Evaluation of Antioxidant Activity in Rubber by Differential Thermal Analysis

May, Walter R.; Bsharah, Lewis; Merrifield, D. Bruce

doi:10.1021/i360025a012

Cited by 17 publications

(7 citation statements)

References 6 publications

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“…As shown in Table I, the amine was the most effective antioxidant, followed by the phosphite and the phenol. The phosphite had a slight edge on the phenol in this application, which is the opposite of observations in rubber systems (May et al, 1968). This implies that interruption of the oxidation reaction by elimination of the peroxide is more important than reaction with the hydrocarbon free radical.…”

Section: Harmless Fragmentscontrasting

confidence: 57%

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Hydrocarbon Oxidation Reactions by High Pressure Differential Thermal Analysis

May¹,

Bsharah²

1971

Product R&D

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The oxidation of n-hexane, cyclohexane, benzene, toluene, xylene, and ASTM isooctane under oxygen at 500 psi was evaluated by a high pressure differential thermal analysis (DTA) technique. The work on isooctane was extended to define the effect of oxygen concentration and pressure on the oxidation reaction. The oxidation of isoctane was observed in the presence of a bisphenol, an amine, and a phosphite antioxidant. The effects of nine metals and their interactions with the antioxidants on the oxidation of isooctane were included. The high pressure DTA technique is a useful tool for

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Section: Harmless Fragmentscontrasting

confidence: 57%

“…However, he was limited to high-boiling compounds because of his restriction to ambient pressure. We have made several studies of the oxidation of rubber by a high-pressure DTA technique Bsharah, 1969, 1970;May et al, 1968). The application of this method to the study of the oxidation of low-boiling hydrocarbons was obvious.…”

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confidence: 99%

Hydrocarbon Oxidation Reactions by High Pressure Differential Thermal Analysis

May¹,

Bsharah²

1971

Product R&D

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“…(4), a plot of ln(r/Tp 2) against l/Tp yields a straight line, whose slope is -E/R. It was reported previously (8,9) that the thermal oxidative stability is directly related to the activation energy of oxidation; the higher the activation energy the more stable the material.…”

Section: Differential Scanning Calorimetry (Dsc)mentioning

confidence: 91%

Chemiluminescence in thermal oxidation of ABS

Parikh

Zlatkevich

1997

Angew. Makromol. Chem.

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SUMMARYTwo concepts in the chemiluminescence researchthe heterogeneous model and the kinetic approachare discussed. The analysis of published data obtained by a highly sensitive photon-counting system reveals the contradictory nature of the heterogeneous model and proves its inconsistency. On the other hand, the kinetic approach has been successfully applied to evaluation of thermal oxidation in a variety of systems, ABS compositions in particular. Emulsion grade ABS were found to be essentially less stable than ionic mass polymerization products. Among the antioxidants studied, Santonox R is clearly more efficient than Irganox 1076. In emulsion grades the superiority of Santonox R to Irganox 1076 is reflected primarily in larger induction period, while in ionic resin it is mostly due to smaller oxidation rate constant values. The introduction of W stabilizers by themselves has no influence on durability in either ionic or emulsion resins. Similarly to systems without W stabilizers, Santonox R is more efficient than Irganox 1076 in mixtures with UV stabilizers as well. The comparative study of various ABScoloring agent compositions by chemiluminescence and DSC reveals much greater sensitivity of the former. While DSC lek one make only a trivial conclusion that the introduction of an antioxidant improves stability, chemiluminescence shows the differences in durability as large as 3 to 4 times for the samples Dsc fails to distinguish. In addition, chemiluminescence furnishes a significant insight on the factors affecting stability. The DSC thermal oxidative stability data can be related to resistance to oxidation during processing, whereas the chemiluminescence resulk are expected to be usefd in predicting materials' lifetime at service temperatures. TWO CONCEPTS IN THE CHEMILUMXNESCENCE RESEARCH 2 1 The Heterogeneous ModelThis model proposed by Celina and George (1) postulates the presence in the material of highly reactive isolated zones. The induction period and the remaining oxidation process are considered separately and the former is defined as the time taken for the zones to spread beyond their initial volume. After the end of the induction period, oxidation is interpreted as a statistical accumulation of rapidly oxidizing centers, and the evidence for this is thought to be the eduction of the individual sigmoidal chemiluminescence curves obtained at various temperatures to a single master curve. The heterogeneous model was based on the following observations:

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“…May and co-workers studied the oxidation of rubber by DTA and high pressure DTA [4]. This work evaluated the nature of the atmosphere in the DTA cell in conjunction with the instrument's ability to resolve sample oxidation.…”

Section: Introductionmentioning

confidence: 99%