Key Engineering Materials Vol. 833

Abstract: Bioadhesives have much potential in the medical field as an alternative to sutures in internal surgery. They are easier to use and have better long-term results. Improvement of a new class of adhesives, tannic acid-polyethylene glycol (TAPE), was done by mixing it with gelatin, since it was found that TAPE alone could not be applied to certain internal applications like in inguinal hernia. It failed to close a fresh inguinal hernia sac. Characterization tests were done on the new material, TAPE-gelatin, which proved to have a tissue adhesion strength of 0.41 MPa which is 5 times greater than fibrin glue, good blood biocompatibility with blood clotting index of 97.46%, burst pressure strength that can withstand 1000 mL that is 10 times more than the volume in the peritoneal cavity, and cheaper, with a production cost of Php28.50, than commercially available bioadhesives, which can reach up to Php2,000 – Php30,000 per application. With its desirable properties, cheaper production cost, and large potential for scalability, TAPE-gelatin as a new candidate for medical adhesive was established.

Abstract: The development of magnesium-based materials, applied for a biodegradable implant, attracted the attention of many researchers. In this research, the initial development of the Mg/carbonate apatite (CA) miniplate was carried out. The miniplate Mg/5CA is fabricated through powder metallurgy and is followed by a sintering process. Pure magnesium is also fabricated with the same process and is used as a reference. The visual form, microstructure (OM), bending test and corrosion test of miniplate were investigated. The results showed that the visual form of the Mg/5CA miniplate is still not perfect. Flexural stress, flexural strain, and elasticity modulus were obtained at 34.02 MPa, 0.9%, and 3.53 GPa, respectively. The corrosion rate is obtained at 12.64 mm/year. The compaction process of Mg/5CA powder followed by sintering is considered to be less appropriate. The addition of the extrusion process and/or the ECAP process in fabrication can be an option to improve its properties.

Abstract: Based on the X-Ray Fluorescence test it was identified that the calcium content in green mussel shells was very high with concentration about 93.83%. The calcium is the main constituent of hydroxyapatite besides phosphorus, so the purpose of this study is to identify a very good potential for synthesized hydroxyapatite from green mussel shells, which is considered the waste of shells that cause environmental pollution. Hydroxyapatite synthesized from green mussels using precipitation method, calcium from green was reacted with phosphate obtained from phosphoric acid. The Fourier transform infrared spectrum show that the functional group in powder is a functional group of hydroxyapatites. The FTIR chart of shellfish hydroxyapatite soaked in acetone and after the precipitation process is heated again to 900°C is the most similar graph to the FTIR commercial HA graph. The results of the X-Ray Diffraction test also prove that the clam shell with this treatment has a diffraction pattern resembling standard hydroxyapatite.

Abstract: The present work is aimed at the synthesis of fluorine substituted and carbonate substituted hydroxyapatites (FHA, CHA) by the mechanochemical method. The shortest milling time required for the synthesis of FHA and CHA using calcium hydroxide and diammonium hydrogen phosphate as precursors was estimated. In addition to the Ca and P precursors, ammonium carbonate and ammonium fluoride were used for carbonate and fluorine substitutions, respectively. Thermal stability of the synthesized FHA and CHA was evaluated. The phase composition and crystallite size were evaluated by the X-Ray Diffraction (XRD). Fourier Transform Infrared Spectroscopy (FTIR) technique was employed to confirm the functional groups corresponding to the FHA and CHA. Thermal stability of the FHA and CHA was determined by the XRD and FTIR studies on the FHA and CHA powders annealed at 900 ^°C. From the XRD and FTIR results, it is observed that the 30 min milling time is the shortest time for the complete formation of FHA and CHA. The powders synthesized with a minimum milling time of 30 min exhibited better thermal stability.

Abstract: Commercial microwave oven 800 W for sintering hydroxyapatite is being developed. The required temperature for sintering hydroxyapatite is 1200°C. A temperature 1200°C can be achieved if commercial microwave combined with susceptor and insulators material. This research is aiming to study about the effect configuration of SiC and Ceramic Fiberboard thickness to temperature rise. The results show that the presence of SiC with a thickness of the thinnest affect significantly temperature rise. The presence of CFb, as a second insulator, decrease the temperature rise and more the CFb thickness increases, more the temperature decreases.

