. "In the mixture, the aluminum alkyl is of the formula AlRn X3-n and the alkoxy aluminum alkyl is of the formula AlR'm OR3-m, in which each R, R' and R is independently selected from alkyl or aryl of 1-20 carbon atoms, X is halogen especially fluorine, chlorine and bromine, n is 2-3 and m is 0-3." . . . .