• Applied Chemistry for Engineering
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• v.31 no.2
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• pp.115-124
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• 2020

Sustainable plastics can be mainly categorized into (1) biodegradable plastics decomposed into water and carbon dioxide after use, and (2) biomass-derived plastics possessing the carbon neutrality by utilizing raw materials converted from atmospheric carbon dioxide to biomass. Recently, biomass-derived engineering plastics (EP) and natural nanofiber-reinforced nanocomposites are emerging as a new direction of the industry. In addition to the eco-friendliness of natural resources, these materials are competitive over petroleum-based plastics in the high value-added plastics market. Polyesters and polycarbonates synthesized from isosorbide and 2,5-furandicarboxylic acid, which are representative biomass-derived monomers, are at the forefront of industrialization due to their higher transparency, mechanical properties, thermal stability, and gas barrier properties. Moreover, isosorbide has potential to be applied to super EP material with continuous service temperature over 150 ℃. In situ polymerization utilizing surface hydrophilicity and multi-functionality of natural nanofibers such as nanocellulose and nanochitin achieves remarkable improvements of mechanical properties with the minimal dose of nanofillers. Biomass-derived tough-plastics covered in this review are expected to replace petroleum-based plastics by satisfying the carbon neutrality required by the environment, the high functionality by the consumer, and the accessibility by the industry.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.4
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• pp.497-502
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• 2013

In this study, the interlaminar fracture toughness in mode I of a hybrid composite inserted with different types of non-woven tissues was determined. The interlaminar fracture toughness in mode I is obtained by a double cantilever beam test. The experiment is performed using three types of non-woven tissues: 8 $g/m^2$ of carbon tissue, 10 $g/m^2$ of glass tissue, and 8 $g/m^2$ of polyester tissue. Considering a specimen with no non-woven tissue as a reference, the interlaminar fracture toughness in mode I of specimens inserted with non-woven carbon and glass tissues decreases by as much as 6.3% and 11.4%, respectively. However, the fracture toughness of a hybrid composite specimen inserted with non-woven polyester tissue increases by as much as 69.4%. It is considered that the specimen inserted with non-woven polyester tissue becomes cheaper, and lighter, and the value of the fracture toughness becomes much greater than that of the non-woven carbon tissue.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.3
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• pp.579-588
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• 2018

There are the plastic resin, fiber and the single metal among materials. There is also the inhomogeneous material whose durability is improved as the composite material with the property of light weight. This study notices the composite material with light weight of CFRP. The strength properties of stainless steel and aluminum which have been used generally are compared and analyzed each other with CFRP. The compact tension specimen of the same standard by each material were designed and the simulation tensile analyses were carried out. As the study result, the maximum deformation, maximum stress and maxium strain energy are shown to be about 0.0148mm, 59.104MPa and 0.00529mJ respectively in case of CFRP specimen model. The maximum deformation, maximum stress and maxium strain energy were shown to be about 0.0106mm, 42.22MPa and 0.002699mJ respectively at stainless steel. It could be checked that the maximum deformation, maximum stress and maxium strain energy of aluminum specimen model were shown to be about 0.023mm, 33.29MPa and 0.00464mJ respectively at stainless steel. Therefore, the results at this study are thought to be applied with the basic data on the strength property of CFRP composite material.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.11
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• pp.925-932
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• 2017

In this study, the analysis of plate under torsion was carried out according to stacking angle at the unidirectional carbon fiber reinforced plastic(UD CFRP) among composite materials. In case of UD CFRP, the material property due to stacking angle becomes different. Also, the stacking angles were designated to 15°, 30°, 45°, 60°, 75° and 90° at the study models. The notch hole was applied at the center part by supposing that rivet or hole was used. The analysis method was used by applying the experimental method at ISO 15310. Two jigs were fixed at the lower part and two jigs were descending at the upper part. As seen by the analysis result values at this study, the shear stress happening at the fracture part was seen with the lowest value in case of the stacking angle of 45°. It is known that the case of the stacking angle of 45°has the structural safety and durability higher than those of the other stacking angles when the torsion applies. It is thought that this result can be applied to the data of basis which can be devoted to the durability when the torsion is applied at CFRP plate.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.6
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• pp.459-467
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• 2016

Using a line scan camera and a Galvano mirror, we constructed a high-speed line-scanning microscope that can generate 2D images ($8000{\times}8000pixels$) without any moving parts. The line scanner consists of a Galvano mirror and a cylindrical lens, which creates a line focus that sweeps over the sample. The measured resolutions in the x (perpendicular to line focus) and y (parallel to line focus) directions are both $2{\mu}m$, with a 2X scan lens and a 3X relay lens. This optical system is useful for measuring defects, such as spalling, chipping, delamination, etc., on the surface of carbon fiber reinforced plastic (CFRP) holes after machining in conjunction with adjustments in the angle of LED lighting. Defects on the inner wall of holes are measured by line confocal laser scanning. This confocal method will be useful for analyzing defects after CFRP machining and for fast 3D image reconstruction.

