ISSN:
0887-6266
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The rheology of hydroxypropylcellulose (HPC) - acetic acid solutions was investigated by using a cone-and-plate rheometer and a capillary rheometer, for polymer concentrations ranging from 10 to 80%. Isotropic solutions exhibit a Newtonian plateau followed at higher shear rates by a pseudoplastic zone. The apparent viscosity varies as C5.2 if concentration C is less than 27% and as C13 for 27% 〈 C 〈 30%. A biphasic interval (isotropic and cholesteric phases) exists between 30 and 35%. A maximum in viscosity is observed at C = 30%, the height of the viscosity peak being a decreasing function of shear rate. Anisotropic solutions are strongly viscoelastic. Both isotropic and anisotropic solutions give results (apparent viscosity, first normal-stress difference, relaxation time, etc.) which are not in good agreement with Doi's theory. This is understandable since the HPC chain cannot be modeled by a rigid rod. Upon heating, anisotropic HPC - acetic acid solutions undergo an anisotropic to isotropic phase transition which is easily detected by a maximum in the temperature dependence of the first normal-stress difference and of the apparent viscosity.
Additional Material:
13 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/polb.1986.180240118
