Effect of reactive poly(ethylene glycol) flexible chains on curing kinetics and impact properties of bisphenol‐a glycidyl ether epoxy

Abstract

Bisphenol-A glycidyl ether epoxy resin was modified using reactive poly(ethylene glycol) (PEO). Dynamic mechanical analysis showed that introducing PEO chains into the structure of the epoxy resin increased the mobility of the molecular segments of the epoxy network. Impact strength was improved with the addition of PEO at both room (RT) and cryogenic (CT, 77 K) temperature. The curing kinetics of the modified epoxy resin with polyoxypropylene diamines was examined by differential scanning calorimetry (DSC). Curing kinetic parameters were determined from nonisothermal DSC curves. Kinetic analysis suggested that the two-parameter autocatalytic model suitably describes the kinetics of the curing reaction. Increasing the reactive PEO content decreased the heat flow of curing with little effect on activation energy (E a ), pre-exponential factor (A), or reaction order (m and n).

Curing behavior of epoxy resins in two‐stage curing process by non‐isothermal differential scanning calorimetry kinetics method

“…Herein, the curing reaction kinetics had been studied by the non‐isothermal differential scanning calorimetry (DSC) technology. Málek method and iso‐conversional method of Kissinger‐Akahira‐Sunose (KAS) were applied to unravel the curing reaction mechanism and activation energy ( E a ) of two curing stages. The pre‐exponential factor ( A ) and reaction order ( m , n ) were tried to obtain by double x fitting method.…”

Synthesis and characterisation of new sulphur-containing epoxy networks

“…An alternative strategy is to create an inherently tougher polymer by incorporating flexible functional groups such as aliphatic methylene linkages 11 into the backbone of the network. 12 This avoids the use of additives that deleteriously affect processability but relies upon enhanced molecular motion of the polymer chains, through bending, rotation or other distortional motions 13 to improve performance. It is proposed that replacing oxygen with strategically located sulphur in an epoxy resin may improve the toughness by allowing greater molecular motion or distortional performance of the polymer arising from the increased atomic weight, lower electronegativity and higher polarisability of sulphur compared with oxygen.…”

Preparation, curing properties, and phase morphology of epoxy-novolac resin/multiepoxy-terminated low-molecular-weight poly(phenylene oxide) blend

“…Both Δ H c and G E decrease with the increase in the fraction of PPO or modified PPO as the macromolecules—PPO or modified PPO—hindered the reaction and the diffusion of EPN, indicating that curing enthalpy could reflect the degree of crosslinking to some extent when the curing reaction proceeds at a low heating rate. Furthermore, the increase of PPO or modified PPO reduced the concentration of epoxy group and the possibility of epoxy group to react with curing agent . Particularly, Δ H c of EPN/modified PPO is much higher because the epoxy group on the end of PPO made it possible for PPO to participate in the curing reaction, and more epoxy groups on the end means higher reactivity, thus EPN/PPOE achieves the highest Δ H c and G E in three blends.…”