Trialkylated phenol, antioxidant

The data in Figure 2 for trialkylated phenol products are similar to those in Figure 1, with two important differences. The abrupt change in effectiveness of the trialkylated phenols occurs when R is Ci0H2i to C12H25. Although in the more severe tests these compounds are about as effective as the 2,6-dialkyl-p-cresols, in the least severe test they are considerably less effective. It is evident that 2,4,6-trioctadecylphenol is also a very potent antioxidant. 

All four types of phenols alkylated by a-olefins are effective antioxidants. However, the alkylated p-cresols are the most effective, followed closely by the 2,4,6-trialkylated phenols. The alkylated xylenols have a lower degree of effectiveness in polypropylene. Of the entire series, 2,6-dioctadecyl-p-cresol has the best over-all properties. It is one of the most effective non-discoloring antioxidants now known for polypropylene. It is especially useful under adverse conditions, such as high temperatures, or in thin films. 

Various product forms may occur during storage (typical for fatty acid derivatives) or production. DSC has been used for detection of polymorphism of butylated hydroxyanisole (BHA) [91]. Similarly, DSC has allowed to detect various product forms of the hindered phenolic antioxidant octade-cyl 3-(3, 5 -di-f-butyl-4 -hydroxyphenyl) propionate (Anox PP 18), which caused handling problems during production [92]. The DSC method for purity determination as used for curatives, such as 2,2 -benzothiazyldisulfide (MBTS) [93], and for sulfur and accelerators [79], is also applicable to other additives, such as antioxidants and antiozonants. DSC and TGA have been used to establish the oxidation and weight loss characteristics of commercially available triaryl, trialkyl and alkyl-aryl phosphate esters, which are widely used as plasticisers and flame retardants in the polymer industry [94]. 

The protection of polyether polyols against self-oxidation and thermo-oxidative degradation is realised by the addition, to the purified polyethers, of 2000-5000 ppm of antioxidants such as hindered phenols, substituted diphenylamines, phenothiazine, trialkyl phosphites and so on. 

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