Investigation of Thermo-mechanical Properties of PMMA

The present paper reports the investigation of thermo-mechanical properties of Poly (methyl methacrylate) or PMMA. The film of PMMA has been prepared by solution casting method taking tetrahydrofuran (THF) as solvent. So prepared film has been used for the measurement of mechanical properties such as storage modulus, loss modulus, Tan delta and stress strain relation employing Dynamic Mechanical Analyzer (DMA). The glass transition temperature of pure PMMA sample has also been obtained in order to determine its physical state and its influence in other properties such as toughness and stiffness. An effort has also been made to study the storage modulus (E`), loss modulus (E '') and Tan delta in a temperature range from 32 degrees C to 140 degrees C by DMA. It has been observed that storage modulus decreases with temperature due to thermal expansion of films. On the other hand Tan delta increases up to glass transition temperature beyond which it shows decreasing trend towards melting. Glass transition temperature (T-g) is found to be 82.1 degrees C. The stress strain curves of PMMA films at room temperature and at different temperature (32 degrees C - 90 degrees C) have been obtained. The results show that the mechanical properties i.e. Young modulus, toughness and tensile strength decrease with increasing temperature whereas the elongation at break shows increasing behavior with temperature. This trend in the different mechanical properties is explained on the basis of free volume theory.