Yellow corn meal was extruded in a ZSK30 Werner and Pfleiderer twin screw extruder. Experiments used a surface response method which included variations in screw speed (100-300 rpm), heating temperature (lOO-200°C) and moisture (20-30%) in the feed. Descriptive sensory analysis characterized appearance, aroma, flavor and texture of extrudates. Temperature was the most significant factor affecting Munsell value, airiness, toasted corn aroma, and flavor, denseness, crispiness, chewiness and hardness of extrudates. Temperature and feed moisture had significant effects on Munsell value, surface texture, raw flour aroma, toasted corn aroma and flavor, chewiness and hardness. Interaction between temperature and screw speed had significant effects on airiness and denseness of extrudates.
SynopsisGamma radiation-induced conductivity and permanent conductivity effects produced by high doses of 2 MeV electrons have been measured in two polyiniidazopyrrolone polymers. Radiation-induced conductivity levels are small compared to those found in many common insulating polymers. Permanent increases in dark conductivity produced by accumulated doses of 5X log rad at temperatures up to 300°C are not sufficient to inhibit ultraviolet-visible photoconductivity. High doses of 2 MeV electrons (5x 109 rad) under the same temperature conditions produce no discernible effect on dielectric properties. Both radiation-induced conductivity and permanent dark conductivity increases were much smaller in one polymer (BTDA-DAB), suggesting the possibility of optimizing radiation resistance in this class of polymers by means of chemical structure variation. The radiolytic and thermal stability reported previously for this class of polymers has been generally confirmed, with particular reference to electrical properties.
SYNOPSISPyrrone polymers are found to exhibit substantial photoconductivity, photocurrentdark current ratios of up to 300 being obtained with incident intensities of pofychromatic light of 10-20 m.w./cm2. The condensation product obtained from 3,3',4,4'-benzophenone tetracarboxylic dianhydride and 3,3',diaminobenzidine (BTDA-DAB) is about 4 to 5 times more photoresponsive than the product obtained from pyromellitic dianhydride and the same diamine (PMDA-DAB). Maximum photoresponse is obtained when samples are cured for at least 24 hours at 300°C. A linear dependence of photocurrent on voltage is found in the range 10' to 1 O5 volts/cm. The temperature dependence of photocurrent indicates that photocarriers are produced by more than one mechanism in the temperature range from room temperature to 300°C. Photoresponse is found to be maximum in the ultraviolet-visible region, with a peak response at 610 mp for PMDA-DAB and 550 mp for
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