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SynopsisThe preparation of 2WO g. quantities of sharply defined fractions of poly-a-methylstyrene, for use as standards in the correlation of molecular weight methods, is described. The procedure involves a moderately careful synthesis and fractionation. Differences in the light-scattering second Virial coefficient appear to be indicative of differences in the stereoregularity of the polymers prepared by different initiators. The intrinsic viscosities of all of the polymers studied are expressed by a Mark-Houwink equation that is the same in all cases.

the final inflection. This is further demonstrated in the titration of a mixture of citric, maleic, benzoic, and butyric acids shown in Figure 5. The dissociation constants and concentrations of the acidic groups present are listed in Table II. The break is sharp, and the total acidity calculated from the midpoint agrees with the theory.No organic acids having dissociation constants in the range of 10 to 1CD9 were available for study. Acidic materials having dissociation constants of about 10 10 (phenol) are not titrated in this system.

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