Studying the Ultrasonic Properties, DC Conductivity and Coefficient of Thermal Conductivity of PVA-Egg Shells Composites

Abstract

The polymer composite used in the present study were made of polyvinyl alcohol (PVA) as a matrix and Iraqi egg shells as filler. Polymer composites were fabricated by mixing PVA with (5, 10, 15, 20, 25, 30, 40 and 50) wt.% of egg shells powder by using a magnetic stirrer at temperature 90⁰C for 4hr to obtain homogeneous solution then samples were prepared by casting techniques. The ultrasonic measurements (transmittance, absorption coefficient and relaxation amplitude, acoustic impedance, compressibility and compressibility) of composites were carried out by using ultrasound technique. Measurement of DC conductivity and coefficient of thermal conductivity were done as a function to wt. % of egg shells. It was found that the samples contain additives of eggshells 5%, 10%, 20% and 30%, the attenuation decreased by increasing frequency up to 40 KHz and then increased after this frequency; while the sample contains 15% of the eggshells, the attenuation not alter significantly with increasing frequency. Sample with 50 % egg shell has two peaks at 20 and 30 kHz. As can be seen that the samples which contain a proportion of eggshells 5, 10, 20, 25, 30 and 40%, the transmittance coefficient increases with increasing frequency up to 40 kHz and then decreases and  relaxation amplitude decreases with increasing frequency from 5 to 50 KHz. Generally observed acoustic impedance decreases with increasing eggshells except percentage 20%, where the highest value for the impedance. Compressibility generally increases with increasing of eggshells up to 40 % and then decreases. The electrical conductivity increase as concentrations of egg shells increase up to 30 % then conductivity decreases at 40 % then increases slightly at 50 %. It was found that coefficient of thermal conductivity increases with increasing of egg shells up to 40 % then decreases.

Keywords:PVA, egg shells, ultrasonic properties, dc conductivity, coefficient of thermal conductivity.