• Composites Research
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• v.28 no.4
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• pp.143-147
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• 2015

This paper proposes laser ultrasonic technique for the impact damage inspection of hydrogen fuel tank and proves that the impact damage can be visualized using an ultrasonic wave propagation imager with an easy detachable sensor head as an impact damage inspection tool for hydrogen fuel tanks. Also the performances of the proposed ultrasonic propagation imager support it can be implemented in real-world technology when the hydrogen car becomes popular.

• Fire Science and Engineering
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• v.33 no.3
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• pp.21-28
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• 2019

To examine the mechanical and combustion characteristics of FRTP, either polycarbonate or nylon were used as a matrix, and either glass fiber or carbon fiber were used as the fiber reinforcement. The fiber reinforcement content was differentiated at 0~40 wt%. The tensile strength and heat distortion temperature increased with increasing reinforcement content. When the fiber reinforcement content was above 30 wt%, the flammability rating showed V-0. As the fiber reinforcement content increased from 0 to 40 wt%, the peak heat release rate of polycarbonate decreased by approximately 51% and that of nylon decreased by approximately 24%. The rate of CO generation decreased for a period of time, and then increased. This appears to have resulted from incomplete combustion. The rate of CO₂ generation shows a similar tendency with the heat release rate. As fiber reinforcement content levels increased from 0 to 40 wt%, the CO₂ peak rate of polycarbonate generation decreased by approximately 50% and that of nylon decreased by 28%.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.1
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• pp.62-67
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• 2011

Nanoparticles-coated and impact-damaged carbon-fiber reinforced plastics(CFRP) laminates were tested under compression-after-impact(CAI) mode and the propagation of damage due to compressive loading has been monitored by acoustic emission(AE). The impact damage was induced not by mechanical loading but by a simulated lightning strike. CFRP laminates were made of carbon prepregs prepared by coating of conductive nano-particles directly on the fibers and the coupons were subjected to simulated lightning strikes with a high voltage/current impulse of 10~40 kA within a few microseconds. The effects of nano-particles coating and the degree of damage induced by the simulated lightning strikes on the AE activities were examined, and the relationship between the compressive residual strength and AE behavior has been evaluated in terms of AE event counts and the onset of AE activity with the compressive loading. The degree of impact damage was also measured in terms of damage area by using ultrasonic C-scan images. From the results assessed during the CAI tests of damaged CFRP showed that AE monitoring appeared to be very useful to differentiate the degree of damage hence the mechanical integrity of composite structures damaged by lightning strikes.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.11
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• pp.595-599
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• 2013

The pipes used in buildings are generally categorized into metallic or plastic materials. Metal pipes, such as copper and stainless steel pipes, are mainly used for water and hot water supply, and for the heating system. However, plastic pipes made of polyethylene and cross-linked polyethylene are used for floor heating, water drainage, and air vent systems. Usually, plastic pipes have thermal demerits, such as high linear expansion coefficients and bending phenomenon by hot water, although the pipes have several merits of light weight, low price, low thermal conductivity, and the comparatively high workability of metal pipes. Therefore, if those kind of demerits are overcome, plastic pipes can be easily accepted for hot water systems. This research is aimed to evaluate the applicability for vertical heating pipes of a plastic pipe system consisting of electric fusion fitting of a conductive carbon compound and propylene random glass fiber pipe, through measurement of the expansion rate and leakage in summer and winter seasons, in the apartment construction field.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.5
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• pp.309-316
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• 2022

This paper presents nonlinear numerical analysis results which were compared with the tested tensile strengths of CFRP(Carbon Fiber Reinforced Plastic) laminates with 14 different stacking sequences. The composite laminate coupons were cured under an autoclave pressure using resin-impregnated unidirectional tapes. The nonlinearity of the matrix was considered for the analysis, which was obtained from lamina tests. The Hashin failure criteria and progressive failure analysis were used for the nonlinear finite element analysis. The comparison results show that the current approach is acceptable to predict the tensile strengths of the CFRP laminate coupons with various stacking sequences and no damage. However, it is not acceptable to predict the tensile strengths of the laminate specimens with a center hole.