Characterization of Nitrocellulose and Certain Other High Molecular Weight Substances Including Studies of the General Applicability of the Light Scattering Method

Citation

Blaker, Robert Hockman (1950) Characterization of Nitrocellulose and Certain Other High Molecular Weight Substances Including Studies of the General Applicability of the Light Scattering Method. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/0gtm-cd81. https://resolver.caltech.edu/CaltechTHESIS:06302025-200842507

Abstract

A description is given of various instruments which have been designed and constructed. These include: a capillary viscometer for use with volatile solvents; dynamic and static osmometers; a recording apparatus for precipitation titration experiments; and instruments for light; scattering experiments, including a photoelectric photometer, a prism differential refractometer, and an angular scattering camera.

Osmotic pressure and intrinsic viscosity measurements on solutions of nitrocellulose fractions were used to establish a new value of the Staudinger Constant, 9.39 · 10^-3, for nitrocellulose dispersed in acetone at 25° C. The suggestion is made that the value of the ratio of the number average to the weight average molecular weight of a polymer varies with the degree of molecular heterogeneity. The use of this criterion indicates that nitrocellulose manufactured from wood pulp is distinctly more heterogeneous than that from cotton linters.

A technique has been developed for the estimation of the degree of molecular heterogeneity of nitrocellulose by means of precipitation titration. The rate of precipitation in a solution is followed by measuring the decrease in light transmission. The method was found to be useful in the characterization of artificial blends of nitrocellulose.

A detailed description is given of the technique for making light scattering measurements on nitrocellulose solutions. Carbon disulfide is recommended as a light scattering standard. The values determined for the absolute scattering power of carbon disulfide for light of wave length 4358 Å and 5461 Å are, respectively, 15.1 · 10^-5 and 4.8 · 10^-5.

Light scattering measurements on solutions of nitrocellulose fractions indicate that the molecule is relatively stiff, and is nearly fully extended up to a degree of polymorization of about 100. The "effective bond length" is about 10 times the len6rth of the monomer unit. The suggestion is made that the validity of the Staudinger viscosity relation for nitrocellulose is fortuitous and results from the fact that t here is little change in the value of [ƞ]/z over a range of z which is usually encountered in nitrocellulose samples.

The interaction between nitrocellulose and the components of a binary solvent has been studied by light scattering and the results have been interpreted in terms of the recent Kirkwood-Goldberg theory. The data indicate that there is considerable interaction between nitrocellulose and certain non-solvents; for example, water, ligroin, butyl chloride.

An investigation has been :made of the special problems involved in the application of the light scattering method to the study of protein solutions, and a technique has been developed for making such measurements. The method has been used to establish the molecular weight of an antibody from rabbit serum.

A tentative value has been established for the molecular weight of a preparation of Blood Group A-specific substance on the basis of light scattering and osmotic pressure data in conjunction with A. Pardee's viscosity and diffusion data.

A preliminary investigation has been made of the usefulness of the light scattering method for the study of heat denaturation of serum proteins.

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