Properties and composition of plastic FCMs

Plastics can be placed into two main categories, thermoplastic and thermoset. Thermoset plastics are irreversibly formed into a permanent shape often by applying heat. Thermosets caimot be softened and remoulded on heating and have few applications in food packaging, except for the iimer linings used for can coatings and many adhesives, as used, for example, in multilayer materials. A limited range of food contact materials is made from thermosets, predominantly melamine resins and unsaturated polyesters used in tableware and utensils. 

The criteria for selection of the most appropriate polymeric materials for food contact applications are generally based upon  

Further factors sometimes come into play for food packaging  

These criteria are not in any particular order and some may conflict with one another. Fortunately for food packaging, in cases where no single plastics monolayer can satisfy all the functional requirements, recently applied technologies such as co-extrusion and lamination can provide complete solutions. The most commonly used plastics for the manufacture of FCMs are given below. 

Ethylene may be copolymerised with vinyl acetate to make ethyl-vinyl acetate, offering high seal integrity and clarity for frozen food applications where a high degree of toughness is required. Ethylene copolymers with other olefins such as propylene, 1-hexene and 1-octene allow a range of properties to be achieved. Linear low density polyethylene (LLDPE) has a 

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