Effects of temperature on the flow of copolymer melts

The temperature dependent flow behaviour of copolymers is useful for obtaining the monomolecular melt, which is essential for processing in order to get the defect free copolymer products. Melt flow index is shown to be useful in depicting the temperature dependence of copolymer melts and in estimation of their flow activation energy. The three copolymer systems included are styrene-butadiene-styrene (SBS), ethyl vinyl acetate (EVA) and a liquid crystalline copolyester based on hydroxybenzoic acid-polyethylene terephthalate (HBA-PET) respectively. The observed behaviour indicates a significant degree of retention of physical network structure below the cross-over point in a MFI-temperature −1 plot.