Plastics react with moisture and oxygen in the air to deteriorate gradually. Besides, their deterioration is hastened by heat, acids, alkalis, ultraviolet light, or the like. To prevent such deterioration, additives are employed during fabrication. Typical additives are as follows:

Heat stabilizer: Prevents decomposition by heat.

Antioxidant: Prevents decomposition by oxygen in the air.

Ultraviolet light absorber: Prevents deterioration caused by ultraviolet rays.

Mildewproofing agent: Protects plastics from microorganisms such as bacteria and molds.

Regarding decompositionof plastics, studies are being conducted aggressively on exactly opposite topics of stabilization and natural decomposition, including:

Photolytic plastics: Plastics that are broken down when exposed to sunlight.

Biodegradable plastics: Plastics that are broken down by microorganisms in soil if buried.