Sl04 JOURNAL OF POLYMER SCIENCE, VOL. 62, ISSUE 174 (1962)

isotactic configuration are not equivalent, while the coupling constants between these two protons and CH protons on both sides, namely JAC and JBC according to the above mentioned nomenclature, are regarded as identical.

With the calculated spectra of the syndiotactic configuration and the observed spectra of the residue (isotactic), the syndiotactic, and the isotactic contents (N. and N i ) o f these samples are determined. From these results, isotactic and atactic contents XI and N A with long-range order, corresponding to those obtained from infrared spec- t ro~copy,~ x-ray diffraction, etc., are obtained with the aid of the assumption that the atactic polymers are composed of the equal contents, N . and Ni. The average chain length in number (s) and (i) of monomer units for the two types of stereospecificity arc calculated with the aid of the theory developed by one of US.^ The results are given in Table 11, where n is the average number of blocks which contain the same configuration only.

References

1. ChdjB, R., S. Satoh, T. Ozeki, and E. Nagai, J. Polymer Sci., to be published. 2. Pople, J. A., W. G. Bernstein, and H. J. Schneider, High Resolution Nuclear Mag-

3. Anderson, W. A., Phys. Rev., 102,151 (1956). 4. Brader, J. J., J. Appl. Polymer Sci., 4,74 (1960). 5. Miyake, A., and R. ChdjB, J . Polymer Sci., 46, 163 (1960).

netic Resonance, McGraw-Hill, New York, 1959.

SHIROH SATOH RIICHIRB CHOJO TOSHIO OZEKI EIICAI NAGAI

The Research Institute Kureha Spinning Co. Ltd. Takatsuki, Osaka, Japan

Received January 2, 1962 Revised February 15, 1962

The Dependence of the Stereospeci5c Action of the Complex Catalyst a-TiClrMe(C&I& during the Polymerization of a-OleJins

on the Metal i n the Metalloorganic Compound

The views of Natta and his collaborators are widely disseminated in the literature.'-3 According to these, the stereospecific action of the catalyst a - TiC13, Me(C2R5),, during the polymerization of a-olefins is closely dependent on the identity of the metal in the metalloorganic compound.

Table I summarizes the results of experiments supporting our conclusion. Propylene was polymerized under the following conditions:

1. Catalyst system CY-T~CI~-Z~(C~H~)~; temperature, 50-70°C.; pressures (varied or kept constant during an experiment), 4-9 atm.; ratio of constituents of catalyst, %n/Ti, 0.8:14.6 (molecular); solvent, n-heptane; reactor brass.

2. Catalyst systems a-l'iC13-Be(C2Hfi)2 and a-TiCla-A1(C2H5)n; temperature, 30-70°C.; pressures (constant throughout an experiment), 200 to 600 mm. Hg; ratio, M/Ti =3 (~nolecular); solvent, n-heptane; reactor, glass.

The figures quoted in the taMe provide evidence thnt the fractionation of polypropyl- ene is a complex process determined rather by the molecular weight compositio~i of the polymer than by its content of stercoregular and atactic structures.

Our investigations indicate that this deduction is in error.

TABLE I Properties of Polypropylene Obtained over the Catalyst System a-TiCI,-Me( C2H&

~

Ionic Crystallinity, Crystallinity, radius of Content of infrared x-ray

Me(C2H5), metal, A. fraction, % spectrum, % spectrum, % [ v ]

Fraction I (polymer insoluble in boiling n-heptane) Be(C2H5)2 0.35 91-98 60.5-69.5 2-11.8 AUCzH& 0.51 77-80 57-62 54-57 3-4 Zn(CzHd2 0.74 47-66 h 58-66.5 0.1-0.4

Fraction I1 (polymer soluble in boiling and insoluble in cold, n-heptane)

8-12 55 55 17-29 55-58 61-64

Fraction I11 (polymer soluble in cold n-heptane)

d(C2H5)S 8-13 18-32 Zn(C2H6)2 13-34 29-31

* Intrinsic viscosity of a representative sample of the polymer. b Because of the extremely high optical density of a film of the polymer no infrared

spectrum could be obtained.

Actually, as the figures in the table show, the samples of polypropylene with the lowest intrinsic viscosity are very soluble in boiling heptane. At the same time, the crystal- linity of polypropylene obtained in the presence of various metalloorganic compounds is practically uniform. A high content of the crystalline phase is found in fractions I and I1 of the polypropylene; in fraction 111, used by Natta for the atactic part of the polymer and therefore not capable of crystallizing, there is also a crystalline-phase content, although a lesser one. From the figures obtained with Be(C2H& it follows that the molecular weight of stereoregular polypropylene is little indication of its ability to crystallize.

We therefore conclude that the stereospecific action of the catalyst a-TiCI3-Me( C2HS),, in the polymerization of or-olefins does not depend on the identity of the metal in the metalloorganic compound. The metalloorganic compound exerts a strong influence on the molecular weight of the polymer formed.

From their conclusions, quoted above, Natta and his collaborators1-3 erroneously assumed on the basis of the solubility of polypropylene in n-heptane that the fractiona- tion of the polymer is determined only by its content of stereoregular and ntactic structures.

References

1. Natta, G., J. Polymer Sci., 34,21 (1959). 2. Natta, G., and J. Sasquon, Advances in Catalysis, Vol. 11, 1959, p. 4. 3. Gaylord, N. G., and H. F. Mark, in Polymer Reviews, Interscicnce, New York-

London, 1959, p. 129.

A. P. FIRSOR B. N. KASHPROV Yu. V. KISSIN N. M. CHIRKOV

Academy of Sciences, U.S.S.R. Moscow, U.S.S.R.

Received April 16, 1962