Publication

Abstract : Blending is a widely used technique in polymer research to improve the physical/mechanical properties of homopolymers. Blending of two polymers may either result in a miscible system or immiscible system. From thermodynamic viewpoint whether one likes it or not, quite often immiscible or partially miscible blends are produced. In order for successful application of these types of blends, interfacial stabilization is required which are done through compatibilization. Recently compatibilization through radiation treatment in binary polymer blends have been gaining importance due to its advantages over other methods. Irradiation by high-energy radiation like electrons has been tried but with little success. The cross-linking between blend constituents which occurs after irradiation is expected to improve many properties such as optical, mechanical, electrical etc. On the other hand use of microwave-irradiation, which is an alternative to conventional heating, seems to be a promising approach for the above purpose. One expect that the polar group present in the blend systems may absorb the microwaves and thus become highly reactive thereby initiating improved interaction between the blend components thereby improving many properties. In the present study we have employed the positron lifetime method to study the microstructural changes brought out by e-beam and microwave irradiation in two polymer blend systems namely PS/PMMA and PVC/SAN through free volume monitoring. Though the free volume data shows the overall modification occurred in the blend sample, but it could not reveal the information about the actual site of modification whether it has occured at the interface or within the blend constituents. To overcome this hurdle, based on Wolf et al. theory we recently developed a new method [3] for characterizing the changes at the interface through hydrodynamic interaction existing between the constituents of binary polymer blend. The hydrodynamic interaction parameter α derived from the very same free volume data measures the excess friction generated at the interface between the chains of constituent polymers. It represents the strength of hydrodynamic interaction or it is a measure of the adhesion strength at the interface. Therefore, through the parameter α, the extent of interfacial stabilization occurred through irradiation in polymer blend systems can be effectively studied. In the present study, a comparison of results with e-beam and microwave induced phase modification is done to figure out which route is better to stabilize the interface depending upon the system of study.