Carboxyl terminated polyethers

the adducts of hydroxyl terminated polytetrahydrofuran and maleic anhydride

were used as toughener for epoxy resins. The morphology of the toughened resins was investigated by means of turbidity measurement

dynamic mechanical testing and scanning electron microscope observation. It turned out that the molecular weight and the carboxyl content of the polyether and the cure conditions are important factors

which affect the particle size of the polyether-rich domains and

in turn

the mechanical properties of the cured resin.Carboxyl terminated polytetrahydrofurans have a low glass transition temperature

and in appropriate amount they do not affect the thermal resistance of the resin.These advantages make them preferable as toughener for epoxy resins.