Papers by Keyword: Sonication

Abstract: Nanolubricants are a critical topic currently due to their outstanding thermal conductivity and system performance. A highly stable nanolubricant dispersion is extremely useful for good lubrication performance. However, maintaining their dispersion stability over time is still a major challenge in this field. As a result, the goal of this paper is to evaluate the influence of sonication duration on the stability and thermal conductivity of nanolubricants. In this work, 0.1 vol% concentrations of graphene (Gr) and aluminium nitride (AlN) nanoparticles and polyolester oil (POE) as the base fluid are used. The duration of mechanical stirrer is constant however the ultrasonication time is varied. The stability of nanolubricants are observed by using visual observation technique for 21 days and measured by thermal conductivity and Zeta potential. The results show that the 45 min of sonication time for AlN and 15 min of sonication time for Gr are the optimum time for the ultrasonication.

Abstract: Hydroxyapatite (HAp) nanoparticles from limestone were successfully synthesized using the precipitation method. HAp synthesis was carried out with variations in the aging time of 12, 24, 36, and 48 hours with sonication treatment. The HAp nanoparticles structure was characterized using FTIR, XRD, and SEM-EDX. The functional groups PO₄^3-, OH-, and CO₃^2- were detected by the infrared spectrum as the main groups of HAp nanoparticles. The hexagonal crystal structure of the HAp nanoparticles was confirmed on the XRD result. A non-uniform particle size of HAp nanoparticles detected on the SEM results undergoes agglomeration. In addition, the particle size ranged from 82.7 nm - 104.9 nm and decreased due to sonication treatment. In this study, it could be proved that the precipitation and sonication treatments are excellent for producing HAp nanoparticles.

Abstract: Addition of Microcrystalline Cellulose (MCC) as filler in to Unsaturated Polyester (UPR) polymer can enhanced the properties of the composite. UPR and MCC was prepared using sonication mixing technique at various loading of (2, 4, 6, 8, and 10 wt %) of MCC at a constant of 60 minutes of sonication. UPR and MCC was mixed in a vial bottle and then immersed in sonication bath for the sonication process. Once the sonication completed, the mixture was added with Methyl Ethylene Ketone Peroxide (MEKP) as curing agent, coated on steel plate and was left for curing process of 7 days. The coating was studied for adhesion, mechanical and corrosive properties using pencil hardness, adhesion tape and immersion tests. 4 wt% of loading showed improvement in mechanical properties where form H grade to 4H grade. It is also recorded there are improvement of adhesion test from 1B grade 35-65% pulled out to 4B grade which is less than 5 % pulled. From the immersion test, it shown that 4 wt % of loading has a good corrosion resistant as compared to the control sample. Thus, it was concluded that 4 wt % of loading filler is suitable to be used because it promotes a better mechanical and adhesion properties and also good corrosion resistant compared to other loading percentage.

Abstract: In this study, the Multi-Walled Carbon Nanotube (MWCNT) and polydimethylsiloxane (PDMS) were prepared by using simple solution mixing method. However, the MWCNT have an issue to achieve stable polymer composite because the nanotubes can easily agglomerate and causes bundling when dispersed in polymer. Thus, the MWCNT was dispersed in toluene using mechanical stirring and sonication process. As a result, sonication process shows excellent dispersion of MWCNT with toluene compared to mechanical stirring method. To prepare conductive polymer composite, MWCNT with 2, 4, 6, 8, and 10 wt% concentrations were used. The dispersion processes of MWCNT in PDMS were characterized using Raman Spectroscopy. The intensity of D-band and G-band, I_D/I_G band decreases from 1.20 to 1.10 as the MWCNT content (6 wt% to 10 wt%) increases. This indicates less MWCNT defect occurred during dispersion process. Besides, the electrical conductivity of MWCNT/PDMS composite was investigated by using two point probe method. The conductivity of fabricated MWCNT/PDMS composite is in the range of 10⁹ to 10⁶ S/cm and a low percolation threshold is achieved at 4 wt% of MWCNT concentration in PDMS. Extension of this study is needed to improve the electrical conductivity of MWCNT/PDMS composite.

Abstract: In this work, graphene was produced by liquid-phase exfoliation of graphite in different organic solvents with addition of picric acid. The graphene was easily produced by one step ultra-sonication of graphite powder in the organic solvents. The addition of picric acid has increased the graphene production yield in most of the solvents tested in this work. Picric acid serves as a “molecular wedge” to intercalate into the edge of graphite, which plays a key role during sonication and significantly improves the production yield of graphene. The products were analyzed by microscopic techniques, including atomic force microscopy (AFM) and scanning electron microscope (SEM). The AFM images indicate that the exfoliation efficiency and amount of graphene increased by addition of picric acid in organic solvents. Moreover, the AFM images also indicate presence of bilayer graphene. SEM analysis also shows that the addition of picric acid into the organic solvent favors the exfoliation process. The produced graphene was also analyzed by XRD, FTIR, Raman and UV-visible spectroscopy. The XRD results illustrate that exfoliation was best achieved in N-methyl-2-pyrrolidone (NMP) as a solvent. FTIR and Raman results indicate that addition of picric acid has slightly defected the produced graphene surface. The amount of graphene concentration was calculated by using Beer Lambert law, and it was observed that the graphene production yield was increased by using picric acid in most of the solvents. The maximum amount of graphene concentration (0.159 mg/ml) was achieved by adding 30 mg of picric acid in NMP.

