Improved Oxidative Stability of Tetra Epoxy Amino Resins
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
Tetrafunctional epoxy made from bis-p,p'-diaminodiphenylmethane, when made into an epoxy polymer has proven to have remarkably superior properties to epoxy polymers prepared from the bis- glycidyl ether of bis-phenol A (Figs. 1 and 2). This improvement in properties, in particular Tg (and related phenomena such as H2O uptake and dimensional stability), is due to the tetra-functionality which leads to greater crosslink density than the difunctional bis-phenol A-based resin. One drawback to this material is its oxidative instability at moderate temperatures (80ŒC). The site of this instability is the central methylene carbon atom (Fig. 3). After initial oxidation, formation of radicals and radical chain reactions leads to massive degradation.