What is added to Type-2 PVC to give it a higher impact resistance?

• A. Glass fiber
• B. Carbon black
• C. Rubber
• D. Silicon oil

Answer: (C)

Increasing impact resistance in PVC is achieved by adding an elastomeric rubbery modifier. In Type-2 PVC, tiny rubber particles are dispersed within the rigid PVC matrix. When a sudden impact happens, these rubbery inclusions deform and absorb energy, and cracks that start in the hard PVC are slowed or halted as they propagate around or through the rubber particles. This creates a two-phase structure where the stiff PVC provides strength while the rubber phase provides toughness, resulting in higher impact resistance and better performance at tougher temperatures. The other options don’t deliver this toughening effect: glass fiber raises stiffness and can make things more brittle, carbon black is mainly a pigment/stabilizer, and silicon oil mainly affects processing or lubrication rather than improving crack resistance.