Antioxidants and effect of environmental exposure

Many of the polymeric matrices will require some type of antioxidants to improve aging properties. The most common primary antioxidants are hindered phenols such as butylated hydroxytoluene (BHT). Typical low toxic antioxidants are reported in Tables 2.40-2.42. 

Primary antioxidants (usually hindered phenols) Thioester antioxidants (usually derivates of thiodipropionic acid) Phosphite antioxidants (usually derivates of aromatic phosphites) 

Dilaryl thiodipropionate (DLTDP) Distearyl thiodipropionate (DSTDP) 

Distearyl pentaerythritol diphosphite Tris (nonylphenyl) phosphite 

The toxicity of commonly used polymer stabilizers and additives are classified in the following table. 

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In addition to needing an appropriate interphase design in order to achieve the desired mechanical properties, the long-term endurance of molded parts depends on the prudent choice of stabilizer packages (antioxidants, UV stabilizers, metal deactivators, and so forth) to withstand elevated ambient temperatures and/ or exposure to the combined effects of moisture and sunlight. Chapter 4 addresses the effects of environmental conditions as well as the need to attain effective stabilizer packages for flame-retardant polypropylene in order to enhance weath-erability and prolonged service lifetime of a molded part. 

Hassoun, E.A., Vodhanel, J., Holden, B. Abushaban, A. (2006). The effects of ellagic acid and vitamin E succinate on antioxidant enzymes activities and glutathione levels in different brain regions of rats after subchronic exposure to TCDD. Journal of Toxicology and Environmental... 

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