Additives such as flame retardants and foaming or blowing agents may be added to provide a foam filled interior for insulation, floatation and/or greater mechanical stability.

Chemically modified polymers permit adhesion to metals or other resins allowing metal threaded inserts to be inserted or to provide a sandwich of two dissimilar resins.

EVA copolymer provide excellent low temperature flexibility, impact resistance and may be used for soft toys etc. colour, texture and function

Polyvinylchoride PVC compounds may be rotationally moulded to obtain semi-rigid or even flexible characteristics for toys and bellows etc.

Nylon 6 has excellent tensile strength, is rigid and has good impact strength and chemical resistance. Applications include fuel tanks, oil and solvent containers, etc.

Nylon 12 has similar characteristics to Nylon 6, but is more easily processed.

Polycarbonate has the highest rigidity of all plastics, its high impact strength making it suitable for vandal resistant items. It also has high heat resistance and may be moulded crystal clear or opaque making it suitable for street lighting and enclosures where toughness is critical.

Polypropylene is stiffer than polyethylene and is less prone to environmental stress cracking. Applications include solar panels and medical storage equipment.