• Composites Research
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• v.33 no.4
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• pp.228-233
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• 2020

In this paper, a single lap shear test was performed using a glass fiber reinforced composite material (GFRC). Pencil lead drawn paper sensor (PLDPS) was applied for single lap shear test being performed. Bisphenol-A epoxy and amine hardener were used as adhesives combining with composite materials. To make a difference in adhesive properties, the adhesive was cured under different conditions. PLDPS was made of a 4B pencil on A4 paper. Because graphite in a pencil was an electrically conductive substance, electric resistance (ER) could be measured. A change in ER was observed by a position where a PLDPS was attached to single lap shear specimens. It was confirmed that the change in ER was different depending on two attached positions and was observed by lap shear strain as well. In case the lap shear strain was large, the change in ER of PLDPS was high. This was because the larger the extension of the adhesive part, the larger the degree of bending of the specimen and thus the larger the distance change between two electrodes.

• Journal of Adhesion and Interface
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• v.21 no.2
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• pp.65-70
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• 2020

Epoxy adhesive was mainly used to combine different composite materials. Epoxy adhesive was a typical thermosetting resin that can be bonded by changing from a linear structure to a three-dimensional network structure by curing reaction of epoxy and hardener. The curing conditions of epoxy adhesive were different with different types of hardener such as mixing ratio, curing time, and temperature. These curing conditions affected to the adhesive property of epoxy adhesive. In industry, it was difficult to proceed the applying epoxy adhesive and combining two parts immediately. The adhesive property decreased by humidity and pre-curing of epoxy adhesive in waiting time between two processes. In this paper, the glass fiber reinforced composite (GFRC) was combined with epoxy adhesive and adhesion property between epoxy adhesive and GFRCs was evaluated using single lap shear test. The different waiting times and humidity conditions were applied to epoxy adhesive in room temperature and adhesive property decreased as the waiting time increased. In small amount of humidity, the adhesive property increased because a small amount of moisture in the surroundings accelerated the curing reaction. In certain amount of humidity, however, the adhesion property decreased.

• Journal of Adhesion and Interface
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• v.23 no.1
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• pp.1-7
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• 2022

As the wind blades become larger, they tend to be made by mixing glass fiber and carbon fiber, and it is important to increase the properties of the adhesive which adheres the two materials. The physical properties of the adhesive vary depending on the content of the additive and curing conditions. In this study, the change in adhesion strength with the difference between the CNT (Carbon Nanotube) content of the epoxy adhesive and the humidity during curing was evaluated. GFRP and CFRP specimens were prepared and adhered using an epoxy adhesive, and to examine changes in characteristics with carbon nanotube contents and with the humidity during curing of the epoxy adhesive, adhesion strength was evaluated by dividing the difference between carbon nanotube content and humidity. To find out the change with the CNT contents, the intelaminar shear strength (ILSS) test was performed by dividing the contents of the CNT into 0, 0.1, 0.3, 0.5, and 1 wt%, and to confirm the change with the humidity conditions, the adhesive was cured by dividing the humidity by 20, 50, and 80%. From the result of the experiment, the adhesive force decreased when the content was excessively large, although the adhesive property was enhanced by adding CNT to the epoxy adhesive. In addition, it was confirmed that the adhesion characteristics were not changed as the humidity increased.

• Journal of Adhesion and Interface
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• v.21 no.1
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• pp.27-33
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• 2020

Adhesion property of epoxy adhesive was evaluated with different surface roughness of glass fiber reinforced composite (GFRC) and optimized condition of surface roughness was confirmed. Different sizes of alumina (Al2O3) particles were blasted to GFRC to control surface roughness of GFRC using sand blasting method. The surface roughness was measured and quantified via surface roughness tester. Contact angle was measured using four types of different solvents. Surface energies and work of adhesion between epoxy adhesive and GFRCs were calculated with different surface roughness of GFRC. Adhesion property between epoxy adhesive and GFRCs was evaluated using single lap shear test and adhesion property increased with surface roughness of GFRC. The fracture surface of GFRCs was observed to evaluate adhesion property. Finally, the optimized roughness condition of GFRCs was confirmed.