• Food Engineering Progress
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• v.21 no.3
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• pp.233-241
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• 2017

Scaffolds of cell substrates are biophysical platforms for cell attachment, proliferation, and differentiation. They ultimately play a leading-edge role in the regeneration of tissues. Recent studies have shown the potential of bioactive scaffolds (i.e., osteo-inductive) through 3D printing. In this study, rice bran-derived biocomposite was fabricated for fused deposition modeling (FDM)-based 3D printing as a potential bone-graft analogue. Rice bran by-product was blended with poly caprolactone (PCL), a synthetic commercial biodegradable polymer. An extruder with extrusion process molding was adopted to manufacture the newly blended "green material." Processing conditions affected the performance of these blends. Bio-filament composite was characterized using field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDX). Mechanical characterization of bio-filament composite was carried out to determine stress-strain and compressive strength. Biological behaviors of bio-filament composites were also investigated by assessing cell cytotoxicity and water contact angle. EDX results of bio-filament composites indicated the presence of organic compounds. These bio-filament composites were found to have higher tensile strength than conventional PCL filament. They exhibited positive response in cytotoxicity. Biological analysis revealed better compatibility of r-PCL with rice bran. Such rice bran blended bio-filament composite was found to have higher elongation and strength compared to control PCL.

• Composites Research
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• v.34 no.1
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• pp.1-7
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• 2021

Fiber-reinforced thermoplastic composites are applied to transport industries to lightweight of body, and applications will be expanded gradually. In this study, the impregnation and mechanical properties of continuous glass fiber (GF) reinforced polycarbonate (PC) composites were evaluated with different molecular weights of PC. The continuous GF reinforced PC composite were prepared by using GF fabric and PC film via continuous compression molding method. The melting flow index and tensile strength of PC matrix were evaluated with different molecular weights. Mechanical properties (tensile, flexural, and compressive) and pore rate of GF/PC composite were evaluated with different molecular weights of PC. The fracture behavior was analyzed to fracture surface of GF/PC composite using FE-SEM images. As these results, it was condition of representing the best mechanical property that the GF/PC composite was prepared by using PC of 20,000 g/mol as matrix.

• Composites Research
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• v.29 no.4
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• pp.125-131
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• 2016

In case of CNT mixing with epoxy, epoxy matrix needs to be diluted. This work studied the effect of the dilution condition of epoxy on CNT dispersion. The optimum solvent condition using acetone and DMF was found via mechanical and solubility methods which affects, the epoxy performance. The dispersion using acetone was better than the DMF and thus higher mechanical properties. Four mixing types of CNT particle were performed. To verify the effects of each step between dilution and dispersion, the dispersion between epoxy and CNT was evaluated via the electrical resistance and optical methods. The optimum dispersion was obtained via mechanical test and thermal analysis by DSC. Among four types, the best was to disperse CNT after epoxy and hardeners were diluted respectively.

• Composites Research
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• v.36 no.2
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• pp.126-131
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• 2023

Growing environmental concerns regarding pollution caused by conventional plastics have increased interest in biodegradable polymers as alternative materials. The purpose of this study is to develop a 100% biodegradable nanocomposite material by introducing organic nucleating agents into the biodegradable and thermoplastic resin, poly(lactic acid), to improve its properties. Accordingly, cellulose nanofibers, an eco-friendly material, were adopted as a substitute for inorganic nucleating agents. To achieve a uniform dispersion of cellulose nanofibers (CNFs) within PLA, the aqueous solution of nanofibers was lyophilized to maintain their fibrous shape. Then, they were subjected to primary mixing using a twin-screw extruder. Test specimens with double mixing were then produced by injection molding. Differential scanning calorimetry was employed to confirm the reinforced physical properties, and it was found that the addition of 1 wt% CNFs acted as a reinforcing material and nucleating agent, reducing the cold crystallization temperature by approximately 14℃ and increasing the degree of crystallization. This study provides an environmentally friendly alternative for developing plastic materials with enhanced properties, which can contribute to a sustainable future without consuming inorganic nucleating agents. It serves as a basis for developing 100% biodegradable green nanocomposites.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.271-278
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• 2012

In this work, we have prepared the nanocomposite by the reaction of mica and zinc oxide, and investigated the application of nanocomposite to UV protecting creams. Mica treated with 3-aminopropyltrimethoxysilane (APTMS) reacted with 1,4-phenylenediisothiocyanate (PDC) to give -N=C=S functionalized surface, which was further reacted with zinc oxides coated with APTMS to give mica-zinc oxide nanocomposites. The composites were characterized by EA, EDS, TGA, SEM, zeta potential measurement, powder XRD, and DRS UV/Vis analyses. Finally, we measured transmittances of ultraviolet protection creams manufactured by using mica composite covered with zinc oxides in the range of 280~400 nm. The nanocomposites developed in this work might be applicable as inorganic hybrid materials for UV protecting creams.

