Curing by oxidation

The spun polysilane fibers are cured by oxidation in air at a temperature of 160 - 200°C. The curing process is necessary to permit the conversion of the green fiber to the ceramic fiber without softening during pyrolysis. It is presumed that the oxidation mechanism results in the formation of Si-O-C and Si-O-Si bonds by the reaction of Si-CH3 and Si-Si in the polysilane. 

Alkyd resins have applications as surface coating materials, and they can be mixed with unsaturated fatty acids or triglycerides of unsaturated acids having the capability to cure by oxidation. 

Uses Drier accelerator and stabilizer used in combination with manganese and/or cobalt in coating systems that cure by oxidative polymerization... 

Oxygen in Si-C-N-0 fibers is introduced in significant amounts when the melt spun precursor fibers are cured by oxidation, but oxygen is present only in trace amounts in Si-C-N fibers where curing of green fibers is achieved under anaerobic conditions. 

Figure 1. XRD-pattems of Si-C-N-0 fibers produced from PCSZ precursor cured by oxidation and pyrolyzed at...

Ube Industries has announced the development of a near-stoichiometric fibre made from a polycarbosilane cross-linked by an aluminium compound. The precursor fibre is cured by oxidation, pyrolysed in two steps first to allow the outgassing of CO and then sintered at a temperature up to around 1800°C. 

Thiol-terminated polymers are by far the most important type of polysulphide polymer manufactured. They may be readily cured by oxidative coupling of the thiol terminals ... 

Despite their name, epoxy esters are not really epoxies. Applanan, in fact, writes that epoxy esters are best described as an epoxy-modified alkyd [20]. They are made by nfixing an epoxy resin with either an oil (drying or vegetable) or a drying oil acid. The epoxy resin does not crosslink in the manner of conventional epoxies. Instead, the resin and oil or drying oil acid are subjected to high tanperature, 240°C to 260°C and an inert atmosphere to induce an esterification reaction. The result is a binder that cures by oxidation and can therefore be formulated into one-component paints. 

The LP polymers are usually cured by oxidation using higher-valence-state metal oxides or peroxides. (Dichromate and manganese dioxide cure systems are used in aircraft systems.) Oxides such as lead dioxide react with the mercaptan groups to form higher polymers as well as crosslinks through disulfide bridges. Cure is accelerated by sulfur and water, and retarded by stearic acid. 

Urethane oils and alkyds, on the other hand, are cured by oxidation in the same way as alkyds and oils, and the urethanes require driers or drying catalysts. However, cure occurs more quickly, and the resultant film is very hard and abrasion resistant, vdth greatly improved resistance to water and alkalies color retention is somewhat poorer. Because of their advantages, urethane oils and alkyds are widely used in premium floor finishes and for exterior clear finishes on wood. The hardness of the film tends to impair intercoat adhesion. 

To prepare the lacquer sap for the actual coating material, the sap is stirred in an open vessel at room temperature for about 1.5 hours, and then at a temperature increasing from 20 to 45 C where it is kept for 2 to 4 hours until the water content is reduced to 2-4% ("sugurome" process). The temperature cycle must be carefully controlled to retain the activity of the enzymes. At this point the sap has become clear, has changed in color and has increased in viscosity. This liquid, known as "raw lacquer", consists of urushiol and oligo-urushiol, small amounts of water and other components and is ready for application. Urushiol is cured by oxidation of the... 

An endless variety of colors and pigments exists. In paints, the film formed after evaporation of the solvent is cured by oxidative polymerization of the double bond in case of alkyd resins and drying oils. Varnishes are unpigmented paints. 

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