Лако-красочные материалы — производство

The photostability of most hydrocarbon polymers is generally not a function of their tendency to absorb light but rather of their propensity toward oxidation (free-radical formation). Although it is well known that the inherent UV stability of an unsaturated polymer is inferior to that of a saturated analog, this effect cannot be attributed to an increase in light absorption by the unsaturated system. For example, the UV spectra of a styrene-butadiene-styrene (SBS) block copolymer compared to the saturated styrene — ethylenebutylene-styrene (SEBS) analog shows no significant absorption in the important 300 to 400 nm UV range for sunlight. Thus for many polymers the relative UV stability correlates well with the thermal stability. Obviously, this may not hold where polymer photolysis becomes important.