Abstract
An apparatus for measuring the elastic recovery, exhibited by viscoelastic fluids after the cessation of steady flow, is designed. This is a coaxial double cylinder type viscometer, in which the shaft of the inner cylinder is set free to rotate by an elastic force of the sample immediately after the revolution of the outer cylinder is stopped. By using the concept of internal strain, the following equation can be derived._??_(1)θe: angular displacement of inner cylinder caused by the elastic recovery of sample after the cessation of flow, σi: shearing stress at the inner cylinder surface, Ri: radius of inner cylinder, R0: radius of outer cylinder, n, k: constants for the sample.For Na-PAA solutions eq.(1) agrees with experimental results.Concentration and temperature dependence of θe at various σi for Na-PAA was measured.For the range of 1-2%, n=1/2 and for the region smaller than 1%, n approached to zero.n=0 means that the strain obeys the Hooke's law in shear.It is considered that the contribution of orientation entropy to the fluid elasticity of Na-PAA solutions is remarkable, because θe is depressed with increasing temperature.Elastic recovery after the cessation of steady flow, which was a kind of non-linear creep recovery, was observed as a function of time.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
