Crosslinked polymers epoxides

The final resin product is obtained by reacting (curing or crosslinking) the above di-epoxide with acid anhydrides or polyamines. The curing agents (sometimes incorrectly called catalysts) react with the three-membered epoxide rings to produce a highly crosslinked polymer. 

To obtain a heat and water resistant crosslinked polymer, Cu naphthenate and an alcohol (e.g. benzyl alcohol) were added to BPA/DC as a catalyst epoxide resins (cf. Sect. 6) can be used as well [19]. The use of Zn acetate together with dicumyl peroxide was also mentioned [20],... 

An investigation of the thermal and thermooxidative stability of crosslinked polymers obtained from BPA/DC and BPA/DC compositions with BPA/ECH epoxide resin or epoxynovolak resin has demonstrated that the epoxy resin decreased the thermal stability of BPA/DC based non-modified polycyanurate [71]. The systems with epoxynovolak resin behave somehow better. 

P = 1) systems while the apparent activation energy markedly decreases in the same series AEapp for the linear polymer DGER-AN is close to the typical value for many polymers 57 59). The results testify that the fragment (segment) of the network which is responsible for a-transition is in average smaller than that of a linear polymer. The temperature range of the T transition for the networks is markedly narrower than that for linear polymers and epoxides prepared from industrial resins 13,19). This points to a narrower distribution of relaxation times in the considered networks as compared with other crosslinked polymers. 

The physical and mechanical properties of polyanhydrides can be altered by modification of the polymer structure with a minor change in the polymer composition. Several such modifications include the formation of polymer blends, branched and crosslinked polymers, partial hydrogenation and reaction with epoxides. 

The DCPDO-based crosslinked polymers and composites exhibit similar mechanical strength and heat resistance in comparison with those prepared from UP-612, UP-632 and THIDO (Table 27). The increase in functionality of the diglycidyl ether or ester modifiers by the epoxidation of the cyclohexene ring results in a simultaneous increase in both mechanical strength and heat resistance... 

Proposed mechanism of crosslinking for epoxidized natural rubber (ENR) and ethylene vinyl acetate (EVA) with HVA-2. (From Zurina, M., Ismail, H., Ratnam, C., The effect of HVA-2 on properties of irradiated epoxidized natural rubber (ENR-50), EVA, and ENR-50/EVA blend. Polymer Testing 2008,27, 480-490. With permission.)... 

Linseed oil presented another interesting opportunity for the production of bioplastics. The highly polyunsaturated nature of the oil allowed for a large number of reactive sites to be introduced onto the material for subsequent polymerization. As has previously been mentioned, this increased reactivity has been shown to limit the physical properties of the materials and as such there has been little commercial interest in taking these materials further. Epoxida-tion, acrylation and maleinization of linseed oil before polymerization produced a heavily crosslinked polymer [59]. A formulation for potential in infusion resins was developed with a mixture of epoxidized linseed oil and phthalic anhydride with the curing catalysed by 2-methylimidazole [60]. 

Recently/ the crosslinking reactions of tetrafiinctional epoxy resins with aromatic primary diamines was investigated. The crosslinked polymers were characterized by UV visible and fluo> rescence spectroscopies after gelation. The amount of tertiary amine fluorescence intensity of the spectra shows significant amounts of such amines in the finished products. The infrared spectra confirm the overall reaction of epoxides with amines, but also show that ether formation becomes significant only late in the cure. In addition, during the cure, especially in air, some oxidations and degradations occur. This results in color formation. 

Cai, G. Weber, W. P., Synthesis of Terminal Si-H Irregular Tetra-Branched Star Polysiloxanes. Pt-Catalyzed Hydrosilation with Unsaturated Epoxides. Polysiloxane Films by Photo-Acid Catalyzed Crosslinking. Polymer 2004,45, 2941-2948. 

Thermosets are based on crosslinked polymers. They harden permanently with the aid of catalysts and/or heat, and cannot be remelted without degrading their polymeric structure. The thermosetting family includes phenolics, epoxides, alkyds, polyurethanes, melamine, urea-formaldehyde and unsaturated polyesters. 

Curing by the reaction of epoxide with phenolic OH is usually done using a phenolic novolac. These are high-temperature cures and produce very highly crosslinked polymers due to the frequency of OH groups on the novolac. 

Cycloahphatic diamines react with dicarboxyUc acids or their chlorides, dianhydrides, diisocyanates and di- (or poly-)epoxides as comonomers to form high molecular weight polyamides, polyimides, polyureas, and epoxies. Polymer property dependence on diamine stmcture is greater in the linear amorphous thermoplastic polyamides and elastomeric polyureas than in the highly crosslinked thermo set epoxies (2—4). 

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