There are two important teams of resins which make up what we phone polymer materials—thermosets and thermoplastics. These resins are made of polymers (big molecules made up of prolonged chains of scaled-down molecules or monomers). The most typical polyester is really an orthophthalic base, but more recent isophthalic dependent polyesters https://www.cybo.com/US-biz/plastic-materials-inc