• Journal of Adhesion and Interface
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• v.22 no.3
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• pp.85-90
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• 2021

Generally, the tensile strength of carbon fiber reinforced composite (CFRP) should be determined to produce this material. The tensile strength was performed based on ASTM D3039, and this test could cause the error by specimens and human. In this research, the CFRP tensile test was performed with different thickness of specimens and tap, adhesive for attaching tap, and pressure of jig to hold the specimens, while the test was performed based on ASTM D3039. The tensile stress and modulus exhibited differently with different specimen thicknesses, and the 1~1.5 mm thickness of the specimen was optimized. In the case of 0.28 MPa jig pressure, the slip or fracture at the clamping area of the specimen has not occurred, and specimens were fractured to the center section of the specimen. The adhesive to attach jig on specimen should be used to exhibit high adhesive stress. Experimental parameters could cause errors. It is expected to achieve an accurate tensile property evaluation of composite materials via improvements in adhesives, tabs, and jigs.

• Textile Coloration and Finishing
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• v.9 no.4
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• pp.47-53
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• 1997

To improve the interfacial bonding of carbon fiber-nylon 6 composite, carbon fiber(CF) were oxidized by nitric acid treatment, and two types of graft polymer(GP) of nylon 6-g-polyacrylamide (PAAm) -water dispersable GP(WDGP) and m-cresol solu ble GP(CSGP) were treated as coupling agents. Introduction of polar groups such as -COOH, -OH, etc, on the surface of the oxidized CF was confirmed by IR spectra. The stem polymer of nylon 6 in the coupling agent (GP) could be compatible with'matrix nylon 5, and the grafted branch of PAAm on GP could react to the polar groups on the oxidized CF in composite. The interfacial strength was measured by the transverse tensile test to the fiber direction for single CF embedded nylon 6 film especially prepared and by the pull-out test method. The interfacial strength of the composite reinforced with oxidized CF is greater than that reinforced with unoxidized CF. The interfacial strength of the composite was increased by treatment of coupling agents(GPs) considerably, and the increasing tendency by the WDGP is greater than that by the CSGP. The optimum conditions of coupling agent treatment are as follows: the concentration, adsorption tlme of GP, and curing temperature are 2%, 20 minutes, and $170^{\circ}$, respectively.

• Textile Coloration and Finishing
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• v.30 no.4
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• pp.313-320
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• 2018

As carbon fiber reinforced composites(CFRP) are widely used in aerospace, automobile, marine, and sports goods applications, they have been studied extensively by various researchers. However, CFRP have been pointed out because of machining problems such as delamination and burr phenomenons. Especially, hole machining process, drilling, has non-smooth features on inlet and outlet surfaces of drilled hole. This kind of machining problem can be controlled to some extent by using high modulus pitch-CF, which has considerable effects on fracture behavior of composite compared with only PAN CF composite. Therefore, PAN and pitch hybridized CF composites were prepared having high strength and modulus. The results demonstrate that the hybrid CFRP specimens with pitch CF offer the good potential to enhance modulus as well as strength properties. Dynamic mechanical, flexural, and impact properties were measured and analyzed. Morphological surface of the composites were also observed by IFS-28, canon after hole machining.

• Textile Coloration and Finishing
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• v.32 no.4
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• pp.245-254
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• 2020

The sheet molding compound composite has been applied divers section. This paper reports processing of carbon fiber reinforced thermosetting composite with diverse resins and which was composed of chopped carbon fiber (30 ~ 60 wt%). Normally the paste that the viscosity is over 15,000 cps has been used in traditional Sheet molding compound (SMC) machine. In this research, SMC machine was designed to make Carbon-sheet molding compound (C-SMC) prepreg which was composed with low viscosity resin (1,800 ~ 2,500 cps increase up to 10,000 cps after aging). In order to confirm the optimal processing condition. Mechanical strength tests including tensile test, shear test, impact test, flexural strength test were conducted on C-SMC composites. Plus we identified the correlation between the mechanical properties and prepreg processing condition (carbon ratio and applied resin).

• Structural Engineering and Mechanics
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• v.55 no.1
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• pp.137-160
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• 2015

The one-way (two-way) flexural strength of RCC prisms (circular slabs) reinforced with glass fiber textiles is addressed. To this end, alkaline-resistant glass fiber textiles with three surface weights were used in the composite, the matrix concrete was designed with zero/nonzero slump, and the textiles were used with/without an intermediate layer provided by epoxy resin and sand mortar. Prisms were tested under a four-point loading apparatus and circular slabs were placed on simple supports under a central load. Effects of the amount and geometry of reinforcement, matrix workability, and the intermediate layer on the ultimate load and deflection were investigated. Results revealed that, with a specific reinforcement amount, there is an optimum textile tex for each case, depending on the matrix mix design and the presence of intermediate layer. Similar results were obtained in one-way and two-way bending tests.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.188-191
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• 2002

3-D orthogonal woven carbon/Al composites were fabricated using a pressure infiltration casting method. Especially, to minimize geometrical deformation of fiber pattern and $Al_4C_3$ formation, the process parameters of the minimum pressurizing force, melting temperature, delay and holding time of molten aluminum pressurizing was optimized through the PC-controlled monitoring system. Resonant ultrasound spectroscopy (RUS) was utilized to measure the effective elastic constants of 3-D orthogonal woven carbon/Al composites. The CTE measurement was conducted using strain gages in a heating oven.

