A New Instrument of the Determination of Molecular Weight By Differential Vapor Pressure

摘要

The differential vapor pressure molecular weight instrument developed previously was subjected to use and further evaluated with regard to sensitivity, reproducibility, and accuracy. To do this, a number of materials having molecular weight in the range 300-to 20,000 were used. The device is capable of measuring number average molecular weights up to 2000 at solution concentrations of 0.1% (gms / lOOcc). In order to extend the range of the instrument to molecular weights of 20,000, it is necessary to work with at least 1% solutions. At these concentrations, the instrument is accurate to approximately±5%, .A glass valve assembly and metal-coated Mylar sensing foils have been developed for use with the instrument. These facilitate the manipulations when making measurements and minimize mainte¬nance problems.