Abstract: Bioactivity is an important aspect in biomaterial science ensuring materials used are safe for clinical application. The study describes fabrication of composites containing polylactic acid (PLA) – polyethylene glycol (PEG) with incorporation of sol-gel derived 45S5 bioactive glass (BG). Thermal analysis via Differential Thermal Analysis shows a favorable point over degree of crystallization that influence cells attachment, although non-significant difference in values indicates BG has homogenously dispersed. This correlates to X-ray diffraction analysis where non-significant difference is seen in intensities of the diffraction peaks, which confirms low impact of BG brittleness properties over the fabricated composite. Composites’ pH and degradation study in Simulated Body Fluid shows a steady increment profile over time and lower degradation rate for the composite after incorporation of BG. In vitro cell proliferation study also showed that HDF cells seeded on composite film of P/BG2.5 exhibit highest cell viability with steady increment of proliferation throughout the observation period.

Abstract: This paper aims to examine the influence of ring stiffener reinforcement on the buckling behavior of cone-cylinder intersection subjected to external pressure. Three different stiffener locations were analyzed; they are (i) cone-cylinder intersection, (ii) cone mid-section, and (iii) cylinder mid-section. Internal and external stiffeners are used in the study. Buckling strength of the stiffened cone-cylinder intersections were obtained with the aid of FE analyses for all the cases above. Cone-cylinder intersections are modelled as elastic-perfectly plastic of Hiduminium alloy (HE-15). Validations of the present results with the published experimental data were presented. Result indicates that the introduction of stiffener reinforcement in externally pressurized cone-cylinder intersections seemed to be desirable in a preliminary design process, thus promotes a stronger shell to resist buckling.

Abstract: This work performs experimental investigations on concrete made with difference replacement percentage of first-class burnt clay brick aggregate (0, 10, 20, 30, 40, 50, 60, 80, and 100%) by steel slag (SS) aggregate. The aim is to evaluate the mechanical properties as well as durability performances, additionally, water absorption porosity test is performed to investigate the influence of steel slag aggregate on the durability of tested concrete. The experimental results have shown that the compressive strength was improved significantly due to the replacement of brick aggregate by steel slag aggregate. The crushing strength of concrete made with 100% steel slag aggregate has gained up to 70% more than the control concrete (100% brick aggregate). However, the porosity of concrete was reduced with the adding percentage of brick aggregate by steel slag aggregate which is consistent with the compressive strength results. Further, a quite good agreement between compressive strength and porosity was observed as well.

Abstract: Tin slag is one of smelting waste that has not been utilized yet. As substitutional, cementious material in concrete replaced the function due to its similar oxide existence with Ordinary Portland Cement (OPC) such as SiO₂, CaO, Al₂O₃, and Fe₂O₃. The objective of this research is to evaluate the corrosion behavior on the surface of carbon steel rebar due to the effect of partial substitution of tin slag in mortar. In this research, final tin slag added with ratio of 0.1, 0.2, 0.3 from total cement. The concrete had been cured for 28 days of immersed in NaCl 3.5% solution for 6 days. The corrosion behavior against steel reinforcement inside concrete measured by Electrochemical Impedance Spectroscopy (EIS) method and the result shows that 20% tin slag from the total of cement give the most competitive corrosion resistance than the others.

Abstract: In this study, the effect of chloride in marine environment on carbon steel reinforcement corrosion was investigated. The nature of corrosion products produced was analyzed through visual inspection and X Ray Diffraction (XRD). It was very difficult using gain and loss technique alone to evaluate passivation conditions and corrosion reactions. It was found that the corrosion rate of steel increases with the increasing of sodium chloride (NaCl) concentration when steel bars without concrete were used. However, a passive film was formed on all steel samples embedded in concrete due to concrete alkalinity. Results reveal that most corrosion products were mainly FeO(OH) along with FeCO₃ and Fe₂O₃.