Improved methods for the determination of Hansen's solubility parameters and the estimation of solvent uptake for lightly crosslinked polymers.
Zellers-ET; Anna-DH; Sulewski-R; Wei-X
J Appl Polym Sci 1996 Dec; 62(12):2081-2096
Two improved methods for determining Hansen's three dimensional solubility parameters (3DSPs) for use in estimating solvent uptake by lightly crosslinked polymers of the type used in glove materials were developed. The methods were developed using commercial glove materials consisting of butyl, natural, nitrile, and neoprene rubber that were immersed in 53 solvents at 25 degrees-C. The extent of uptake of each solvent by each material was assessed from measurements of its increase in weight after immersion. In the first method, the polymer 3DSPs were determined by computing a weighted average of the 3DSPs from the results of the immersion tests. The weighting factor was defined as the product of the molar volume of the solvent and the fractional uptake of the solvent by the polymer. To evaluate the accuracy of the method, the computed 3DSPs were used along with the Hildebrand-Scott and modified Flory- Rehner equations for the Flory interaction parameter to calculate the solubility of the polymers in the solvents. The computed solubilities were then compared with the experimental values. In the second method, Flory interaction parameters for the 212 solvent/polymer pairs (four polymers/53 solvents) were computed using the modified Flory-Rehner equation and then used to solve for the polymers' 3DSP values by a multiple regression technique. The 3DSP values were used to back calculate the solubilities of the polymers in the solvents which then compared with the experimental values. The densities and molar volumes of the solvents and other parameters needed for the computations were taken from published references. The solubility values of 176 solvent/polymer pairs (83%) determined by method-I came within a factor of two of the experimental values. The best results were obtained with natural rubber where 96% of the estimates came within a factor of two and 100% came within a factor of three of the experimental values. By contrast, only 80% of the solubility estimates obtained with the standard graphical technique used for determining 3DSPs came within a factor of two of the experimental values. Many were off by a factor of 20 or more. The second method yielded solubility estimates comparable to those obtained by method-I although negative values of one of the solubility parameters (representing dipole/dipole interactions) were obtained in the case of butyl and natural rubber. The authors conclude that both alternative methods address several problems associated with the standard graphical method used for determining 3DSPs for lightly crosslinked polymers. The advantages of the two alternative methods over the graphical method were discussed.
NIOSH-Publication; NIOSH-Grant; Control-technology; Synthetic-rubbers; Organic-solvents; Physical-properties; Chemical-properties; Gloves; Mathematical-models; Thermodynamics
Environmental & Indust Health University of Michigan 1420 Washington Heights Ann Arbor, MI 48109-0292
Journal of Applied Polymer Science
University of Michigan at Ann Arbor, Ann Arbor, Michigan