Epoxy mixtures

The end result of the surface chemistry of the reinforcement, the adsorbed material, topographical features, and epoxy composition is in the formation of the polymerized epoxy on the reinforcement surface. In order for this to happen, the fluid epoxy mixture must be brought into contact with the reinforcement surface, wetting must take place and energy added to aid the polymerization. The wetting of the reinforcement by the epoxy is a necessary criterion for optimum mechanical properties. 

FIGU RE 24.2 TGA curves in air of (a) glass, carbon, and aramid fibers and (b) fiber/epoxy mixtures in 1 1 mass ratio. (From Kandola, B.K. et al., Recent advances of flame retardancy of polymeric materials, in Proceedings of the 17th Conference, Lewin, M. (Ed.), BCC, Stamford, CT, 2006. With permission.)... 

However, several inherent drawbacks limit the utility of aryldiazonium salts as photoinitiators in a number of practical applications for epoxy curing. Nitrogen evolution during photolysis of the initiator causes bubbles and pinholes in coatings. Other problems arise from the poor thermal stability of aryldiazonium compounds and from their inherent sensitivity to moisture. The addition of stabilizing additives such as nitriles amides sulfoxides and poly(vinylpyrrolidone) has proven effective in extending the solution stability of aryldiazonium salt/epoxy mixtures. 

Later, McPherson (39) demonstrated that the Inclusion of a CTBN/liquid epoxy adduct enhanced both the flexibility and adhesion of a dimer acid flexibllized epoxy/brominated epoxy mixture when cured with a combination of chlorendic and nadic-methyl anhydrides. With an epoxy-glass laminate as substrate, such mixtures were coated at 0.5-2.0 mils thickness, cured, sensitized and copper plated (1.5 mils) by an electroless process. 90 peel testing (2 inches/mln. rate, 25 C) gave 14.0 pli peel force where 5.0 pli is considered normal. 

Schroeder. J., Madsen, P., and Foister, R., Structure-property relationships for a series of crosslinked aromatic/aliphatic epoxy mixtures. Polymer. 2d. May. 929-940 (1987). 

OOMar Martinez, L, Martin, M. D., Eceiza, A., Oyanguren, P., Mondragon, I. Phase separation in poly-sulfone-modified epoxy mixtures Relationships between curing conditions, morphology and ultimate behavior. Polymer 41 (2000) 1027-1035. 

FrOlich et al. [ 140] investigated a system in which DGEBA was mixed with hydroxy-terminated poly(propylene oxide-block-ethylene oxide) as the rubber, with the nanoclay being a synthetic fluorohectorite treated with bis (2-hydroxyethyl) methyl tallow alkylammonium ions. The clay was first blended with rubber, before being dispersed into the reactive epoxy mixture. Modification of the rubber allowed variation in miscibility and differing morphologies and properties. If the rubber was miscible, the intercalated clay led to improved toughness. If the rubber is sufficiently modified, such as with... 

The epoxy prepolymer and the curing agent were mixed together prior to use, then the epoxy mixture (13 g) was poured into moulds (inside dimension 96 mmx 16 mmx8 mm), which were irradiated in a microwave applicator with TEqi propagation mode. The sample temperature was measured continuously by means of an infrared pyrometer that gave the surface temperature and fiber-optic thermometer that recorded the bulk temperature. Samples cured by both thermal... 

The various molecular weight polyamides show different degrees of compatibility with epoxies. To ensure optimum properties the polyamide/epoxy mixture must be allowed to react partially before being used. This partial reaction assures compatibility and is known as the induction period. Because polyamides have a long pot life, the induction time does not significantly shorten the usable time of the system. 

The original GO suspension was diluted to 1 mg/mL using ethanol. The mixtures were ultrasonicated in a bath for 30 min. The prepared GO suspension was mixed with epoxy resin under magnetic stirring. The epoxy mixture was then stirred at 100 °C to remove the solvents. After complete solvent removal, the epoxy mixture was allowed to cool down to room temperature. Then the epoxy mixture was placed in a vacuum chamber for approximately 10 min to remove any air bubbles. 

Peng, M., Li, D., Chen, Y, and Zheng, Q. (2007) Effect of an organoday on the reaction-induced phase-separation kinetics and morphology of a poly(ether imide)/epoxy mixture. Journal of Applied Polymer Science, 104,1205-1214. 

---