Cure kinetic study of epoxidized hemp oil cured with a multiple catalytic system

Abstract

The cure kinetics of two epoxidized hemp oil (EHO) based bioresins were studied and compared under both dynamic and isothermal conditions using differential scanning calorimetry (DSC). Neat triethylenetetramine (TETA) for the first system and a combination of isophorone diamine (IPD) and TETA for the second system were used as the hardeners for the two EHO‐based bioresins. Lower total heats of reaction and an approximate 10% decrease in activation energies were observed for the IPD/TETA system. Maximum conversions of the TETA/IPD system were consistently higher than those of the TETA system throughout the entire temperature range suggesting enhanced curing characteristics. Kissinger and Ozawa–Flynn–Wall models were used to determine activation energies from dynamic DSC data. Both bioresin systems were found to display autocatalytic behavior with the TETA/IPD system showing high nth order influence. Kamal's autocatalytic isothermal model, modified to account for diffusion postvitrification was found to satisfactorily describe the cure behavior of both bioresin systems. Overall, the addition of IPD was found to increase the curing rate of the EHO bioresin systems. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Cure kinetics of an acrylated epoxidized hemp oil‐based bioresin system

“…The curves obtained from the dynamic DSC runs at different heating rates are shown in Figure 2. It can be seen that both peak temperature and heat of reaction increased with increased heating rates, showing the same trend observed previously for the EHO/TETA,22 EHO/TETA/IPD,23 and epoxy44–46 systems. On the other hand, many authors did not find a clear trend regarding epoxy,47,48 polyester and vinyl ester26,49 systems.…”

Thermal and Flammability Characteristics of Blended Jatropha Bio-Epoxy as Matrix in Carbon Fiber–Reinforced Polymer

“…Then in the fourth region, the spectrums became less sharp and a little broader in some of the bands. Essentially at band 829 cm −1 , C-O-C stretching of oxyrane group was identified in the blended bio-epoxy as reported in some research papers [11,19,20]. There were O-H bending of phenol group and C-O stretching of aromatic ester at band 1361 cm −1 and 1295 cm −1 , respectively.…”

Carbonyldiimidazole‐accelerated efficient cure of epoxidized soybean oil with dicyandiamide

“…However, the curing system provides a much higher reaction enthalpy of 196 kJ mol −1 epoxy units when the epoxy functionality is up to nE p = 3. This reaction enthalpy is higher than the addition reactions of NH to the epoxy groups that report the reactions of aliphatic amines with the internal epoxy groups, this finding suggests different reaction mechanisms between ESO and DICY in the presence of CDI. Formulations containing more than 3 epoxy groups per mol DICY release lower overall enthalpy compared with those with nE p = 3.…”

“…[1][2][3][4][11][12][13] The curing strategy of EVO through both step-growth polymerization and chain-growth polymerization (i.e., ring-opening polymerization) has been widely studied. For example, various anhydrides, [14][15][16][17][18][19][20][21][22] acids, 23 amines, [24][25][26] pyridine derivatives, 27 and phenols 28 were used to cross-link the epoxy groups contained in EVO chains, and several photo-initiators 29 and cationic polymerization initiators [30][31][32] were reported as a successful initiator for chaingrowth polymerizations. However, in contrast with the termi-nal epoxy groups (glycidyl), the internal epoxy groups of EVO hardly accept nucleophilic attacks, resulting in poor reactivity for curing.…”