ydrolyzable organic radical free of nitrogen, each A radical is selected from the group consisting of R-- and halohydrocarbon radicals of from 1 to 6 inclusive carbon atoms, each Z radical is A-- or QR--, each R is a divalent alkylene radical of from 1 to 6 inclusive carbon atoms, each Q is an organofunctional monovalent radical selected from the group consisting of RCOE', RE'OC--, NC--, R'E'--,