Epoxy resins copolymerisation

Another important use of BCl is as a Ftiedel-Crafts catalyst ia various polymerisation, alkylation, and acylation reactions, and ia other organic syntheses (see Friedel-Crafts reaction). Examples include conversion of cyclophosphasenes to polymers (81,82) polymerisation of olefins such as ethylene (75,83—88) graft polymerisation of vinyl chloride and isobutylene (89) stereospecific polymerisation of propylene (90) copolymerisation of isobutylene and styrene (91,92), and other unsaturated aromatics with maleic anhydride (93) polymerisation of norhornene (94), butadiene (95) preparation of electrically conducting epoxy resins (96), and polymers containing B and N (97) and selective demethylation of methoxy groups ortho to OH groups (98). 

Epoxidised allyl soyate resin (a mixture of epoxidised fatty acid esters) copolymerised with the base Shell Epon epoxy resin is used as matrix for glass fibre reinforced composite, which is prepared using a Durapul 6000 Labstar Pultrusion machine. The lubricating quality of soybean oil-based resin significantly reduces the pulling force which improves the structural performance characteristics of the composites. Curing is carried out in an oven at 80°C for one hour, followed by heating to 177 C for 1.5 h. 

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. 

Latices of PVAc, copolymers of vinyl acetate and acrylamide and copolymers of methyl methacrylate and butyl methacrylate were synthesised by free-radical polymerisation or copolymerisation using different ionic or non-ionic surfactants and protective colloids. The effects of the amount of surfactant, copolymer composition and quantity of monomers on the particle size of the latex were examined and the use of the latex obtained from the methyl methacrylate-butyl methacrylate copolymer as an ink on PP syringes and of the PVAc latex with various amounts of epoxy resin as an adhesive for wood evaluated. 7 refs. 

IPNs are found in many applications though this is not always recognised. For example conventional crosslinked polyester resins, where the polyester is unsaturated and crosslinks are formed by copolymerisation with styrene, is a material which falls within the definition of an interpenetrating polymer network. Experimental polymers for use as surface coatings have also been prepared from IPNs, such as epoxy-urethane-acrylic networks, and have been found to have promising properties. 

Prime coating is either a two-pack, zinc-rich epoxy primer with a DFT of ca. 30-40 pm, or a chromate-free, two-pack epoxy primer. Topcoats based on PVC copolymerisates, chlorinated rubber, silicone-reinforced epoxy esters, or alkyds were used for many years. Now, the standard European topcoat is based on acrylic resins with terminal epoxy groups that are cross-linked with amine adducts or aminoamide resins. 

Before vitrification, a heat capacity change as a result of chemical reaction, ACp,react, is noticcd. For the anhydride-cured epoxy and the polyester-styrene resin a minor, but reproducible, and almost linear decrease of Cp with conversion is observed. The former system is supposed to be an anionic chain-growth living polymerisation (without termination), the latter is a chain-growth copolymerisation with termination. 

Vinyl ether monomers, like DVE-3, proved to be very effective reactive diluents in UV-curable epoxy-based resins, not only to lower the formulation viscosity and make it suitable for spray or roller applications, but also to achieve a faster and more complete curing, as VE and epoxy monomers were shown to undergo copolymerisation by a cation-driven mechanism [50]. Moreover, the addition of vinyl ether may impart some flexibility to the UV-cured epoxide, thus improving its adhesion on flexible substrates. 

Thermosetting (crosslinking) acrylics normally require a crossUnker to be present. Their actual cure behaviour is dependent upon the pendant (side chain) functionality of the copolymerised co-monomers. Acrylamide will crosslink with itself, epoxy or amino resins, whilst amino or melamine crosslinkers will react with hydroxyl or acid groups. Isocyanates can react with hydroxyl groups at room temperature. To reduce the hazards of isocyanates and the inconvenience of two pack systems, blocked isocyanates can be used. At elevated temperatures used for stoving they can unblock generating an alcohol and an isocyanate which will react with any hydroxyl or acid groups on the acryUc resin. 

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