Copolymerization of Propadiene with Ethylene

Abstract

Study was made on the copolymerization of propadiene with ethylene in the presence of catalysts of Ziegler type. The copolymerization proceeded with Al (i-C₄H₉) ₃-VOCl₃, but did not appreciably with Al (i-C₄H₉) ₃-TiCl₄. The optimum molar ratio of Al (i-C₄H₉) ₃ to VOCl₃ was found to be 2.4. The Al (C₂H₅) ₂Cl combined with VOCl₃ brought about the decreases in yield, propadiene content and molecular weight of copolymers.
The copolymerization with varied monomer composition in the presence of Al (i-C₄H₉) ₃-VOCl₃ catalyst, revealed that the yield and molecular weight of polymer decreased with increasing in amount of propadiene, especially very markedly until the propadiene contentexceeded ca. 10%.
This fact was explained in view of the assumption that propadiene, which was shown to be less polymerizable than ethylene, would be more favorably adsorbed on the active sites of catalysts.
From the monomer-copolymer composition curve, the apparent monomer reactivity ratio of propadiene was found to be smaller than that of ethylene.
X-ray diffraction and solubility measurements indicated that the crystallinity of copolymerizatation products was lower than that of homopolymers, suggesting that the resultant polymer did not consist of the mixture of homopolymers, but consisted of the copolymer.