• Advanced Composite Materials
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• v.17 no.3
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• pp.247-258
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• 2008

This paper is concerned with the long-term performance of geo-textile (GT) composites in terms of creep deformation and frictional properties. Composites of PVA GT and HDPE GM were made to investigate the advanced properties of long-term performance related to waste landfill applications. The same experiments were also performed for typical polypropylene and polyester GT and compared to PVA GT/HDPE GM composites. We also develop high performance GT composites with GM by using PVA GT, which is capable of improving the frictional properties and thus enhances long-term performance of GT composites. Experimental study reveals that the friction coefficient of GT composites is relatively large compared with those of polyester and polypropylene non-woven GT as long as the friction media has similar size to the particles of domestic standard earth. In addition, the geo-composites bonded with geo-grid by a chemical process were investigated experimentally in terms of strain evaluation and creep response values. Geo-grid plays an important role as a reinforcing material. Three kinds of geo-grid were prepared as strong yarn polyester and they were woven type, non-woven type, and wrap knitted type. The sample geo-grids were then coated with PVC. The rib tensile strength tests were conducted to evaluate geo-grid products in terms of tensile strength with regard to single rib. The test was performed according to GRI-GGI. It was concluded again from the experiments that the tensile and creep strains of the geo-grid showed such stable values that the geo-grid prepared in this study could protect geo-textile partially in practical structures.

• Composites Research
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• v.36 no.1
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• pp.1-15
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• 2023

Demand for energy consumption reduction is increasing according to the development expectations of future mobility. Lightweight structural materials are known as a method to reduce greenhouse gas emissions and improve energy efficiency. In particular, fiber reinforced polymer composite (FRP) is attracting attention as a material that can replace existing metal alloys due to its excellent mechanical properties and light weight. In this paper, industrial applications and research trends of carbon fiber reinforced composites (CFRP, carbon FRP) and self-reinforced composites (SRC) were reviewed based on the reinforcement, polymer matrix, and manufacturing process. In order to overcome the expensive process cost and long manufacturing time of the epoxy resin-based autoclave method, which is mainly used in the aircraft field, mass production of CFRP-applied electric vehicles has been reported using a high-pressure resin transfer molding process including fast-curing epoxy. In addition, thermoplastic resin-based CFRP and interface enhancement methods to solve the recycling issue of carbon fiber composites were reviewed in terms of materials and processes. To form a perfect matrix-reinforcement interface, which is known as the major factor inducing the excellent mechanical properties of FRP, studies on SRC impregnated with the same matrix in polymer fibers have been reported. The physical and mechanical properties of SRC based on various thermoplastic polymers were reviewed in terms of polymer orientation and composite structure. In addition, a copolymer matrix strategy for extending the processing window of highly drawn polypropylene fiber-based SRC was discussed. The application of CFRP and SRC as lightweight structural materials can provide potential options for improving the energy efficiency of future mobility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.80-85
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• 2016

Carbon fiber-reinforced composite materials have been widely used in various industrial fields, but there are limits to increasing their strength and stiffness, because of the short-length fibers that are impregnated in them. In this study, a lab-scale small extruder system was developed with the capability to perform the carbon fiber impregnation and extrusion process in order to evaluate the properties of long-length carbon fiber reinforced thermoplastic composite materials molded by the LFT-D method. Specimens were made with the small extruder to press-mold long-length carbon fiber composite materials and evaluate their material properties. As a result, it was found that the carbon fiber length, press load and carbon fiber contents have a considerable influence on the strength and stiffness. Additional studies on such factors as the mixing screw design and coating of the carbon fiber are needed in order to improve the mechanical properties of carbon fiber composite materials.

• Advanced Composite Materials
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• v.16 no.4
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• pp.299-314
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• 2007

In the present study, natural fibers (jute, kenaf and henequen) reinforced thermoplastic (poly(lactic acid) and polypropylene) and thermosetting (unsaturated polyester) matrix composites were well fabricated by a compression molding technique using all chopped natural fibers of about 10 mm long, respectively. Prior to green composite fabrication, natural fiber bundles were surface-treated with tap water by static soaking and dynamic ultrasonication methods, respectively. The interfacial shear strength, flexural properties, and dynamic mechanical properties of each green composite system were investigated by means of single fiber microbonding test, 3-point flexural test, and dynamic mechanical analysis, respectively. The result indicated that the properties of the polymeric resins were significantly improved by incorporating the natural fibers into the resin matrix and also the properties of untreated green composites were further improved by the water treatment done to the natural fibers used. Also, the property improvement of natural fiber-reinforced green composites strongly depended on the treatment method. The interfacial and mechanical results agreed with each other.