Process thermooxidation

Figure 7.10 The sequence of a stage of initiation of process thermooxidation...

In so-called thermooxidative degradation, primary radicals are produced in the presence of oxygen due to the effects of heat, possibly coupled with mechanical stressing of the plastic. Certain substances like sterically inhibited phenols or amines can trap (scavenge) these radicals. For example, di-tert-butylphenols act as radical scavengers (antioxidants). The reaction scheme described below makes it clear that the oxidation inhibitor is consumed in the process. Thermooxidation can therefore be delayed until the radical scavenger is completely used up. 

The aim of this work was to study the effects of certain terpenphenols on the process thermooxidative dehydrochlorination hard and plasticized PVC, the study of antioxidant activity the terpenphenols in autocatalytic oxidation of the plasticizers. 

LARC-TPI is a linear thermoplastic PI which can be processed ia the imide form to produce large-area, void-free adhesive bonds. Mitsui Toatsu Chemicals, Inc., has obtained Hcense to produce this product commercially for appHcations such as adhesives, films, mol ding compounds, etc. These are thermooxidatively stable and show essentially no loss ia weight at 300°C ia air. Weight loss does not exceed 2—3% after isothermal aging ia air at 300°C for 550 h. 

Methods for recycling used plastic materials are reviewed. Emphasis is placed on the research projects into chemical recycling methods for used plastics at the Leuna location. These include development of a process for the thermaL thermooxidative pretreatment of used plastic materials, utilisation of pretreated used plastic materials in the visbreaker by gasification and by hydrogenation and the production of wax oxidates from pretreated used plastics. The results are discussed. 

Muradov, N., Rustamov, M., and Guseinova, A., Hydrogen production by thermooxidative processing of residual oil, Nuclear-Hydrogen Energy Technol. Ser., 3(19), 34,1984 (in Russian). 

Aromatic poly(benzothiazole)s are thermally and thermooxidatively stable and have outstanding chemical resistance and third-order nonlinear optical susceptibility. Aromatic poly(benzothiazole)s can be spun into highly-oriented ultrahigh strength and ultrahigh modulus fibers. However, this type of polymer is insoluble in most organic solvents. Therefore, hexafluoroisopropylidene units are introduced in the polymer backbone to obtain soluble or processable aromatic poly(benzothiazole)s. 

To improve the processability of PPQ, appropriate phenylquinox-aline oligomers were end-capped with acetylenic groups using 3-(3,4-diaminophenoxy)phenylacetylene (43) or 4-(3- and 4-ethynyl-phenoxy)benzil (44, 45) (Eq. 10). The processability was improved but at the sacrifice of the thermooxidative stability. In general, cured acetylene-terminated heterocyclic polymers are less stable in a thermooxidative environment than the parent linear polymer. 

Polyphenylquinoxalines (PPQ) are easier to make than the polyquinoxalines and offer superior solubility, processibility, and thermooxidative stability (65). The PPQs exhibit excellent high temperature adhesive, composite, and film properties. However, to increase the use temperature of PPQs, acetylene... 

Many commercial processes involving surface dyeing and printing (e.g., on film and containers) employ thermooxidation as a pretreatment step. Dyes adhere poorly to HDPE surfaces but their adhesion can be improved by thermooxidation of the surface layer by treatment with an open flame or 111 a strong electric field. 

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