You should really do this by yourself, if you haven't already; if no-one helps and you haven't prepared, remember, you're the one responsible for your stuffing-up, and you're the one who's getting your HSC in the end.
Discourse over and done, here; I won't give it to you in the form you want, just the info (the lay-out's bad, soz):
PVC (polyvinyl chloride), or polychloroethene - addition polymer of chloroethene/vinylchloride - H2O-resistent, hard, unstable to UV, insulator - underground/indoor water piping/electrical insulation - hard due to larger/more massive Cl atoms, compared to H's as in p.eth. - larger molecular size, greater crystallinity, less flexibility - plus plasticiser, plus flexibility.
LDPE - chain branching, etc. - low density, soft, stable to heat, clingy - flexible food bags/carry bags, cling wrap
HDPE - high density, hard, stable (unreactive) to air and water - milk cartons, etc. - lack of chain branching.
Polystyrene
*large phenyl (-C6H5-) - stiff, rigid; compensates flexibility, though --> tool handles
*C-C and C-H bonds - stable to heat and uv --> car battery cases
*minimal chain branching --> v. crystalline --> property exploited in transparent objects
