Working of Organic Peroxides
Mechanism of action
Unsaturated polyester resins (or UP resin) refer to a large variety of products all containing reactive double bonds in the polymeric chain. The presence of double bonds provide the product with the ability to crosslink in the presence of a monomer, also acting as a diluent, via a free-radical mechanism.
The reactivity, the viscosity and the final properties of UP resins can be adjusted by:
- chemical composition (aliphatic, aromatic, number of double bonds)
- resin molecular weight
- Nature and concentration of the crosslinking monomer (containing at least one double bond)
Mechanism of action
Unsaturated polyester resins (or UP resin) refer to a large variety of products all containing reactive double bonds in the polymeric chain. The presence of double bonds provide the product with the ability to crosslink in the presence of a monomer, also acting as a diluent, via a free-radical mechanism.
The reactivity, the viscosity and the final properties of UP resins can be adjusted by:
- chemical composition (aliphatic, aromatic, number of double bonds)
- resin molecular weight
- Nature and concentration of the crosslinking monomer (containing at least one double bond)
The crosslinking monomer
In most cases the crosslinking monomer is Styrene introduced at concentrations between 25 and 45 wt%, but other monomers can also be used.
Curing catalyst
To initiate the curing reaction a source of radicals is needed. In most of the cases organic peroxides are used.
- The first step is the decomposition of the peroxide.
- The second step is chain propagation reaction via styryl radical formation capable to react with a double bond
For cold curing, initiators such as amines or metallic salts are also introduced.
Inhibitors
In order to prevent premature curing and to extend pot-life, inhibitors are also introduced into the system. Inhibitors are free radical scavengers like Hydroquinone derivatives, terbutylcatechol, cresol derivatives
Popular Products
Plasperox BP-75
Plasperox K-8
Plasperox TBH-80
Plasperox TBPO
Plasperox K-9
Awards
President's Gold Medal
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M/s. Plasti Pigments Pvt. Ltd.
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