Thermal degradation/oxidation

Levi, Literature Survey on Thermal Degradation, Thermal Oxidation, and Thermal Analysis of High Polymers , PLASTEC Note 7 (1963)... 

Literature Survey on Thermal Degradation, Thermal Oxidation, and Thermal Analysis of High Polymers. Ill , PLASTEC Note 20 (1969) 29) N T. Baldanza, Literature Search Injection Molding Processing Parameters , PLASTEC Note 21 (1969) 30) A.H. Landrock, Polyurethane... 

As in purely thermal degradation, thermal oxidation of rubber is accompanied by formation of low-molecular-weight products in yields too high to be accounted for by random attack on the... 

If exposed to sunlight, an ultraviolet absorber or screening agent should be in the formulation to protect it from degradation. Thermal oxidative degradation, particularly where copper is involved will pose a problem. 

Keywords antioxidants, thermooxidative degradation, thermal oxidation, chain breaking antioxidants, preventive antioxidants, peroxide decomposers, vitamin E, phosphites, phosphonites, hindered phenols, sulfur-containing compounds, synergism, migration, toxicity. 

Heat (thermal degradation, thermal oxidative degradation)... 

Finishing. AH acetal resins contain various stabilizers introduced by the suppHer in a finishing extmsion (compounding) step. The particular stabilizers used and the exact method of their incorporation are generally not revealed. Thermal oxidative and photooxidative stabilizers have already been mentioned. These must be carefully chosen and tested so that they do not aggravate more degradation (eg, by acidolysis) than they mitigate. 

Methylphenol is converted to 6-/ f2 -butyl-2-methylphenol [2219-82-1] by alkylation with isobutylene under aluminum catalysis. A number of phenoHc anti-oxidants used to stabilize mbber and plastics against thermal oxidative degradation are based on this compound. The condensation of 6-/ f2 -butyl-2-methylphenol with formaldehyde yields 4,4 -methylenebis(2-methyl-6-/ f2 butylphenol) [96-65-17, reaction with sulfur dichloride yields 4,4 -thiobis(2-methyl-6-/ f2 butylphenol) [96-66-2] and reaction with methyl acrylate under base catalysis yields the corresponding hydrocinnamate. Transesterification of the hydrocinnamate with triethylene glycol yields triethylene glycol-bis[3-(3-/ f2 -butyl-5-methyl-4-hydroxyphenyl)propionate] [36443-68-2] (39). 2-Methylphenol is also a component of cresyHc acids, blends of phenol, cresols, and xylenols. CresyHc acids are used as solvents in a number of coating appHcations (see Table 3). 

Stabilizers. Antioxidants provide protection against UV light and thermal oxidative degradation. Hindered phenols are the most common nonstaining antioxidants. For SBR latices, two additional type of stabilizers must be used. 

There appear to be conflicting reports regarding the degradation of urethanes. For example, some urethanes are reported to have relatively poor hydrolysis resistance and good biodegradability [77], while other urethanes are reported to be so hydrolytically stable that they have been successfully used as an artificial heart [78]. Both reports are correct. It will be shown that the thermal, oxidative, and hydrolytic stability of urethanes can be controlled, to some degree, by the choice of raw materials used to make the urethane. 

CL must be very carefully purified to exclude small concentrations of (1) ferric ions which would catalyze die thermal oxidative degradation of polycaprolactam and (2) aldehydes and ketones which would markedly increase oxidizability of CL. The impurities in CL may retard die rate of CL polymerization as well as having a harmful effect on die properties of die polymer fiber. In die vacuum depolymerization of nylon-6, a catalyst must be used because in die absence of a catalyst by-products such as cyclic olefins and nitrides may form, which affects the quality of die CL obtained.1... 

Phenolic degradation, thermal and thermo-oxidative, 418-425 Phenolic-epoxy networks, 413 Phenolic monomers, second-order reaction rate constants of formaldehyde with, 403... 

Combustion in a thermal oxidizer is the only practical way to deal with many waste streams. This is particularly true of solid and concentrated waste and toxic wastes such as those containing halogenated hydrocarbons, pesticides, herbicides, and so on. Many of the toxic substances encountered resist biological degradation and persist in the natural environment for a long period. Unless they are in dilute aqueous solution, the most effective treatment is usually thermal oxidation. 

The temperature resistance of the polysiloxane on the samples was tested by stepwise heating up to 500°C. Whereas the pure hydrolysis product undergoes a complete thermal degradation via oxidative conversion of the CH3-Si groups into HO-Si groups, the polysiloxane persists on the silica sample. This stabilization effect most likely results from the covalent attachment of the methyl-polysiloxane. 

Imaging chemiluminescence technique. Chemiluminescence analysis is suitable for studying the early stages of the thermal oxidation of rubbers. A weak emission of light formed by chemical reactions appears during the oxidative degradation of hydrocarbons. This technique can be used to depth profile the oxidation of rubbers. MR... 

These results are quite different from others which have been reported in the literature concerning the high temperature (>600° C) thermal and thermal oxidative degradation of DBDPO, in which >90% degradation was reported (28). We confirmed that temperature was the principal cause for these different observations, by reproducing the 600° C isothermal pyrolysis of DBDPO in which less than 10% unreactive DBDPO was recovered. 

W. Zhao, T. Cao, and J.M. White, On the origin of green emission in polyfluorene polymers the roles of thermal oxidation degradation and crosslinking, Adv. Fund. Mater., 14 783-790, 2004. 

The comparison of physical and chemical properties of Parylene-N and Parylene-F is shown in Table 18.4. Parylene-N is considerably less stable in air than in nitrogen as a result of oxidative degradation. However, the similarity between its behavior in air and in nitrogen suggests that Parylene-F has very good thermal oxidative stability, which is most likely the result of the high stability of the C—F bond, and provides evidence that oxidative attack starts at the benzylic C—H bonds in Parylene-N.15... 

The behaviour of chain-length distribution is non-characteristic during thermal-oxidative degradation of isotropic PP films the degradation shifts towards decrease in molecular mass, while during oxidation in deformed films it shifts towards increase in molecular mass. It means that with oxidation in isotropic samples in the induction period the destruction of molecules prevails. On the other hand, with oxidation in deformed samples attachement and cross-linking dominate. 

Reaction 9 Thermal Oxidative Degradation - Hydroperoxide Formation [105]... 

In general, the degradation of PET is characterized by a loss in molecular weight, a loss in weight in the case of thermal and thermal oxidative degradation, and an increase in the carboxyl end groups. This is usually accompanied by the material first turning yellow, then brown and finally black [17]. 

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