Homogeneous CaO-P2O5 and Cu2O-CaO-P2O5 glasses were prepared using a meltquenched method under controlled conditions. The binary glasses were found to be colourless and transparent while the ternary glasses changed from light green to dark green as the Cu2O content increased. From the absorption edge studies, the values of the optical band gap, Eopt and Urbach energy, ΔE were evaluated. The position of the absorption edge and hence the optical band gap were found to depend on the glass composition. Analysis of the optical band gap shows that for the binary glasses, the value increases as the content of CaO decreases, while for the ternary glasses, the value of the optical band gap increases as the content of the Cu2O decreases. The density of the glasses was also measured and was found to increase with the increase in CaO and Cu2O contents.

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The effect of starch granule sizes, shapes, composition, and frequency on the dielectric properties (dielectric constant, loss factor, and conductivity) of native and hydrothermally modified starches (potato, corn, and rice starch) are investigated in this work. Dielectric properties are determined from 5 Hz to 5 GHz. The modified starches exhibit lower dielectric properties than the native starches from 5 Hz to 5 GHz due to the disruption of the native polysaccharide’s molecular arrangement. The modified potato starch shows the highest loss factor (208.12 at 50 Hz and 19.95 at 500 Hz) and stable conductivity (~5.33 × 10−7 S/m at 50 Hz and 500 Hz) due to the larger continuous network structure after hydrothermal modification. The rice starch shows the largest difference in dielectric constant (47.30%) and loss factor (71.42%) between the modified form and native form in the frequency range of 5 MHz–5 GHz. This is due to the restriction of dipole motions in the closely packed structure after hydrothermal modification. The findings indicate that the quality of starch modification can be characterized by dielectric properties for assisting starch-based plastic production’s design.

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