90 MPa. Consequently, elastic modulus of PLA was 2222.87 MPa, indicating that PLA is strong and tough at this temperature. From the peak of the loss modulus graph the Tg was 65oC. Tg from variation of loss tangent with temperature occurred at 74.3oC.