Non-isothermal cure and decomposition kinetics of hydroxyl and propargyl functional poly (ether ether ketone): epoxy resins

This paper presents the cure behavior and decomposition kinetics of epoxy resins incorporated with hydroxyl functionalized poly (ether ether ketone)s (PEEKTOH) and propargyl telechelic poly(ether ether ketone)s (PEEKPR). PEEKTOH and PEEKPR were blended with diglycidyl ether of bisphenol A (DGEBA) resin. The unmodified DGEBA without any PEEK modifier was also processed and evaluated for comparison. 4, 4 ' diamino diphenylsulfone was used as the curing agent for the blends. Non-isothermal cure kinetics was derived by differential scanning calorimetry, and the kinetic parameters including activation energy, pre-exponential factor and rate constant were determined. The cure initiation temperature was significantly influenced by the composition of the blend. Neat epoxy system without any modifier showed a cure initiation temperature in the range of 130-150 degrees C for different heating rates studied. PEEKTOH and PEEKPR modified epoxies exhibited cure initiation in the range of 118 to 145 degrees C and 121-149 degrees C, respectively, for different heating rates. Activation energies, E-a, at various extents of curing conversion were derived by Kissinger-Akahira-Sunose (KAS) method. The highest average activation energy range was exhibited by EP-Neat in the range of 77-80 kJ mol(-1), whereas the EP-PEEKTOH showed E-a in the range of 66-70 kJ mol(-1). Cured systems were subjected to thermal decomposition by thermogravimetric analysis. The activation energy for different extents of decomposition was studied by KAS method. The PEEKPR blended epoxy exhibited the highest values of activation energy for the entire range of decomposition, whereas the PEEKTOH system exhibited the lowest values.

Automated summary

This study investigated the curing behavior and decomposition kinetics of epoxy resins blended with PEEKTOH and PEEKPR modifiers. The modified epoxies showed lower cure initiation temperature and activation energy compared to unmodified epoxy systems. In terms of thermal decomposition, the PEEKPR blended epoxy exhibited the highest activation energy values while the PEEKTOH system exhibited the lowest values.