ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Viscosities were measured on 11 polyisobutenes with molecular weight of 224 to 71,000. Measurements were made on cetane and tetralin solutions containing 11.2-100 wt.-% polymer. Tests were made at 80-135°C. and a t shear rates to 8 × lo6 sec.-l. Low shear capillary and two types of rotational viscometers were used. The data confirm that polyisobutene systems show an abrupt transition in log viscosity - log molecular weight correlations. This transition occurs near 15,000 for MV where M is Viscosity-average molecular weight and V is polymer volume fraction. Below a product of 15,000, polyisobutene systems exhibit essentially Newtonian flow and an absence of laminar flow shear degradation to stresses above 2 × 105 dynes/cm.2. In this region the viscosity dependence on molecular weight approaches fist order at higher temperatures and lower polymer concentrations. For polyisobutene systems above the transition near 15,000, low shear viscosities uniformly increased aa the 3.4 power of molecular weight. Systems in this range exhibited large and predictable non-Newtonian effects and frequently showed laminar flow shear degradation at low rates of shear.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1961.1205015410
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