Polyolefins ozonization

The low concentrations of ozone normally present in the atmosphere are sufficient to cause severe oxidation and cracking in polyolefins (2-13) and many other polymers such as polystyrene (6,11,12,14.15). poly(vinyl chloride) ( y, J 2,J 6) and rubbers (11,12,17-20). Where the ozone concentration is increased by air pollution, higher altitudes or the present of electrical machinery, the rate of degradation considerably increases.The prevention of such degradation represents a matter of considerable economic interest since it can greatly improve service life of polymers and plastics. An additional application of this research is to apprise the suitability of polymers for upper atmosphere application (Space Shutle flights) where a plentitude of ozone and atomic oxygen prevails. 

Daubendiek, R. L., and J. G. Calvert. The reaction of ozone with perfluorinated polyolefins. Environ. Lett. 6 253-272, 1974. 

Modification des polyolefines saturees par l ozone. Symposium fiber... 

The processes described in Table 2 present a peculiar interest in the working out of new materials as polyurethanes. These last polymers are very often based on macro diols coming from polyethers or polyesters, a-co functional polyolefins being relatively uncommon. Hence, Rhein and Ingham [139] prepared macrodiols by ozonization of polyisobutylene in CC14 at... 

Table 3 Summary of studies devoted to graft copolymers from ozonized polyolefins or chlorinated polymers...

Boutevin et al. [177-180] treated different types of wastes of polyolefins (more often low density polyethylene) with a mixture air/ozone. They focused their studies on the quantification of the formed oxygenated species based on colorimetric titration using stable radicals such as diphenylpicryl-hydrazyl. They investigated the influence of mineral compounds (iron oxide, for example) used as catalysts for oxidative reactions. The ozonized polymers have been used as binders for composites materials containing mineral materials (sand, stones, etc.). 

At last, we must mention studies developed by Robin [181-183] who added ozonized polyolefins to bituminous materials to obtain new binders... 

Kulik et al. [205] focused their studies on the identification of chemical species formed during the treatment of polyolefins such as polyethylene or polypropylene by gaseous ozone or ozone in aqueous medium. Experimental conditions have a great influence on the nature of the obtained species. For example, peroxidic functions, carboxylic acids, and ketones have been identified, aldehydes being absent of the surface of the materials. It must be noted here the instability of the peroxidic species formed during the treatment... 

The prime factors causing degradation of polymers are UV light and the heating effects of solar radiation. Additional relevant factors include ozone, atmospheric contaminants and induced radiation. It is the impurities present in the commercial polymers that initiate photochemical reactions because pure saturated polyolefins... 

The seven chapters of the third section examine the effects of hostile environments on bulk properties. The environments range from acids or pickling baths to water. The materials range from polyolefins to specialty block copolymers. The final chapter in this section contains recent findings about the effect of ozone on bulk properties. 

Ozone (Oj) plays a significant role in oxidation and degradation of several pglyg rg s h gs polyolefins, rubber, polystyrene and polyamides . Ozone may abstract hydrogen... 

Reactions of ozone with polyolefins at room temperature produce oxidized surface layers that act as jAiysical barriers to further attack. Bie layers are too thin (affect mechanical properties but the products are capable of initiating thermal and photooxidations. 

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