Chemiluminescence from oxidation of polypropylene: Some comments on a kinetic approach

A new kind of antioxidant 4-[(3-(triethoxysilyl)propylimino)methyl]-2,6-di-tert-butylphenol consisting of an alkoxysilyl group and a 2,6-di-tert-butylphenol stabilizing moiety was synthesized and tested in isotactic poly(propylene). FT-IR, 1 H-NMR, 13 C-NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) were used for characterization of synthesized silane stabilizer. The derivative of 4-[(3-(triethoxysilyl)propylimino)methyl]-2,6-di-tert-butylphenol was also prepared by the condensation reaction using the sol-gel process. Stabilizing activity of the new silane stabilizer and its condensed form was verified by chemiluminiscence and thermogravimetry measurements in oxygen atmosphere and compared with conventional 2,6-di-tert-butyl-4-methylphenol as well as with the conventional stabilizing system based on the mixture of Irganox 1010/ Irgafos168 (weight ratio of 1:2).

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“…8. Chemiluminescence arises in self recombination of secondary peroxyl radicals according to Russel's mechanism [8][9][10][11][12] (Scheme 3).…”

Section: Chemiluminiscencementioning

confidence: 99%

Synthesis and characterization of the new silane‐based antioxidant containing 2,6‐di‐tert‐butylphenolic stabilizing moiety

Nedelčev

Krupa

Csomorová

et al. 2007

Polymers for Advanced Techs

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“…Although there were several attempts to discredit the kinetic approach (1,3,6),all what its opponents could come up with was rhetoric and misrepresentation of the facts. Not a single substantive argument has been produced.…”

Section: Kinetic Approachmentioning

confidence: 99%

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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“…In our papers [2][3][4][5][6] on degradation of cellulose we complement the above methods by the chemiluminescence method which is based on the measurement of extremely weak light emitted from the oxidized material. Similarly as with other polymers [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] the intensity of the light emission may be related to the mechanism of the reactions taking place on the polysaccharide surface via one of the following processes:…”

Section: Introductionmentioning

confidence: 99%