0 VA, N auchno-I ssledovalelski!£ I nstitut Sintelicheslcogo Kauchuka im S. V . Lebedeva, Leningrad, U.S.S.R .
IFor solving the problem of cis-polyisoprene or cis-polybutadiene synthesis one must take into consideration not only the nature of the catalyst determining the character of the monomer addition during the polymerization but also secondary reactions proceeding in the polymer cha in under the influence of the eatalytic complex components. We have found that titanium halides and organoaluminum compounds cause isomerization of the cis uni ts of natmal rubber into the trans units. 1 The percentage of different configurations of the polymer chain uni ts has been determined by infrared spectmscopy from the absorption at 840 em. -l. In some cases it has been dete rmined qualitatively from t.he absorption bands at 1300 and 1100 em. -1 • The data on the relative proportion of cis and trans units are only qualitative sin ce, simultaneously with the polymerization proce s, a considerable TABLE I Tso mPriza tion of Na tura l Ruhlw r ( in a2 % Benzene Solution during 10 hr. ) % by % of units from total number of Hn Rat11ratNI " ·eigh t units o f T Ptnp. , Vnsatura t ion , Catalyst rubber oc. % Ct S tran s DO 99.2
Es wird eine Ubersicht uber Arbeiten zur Copolymerisation von Episulfiden mit Epoxiden, Isothiocyanaten und polaren Monomeren der Vinylreihe unter dem EinfluS von anionischen, kationischen und koordinativ-ionischen katalytischen Systemen gegeben.
On the copolymerization of episulphides with monomers of other chemical natureA survey of investigations on the copolymerization of episulphides with epoxides, isothiocyanates and some polar vinyl monomers under the influence of catalyst systems of anionic, cationic and coordinate-ionic types is presented.
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