General Description : Often just called "acrylic" - though this really describes a large family of chemically related polymers - PMMA is an amorphous, transparent and colourless thermoplastic that is hard and stiff but brittle and notch-sensitive. It has good abrasion and UV resistance and excellent optical clarity but poor low temperature, fatigue and solvent resistances. Though flammable, it has low smoke emission.

General purpose grades can be extruded and injection moulded. Monomer casting (for a description, see Nylon 6) is also used to achieve much higher molecular weights - which are not melt processable because of their extremely high melt viscosity - with somewhat improved properties. The monomer cast items most commonly encountered are sheets and novelty displays in which e.g. insects or watch parts are embedded.

Thin films are normally made from impact modified grades, which incorporate a small proportion of elastomer(s), in order to improve their flexibility.

Perspex CQ is a particular example of monomer cast sheet which was, until recently, made for intra-ocular use by the original, ca.1940, process because war-time air crew experience had shown that splinters of it that had entered the human eye were biologically inert. They are additive-free and the purest (and probably the highest molecular weight) grade of PMMA available. Almost all of our other PMMA items contain UV absorber; these two items are identified as "free from UV absorber" in the item description.

Applications include sinks, baths, displays, signs, glazing (especially aircraft), lenses and light covers. Cast sheet is also used for guards and the like.