3 al and q value of the copolymers increased from 13 2 at 5 mole 4vch in feed to 16 7 at 15 mole 4vch by comparison the corresponding homopolymer of c 4 and c 4 4vch copolymers have q ranging from 7 8 to 11 4 and 9 9 to 12 6 respectively relative to poly 1 butene copolymers of 4vch made with ticl 3 aa et 3 al catalysts were more isotactic iso 79 82 and def 13 14 and crystalline crystallinity u02dc 41 to 44 whereas copolymers of vch were slightly less crystalline but had tacticity parameters iso 64 68 def 21 42 comparable to those of corresponding polybutene iso 67 def 29 a possible explanation for the higher stereoregularity in 4vch copolymers is the selective inhibition of atactic sites by 4vch via chelation x ray analysis of freshly compression molded and pressure aged copolymer films showed no inhibition of the transformation of form ii crystalline state to form i such an effect has been reported in u k pat no 1 101 435 for butene copolymers containing higher amounts gt 5 mole of bulky comonomers the tensile properties of the butene polymers showed the expected increase in stiffness with crystallinity copolymers of c 4 4vch have broader molecular weight distribution higher degree of isotacticity.