Papers by Keyword: Microwave Processing

Abstract: Polymers modified with carbon nanomaterials exhibit enhanced electrical conductivity. The modifier, which is qualitatively distributed in the polymer matrix, actively absorbs microwave waves even with an extremely small introduced volume (up to 1.5 mass parts). Photographs obtained by scanning electron microscopy indicate a uniform distribution of carbon nanotubes in the matrix of fluoroplastic 4. The microwave treatment of the obtained composites showed a significant increase in the temperature of the samples with a heating time of up to 100 sec. even with minimal amounts of modifier added. Strength characteristics for a uniaxial plant of modified materials after microwave increase by 40-50%. The obtained modified materials based on a non-polar polymer matrix have enhanced characteristics of absorption of microwave radiation.

Abstract: The present investigation is based on fabrication of sisal reinforced high density poly ethylene (HDPE) composites using a novel manufacturing route of microwave processing. Microwave processing was carried out in a multimode applicator at 2.45 GHz with single and multi-layered sisal fibre reinforcement. The comparison between single and multilayered sisal fibre reinforced composites were assessed in terms of tensile, flexural and impact strength. It was found that the multi-layered sisal fibre microwave processed composite has superior properties than single layered reinforced composite. The fractography of tensile fractured surfaces was assessed using electron microscopy. The microwave processed HDPE/sisal composites can be used as a dashboard material of an automobile.

Abstract: Studies of microwave radiation on polymeric materials have shown the possibility of modifying the characteristics of materials. At the same time, the efficiency of the microwave effect can be increased by introducing into the polymer matrix electrically conductive particles (carbon, metal particles, etc.). In this case, the absorption coefficient of the microwave waves is greatly increased. The paper evaluated the physical and mechanical properties of polyamide 6 subjected to microwave exposure. To intensify the microwave, well-proven carbon nanotubes were used, which were added to the polymer in small amounts. The most effective was the addition of carbon nanotubes in an amount of 1 wt%. The data obtained are changes in strength under tensile, Shore D hardness conditions, as well as thermophysical characteristics (heat resistance and change in the specific energy absorption rate in the melting zone of the samples). Microwave can be used as a modifying radiation, and as a method of heating polymers for subsequent molding in products. This method significantly reduces the technological process of obtaining materials and products with improved performance characteristics.

Abstract: An innovative two-step route was successfully applied to the ionic liquid-assisted synthesis of C@ZrSiO₄ ceramic pigments, which is able to reduce the reflux time from many hours to a few minutes. The structure and morphology of the inclusion pigments were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). And the chromatic value of the pigments was measured by the CIE color system. The results show that the pigment in the absence of ionic liquid (IL) exhibited homogeneous single t-ZrO₂ phase, while the samples in the presence of IL showed coexistence of two crystal phases (m-ZrO₂ and ZrSiO₄). The CIE coordination L* value decreased with the increase of TEOS amounts due to the pure zircon formation. The as-prepared pigment showed high tinting ability, as L*=37.16, a*=0.71, b*=0.3, making it promising candidate for ceramic decoration.

Abstract: Energy crisis and continuously fluctuating cost of petroleum have move attention of researchers toward renewable and sustainable energy sources and materials. Biomass or bioresources is one of the abundant and cheap renewable energy sources and materials that is environment friendly in Malaysia and other tropical countries in the world. It has been identified as one of the main sources of the sustainable energy in the fifth fuel strategy in Malaysia. This paper describes several possible routes to provide energy as well as potential value-added products from bioresources. The future trend in thermo-conversion processing of the biomass is the utilization of microwave energy into renewable bio-fuels, materials and chemicals. The potential of uses of bio-oils and bio-chars from oil palm solid wastes for biofuels, materials and chemicals are given. The applications of these renewable sources to produce biofuels, materials and chemicals have been applied in some countries around the world. The implementation of the biomass technology will be best utilized and feasible when the technology is developed locally, fabricated and commission with the utilization of locally produced biomass. With the research and development efforts developed locally towards local expertise will help to produce indigenous technologies, thus reducing the high cost of import technology.