• Elastomers and Composites
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• v.42 no.4
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• pp.209-216
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• 2007

Fatigue life prediction methodology of the rubber component made of vulcanized natural rubber under variable amplitude loadings was studied. The displacement-controlled fatigue tests were conducted at different levels and the maximum Green-Lagrange strain was selected as damage parameters. A fatigue life curve of the rubber represented by the maximum Green-Lagrange strain was determined from the nonlinear finite element analysis. The transmission load history of SAE as variable amplitude loading was used to perform the fatigue life prediction. And then a signal processing of variable loading by racetrack and simplified rainflow cycle counting methods were performed. The modified miner's rule as cumulative damage summation was used. Finally, when the gate value is 30%, the predicted fatigue life of the rubber component agreed well with the experimental fatigue lives with a factor of two.

• The Korean Journal of Ceramics
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• v.3 no.1
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• pp.47-51
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• 1997

The dense sintered bodies of Si/SiC composite with various Si contents could be fabricated by changing the green density in the forming process. The Si/SiC/graphite composites with various graphite contents could be also fabricated by changing a graphite content in the starting composition. Their mechanical and tribological properties were characterized and wear mechanism was also studided. The hardness and strength of the Si/SiC and the Si/SiC/graphite were decreased with increasing the contents of free Si and graphite, respectively. However, the friction coefficient and specific wear rate had no specific relations to their hardness and strength. Adhesion of free Si was a main factor to determine a wear resistance of the Si/SiC composite. In the case of the Si/SiC/graphite, solid lubricationl and liquid reservoir of the graphite particles played the main role of the reduction of the friction force. In the torque test to estimate the possibility of practical of practical applications, the value of torque between the Al2O3 disk and Si/SiC/graphite disk was 1/6 lower compared with two $Al_2O_3$ disks on the basis of 100,000 cycles.

• Structural Engineering and Mechanics
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• v.89 no.4
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• pp.349-362
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• 2024

High-performance fiber-reinforced cement composites (HPFRCC) are new materials created and used to repair, strengthen, and improve the performance of different structural parts. When exposed to tensile tension, these materials show acceptable strain-hardening. All of the countries of the globe currently seem to have a need for these building materials. This study aims to create a low-carbon HPFRCC (high ductility) that is made from materials that are readily available locally which has the right mechanical qualities, especially an increase in tensile strain capacity and environmental compatibility. In order to do this, the effects of fiber volume percent (0%, 0.5%, 1%, and 2%), and determining the appropriate level, filler type (limestone powder and silica sand), cement type (ordinary Portland cement, and limestone calcined clay cement or LC3), matrix hardness, and fiber type (ordinary and oxygen plasma treated polypropylene fiber) were explored. Fibers were subjected to oxygen plasma treatment at several powers and periods (50 W and 200 W, 30, 120, and 300 seconds). The influence of the above listed factors on the samples' three-point bending and direct tensile strength test results has been examined. The results showed that replacing ordinary Portland cement (OPC) with limestone calcined clay cement (LC3) in mixtures reduces the compressive strength, and increases the tensile strain capacity of the samples. Furthermore, using oxygen plasma treatment method (power 200 W and time 300 seconds) enhances the bonding of fibers with the matrix surface; thus, the tensile strain capacity of samples increased on average up to 70%.

• Composites Research
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• v.28 no.4
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• pp.219-225
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• 2015

Air spoiler, which can reduce the drag during operation, can be considered as a possible means to reduce carbon dioxide emission and to increase fuel efficiency. In this study, a composite air spoiler was designed and tested by static and repeated loads. The Green Water Pressure of 0.1 MPa a ship experiences during operation was perpendicularly applied to the air spoiler. Air spoiler was manufactured with sandwich panel which has glass fabric face and balsa core. Multiple sandwich panels were assembled to steel frame by bolt joint. The joint was designed to have bearing failure and examined by static and fatigue tests. Tests showed that the designed joint has enough margin of safety to endure joint failure. The developed sandwich panel to air spoiler is planned to be applied to a large scale commercial ship.

• Korean Journal of Ecology and Environment
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• v.46 no.2
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• pp.225-233
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• 2013

We examined the effect of different field temperatures on water quality improvement (WQI) of natural domestic plant-mineral composites (PMCs). This method was previously used by Kim et al. (2011), to monitor the restoration of water quality of a eutrophic lake, Lake Shingal (Korea). Results indicate that PMCs on phytoplankton, BOD and phosphorus showed more than 70% WQI below $20^{\circ}C$, and less than 40% WQI over $25^{\circ}C$, respectively. The WQIs of PMCs on blue-green algae were gradually decreased with the increase of temperature, whilst diatoms exhibited more than 90% higher WQIs, regardless of water temperature. Additionally, the WQIs on bacterial biomass and total nitrogen were low at all temperatures. These results collectively indicate that water quality improvement activity of plant-mineral composites was dependent on the water temperature, and that the field application of above chemical during temperatures over $25^{\circ}C$, would be less effective in treating a cyanobacteria bloom dominated by Microcystis aeruginosa, than by diatoms.