Curing of DGEBA epoxy resin by low generation amino‐group‐terminated dendrimers

Abstract

Low generation amino-group-terminated poly(ester-amine) dendrimers PEA1.0 (NH 2 ) 3 and PEA1.5 (NH 2 ) 8 , and poly(amido-amine) dendrimer PAMAM1.0 (NH 2 ) 4 were used as diglycidyl ether of bisphenol A (DGEBA) epoxy resin hardeners. Thermal behavior and curing kinetics of dendrimer/DGEBA systems were investigated by means of differential scanning calorimetry (DSC). Compared with ethylene diamine (EDA)/DGEBA system, the dendrimer/DGEBA systems gradually liberated heat in two stages during the curing process, and the total heat liberated was less. Apparent activation energy and curing reaction rate constants for dendrimer and EDA/DGEBA systems were estimated. Thermal stabilities and mechanical properties of cured thermosetting systems were examined as well.

Upgrading the adhesion properties of a fast‐curing epoxy using hydrophilic/hydrophobic hyperbranched poly(amidoamine)s

“…Hence, the impact resistance was markedly improved. This finding is in accordance with results obtained by other researchers who used other HBPs or low generation PAMAM and found them as effective toughening agents for thermosetting materials such as bismaleimide,24 urea‐formaldehyde resins,25 and DGEBA epoxy 26. However, they did not extend their use for adhesion or coating purposes.…”

Learning about novel amine-adduct curing agents for epoxy resins: Butyl-glycidylether-modified poly(propyleneimine) dendrimers

“…9B) which decreases gradually with increasing the number of the bonded BGE segments of the curing agents. In contrast, these cured epoxy resins are much more thermally stable than that cured with PAMAMs [14] or silica-supported PAMAMs [13], in which cases the obvious weight loss can be detected in a much-lower temperature range (∼160 • C).…”

“…For example, Tande et al [12] used ester-terminated poly(propyleneimine) dendrimers to plasticize polyvinyl chloride (PVC) with the decreased glass-transition temperature found, which is due to the additional free volume provided by the dendrimers. Other reports indicated that PAMAMs and these of similar molecular structures [13][14][15][16][17] could effectively crosslink epoxy resins. These dendrimers also exhibit the advantages of lowered vapor pressure, alleviated toxicity, reduced unfavorable odor, retarded carbonation in air, and improved compatibility with epoxy resins over the conventional linear-aliphatic-amine curing agents of low molecular weights (e.g., ethylenediamine).…”

Molecular Mobility in Hyperbranched Polymers and Their Interaction with an Epoxy Matrix

“…Some authors [9,10] have used polyamido-amine dendrimers grafted onto silica as the curing agent in epoxy systems, and report increased thermal stability in comparison with the same epoxy cured with ethylene diamine (EDA), but there was no consensus on whether the glass transition temperature is increased or not. More generally, the reaction kinetics of bisphenol-A epoxy resins cured with polyamido-amine dendrimers has been studied [11,12], and it has been reported that, in comparison with the use of EDA as curing agent, the curing kinetics using polyester-amine dendrimers is very different, presenting two stages of cure and less heat of reaction [13]. The use of polypropylene-imine dendrimers as curing agents in epoxy systems is quite widely reported [14,15,16], and it appears that the molecular architecture of the dendrimers, in particular their steric hindrance and the number of attached –OH groups [14], greatly affects the reaction kinetics.…”