Polyolefins thiodipropionate

When used alone at low temperatures, diaLkyl thiodipropionates are rather weak antioxidants. However, synergistic mixtures with hindered phenols are highly effective at elevated temperatures and are used extensively to stabilize polyolefins, ABS, impact polystyrene (IPS), and other plastics. 

It is an important fact, that there is an explicit synergistic effect observed by combining primary and secondary antioxidants. A well known example of such synergistic mixtures is the use of thiodipropionates together with sterically hindered phenols for long-term stabilization of polyolefins. Of course, the different polymers and different applications require laborious optimization of each case. 

Materials that are not eflfective inhibitors when used alone may nevertheless be able to function as synergists by reacting with an oxidized form of an antioxidant to regenerate it and thus prolong its effectiveness. For example, carbon black forms an effective combination with thiols, disulfides, and elemental sulfur, even though these substances may be almost completely ineffective alone under comparable conditions. Synergistic combinations from a variety of chain terminators and sulfur compounds have been reported. A widely used combination of stabilizers for polyolefins is 2,6-di-ferf-butyl-4-methylphenol (BHT) (Figure 1.41a) with dilauryl thiodipropionate (DLTDP) ... 

Thiodipropionic acid antioxidant, food packaging polyolefins Triisopropanolamine antioxidant, food-contact... 

Phenol, 4,4 -thiobis 2-(1,1-dimethylethyl) phosphite Poly (1,4-cyclohexylenedimethylene 3,3 -thiodipropionate terminated with 1-octadecanol 2,2 -Thiobis-(6-t-butyl-4-methyl phenol) antioxidant, polyolefins Bis [3,3-bis (4-hydroxy-3-t-butylphenyl) butanoic acid], glycol 1,2-Bis (3,5-di-t-butyl-4-hydroxyhydrocinnamoyl) hydrazine 2,2-Bis (4-2-(3,5-di-t-butyl-4-... 

Sedlar and co-workers [27] has described a gas chromatographic procedure, outlined below, for the determination of dilauryl p, P thiodipropionate antioxidant and its primary oxidation products in polyolefins, ethylene-vinyl acetate co-polymers, acrylonitrile-butadiene-styrene resins and high impact polystyrene. These workers examined the conditions under which di-lauryl-thiodipropionate and its oxidation products are hydrolysed, by 5 N methanolic potassium hydroxide at 80 °C, quantitatively to lauryl alcohol, thus making gas chromatographic determination possible. The method described next has the advantages of being rapid, accurate and simple. It has been applied successfully to the... 

SFE chromatography has also been used in the determination of erucamide and antioxidants in polyethylene (PE) [22], butylated hydroxyl toluene, Isonox 129 and Irganox 1010 in PE [23], and PP [23], antioxidants and UV stabilisers in food packages [24] and secondary antioxidants such as distearyl thiodipropionate and phosphonites in polyolefins [25],... 

PVC Polyolefins Dilauryl PP thiodipropionate Dilauryl sulfonyl PP dipropionate [324-334]... 

Like other forms of molecular spectroscopy, MS may be used as a fingerprint technique to identify the components of additive systems extracted from polymer compositions. The strengths of MS are high sensitivity and the ability to distinguish between closely related compounds of differing relative molecular mass, e.g., the various alkyl thiodipropionates used as synergistic stabilisers in polyolefins and the UV-absorbing benzotriazole derivatives. 

Thin-layer liquid chromatography has been employed for the determination of alkylated cresols and amine antioxidants [102, 103] in polybutadiene, phenolic antioxidants in PE [104-106] and PP [106], dilauryl and distearyl thiodipropionate antioxidants in polyolefins, ethylene-vinyl acetate copolymer, acrylonitrile-styrene terpolymer and PS, UV absorbers and organotin stabilisers in polyolefins [102], and accelerators such as guanidines, thiazoles, thiurans, sulfenamides, diethiocarbamides, and morpholine disulfides in unvulcanised rubber compounds. 

Polygard Is a cost effective secondary liguid phosphite antioxidant that functions as a peroxide decomposer and as a processing stabilizer. When used in conjunction with hindered phenolic and thiodipropionate antioxidemtS/ a synergism is seen. In addition to i roved antioxidant activity of these combinations, Polygard also inhibits discoloration of the polymer caused by some phenolic auitioxidants. Polymer applications include polyolefins, styrenics and a variety of thermoplastics. Product Features ... 

For additives extracted from polyolefins, usually with diethyl ether, the extract is refluxed with ethanol and the solution is decanted from the insoluble residual polymer. On cooling, additives such as dilauryl and distearyl thiodipropionate separate out and are identified by infrmed examination. A 30 ul volume of the ethanolic solution is then spotted on to a thin Kieselgel 60 TLC plate and eluted with a suitable solvent, usually 98.5 + 1.5 toluene-ethyl acetate. The eluted plate is dried and sprayed with colour-developing reagents and the spots are examined. If the spots are to be submitted to mass spectrometric examination, methanolic iodine is used as the colour-developing reagent as this does not over-complicate the mass spectrometry. 

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