Question

7. There are two main types of thermoset unsaturated polyesters laminating resins. Each has a significant impact on part properties. What are they and explain their differences.

Answer 1

Thermoset unsaturated polyesters laminating resins are two principle types

1) Orthophthalic unsaturated polyester resins

2) Isophthalic unsaturated polyester resins

Orthophthalic unsaturated polyester resins are typically less expensive than isophthalic unsaturated polyester resins. They are the general purpose polyester resins and their properties are generally inferior with respect to strength, corrosion resistance and chemical resistance compared to isophthalic polyester resins. However, Orthophthalic unsaturated polyester resins have the advantages of fast curing time, tack-free finish and good mechanical properties. Isophthalic unsaturated polyester resins are regarded as a higher grade because of the better flexibility higher strength, chemical resistance and UV resistance