A dielectric, mechanical, rheological and electron microscopy study of cure and properties of a thermoplastic-modified epoxy resin

Abstract

Dielectric, mechanical, thermal, rheological, and electron microscopy measurements are reported on the effect of varying the proportion of a blended thermoplastic, poly (ether sulfone), on the cure and properties of an epoxy resin system, an aromatic diamine cured trifunctional aromatic epoxide. Data presented cover both changes in physical properties during cure and final properties of the cured matrix. The initial mixture, prepared by solution casting, is homogeneous, but phase separation occurs rapidly in the initial stages of curing. Dielectric, thermal, and rheological measurements obtained during the curing process are consistent with phase separation occurring within the resin. Analysis of the dielectric data obtained from fully cured materials demonstrates the existence of a relaxation process which can be ascribed to polarization of a conducting occluded phase. Correlation of these data with those obtained from electron micrographs indicates that the type of phase structure changes with thermoplastic content. A number of the mechanical properties are observed to change at about 20-25% (w/w) of incorporated thermoplastic, coincident with the occurrence of a cocontinuous phase. The effects of these changes in the morphology on the mechanical, dielectric, and thermal properties of this thermoplastic-modified thermoset are discussed.

Polyetherimide-modified epoxy networks: Influence of cure conditions on morphology and mechanical properties

“…The valduced. [22][23][24] The only published results defying this trend ues (U a /U t )Å (U a /U e /U a ) are given in Table VI as a function of PEI content. It appears that (U a / surprisingly concern tetrafunctional epoxy resins modified by the same PEI for which spectacular U t ) increases with the modifier concentration.…”

“…The opposite evolution is generally expected if the yielding phenothe only observation of fracture surfaces is not sufficient to attribute the failure to any particular mena is dominant. 6,22 To try to interprete our results, the strain recoveries of neat and modified mechanism. But on the basis of more comprehensive works in this field, 5,6,27,28 an explanation of systems were compared.…”

Toughness of syndiotactic polystyrene/epoxy polymer blends: microstructure and toughening mechanisms

“…An alternative approach to toughening epoxies for use with fibre-composites is based upon blending with a thermoplastic polymer that phase-separates upon curing of the resin [5][6][7][8][9][10][11]. The thermoplastic phase has a relatively good thermal stability and low water uptake compared to the rubbers described above.…”

“…The thermoplastics employed have typically been functionalized poly(ether sulfone) [6,[9][10][11], poly(ether imide) [7,[15][16], polyimide [17], polysulfone [18][19] and polyester [11], which are all amorphous polymers. Semi-crystalline thermoplastics have been used previously, but as preformed particles; and all processing was conducted below the melting point of the thermoplastic [20][21][22].…”

Thermoplastic toughening of epoxy resins: a critical review

“…MacKinnon et al [30,31] achieved good toughness enhancement for a TGAP/DDS system in two studies using a commercial PES (Victrex 5003P), which is also considered to have non-reactive endgroups. The latter study showed that the nonfunctionalized PES was found to toughen the epoxy system to a greater extent than reactively terminated PES's, admittedly the unreactive PES had a significantly higher molecular weight; but it does not take away the fact that excellent toughness enhancement was achieved.…”