Critical analysis of the graphical determination of Hansen's solubility parameters for lightly crosslinked polymers.
Zellers-ET; Anna-DH; Sulewski-R; Wei-X
J Appl Polym Sci 1996 Dec; 62(12):2069-2080
An analysis of the validity of the graphical procedure for determining Hansen's three dimensional solubility parameters (3DSPs) for use in estimating solvent uptake by lightly crosslinked polymers of the type used in commercial glove materials was performed. The 3DSPs consisted of parameters representing the contributions of dispersion and dipole/dipole forces and hydrogen bonding contributions to a polymer's solubility in a given solvent and, consequently, the extent to which it could be penetrated by the solvent. The graphical procedure was based on immersing the glove materials in a number of solvents, measuring the increase in weight, which was taken as a measure of the material's solubility in the solvents, and plotting the data in a spherical 3DSP coordinate space, and determining the center of the sphere (a circle in a two dimensional coordinate system). The minimum radius that produced a sphere (circle in two dimensional plots) that encompassed all data points could be related to the individual 3DSPs. The method was evaluated by immersing glove materials consisting of butyl, natural, neoprene, and nitrile rubber in 53 solvents at 25 degrees-C. The spheres were constructed by drawing radii corresponding to circles that contained data points for weight gains of 10%, 50%, or 200%. The experimentally measured weight gains ranged from 0.8% for ethanol (64175) in butyl rubber to 887% for chloroform (67663) in nitrile rubber. Relative standard deviations (RSDs), based on two to 14 replicate measurements, were 10% or less for 96% of the solvent/glove combinations. The RSDs for most of the remaining solvent/glove combinations did not exceed 18%. Attempting to determine the circle or sphere presented a number of difficulties that impacted seriously on the reliability of the 3DSP estimates. For example, determining the smallest circle that encompassed all of the solvents meeting the specified uptake criterion, such as 10% uptake, proved to be arbitrary. In many cases when the circles drawn on the two dimensional plots were compared, it was found that the spherical coordinate space defined by the radii was not really spherical. The authors conclude that the graphical method for estimating 3DSPs for lightly crosslinked polymeric glove materials is inefficient and unreliable. Alternative methods for estimating the 3DSPs which are more efficient and more consistent with known theories of polymer/solvent interaction phenomena are needed.
NIOSH-Publication; NIOSH-Grant; Control-technology; Synthetic-rubbers; Organic-solvents; Physical-properties; Chemical-properties; Gloves; Mathematical-models; Laboratory-testing; 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