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Thus, organic peroxides are useful as initiators for some types of polymerization, such as the acrylic, unsaturated polyester, and vinyl ester resins used in glass-reinforced plastics. MEKP and benzoyl peroxide are commonly used for this purpose. However, the same property also means that organic peroxides can explosively combust.
Since vinyl ester resins must be pre-accelerated with amine accelerator or cobalt, their processing time at room temperature is shorter than with epoxy-based prepregs. Catalysts (also called hardeners) include peroxides such as methyl ethyl ketone peroxide (MEKP), acetyl acetone peroxide (AAP) or cyclohexanone peroxide (CHP).
MEKP is a colorless oily liquid. It is widely used in vulcanization (crosslinking) of polymers. [3] It is derived from the reaction of methyl ethyl ketone and hydrogen peroxide under acidic conditions. Several products result from this reaction including a cyclic dimer. [4] The linear dimer, the topic of this article, is the most prevalent.
Vinyl ester resin is extensively used to manufacture FRP tanks and vessels as per BS4994. For laminating process, vinyl ester is usually initiated with methyl ethyl ketone peroxide. It has greater strength and mechanical properties than polyester and less than epoxy resin. Renewable precursors to vinyl ester resins have been developed. [2]
The most common resin system used for the spray-up process is general purpose or DCDP polyester; isophthalic polyesters and vinyl ester resins are also sometimes used. Fast-reacting resins with a pot life of 30 to 40 minutes are typical. The resin often contains a significant amount of filler.
Vinyl ester resins made by addition reactions between an epoxy resin with acrylic acid derivatives, when diluted/dissolved in a vinyl functional monomer such as styrene, polymerise. The resulting thermosets are notable for their high adhesion, heat resistance and corrosion resistance.
Similarly, DGEBA reacts with acrylic acid to give vinyl ester resins. The reaction results in opening of the epoxide ring, generating unsaturated esters at each terminus of the molecule. Such materials are often diluted with styrene and converted to resin. Epoxy resins are thermosetting polymers, which are crosslinked using hardeners (curing ...
In polymer chemistry, polymerisation inhibitors (US: polymerization inhibitors) are chemical compounds added to monomers to prevent their self-polymerisation. Unsaturated monomers such as acrylates, vinyl chloride, butadiene and styrene require inhibitors for both processing and safe transport and storage.