Abstract: Acid treatment of mordenite was conducted using acetic acid to increase the Si/Al ratio. The acid treatment of mordenite by acetic acid was performed using sonication. The various time of treatments was used to investigate the effect of sonication in acid treatment of mordenite. Mordenite and all samples after treatment were characterized by ICP, FT-IR, XRD, and ammonia adsorption to measure their acidity. The Si/Al ratio of mordenite was increased from 11.33 to 17.31, 19.47, and 20.58 respectively for 3, 6, and 9 h of sonication. This result was supported by the T‒O bond vibration of samples which shift to higher wavenumber. The increase of the Si/Al ratio was followed by the decrease of acidity. The XRD test result revealed partial loss of mordenite framework after acid treatment. The results indicated that the sonication method can be used for acid treatment of mordenite.

Abstract: Nanocarbons (NCs) have exceptional mechanical, electrical, and thermal properties as compared to conventional carbon fibers. In previous studies, chemical agent has been used to disperse NCs in the colloid. The main objective of this study is to investigate the dispersion stability of NCs in distilled water and measurement the Zeta Potential value after using ultrasonic dispersion method (physics method). Two types of NCs were used in this study, carbon nanotube (CNT), and Carbon nanofiber (CNF) with different amounts and sonication time of 2 to 12 minutes. The field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) is utilised to inspect the efficiency of the dispersion methodology. The result has shown the significate dispersion of NCs. It was found that the Zeta Potential was 57.5 mV, and 50.9 mV for CNT, and CNF respectively after one month of sonication process. Moreover, the result indicates that the solution is in good stability according to ASTM standard D418-82. Thus, this physical method used in this study can be further considered as a potential method for NCs dispersion when mixed with a different application. Keywords: Nanocarbons, Dispersion, Zeta Potential, Sonication, Nanomaterials

Abstract: Generally it is difficult to disperse nanosized particles uniformly in metal matrix. In this paper nanoSiC particles reinforced Al-5%Cu matrix composites were prepared by molten-metal process, combined with high energy ball-milling and ultrasonic vibration methods. Ultrasonic vibration treatment (UV) has been successfully used to disperse the particles distribution of nanoSiC_p particles in the matrix. Big aggregates of particles are eliminated by the effects of cavitation and the acoustic streaming of UV for 1 min. All the particles aggregates are eliminated and the particles are uniformly distributed in the melt after treated by UV for 5 min. The refinement of Al₂Cu phase in Al-Cu alloy is more obvious and more uniform distributed with the increase of UV time. The ultimate tensile strength (UTS), yield strength and elongation of the 1wt% nanosized SiC_p/Al-5Cu composites treated by UV for 5 min are increased by 37%, 9.5% and 270% respectively, compared with the untreated composites.

Abstract: The research is to investigate influence of sonication treatment on the morphologi and mechanical properties of bioplastic filler nanoclay with different nanoclay concentration. The bioplastic was prepared using blending method among bioplastic, glycerol, and nanoclay with assistance of sonication treatment of 30 mins. Structural characterization of bioplastic was examined using scanning electron microscopy (SEM), mechanical properties using durumeter Shore A, tensile strength and the physical properties using density. SEM evidence on a bioplastic basis. Hardness of bioplastic with addition of nanoclay 5.0% (b/b) and sonication treatment produce bioplastic with maximum hardness properties increased to 76.24 Shore A, tensile strength of 13.5 and Young’s modulus of 47, as well as the added density of 1.238 g/cm³. Nanoclay 7.5% (b/b) upwards will experience decreased hardness and experience agglomerate and debonding.

Abstract: This study focused on the mixing methods used in the manufacture of ultra-high molecular weight polyethylene (UHMWPE) reinforced by multi-walled carbon nanotubes (MWCNTs) and how these methods enhance the wear performance of the composite. Two mixing methods, ball milling and ultra-sonication, were used in this study, and the most effective forms of these mixing methods were analysed to allow an effective comparison. The performance of the mixing methods was evaluated through a comparison of wear volume loss, coefficient of friction, and hardness. The optimal power and mixing time for sonication in this study was determined and composites with 0.5% CNTs w/w concentration were conformed. It was evidenced that the mixing process influence the mechanical and wear performance of UHMWPE / MWCNTs composites and ultrasonication was identified as an effective mixing method that improves significantly the wear performance of the composite.