Two samples of cellulose (molecular weight 2.97 × 105 and 1.25 × 105) were transformed into carbanilates (CTC) which were then fractionated by the elution method at a constant composition of the acetone‐water elution mixture with the column temperature gradually increasing from −30°C to 30°C, and by the GPC method in acetone and tetrahydrofuran. Tetrahydrofuran appeared to be a more suitable solvent. The molecular weights of fractions obtained by the elution fractionation were determined by the light‐scattering method in tetrahydrofuran. The width of fractions was determined by the GPC method (average Mw/Mn = 1.37); the [η] values and the Mark‐Houwink constants (K = 5.3 × 10‐3, a = 0.84) for tetrahydrofuran at 25°C were determined. The calibration curve for the GP method was constructed by means of the fractions thus obtained; it was demonstrated that the universal calibration curve according to Benoit can also be used. It was demonstrated that the molecular weight distribution of cellulose can be conveniently determined by conversion into CTC followed either by the elution fractionation (for preparative purposes) or by fractionation by the GPC method (for analytical purposes).

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Polymerization of isoprene, butadiene, and chloroprene with complex catalysts consisting of alkyl or arylmagnesium bromide or triethylaluminum and excess TiCl4 leads to the formation of powdery, insoluble, probably crosslinked polymers with high density and high heat resistance (>370°C). The structure of these polymers differs from that of those prepared at higher molar ratios of organometallic compound to titanium tetrachloride. The infrared analysis of the powdery polymers and comparisons with the spectra of cyclized 3,4‐polyisoprene and cyclized 1,4‐cis‐polyisoprene indicate that the polymer chain consists of fused six‐membered saturated rings in the form of a linear ladder or spiral ladder structure. The residual linear segments with 1,4 units, present in the predominantly cyclic polymers, may be isomerized to a cyclic form by the action of H2SO4. Removing the linear segments from the polymer chain further improves the heat resistance. It is proposed that the cyclic structure is formed during the polymerization from 1,2‐polymer and not as a result of the action of catalyst components on primarily formed linear chains. The cyclic structure may be ascribed to all three investigated polymers.

The polymerization of isoprene with C2H5AlCl2 to yield solid cyclopolyisoprene is markedly accelerated by the addition of TiCl4. The polymer yield passes through a maximum on increasing the catalyst reaction time with or without monomer present. The active species are probably cations formed by dissociation of the reaction product of C2H5AlCl2 and TiCl4. The polymerization of isoprene with (C2H5)2AlX–TiCl4 (X = F, Br, Cl) has maximum activity at an Al/Ti mole ratio of 0.75 corresponding to conversion of R2AlX to RAIX2 which then reacts with remaining TiCl4. A proposed mechanism of cyclopolymerization of conjugated dienes involves monomer activation, i.e., conversion to cation radical by one‐electron transfer to catalyst cation which is itself neutralized, addition of cation end of monomer cation radical to terminal or internal unsaturation of fused cyclohexane polymer chain, one‐electron transfer from “neutral” catalyst to cation on polymer chain which is then transformed to a diradical which undergoes coupling to form a cyclohexene ring. The mechanism of the “living” polymerization involves addition of catalyst‐activated monomer to a “dead” polymer with a terminal cyclohexene ring and regeneration of the active catalyst.

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