(a) on solidification from a melt, the polymer polyethylene forms a semi-crystalline spherulite structure (i) sketch an individual spherulite and label the amorphous and crystalline regions. (ii) draw a schematic to show the changes in specific volume with temperature during cooling from the melt, comparing it to the theoretical extremes of fully crystalline and fully amorphous (indicate tm and t^) (b) (i) define thermoplastic polymers and thermosetting polymers in terms of their structures, and (ii) describe briefly a process suitable for the production of products from each type of polymer