What are the differences in chemical reactivity between PVC and polypropylene?

PVC (polyvinyl chloride) and polypropylene are two widely used polymers with distinct chemical reactivity profiles. PVC exhibits higher resistance to acids, bases, and many organic solvents due to its polar C-Cl bonds, which provide strong intermolecular forces. However, PVC can degrade under UV exposure or high temperatures, releasing hydrochloric acid.

Polypropylene, on the other hand, is non-polar and highly resistant to most chemical solvents, including alcohols and detergents, but it's less resistant to oxidizing acids and chlorinated hydrocarbons. Its saturated hydrocarbon structure makes it more stable against UV and thermal degradation compared to PVC.

Key differences include:

1. PVC reacts with ketones and aromatic hydrocarbons, while polypropylene resists them

2. Polypropylene has better resistance to steam sterilization

3. PVC is more susceptible to plasticizer migration

4. Polypropylene maintains properties in wider pH ranges

These reactivity differences determine their applications - PVC for chemical storage tanks and polypropylene for medical devices and food containers.