The curing reaction of poly(ether‐sulfone)‐modified epoxy resin

Abstract

One of the useful methods to improve the toughness of epoxy resin is by mixing the resin with poly(ether-sulfone) (PES). In the present work, two hydroxyl-terminated PESs with molecular weights an = 28600 and 4200 were used for blending with epoxy resin. The curing reaction of diglycidyl ether/bisphenol-A (DGEBA) with 4,4'-diaminodiphenyl sulfone (DDS) in the presence of hydroxyl-terminated PES was studied by means of differential scanning calorimetry (DSC) and gel-permeation chromatography (GPC). For the DGEBA-DDS-PES system with a stoichiometric ratio of epoxy and amino groups the DSC experimental results showed that at a fixed molecular weight of PES the curing reaction rate decreases with increasing PES concentration. At a fixed PES concentration (in the range of between 0 and 20 wt.-Yo of PES), the DGEBA-DDS system modified with hydroxylterminated PES with lower molecular weight had a faster curing reaction rate at low conversion and a slower curing reaction rate at high conversion. The GPC results showed the evidence of etherification between low-molecular-weight PES with epoxy resin. However, very little etherification of high-molecular-weight hydroxyl-terminated PES with epoxy resin was found. Based on the experimental results, a curing reaction mechanism of DGEBA with DDS in the presence of hydroxyl-terminated PES is proposed.

Polymerization-Induced Viscoelastic Phase Separation in Polyethersulfone-Modified Epoxy Systems

“…As most of the epoxy monomer remains unchanged (x-CP at q m (t) ) q 0 + A 0 exp(-t/τ) (2) about 0.1 and x-END at about 0.2) during the phase-separation process, then the relaxation time τ may be regarded as the viscous flow capability of epoxy monomer or growing-thermoset (low molecular weight) droplets. It is understandable when the blend cure at a higher temperature, the diffusion rate of the thermoset monomer, or the growing thermoset increase and impel the PES and growing epoxy chain to disentangle then two or more epoxy droplets combine more quickly.…”

Effect of Polyethersulfone on the Mechanical and Rheological Properties of Polyetherimide-Modified Epoxy Systems

“…2 However,when the curing agent was added to the PEI/ PES/epoxy solution, it changed the ternary solution into a quaternary system; the miscibility shown in Table 2 can only be a referential indication for the PEI/PES/ epoxy oligomer solutions. Although the curing agent Scheme 1.…”

Novel phosphorus‐containing hardeners with tailored chemical structures for epoxy resins: Synthesis and cured resin properties

“…The heat of reaction was found to vary between 105 and 114 kJ/equiv for the various systems, which is in very good agreement with the values reported for a full cure of stoichiometric mixtures. [38][39][40] A comparative plot of the rate of reaction for all different epoxy formulations as a function of the epoxy conversion at 1808C is shown in Figure 1(a), whereas a more detailed insight into the rate of reaction at various temperatures as a function of the epoxy conversion is highlighted in Figure 1(b) for the DGEBA-PO3 system. Typical characteristics of autocatalytic reaction mechanisms such as an initial nonzero rate of reaction (when x ?…”