Antioxidants and Heat Stabilizers

Acid-treated clay catalyst Engelhard F-24 was found to be very effective for the alkylation of diphenylamine (DPA) with an olefin such as a-methyl styrene (AMS) to obtain a mixture of mono and dialkylated diphenylamines (Chitnis and Sharma, 1995). For example, alkylation of DPA with AMS produced a mixture of 4-(a,a-dimethyl benzyl) diphenylamine, i.e. monocumyl-diphenylamine (MCDPA) and 4,4 -bis(a,a-dimethylbenzyl) diphenylamine, i.e. dicumyldiphenylamine (DCDPA) (Eqn.(l 1)). The dialkylated diphenylamine, i.e. DCDPA, is indu.strially important as an antioxidant and heat stabilizer. DCDPA is reported to be an ideal antioxidant for many materials like polyethylene, polypropylene, polyether polyol, polyacetals, nylon 6, synthetic lubricants, hot melt adhesives, etc. 

The effects of release additives on bulk properties must also be carefully considered, particularly with integral additives to plastics. For example, partial solubility usually confers some plasticizing effect. This may improve impact strength but could reduce the heat distortion temperature. Some release additives such as metallic soaps have secondary antioxidant and heat-stabilizer benefits. Such effects are exploited in multipurpose formulations. 

The isosorbide diester 167 acts as an excellent antioxidant and heat stabilizer for several polymers.261... 

Sulfur containing, high performance primary (phenolic) antioxidant and heat stabilizer used for the base stabilization of polyethylene wire and cable resins. 

Use Polymerization catalyst, antioxidant, and heat stabilizer for PVC (not approved by FDA for food containers), electrically conducting tin oxide coatings, alkaline-earth-metal phosphates in fluorescent light bulbs, intermediate for silicones. 

To the LC polyester composition additives can also be used in the form of antioxidants and heat stabilizers such as a hindered phenol, hydroquinones, phosphites etc. Another additives, also added as required, can be mentioned as, ultraviolet absorber (resorcinol, salicylate etc.), color protecting agent (phosphate, hypo-phosphite etc.), lubricant and mold lubricant (stearyl alcohol, stea-ramide etc.) [137]. 

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