Synthetic resin (5)
'synthetic resin' is the definition.
(epoxy is a kind of synthetic resin)
This is all the clue.
(Other definitions for epoxy that I've seen before include "Type of adhesive" , "Hard-setting resin" , "Type of adhesive/paint" , "Adhesive; plastic" , "Type of resin" .)
'synthetic resin' is the definition.
(polythene is a kind of synthetic resin)
This is the entire clue.
(Other definitions for polythene that I've seen before include "Packaging material -- telephony (anag)" , "Strange telephony provides a lightweight material, used in packaging" , "Synthetic resin" , "A lightweight thermoplastic" , "Synthetic thermoplastic used for packaging, etc" .)