Measuring viscosity of pharmaceutical and cosmetic semisolids using normal stress

ed in part from a dissertation submitted by Shivaji Purwar to the graduate School of West Virginia University, in partial fulfillment of the Doctor of Philosophy • ; ...... • ...... •'='• partly •' .... •.•lo•;p grants c•,• •h,• qo,-i,•y •c •_ roetic Chemists to Mr. Purwar. The authors wish to thank Drs. William R. Powell and J. Krall, formerly of the Department of Mechanical En•ineerin• and the School of Medicine at West Virginia University, respectively, for their valuable assistance. REFERENCES (1) S. Purwar, A. R. Padhye, and J. K. Lim, A new method for measuring the viscoelastic parameters of pharmaceutical nd cosmetic semisolids, J. Soc. Cosmet. Chem., 35, 115-129 (1984). (2) S.S. Davis, E. Shotton, and B. Warburton, Some limitations of continuous shear methods for the study of pharmaceutical semisolids, J. Pharm. Pharmac., 20, [Suppl.], 157S167S (1968). (3) B. W. Barry and E. Shotton, Performance of the Ferranti-Shirley viscometer with automatic flow curve recorder unit, 1bid., 20, 167-168 (1968). (4) G. B. Thurston and A. Martin, Rheology of pharmaceutical systems: Oscillatory and steady shear of non-Newtonian viscoelastic liquids, J. Pharm. Sci., 67, 1499-1506 (1978). (5) J. C. Boylan, Rheological estimation of the spreading characteristics of pharmaceutical semisolids, 1bid., 56, 1164-1169 (1967). (6) G. W. Radebaugh and A. P. SimoneIll, Phenomenological viscoelasticity of a heterogeneous phar- maceutical semisolid, 1bid., 72, 415-422 (1983). (7) B. W. Barry, Advances in Pharmaceutical Sciences, Vol. 4 (Academic Press, New York, 1974), pp. 1-72. (8) A. N. Martin, J. Swarbrick, A. Cammarata, and A. H. C. Chun, Physical Pharmacy (Lea & Febiger, Philadelphia, 1969), p. 500. (9) L. H. Block and P. P. Lamy, The rheological evaluation of semisolids, J. Soc. Cosmet. Chem., 21, 645-660 (1970). 258 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS