Patrick Loock, Business Leader, Products and Applications, at composite tubing manufacturer Exel Composites, discusses how composites made with thermoplastic functional coatings can better control properties such as friction, adhesion and finish. There are two main types of resins used in the production of composites: thermosetting resins and thermoplastic resins. Thermoset resins, the most common of the two types, harden by curing to form highly cross-linked polymers with insoluble or insoluble rigid bonds that do not melt when exposed to heat. Although uncommon in pultrusion, thermoplastic resins are being increasingly exploited. A thermoplastic is a polymer materials that softens when heated and solidifies when cooled. It's a reversible process, with no chemical bonds being made and broken, which means you can remelt and shape them as needed and shape them into any shape. Thermoplastics that can be used in composites include thermoplastic polyurethane (TPU), polymethyl methacrylate (PMMA), polyethylene (PE), polyamide (PA) and polypropylene (PP), among others.