21. The filled mold then continues to spin as the metal solidifies or the thermoset plastic sets. 22. Thermoset foams, such as spray foam insulation, have the ability to reflect radiant heat.23. Thermosets can melt and take shape once; after they have solidified, they stay solid.24. In the early 30's, companies started to experiment with housings of thermoset polymer plastics. 25. Thermoset polymer matrix properties can be fine tuned by the choice of substituents in the bisphenolic compound.26. The cut of polyimides is, highest of all thermosets , with short term exposure capabilities of. 27. Thermosets cannot be melted, therefore, once a thermoset has set it is impossible to weld it.28. Thermosets cannot be melted, therefore, once a thermoset has set it is impossible to weld it. 29. Many advanced thermoset polymer matrix systems usually incorporate aramid fibre and carbon fibre in an epoxy resin matrix. 30. There are also thermoset polyurethanes shown to have transient properties and which can thus be reprocessed or recycled.
