Non-destructive, quantitative characterization of extruded starch-based products by magnetic resonance imaging and X-ray microtomography

Effect of screw configuration on the dispersion of nanofillers in thermoset polymers

This paper deals with the study of screw configuration for dispersing nanofillers in thermoset polymers using an intermesh co-rotating twin screw extruder. The influence of kneading elements on the dispersion of nanoclay in epoxy was examined using 10 different screw configurations. Nanoclay was dispersed in epoxy at a barrel temperature of 5°C and a screw speed of 100 rpm. The combination of right hand kneading block and three/four lobed kneading blocks resulted in uniform dispersion of nanofiller. Positive staggered angle with right hand kneading elements yielded uniform dispersion of the nanofiller. Mechanical properties of epoxy nanocomposites processed with these configurations were better than those of neat epoxy. Excessive shear was associated with four lobed kneading block (4KB)/4KB configuration and hence degradation of polymers leading to shorter chains, whereas inadequate shearing in neutral kneading block (NKB)/NKB configuration led to agglomerations. These observations were evidenced by scanning electron microscopy (SEM) and X-ray diffraction (XRD).

A Method to Determine the Density of Foods using X-ray Imaging

Density of foods is an important physical property, which depends on structural properties of food. For porous foods such as baked foods, accurate measurement of density is challenging since traditional density measurement techniques are tedious, operator-dependent and incapable of precise volume measurement of foods. To overcome such limitations, a methodology was developed using both digital radiography(DR) and computed tomography(CT) x-ray imaging to directly determine density of foods. Apparent density was determined directly from x-ray linear attenuation coefficients by scanning at 40, 60, 80 kVp on DR and 45, 55, 70 kVp on CT. The apparent density can be directly determined using CT however sample thickness is needed to determine density using DR. No significant difference (p<0.05) was observed between density obtained from traditional methods, with density determined from x-ray linear attenuation coefficients. Density determined on CT for all foods with mean 0.579 g/cm3 had a standard deviation, SD = 0.0367 g/cm3. Density determination using x-ray linear attenuation was found to be a more efficient technique giving results comparable with conventional techniques.