Most varicose and spider veins appear in the legs due to the pressure of body weight, force of gravity, and task of carrying blood from the bottom of the body up to the heart. Compared with other veins in the body, leg veins have the toughest job of carrying blood back to the heart. They endure the most pressure.
Curing a thermosetting resin transforms it into a plastic, or elastomer by crosslinking or chain extension through the formation of covalent bonds between individual chains of the polymer. Crosslink density varies depending on the monomer or prepolymer mix, and the mechanism of crosslinking:
Heat Curing â can be used to accelerate the cure of polyurethane rubbers and plastics, platinum silicone rubbers, epoxy resins and other materials. For example, subjecting a urethane mold rubber mold to mild heat (150 F / 60 C) will reduce the cure time from 16 hours to around 4 hours.