With the increase of temperature, the macromolecular energy, activity, molecular gap, chemical medium penetration and dispersion, adsorption and addition, reaction speed and erosion are accelerated.
Sometimes the temperature is a little higher, but it will help to relax the internal stress, reduce the stress concentration, and the temperature change is too large and too frequent, which will cause thermal shock. The installation life is reduced or even damaged.
The destruction of plastics by heat and stress can also have synergistic effect. For example, wet nylon will become brittle after being used for two months at 70 ℃, while dry nylon will remain unchanged after being used for two years at the same temperature. This is because the former has oxidation reaction and hydrolysis reaction of main chain. This is the result of the effect of heat and water. Most plastics have low heat-resistant temperature. When the plastics are used in the medium at near critical temperature, it is necessary to pay attention to the damage of plastics caused by the triple synergistic effect of heat, stress and condition.
The so-called erosion is a kind of scene of destruction and transformation caused by the effect of substance and situation. Under the effect of chemical medium, the appearance and mechanical function of plastics degrade and destroy, which is called erosion or chemical aging of plastics. Chemical aging is one of the ways of plastic aging.