Semiempirical correlations have been developed between solubility parameters and refractive indices for series of model hydrocarbon compounds and organic polymers. Measurement of intermolecular forces is useful for assessment of material compatibility, glass-transition temperature, and transport properties

Ingham, J. D.

Lawson, D. D.

English

NASA Technical Reports Server

January 1973	 B73-10022 
NASA TECH BRIEF 
NASA Pasadena Office	 -4r 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Method for Estimating Solubility Parameter 
The rapid method for estimation of solubiity pa-
rameter which has recently been developed is of 
great value to laboratory workers because it reduces 
the amount of experimentation and computation 
required to obtain the cohesive density value or the 
solubility parameter of polymers. The solubility pa-
rameter is a measure of intermolecular forces; it is 
useful for assessment of material compatibility, glass-
transition temperature, and transport properties. 
Semiempirical correlations between solubility pa-
rameters and refractive indices for a series of model 
.
hydrocarbon compounds and organic polymers have 
been developed. The correlations are developed from 
theoretical considerations; initially, it is indicated that 
cohesive-energy density is numerically equal to the 
negative potential energy of one cubic centimeter of 
the material (—Ely), where V is the molar volume 
and E is the potential energy of a mole of material. 
Then, the solubility parameter, 6, is defined as the 
square root of the cohesive-energy density, and it is 
noted that its value can be obtained from the heat of 
vaporization and the molar volume. Since the heat of 
vaporization for a polymer cannot be obtained di-
rectly, there is invoked Walden's empirical relation-
ship for obtaining latent heat of vaporization from 
refractive index; after dropping minor terms, the re-
sulting equation for solubility parameter is found to 
be:
6	 [C(n2-1/n2+2)]112 
where n is the refractive index and C is a constant 
which was found to have an average of 305 for fifty 
seven model compounds. However, the value of C
varies significantly for different chemical types, and 
it is necessary to use the appropriate value of C (as 
determined by chemical structure) in order to obtain 
satisfactory values of solubility parameters. Following 
are C-values for a vtiriety of polymers: poly(ethylene), 
254.1; poly(isobutylene), 230.9; natural rubber, 230.9; 
poly(styrene), 287.6; poly(methyl acrylate), 304.5; poly 
(ethyl acrylate), 304.5; poly(propyl acrylate), 304.5; 
poly(butyl acrylate), 304.5; poly(vinylidene chloride), 
330.8; poly(tetrafluoroethylene), 205.1; nitroso rubber, 
205.1. C-values for different chemical types are: 
normal aliphatic hydrocarbons, 254.1 ±11; branched 
aliphatic hydrocarbons, 230.9 ±9.3; aliphatic ethers, 
279.2 ±25.0; aliphatic esters, 353.3 ±30.9; normal 
aliphatic fluorocarbons, 205.1 ±9.5; chiorocarbons, 
330.8 ±53.1; aromatics, 287.6 ±10.4. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP 73-10022 
Patent status: 
NASA has decided not to apply for a patent. 
Source Daniel D. Lawson and John D. Ingham of 
Caltech/JPL 
under contract to 
NASA Pasadena Office 
(NPO-11647) 
Category 04 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19730000022 2020-03-17T06:37:43+00:00Z


Method for estimating solubility parameter

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server