Epoxidised castor oil

Latent initiators that are activated photochemically or by heating, such as benzylpyrazinium salts, enable controlled polymerisations. In fact, the activity of pyrazinium salts can be controlled by electronic modifications of benzyl and pyrazine groups [5]. Epoxidised soybean and castor oils have been polymerised by cationic means in the presence of the latent initiator N-benzylpyrazininm hexaflnoroantimonate [6]. Cationic resins prepared from epoxidised castor oil display higher glass transition temperature (Tg) values and lower coefficients of thermal expansion than counterparts prepared from epoxidised soybean oil (ESO) because of increased intermolecnlar interactions in the former materials when compared with the latter polymer [6]. 

Both epoxidised oils have also been copolymerised with the diglycidyl ether of bisphenol A to give networks with better mechanical properties [7, 8]. For example, a copolymer containing 10 wt% of epoxidised castor oil prodnces an epoxy resin with better interfacial mechanical properties, and addition of a large amount of soft-segments resnlts in a decrease in the crosslink density and an increase in the tonghness of the final copolymer. 

Epoxidised soybean oil Epoxidised castor oil Diglycidyl ether of neopentyl glycol... 

The preparation of epoxy resins from a large number of vegetable oils such as sunflower, cotton-seed, linseed, vernonia, soybean, castor and Mesua ferrea has been reported. " However, most of these epoxy resins exhibit poor mechanical properties which limit their applications. Vegetable oil-based epoxy resins rather than epoxidised vegetable oils are also used as reactive diluents. These are low viscosity materials used in conjunction with industrial epoxy resins to reduce viscosity and to increase the molecular mass of the latter. As a reactive diluent can also act as a solvent for the resin system, it enables the production of high-solid and low VOC (volatile organic compound) coatings. 

The field is wide and the topics quite different in terms of relative experimental complexity and economy with respect to potential industrial applications. Synthetic processes for some of the monomers and polymers described in the various chapters appear to comply with the requirements associated with a viable scale-up. This is particularly the case if the precursors are already industrial commodities or readily available, as in the cases of the direct polymerisation of pristine oils, use of different derivatives of castor oil, or exploitation of epoxidised oils. Other systems, despite their high potential, appear to require further work at a more practical level to assess their feasibility and possible implementation. This will require the combined efforts of polymer chemists and process engineers, among other experts. 

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