Abstract
Unsaturated polyester resin (UP), cured (crosslinked) with styrene, is probably the most widely used thermosetting resin in composites for marine, rail and construction sectors. However, a major drawback of cured UP is that it is highly flammable, largely owing to the copious amounts of flammable styrene evolved in a relatively low temperature depolymerization process, that burn with the production of a dense smoke. The chemical modification of the base resin or the crosslinker with halogenated elements, is the most common and effective method of rendering UP resin flame retardant. An alternative method of fire retarding is to blend UP with micro/nano particulate flame retardants (FR) or additional inherently flame retardant/char forming resins. This chapter discusses the effect of the FR blending component on the curing and morphology of the resin. The thermal stabilities and fire performances of the blends are also discussed.