Faculty Advisor

Phillies, George D.


The purpose of this project was to use quasi-elastic light scattering spectroscpy (QELSS) to study the temperature dependence of probe diffusion in hydroxypropylcellulose (HPC) solutions. HPC is a polymer that is soluble in water and has no charge. The HPC used in this project had a molecular weight of one million Daltons. The polymer concentration was varied from 0.5g/L to 12.8g/L. The probes used in this project were carboxylate modified polystyrene latex (PSL) spheres, 0.189[mu]m in diameter. PSL scatters light well, so a minimal amount of PSL could be used to study the light scatter of probes in HPC solutions using QELSS techniques. The temperature was varied from 10?c to 35?c in 5? increments. All the spectra that were generated were analyzed with the equation g(?)(q,t)=(1-A[subscript f])exp(-[theta]t[superscript ])+Afexp(-[theta]t[superscript ][subscript f]) and g(?)(q,t)=(1-A[subscript f])exp(-(t/[tau])[superscript ])+Afexp(-(t/[tau]f)[superscript ][subscript f]). Comparison of the analyses showed that several of the parameters had temperature dependence. However, these analyses were not conclusive about whether or not [theta] or [tau] (both parameters for the relaxation rate of the spectrum) was more fundamental as transport coefficients.


Worcester Polytechnic Institute

Date Accepted

January 1999



Project Type

Major Qualifying Project


Restricted-WPI community only

Advisor Department