PVC is a white powder with an amorphous structure and low branching
degree. It begins to decompose at a glass transition temperature of
*7~*0 ℃ and around **0 ℃. However, it has poor stability to light
and heat. When exposed to sunlight for a long time or above **0 ℃,
it decomposes to produce hydrogen chloride, which further catalyzes
decomposition and causes discoloration. Its physical and mechanical
properties also rapidly decrease. In practical applications,
stabilizers must be added to improve stability to heat and light.
