synopsisThe mechanism by which TiOz exerts a phototendering effect on nylon 66 photodegradation has not been previously explained. To aid in the elucidation of this mechanism, the wavelength dependence curves of photodegradation of nylon 66 both with and without Ti02 have been accurately determined. These dat,a, in conjunction with reflectance and phosphorescence measurements, indicate that the phototendering effect of TiOz proceeds by a chemical rather than an energy transfer mechanism.
SynopsisMelt and solution viscosity properties of laboratory-prepared batch polymerized high pressure polyethylene have been found to correlate well with molecular weight. These polymers have narrow and nearly constant molecular weight distributions and contain essentially no long-chain branches. Short-chain branching was found to have little or no effect on the relationships. Polyethylene made in the same reactor having longchain branches had melt and solution viscosity properties which deviated seriously from these relationships. The deviations serve as a semiquantitative measure of long-chain branching. When long-chain branching is absent, the correlations serve as rapid methods of determining a,, for narrow-distribution polymers.
copy before it was run through the chromatographic column and after separation both fractions were identified by their infrared spectra. The sample of diborane obtained by collecting the fraction as it came off the column was spectroscopically pure. This method of purification would prove convenient, especially in preparing standard samples for mass speetrographic fragmentation patterns and infrared calibration runs, where even small amounts of impurities can lead to spurious results.
ACKNOWLEDGMENTThe authors would like to thank Richard J. Kokes for several stimulating and helpful discussions on the subject of vapor phase chromatography.
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