Polyester Resin is a thermosetting plastic used for which purpose?

• A. Casting or making fiberglass
• B. Electrical wiring insulation
• C. Textile coatings
• D. Food packaging

Answer: (A)

Polyester resin is a thermosetting resin that, when cured, forms a rigid, heat- and chemical-resistant network. This makes it ideal as a casting medium and as the matrix in fiberglass composites. In fiberglass, the resin binds glass fibers together, creating a strong, lightweight material used for things like boat hulls and automotive parts. The other options aren’t typical uses: electrical insulation needs materials with reliable dielectric strength and stability under electrical stress, which aren’t the main strengths of cured polyester resin; coating textiles requires flexibility, which a cured polyester resin does not provide; and food packaging demands food-grade materials with specific safety and barrier properties, which polyester resin in this form isn’t typically chosen for. So casting or making fiberglass best matches how polyester resin is used.