B. A. Krentsel

Copolymerization of 4-methylpentene-1 and styrene with TiCl3 and iBu3Al and the copolymer structure

Abstract Copolymers of 4-methylpentene-1 and styrene were prepared (TiCl 3 -AliBu 3 , 70°) and their structure investigated. Monomer reactivity ratios calculated from the copolymer compositions were found to be 3·92 and 0·98. Comparison of the i.r. spectra of copolymers thus prepared and of isotactic homopolymers (poly-4-methylpentene-1 and polystyrene) allowed some estimation of monomer distribution in copolymers of different composition; this estimation for styrene units was based on band intensities at 565, 1084 and 985 cm −1 , and for 4-methylpentene-1 units on band intensity at 997 cm −1 . These data show the copolymers of 4-methylpentene-1 and styrene to have random structure, and to be described by statistic relationships corresponding to r 1 r 2 ≈ 1. Possible reasons for discrepancies between r 1 r 2 -values from compositional studies and those obtained from i.r. data are discussed.

Polymerization of 4-methylpentene-1 and its copolymerization with propylene on the TiCl3 + (C2H5)2AlCl complex catalyst

Abstract The main kinetic laws governing 4-methylpentene-1 (MP) polymerization and copolymerization with propylene (P) on the catalytic system TiCl 3 + ( C 2 H 5 ) 2 AlCl between 30 and 70° were studied. The MP homopolymerization is kinetically first-order in monomer and TiCl 3 . The effective activation energy is 8·5 kcal/mole. The active site concentrations in MP polymerization at various temperatures were evaluated. The copolymerization constants were determined: for P r 1  6·44 ± 0·5: for MP r 2  0·31 ± 0·05. The structure of the copolymers was studied; some of their properties are described.

The structure of copolymers of vinyl cyclohexane with styrene

Abstract Copolymerization of vinyl cyclohexane (monomer-1) with styrene was investigated in the presence of the stereospecific complex catalyst TiCl3 + Al(iso-C4H9)3. Monomer reactivity ratios were r1 = 0·177 ± 0·051 and r2 = 2·117 ± 0·370. The monomer unit distributions in the copolymers were estimated by comparison of the i.r.-spectra of copolymers and the isotactic homopolymers using absorption bands at 565 and 1084 cm−1 which correspond to the vibrations of styrene blocks containing ⩾ 5 styrene units and the band at 985 cm−1 characterizing polystyrene crystallinity. The data indicate the tendency towards alternation in the copolymerization. Analysis of the experimental and literature data led to the conclusion that distribution of the units in copolymers of vinyl cyclohexane with α-olefins is determined by the nature of the α-olefin. The following activity series is proposed for α-olefins in their copolymerization with vinyl cyclohexane in the presence of catalytic systems based on titanium salts and organo-aluminium compounds: propylene >; 4-methylpentene-1 >; styrene >; 3-methylbutene-1 ∼ vinyl cyclohexane.

Chromium oxide catalysts for the polymerization of ethylene

1. The activity of the catalyst depends on the relative amounts of CrVI and CrIII and on the extent of the dehydration of the aluminum silicate. The deactivation of the catalyst is due to the more complete removal of active oxygen occurring either at too high a temperature or when the supply of air is inadequate. 2. In the course of the thermal treatment of the catalyst aluminum oxide enters into chemical reaction with CrO3, and this retards the reduction of CrVI to Cr111. No interaction is observed between silicon oxide and CrO3. 3. The activation of the catalyst at high temperatures is necessary only for the dehydration of the aluminum silicate, as the maximum amount of CrVI is present before the heating and the interaction between Cr compounds and alumina starts at low temperatures (103–108°). 4. The chromium catalyst investigated has high sorptive power and is readily reduced to Cr111 under the action of high temperature and hydrocarbons. 5. Spent catalysts can be regenerated.

Copolymerization and consecutive polymerization of propylene and 4-methylpent-1-ene on a TiCl3+Al(C2H5)2Cl complex catalyst☆

Abstract The results for the compolymerization and consecutive polymerization kinetics of propylene and 4-methylpent-1-ene (MP) are described. The copolymerization constants have been determined for propylene ( r 1 = 6·44 ± 0·5) and for MP ( r 2 = 0·31 ± 0·05). The elementary addition constants k 12 and k 21 , and the rate constants of propagation k 11 and k 22 have been assessed on the liv macro-chains of poly-MP and polypropylene (PP) respectively. The reasons for the lower rate of the MP polymerization, compared with propylene, are the smaller number of growth centres (by a factor of 1·5), and the smaller value of the rate constant of propagation (by a factor of 3). An explanation is given for the detected differences in the number of propagation centres and the k p values. The composition of the copolymers as a function of the main parameters of copolymerization has been extablished by experiments and some of the properties of the produced copolymers are described.

Transformations of 3-methyl- 1-butene on complex organometallic catalysts

1. The transformation of 3-methyl-1-butene was studied and it was shown that on complex organometallic catalysts the maximum yield of poly(3-methyl-1-butene), which is equal to 3–8 g/g of Ti, and the stereoregularity of the polymer, are respectively practically independent of the nature of the catalytic system and the nature of the aluminum alkyl. 2. The catalytic activity of the various complex organometallic catalysts, determined from the values of the initial polymerization rates of 3-methyl-1-butene, correspond to the order: Al(i-C4H9)3+TiCl4 > A1(C2H5)3+TiCl4 ≈ Al(i-C4H9)3+ TiCl3 > Al(C2H5)2Cl+TiCl4. 3. The low specific yield of poly (3-methyl-1-butene) is apparently caused by the adsorption of the polymer on the catalytically active centers and the resultant diffusion inhibition of the polymerization, and also by the adsorption of 2-methyl-2-butene and 2-methy 1-1-butene, which are formed as the result of the competing isomerization reaction, on the catalytically active centers.

Polymerization of 4-methyl-1-pentene on complex catalytic systems

1. A study of the comparative catalytic activity of above systems has shown that the system TiCl3+(i-C4H93)Al is the most active of them for the polymerization of 4-methyl-1-pentene (4-MP-1). 2. In the case of the catalytic systems TiCl3+(i-C4H9)3Al or VCl3+(i-C4H9)3Al, the concentration of the catalyst has a very great effect on the polymer yield. 3. Chromatographic study of the composition of the reaction mixture has shown that, along with the polymerization process, an isomerization of 4-MP-1 takes place. 4. A study of the rate of polymerization of 4-MP-1 on the system TiCl3+(i-C4H9)3Al has been performed by the dilatomeric method. An activation energy equal to 13.8 kcal/mole has been found.

Infrared spectra and structure of polyisobutenes produced on a complex organometallic catalyst

Isobutene polymerizes with parts of anomalous structure when an Al(C2H5)3+TiCl4, catalyst with a high Al∶Ti ratio is used. It is found that isobutene can polymerize by head-to-head and head-to-tail mechanisms when a TiCl4 or Ziegler catalyst is used.

Preparation of polypropylene over a chromium oxide catalyst

The yield of highly crystalline polypropylene was considerably increased by polymerization of propylene on a chromium oxide catalyst in the presence of small amounts of i-(C4H9)3Al.

Polymerization of ethylene over a chromium oxide catalyst at at mospheric pressure in absence of solvent

Polyethylene was prepared by the gas-phase polymerization of ethylene over a chromium oxide catalyst at ordinary pressure in absence of solvent at 110–180°.