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This study aims to determine the effect of the amylose/amylopectin contents of starch on the porosity and dielectric properties of porous hydroxyapatite/starch composites. The porous hydroxyapatite/starch composites were prepared by utilizing the starches (rice, corn and potato starch) via gelatinization and retrogradation process. The complex permittivity of the porous hydroxyapatite/starch composites were evaluated in the frequency range of 12.4-18.0 GHz. The porous composites were exhibited the higher average porosity by using the starch with higher amylopectin content. The highly porous hydroxyapatite/starch composites with higher amylopectin content show the significant fluctuation peaks (at 13.8 and 16.6 GHz) and the higher imaginary part of the complex permittivity (ε′′) at higher frequency in the dielectric spectrum, respectively. The real (ε′) and imaginary part (ε′′) of the complex permittivity of the porous composites could be enhanced by increasing the average porosity and the amylopectin contents.

This study aims to investigate the dielectric response of the porous hydroxyapatite/starch composites by varying the starch proportion in determining the feasibility of the microwave sample characterization technique in bone tissue engineering. The porous hydroxyapatite/starch composites were fabricated by using natural starch (gelatinization and retrogradation) through the solvent casting and particulate leaching technique. The dielectric constant (ε′) and loss factor (ε′′) of the complex permittivity of the porous hydroxyapatite/starch composites were measured in the Ku band frequency of 12.4-18.0 GHz. ε′ and ε′′ of the porous composites increase with frequency. The highly porous composite that due to higher starch proportion exhibit higher ε′ and ε′′, resulting in the significant dielectric responses.

Tapioca starch-hydroxyapatite (HA) composites scaffold was fabricated using solvent casting and particulate leaching. The solvent casting involved the casting of polymer while particulate leaching involved the removal of porogen agent. The percentage of tapioca starch used were 50%, 60%, 70%, 80% and 90%, with the percentages of hydroxyapatite (HA) were set as 50%, 40%, 30%, 20% and 10% respectively. Here, sodium chloride was used as a porogen agent. SEM analysis was conducted to determine the micro structural of the scaffold surface. Based on the results, the pore size of composite scaffold is between ranges of 198 µm to 786 µm. For the dielectric study, the dielectric constants (D’) and dielectric loss factor (D”) over frequency range from 12.4 GHz to 18.0 GHz were obtained by transmission line method. Based on the result, both dielectric constant (s’) and dielectric loss factor (s”) was declined with the increment of the frequency.

This study aims to investigate the electromagnetic properties of a composite of hardened glass particle and carbon using resin in determining the absorbability of the composite for electromagnetic interference (EMI). The electromagnetic absorption measurement was conducted using T-R method (transmission-reflection) by measuring the dielectric constant, loss factor, real and imaginary part of permeability, reflection coefficient and transmission coefficient. The measurement is taken for X band frequency and Ku band frequency within the frequency range from 8.2GHz to 12.4GHz and 12.4GHz to 18GHz, respectively. Dielectric constant of sample decrease when frequency increases. The high dielectric constant of material implies that the material has high absorbability of field energy, resulting in high attenuation of the applied field.

Hydroxyapatite commonly used in medical field for tissue disease, bone disease, drug delivery and also for non-medical field purpose such as wastewater treatment. Due to excellent biocompatibility and bioactive properties, hydroxyapatite (HA) which is a group of calcium phosphate (CaP) and similar to the natural bone composition has been broadly ventured in medical area. Synthesising the HA was done via precipitation method by implementing the Corbiculacea (Etok) shells as the resource of calcium precursors. Calcination of Corbiculacea (Etok) shells took place to convert calcium carbonate (CaCO3 ) to calcium oxide (CaO). CaO were then reacted with water to form calcium hydroxide (Ca(OH)2) and later, reacted with phosphoric acid(H 3 PO 4). This experiment manipulated the CaP ratio to study the properties HA formed. CaP ratios used are 1.50, 1.67 and 2.00. The characterization were performed using Energy Dispersive X-Ray Spectroscopy (EDS), Scanning Electron Microscopy (SEM) and Fourier Transformation Infrared (FTIR).