Polyurethane foams and elastomers based on modified polyether polyols

In a process for the preparation of a cellular or non-cellular polyurethane resin comprising reacting

• (A) a polyisocyanate with
• (B) a polyether polyol modified by graft polymerization and optionally
• (C) other higher molecular and/or low molecular compounds containing isocyanate reactive hydrogen atoms, optionally in the presence of
• (D) blowing agents, catalysts and other known additives, the improvement comprising employing a modified polyether polyol prepared by a process comprising polymerizing from 1 to 50 parts by weight of a mixture of 20 to 100% by weight (based on the total quantity of monomers) of acrylonitrile and 0 to 80% by weight of styrene in 50 to 99 parts by weight of the polyether polyol in the presence of a polymerization initiator which yields free radicals, wherein said polymerization is carried out in the presence of from 0.1 to 1.5% by weight, based on the total quantity of monomers put into the process, of a compound of the formula:
• A=CH--X--R
• wherein
• A represents a divalent group ##STR11## R represents a C.sub.1-18 alkyl, C.sub.1-10 cycloalkyl, or substituted or unsubstituted benzyl group,
• R' represents C.sub.1-8 alkyl group,
• n represents 0, 1 or 2 and
• X represents oxygen or sulfur.