PEI-modified epoxy

The solvent-etched fracture surface of folly cured PEI modified epoxy with different composition is shown in Figure 3.8. For PEI content smaller than 10wt%, the PEI-rich phase is dispersed in a continuous epoxy-rich matrix [i.e., sea-island morphology is observed (a and b)]. Above 25 wt% PEI content, nodular structure was observed (e and f) where the epoxy-rich phase forms spherical nodules and the PEI rich phase forms the matrix. With PEI content between 15 wt% and 20 wt%, dual phase morphology, where sea-island morphology and epoxy nodular structure coexist, is present (c and d). Similar morphology was observed in PEI/BPACY blend [47],... 

Figure 3.8 Morphology of PEI modified epoxy with various compositions cured at 170°C, PEI = (a) 5 wt% (b) 10wt% (c) 15wt% (d) 20wt% (e) 25wt% (f) 50wt%...

Table 3.2 Domain Size and Volume Fraction of Dispersed Phase for PEI Modified Epoxy Cured at Different Precure Temperature... 

Solution blending (39) has been employed for preparing a polyetherimide (PEI) modified epoxy resin, for which DGEBA was mixed with the PEI and methylenedianiline curing agent in dichloromethane solvent When films were cast fiom the solvent and cured at various reaction times and temperatures, it was found that the mixture had a single which was measured by DSC. increased with increased curing temperature for both the neat and the modified resins, and decreased... 

The formation of a dual-phase morphology in PEI-epoxy IPNs is explained in the following way [90,171]. Two cases were discussed. First, when phase separation is induced by the curing reaction, PEI-modified epoxy shows bimodal UCST behavior (Fig. 30). At composition (p (volume fraction of component 1) phase separation starts at conversion x when the curing temperature is Ti. Because of the spinodal mechanism of decomposition and due to the lower viscosity of the medium, the system will have macroscale phase separation and domains with volume fraction cp[ and. As the reaction proceeds and the conversion X2 is reached, an abrupt change in the equilibrium composition of the PEI-rich phase occurs from cp l to (p " in a very short time. This abrupt change is similar to the effect of the two-... 

The phase separation behavior during curing of polyetherimide (PEI) modified diglycidyl ether of bisphenol A (DGEBA) epoxy and PEI modified bisphenol A dicyanate (BPACY) were studied using SEM, light scattering, and dynamic mechanical analyzer. 

Figure 8.10 TEM photographs of thermoplastic-modified epoxy networks. The epoxy system is DGEBA-MCDEA (same as in Fig. 8.9), and the thermoplastic is a polyetherimide, PEI. The figure illustrates both the influence of the cure schedule and the PEI concentration, (a) 10 wt% PEI precured at 80°C and postcured at 190°C (b) 20 wt% PEI, same cure schedule (c) 10 wt% PEI precured at 160°C and postcured at 190°C (d) 20 wt% PEI same cure schedule as (c). Phase inversion is around 20 wt%. (From LMM Library.)...

Diglycidyl ether of bisphenol-A (DGEBA), epoxy resin (YD 128, Kuk Do Chem., Mn = 378), and bisphenol-A dicyanate (BPACY, Arocy B-10, Ciba-Geigy) were used as the thermoset resin. 4,4 -diaminodiphenyl sulfone (DDS, Aldrich Chem. Co.) was used as a curing agent for epoxy. Polyetherimide (PEI, Ultem 1000, General Electric Co., M = 18,000) and 2-methyl imidazole (2MZ, Aldrich Chem. Co.) were used as the thermoplastic modifier and catalyst. 

X.-J. Shen, X.-Q. Pei, S.-Y. Fu, and K. Friedrich, Significantly modified tribological performance of epoxy nanocomposites at very low graphene oxide content. Polymer (United Kingdom), 54 (3), 1234-1242, 2013. 

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