is a integer from 0 to 10 or more and wherein R is an ethylene group or propylene group, or mixture thereof, and b is an integer from 1 to 10 or more and wherein R' is hydrogen or a lower alkyl group having 1 to 10 carbon atoms and when less than four of the groups R1, R2, R3 and R4 are alkoxy groups, the remaining non-alkoxy groups R1, R2, R3 and R4 are alkyl groups having 1 to 30 carbon atoms