Über die Synthese und das Verhalten von Polyoxypropylenglykol‐Diglycidäthern

Polyoxypropylene glycols with average molecular weights of 270, 425, 565, and 920 are converted by two different methods to the corresponding diglycidyl ethers. Polyoxypropylene glycol diglycidylethers (A) synthesized via chlorohydrin contain ClCH2 groups as a result of competition between the secondary hydroxyl groups of the poly-oxypropylene glycol and those of the already formed chlorohydrin ethers in the presence of the epichlorohydrin. The formation of these ClCH2 groups consumes epichlorohydrin, thus causing a corresponding deficit of glycidyl groups. Treating the sodium alkoxides of the polyoxypropylene glycols with allyl bromide followed by epoxidizing the diallyl ethers with peracetic acid yields diglycidyl ethers (B), which contain acetyl groups Crosslinking mixtures from diglycidyl ether of bisphenol-A and polyoxypropylene. glycol diglycidyl ethers A or B with diethylene triamine yields flexible epoxy resins. Properties of epoxy resin systems containing diglycidyl ethers A or B differ only slightly. By applying the theory of rubberlike elasticity the crosslinking density and thes hear modulus G of the flexible epoxy resins systems are calculated. The calculated shear moduli and those measured above the glass transition temperature are in relatively good agreement. Epoxy resin systems with none or a high content of flexibilizer show differences, which are caused by two effects.