A series of (2-hydroxyethylmethacrylate)( n-propoxy)cyclotriphosphazenes (HPCP) has been prepared by the reaction of N 3 P 3 Cl 6 with n-propanol and 2-hydroxyethylmethacrylate (HEMA) sequentially in the appropriate solvents. These phosphazene compounds are characterized by a combination of Fourier transform infrared, ultraviolet, and nuclear magnetic resonance spectroscopies. It was found that the compounds were soluble in most of the organic solvents, exhibited an absorption between 207-216 nm, and were curable by UV irradiation. After curing, the surfaces of the HPCP-coated woodblocks were transparent and had a fire-retardant property, which has been ascribed to the intumescent behavior during the burning process.
synopsisTwo types of high performance size exclusion chromatographic (SEC) columns were tested for the characterization of starch samples: pbndagel and Aquapore. The mobile phase was dimethyl sulfoxide (DMSO) containing 0.03 M sodium nitrate maintained at 80°C. The results indicated that both pBondagel and Aquapore can be used to determine the relative molecular weight of starch. The exclusion limits for these columns exceed ten million. Preliminary results using pstyragel are also reported. Examples of SEC analysis of starch, including starch with anionic groups, are given.
SynopsisOperation of gel permeation chromatographs in the differential mode provides a sensitive method for detecting small differences in molecular weight distribution between similar samples. The solvent bsed in this case is a dilute solution of the reference polymer in an organic solvent. This solution is used in both the reference and the separation column. Samples of the material to be compared are injected in the normal manner. Only differences between the samples are reflected in the resulting chromatogram. For process control, this offers a simplified data presentation and should lead to easier detection of changes in operating conditions.
SynopsisThe effect of flow rate on efficiency in gel permeation chromatoraphy has been examined over wide ranges of flow rate, i.e., linear flow velocities using columns of different diameters using both organic and inorganic packings. The results indicate a considerable increase in efficiency a t flow velocities below 0.02 cm/s. No lower limit to this increase could be determined due to experimental difficulties. Between flow velocities of 0.02-0.2 cm/s little efficiency is lost. '
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