ps, hydroxyl groups at the end, and so on.External or environmental factors are mainly sunlight, oxygen, ozone, heat, water, mechanical stress, high energy radiation, electricity, industrial gases (such as carbon dioxide, hydrogen sulfide, etc.), sea water, salt fog, mold, bacteria, insects, etc. The usual?aging tests mainly include light aging, humid heat aging, hot air aging, high and low temperature test, salt spray corrosion, ozone aging, thermal oxygen aging test, buried soil corrosion tes