Thermosets - properties & applications

What are the properties of thermosets?

• hard

• Brittle

• Low thermal expansion (increase of dimensions as temp increases)

• Thermal decomposition w/ melting

List all the thermosets you know

• EP epoxy resin

• PF phenolic resins

• PUR cross-linked polyurethane

• UP unsaturated polyester

Properties & applications of unsaturated polyester resins UP

• dissolved in styrene when supplied to users

• Cross-link when a hardener is added → rigid structure

• Hardening leads to the resins shrinkage up to 10% (to compensate, the mould used for shaping the resin must be ~10% larger than the final desired size)

• → create strong materials

• paint

• Adhesive

• Binder in fibre-reinforced plastics (ex: combination with glass fibres)

• Binder for fire-dried mineral aggregate (granulats minéraux séchés au feu) (polyester concrete)

Properties & applications of epoxy resins EP

• harden by polyaddition w/ little volume shrinkage

• More resistant than UP (especially in alkaline = chemical environments with ph>7)

• Very expensive: production costs at least x2 as UP

• binder for fibre-reinforced plastics (liant)

• Paint ]coating

• Adhesive

• Binder for repair mortars (mortiers de réparation)

Properties & applications of polyurethane resins PUR

• ranges from rubber-elastic (soft & flexible) to hard-brittle (rigid)

• If water is added during the reaction, the resulting product foams up (mousse)

• One-component PUR (no hardener) hardens with air moisture (humidity)

• joint compounds

• Fast-bonding adhesives (superglues)

• Casting resin (moulage)

• Rigid & flexible foams

• In-situ foams (formed directly in the place where they’re needed)

• Coatings

• Varnishes

Properties & applications of phenolic resins

• produced since 1907

• Temperature resistance

• Surface hardness

• Cheap

• laminates (stratifiés, plusieurs couches)

• Castings (moulages)