ISSN:
0022-3832
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
The effect of Al/Ti molar ratio, temperature, and solvent on the microstructure of polybutadiene prepared with an aluminum triisobutyl-titanium tetrachloride catalyst system was investigated. Although polymers containing as much as 98% trans-1,4 structure were obtained, under appropriate conditions, no polymers with greater than 60% cis-1,4 structure were obtained. The amount of 1,2-structure was generally below 10%. The rate of polymerization was measured at 25°C. in heptane by following the drop of butadiene pressure with time in a constant volume apparatus. The rate was a function of the Al/Ti molar ratio and was directly proportional to the amount of catalyst used. The rate of polymerization was proportional to the square of monomer pressure at Al/Ti ratios greater than 2.0. When the molar ratio was between 1.0 and 1.6, the rate was proportional to the first power of the monomer pressure. At molar ratios of 1.8 and 1.9 the dependence of rate on monomer pressure could be represented by -dP/dt = aP + bP2, indicating the possible existence of two concurrent reactions. When the ratio fell below unity the uptake of butadiene was at first rapid but soon slowed to a stop. Possible kinetic schemes are discussed in terms of Rideal and Langmuir-Hinshelwood mechanisms.
Zusätzliches Material:
10 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1960.1204214011
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