Modification of properties of epoxy polymers by high hydrostatic pressure

Abstract

A study was made of the changes in density, thermal resistance and mechanical and dielectric properties of a number of epoxy polymers cured at high hydrostatic pressure. The possibility of controlling characteristics under pressure is shown. The most important is the change in the glass-transition temperature; the effect of pressure on the mechanical properties and thermal resistance is small.

Synthesis of tri‐aryl ether epoxy resin isomers and their cure with diamino diphenyl sulphone

“…The T g of the network was determined from the peak in the tan δ trace while E r was used to calculate the crosslink density of the network from rubber elasticity theory. [ 13,14 ]…”

“…Again, the integrals correspond well with the predicted structure. For the 13 C-NMR spectra, peaks between 40 and 60 ppm are the methylene (a) and methine (b) carbons of the oxirane rings, while 62 ppm corresponds to the methylene carbon (c) of the glycidyl amine group. The aryl carbon signals centered around 120 ppm are the methine quaternary carbons of the outer aryl rings adjacent to other carbon atoms, while the aryl carbon signals centered between 140 and 160 ppm are the methine quaternary carbons adjacent to ether or glycidyl amine groups.…”

“…The T g of the network was determined from the peak in the tan δ trace while E r was used to calculate the crosslink density of the network from rubber elasticity theory. [13,14] TMA was performed using a Mettler Toledo TMA/STDA840 to determine CTE (α) in the glassy (α glassy ) and rubbery (α rubbery ) regions. Cured resin cubes of dimensions about 3 mm 3 were directly placed between a 3 mm diameter ball-point probe and sample support (quartz glass).…”

Remarkable Thermal Conductivity of Epoxy Composites Filled with Boron Nitride and Cured under Pressure

“…One possibility is related to the effect of pressure on the cure process, and in particular on the density of the cured epoxy. Although there is one report that the density is independent of the cure pressure, in the range up to 1000 MPa [42], the majority of studies suggest that increasing the cure pressure results in a higher density of the cured epoxy [43][44][45][46]. Beloshenko and co-workers [43,44] investigated various epoxy resins and found that increasing pressure during cure results in a higher density of the cured epoxy, attributing this effect to the inhibition of voids and a reduction of the free volume.…”

“…Although there is one report that the density is independent of the cure pressure, in the range up to 1000 MPa [42], the majority of studies suggest that increasing the cure pressure results in a higher density of the cured epoxy [43][44][45][46]. Beloshenko and co-workers [43,44] investigated various epoxy resins and found that increasing pressure during cure results in a higher density of the cured epoxy, attributing this effect to the inhibition of voids and a reduction of the free volume. This latter aspect is equivalent to the effects of densification, discussed elsewhere [22], which requires not only that the cure be made under pressure but also that the pressure be maintained while the sample is cooled from the curing temperature.…”