Polymethyl methacrylatePMMA

A two-part structural acrylic adhesive based on methyl methacrylate monomer, cured by a free-radical reaction between resin and activator. MMAs bond metals, composites and many plastics with minimal surface preparation and combine high strength with toughness, making them popular for bonding GRP structures and vehicle assemblies.

A substance that initiates or speeds a resin's curing reaction without being consumed in stoichiometric amounts. In the GRP trade the organic peroxide added to polyester resin, usually MEKP, is called the catalyst, although strictly it acts as an initiator.

The chemical process by which a liquid resin or adhesive hardens into its final solid state through crosslinking, driven by a hardener, catalyst, heat, moisture or radiation depending on the chemistry. Full properties develop only when cure is complete, which can take considerably longer than the initial set.