Abstract: Mg-Ti alloys are attractive for structural applications because of low density and improved corrosion resistance by selective oxidation including hydrogen storage and switchable mirror applications. Titanium has a melting point (1670°C) that greatly exceeds the boiling point of magnesium (1090°C) and therefore, alloying of Mg and Ti by conventional methods is extremely difficult. Secondly, the solubility of Ti in liquid Mg is very low and it is difficult to extend solubility by rapid solidification. Physical vapor deposition by electron beam deposition and magnetron co-sputtering has been used to extend the solubility of Ti in Mg. Mechanical alloying and anvil-cell processing at extreme temperatures and pressures have also used to enforce alloying of Mg with Ti. The present paper deals with the consolidation of blended magnesium-titanium powders by microwave heating, an approach that appears highly cost effective.

Abstract: Conventional methods of processing hollow silica granules are tedious, expensive and time consuming. The present work aims at the production of hollow silica granules by a rapid, simple & cost-effective process, by employing microwave heat treatment which reduces the time factor drastically. Microwave processing is an emerging field and is fast catching up as an excellent alternative to the electrical heating methods. Spherical hollow silica granules with in-situ fibrous network were obtained by firing the sol-gel derived silica gel in a microwave furnace. Sol was synthesized using TEOS, distilled water, HCl & Ethanol and was allowed to age in a wide tray at ambient temperature & pressure. The ageing time of the gel was varied from 1-80 days and the characteristics of the granules hence obtained were studied. The temperature of heat treatment was also varied and it was observed that spherical granules form in the temperature range of 1250-1400°C. For comparison, the same gel was heat treated in a conventional furnace and the characteristics of the granules hence obtained were also studied. It was observed that conventionally sintered granules were less dense than the microwave derived ones but were not hollow. This paper describes the processing of hollow silica granules and the effect of gel ageing duration and temperature of sintering on the final product obtained.

Abstract: Natural fiber based bio-composites are gaining prime importance these days because of their high strength to weight ratio and environmental benefits. An increase in the application spectrum of these materials necessitates cost effective high quality processing in order to meet the stringent design requirements. In the present investigation, fully biodegradable natural fiber (grewia optiva) reinforced poly lactic acid (PLA) composite has been developed. The tensile strength of the composite has been found to increase by 75% of that of the neat polymer. The developed composites have been joined using the adhesive bonding and the microwave joining. The tensile shear strength of the joint has been experimentally evaluated and it has been found that the bond strength of adhesively bonded specimen (4.9% of the parent material strength) is substantially lower as compared to microwave joined specimen (62.85% of the parent material strength). The process of microwave joining has also been simulated using standard Multiphysics software and the results were in close agreement with the experimentally recorded values.

Abstract: The aim of this study was to evaluate the osteoconductive properties of synthetic porous hydroxyapatite prepared by low-temperature microwave processing OssaBase^® HA (SPHA) in comparison with biological apatite, non-sintered deproteinized bovine bone Bio-Oss^® (DBB). The materials were implanted into the bone sockets of the tibia of Beagle dogs for 3 and 6 months. The bone response to granules of the materials of similar sizes was compared. Histological analysis of the specimens with histomorphometry was performed at different times after in vivo implantation. Based on the histological analysis, the level of bone formation in the spaces between the implanted granules and through the interconnected pores of both implanted materials within a cortical region was significantly higher (bone area ingrowth 72–85%) than within a cancellous bone site (bone area ingrowth 16–28%) at three and six months after implantation. According to our study, the bioactive and osteoconductive properties (bone implant contact and bone area ingrown) of the synthetic porous hydroxyapatite are very high and comparable with the biological apatite, non-sintered deproteinized bovine bone. The favourable influence of the high specific surface area and carbonate content of the synthetic, porous hydroxyapatite on bone formation was confirmed.

Abstract: In order to evaluate the pavement performance of recycled asphalt mixture processed by microwave, an experimental method was designed to compare the microwave heating with the conventional heating in recycling affection of asphalt mixture. The samples AC-13 were produced. Conventional and microwave heating performance of modified asphalt recycling test including the rutting test, the trabecular cold bending test, the Marshall immersion test, the freeze-thaw split test, and the splitting strength mechanical properties were test. The experimental results show that it is roughly the same in the high temperature stability and mechanical properties of these two areas, and at low temperature cracking resistance the use of microwave processing can improve the low temperature flexibility to reduce the surface temperature seasonal prone temperature shrinkage cracks and fatigue cracks. The stability on the water by using microwave processing can enhance the asphalt and aggregate adhesion so that mixture enhanced resistance to water damage, there is a better role in improving the water stability. These results could promote microwave recycling and provide the basis for the promotion applications.