Organic peroxides can be decomposed into free radicals and are therefore used primarily as initiators in the polymerization of various monomers. We use organic compounds with different properties depending on the production conditions of the polymerization reaction.
An organic compound containing -O-O-peroxy functional group formed by replacing hydrogen atoms in hydrogen peroxide with an Organic Peroxides organic group such as an alkyl group, an acyl group, an aromatic group or the like. Characterized by heating more than a certain temperature will decompose to produce oxygen free radicals, unstable, easy to break down. Chemical production of organic peroxides is mainly used for synthetic resin polymerization initiator, catalyst. In the field of polymer materials, it can be used as a radical polymerization initiator, graft reaction initiator, rubber and plastic cross-linking agent, unsaturated polyester curing agent and spinning grade polypropylene in the preparation of molecular weight and Molecular weight distribution regulator. Environmental pollution in the air under the action of light through the free radical reaction can produce peroxy nitrates compounds, photochemical oxidants in one of the species. On the skin, eyes, Organic Peroxides mucous membrane has a strong irritant, is an important pollutant in the atmosphere. Such substances are flammable and explosive dangerous goods, the use should pay attention to safety. Generally, the active oxygen content, activation energy, half-life and decomposition temperature were used as the basis of selection.
Organic peroxide chemical properties
The structural characterization of the peroxy functional groups in organic peroxides determines that the peroxide has the following chemical properties:
(1) has a strong oxidation.
(2) with natural decomposition properties, above 40 ℃, most of the peroxide active oxygen decreased.
(3) acid, alkaline substances can promote decomposition. Strong acids and alkali metals, alkaline earth metal hydroxides (solid or high concentration of aqueous solution) can cause intense decomposition.
(4) iron, cobalt, manganese organic peroxides and redox system compounds significantly promote decomposition.
(5) Strongly reducing amines and other reducing agents significantly promote decomposition.
(6) iron, lead and copper alloy can promote its decomposition.
(7) rubber can promote its decomposition.
(8) friction, shock or shock storage containers caused by local temperature rise, can promote decomposition.
Organic peroxide classification
The main varieties of organic peroxides are hydroperoxide (ROOH), dialkyl peroxides (ROOR '), diacyl peroxides (RCOOOOCR'), peroxyesters (RCOOOR '), peroxycarbonates ROCOOOOCOR ') and ketone peroxides [R2C (OOH) 2], which each have different application characteristics. For example, benzoyl peroxide BPO is usually used as a radical polymerization initiator and a Organic Peroxides curing agent for unsaturated polyesters; diethoxylated benzene DCP can be used as a crosslinking agent and a melt grafting initiator. Generally, the active oxygen content, activation energy, half-life and decomposition temperature were used as the basis of selection.
Oxidation of benzoic acid is the first and commonly used organic peroxide, as a granular solid, stable at ambient temperature. To improve safety, benzoic acid can add 22% or 30% by weight of water to a wet product to reduce flammability Organic Peroxides and vibration sensitivity. In addition there is a concentration of 25% to 50% of the oxidized benzoic acid paste formula.
Peroxidation of benzoic acid can be used in vulcanized polyesters over a wide temperature range. It can be activated by tertiary amines at room temperature and used in vulcanized filled polyester composites over a temperature range of 250 to 300 ° F. In the suspension polymerization of styrene, benzoic acid peroxide can be used as a good initiator.
Methyl ethyl ketone peroxide (MEKP) is widely used in the vulcanization of unsaturated polyester resins, the most common product form by the reaction of ketones with hydrogen peroxide, containing peroxide and hydroperoxide mixture. Because the pure ketone peroxide is sensitive to vibration and friction, the product is sold in dilute form only, and the active oxygen content is usually not more than 9% in the plasticizer solution.