• Composites Research
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• v.22 no.5
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• pp.8-14
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• 2009

Interfacial evaluation of glass fiber reinforced carbon nanotube (CNT)-epoxy nanocomposite was investigated by micromechanical technique in combination with wettability test. The contact resistance of the CNT-epoxy nanocomposite was measured using a gradient specimen, containing electrical contacts with gradually-increasing spacing. The contact resistance of CNT-epoxy nanocomposites was evaluated by using the two-point method rather than the four-point method. Due to the presence of hydrophobic domains on the heterogeneous surface, the static contact angle of CNT-epoxy nanocomposite was about $120^{\circ}$, which was rather lower than that for super-hydrophobicity. For surface treated-glass fibers, the tensile strength decreased dramatically, whereas the tensile modulus exhibited little change despite the presence of flaws on the etched fiber surface. The interfacial shear strength (IFSS) between the etched glass fiber and the CNT-epoxy nanocomposites increased due to the enhanced surface energy and roughness. As the thermodynamic work of adhesion, $W_a$ increased, both the mechanical IFSS and the apparent modulus increased, which indicated the consistency with each other.

• Journal of the Korea Institute of Building Construction
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• v.24 no.1
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• pp.35-42
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• 2024

This research explores the potential of methyl methacrylate(MMA) as a material for road repair applications. It specifically examines two MMA formulations, referred to as type A and type B, in relation to their performance on concrete substrates. The evaluation criteria included drying time, tensile bond strength, and resistance to alkali. The condition of the substrate surface was varied across three curing environments: constant temperature and humidity(R), immersion in water(W), and immersion in water with chloride ions(N). The findings indicate that type B MMA exhibits a quicker drying time and superior resistance to alkali compared to type A. While type A demonstrated greater tensile bond strength, it failed to maintain adhesion with the concrete base. Based on the parameters tested in this study, type B MMA emerges as the more favorable option for road repair contexts. Nonetheless, the study underscores the necessity for additional testing on asphalt substrates to fully assess the material's durability and applicability for long-term road maintenance.

• Journal of Adhesion and Interface
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• v.10 no.4
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• pp.155-161
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• 2009

The most upcoming technical issue of automotive coating is the compact coating process. Pre-primed coating is the outstanding technology eliminating electro-deposition and primer coating process. The main properties of pre-primed coating for automotive are flexibility, corrosion resistance, and weldability. Therefore, we synthesized the conventional polyester, elastomeric polyester and polyvinylidene fluoride resins and evaluated their properties to use as weldable pre-primed automotive coatings. As the results of flexibility and curing behavior, the elastomeric polyester coating was most appropriate to use for the pre-primed automotive coatings.

• International Journal of Highway Engineering
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• v.16 no.6
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• pp.121-128
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• 2014

PURPOSES : The objective of this study is to evaluate the tack-coating material's properties using the bitumen bond strength(BBS) test and damping test as function of changed curing times. In this study, bonding strength tests were performed according to the curing time of tack coating materials. METHODS : In order to investigate bonding characteristic of tack coating materials, the Pneumatic Adhesion tensile Testing Instrument(PATTI) device is used to measure the bond strength between the tack coating materials and aggregate substrate based on the AASHTO TP-91. Also, damping test as in situ test was used to determine an appropriate traffic openting time for construction vehicle. Four different tack-coating materials were used in this study. The BBS tests were performed a one hour curing and testing temperatures of $5^{\circ}C$, $15^{\circ}C$, and $25^{\circ}C$. Damping test was conducted at 30min, 60min, 90min, and 120 min of curing times with temperatures of $20^{\circ}C$ and $30^{\circ}C$. RESULTS and CONCLUSIONS : The BBS test results show various bond strength as function of tack coat materials. At the same testing condition, A tack coat material shows almost two times higher than D tack coat materials although both materials are satisfied the criteria of material's physical properties. Also, Dampting test results shows similar trend with BBS test result. The damping test result was significantly changed as function of tack coat materials. Based on this study, the tack coating material's curing time is very important. Therefore, both curing time and the bond strength's characteristic has to be considered in standard specification.

• Journal of Adhesion and Interface
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• v.12 no.1
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• pp.16-25
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• 2011

Multi core-shell composite particles were prepared by the water-born emulsion polymerization of various core monomer such as methyl methacrylate (MMA), n-butyl methacrylate (BMA), and shell monomer such as MMA, BMA, stylene (St), 2-hydroxyl ethyl methacrylate (2-HEMA) and acrylic acid (AA) in the presence of different concentration of sodium dodecyl benzene sulfonate (SDBS). The following conclusions are drawn from the measured conversion, particle size and distribution, average molecular weight, molecular structure, glass transition temperature with DSC, morphology, tensile strength and elongation. In the case of the concentration of 0.02 wt% SDBS, the conversion of MMA core-(BMA/St/AA) shell composite particle was excellent as 98%. In the case of the concentration of 0.03 wt% SDBS, the particle size of BMA core-(MMA/St/AA) shell composite particle was high as $0.47{\mu}m$. We confirmed that 3 points of glass transition temperatures appear for multi core-shell composite particles compared to 2 points of glass transition temperatures appear for general core-shell composite particles. We showed that it is possible to adjust glass transition temperatures according to the kind and composition of the inner shell monomer that it is can be used as a adhesive binder material with improved adhesive power.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.2
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• pp.29-51
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• 1990

This study was designed to compre the tensile bond strength of 4-META containging denture base resin to Co-Cr alloys after various surface treatments. Especially the surface treatment of sandblasting the mental with aluminum oxide and treating in oxidizing solution composed of 3% aqueous sulfuric acid with 1% potassium manganate were compared. Effect of surface roughness on bonding was measured after sandblasting with 50um, 300um aluminun oxide and polishing with emery pater. Also the effects of wax and wax solvent on bonding were observed. According to the type of polymerization process, heat-cured Meta-Dent resin and autopolymerizing Meta-Fast resin were used. For some specimnens, the tensile bond strength were measured agter three pre-conditions : 1day after bonding, immersed in water at $75^{\circ}C{\pm}3^{\circ}C$ for 4weeks, under normal ambient condition for 4weeks. The following results were obtained from this study : 1. The bond strengths of resins containing 4-META were significantly higher than those of conventional denture base resins(p<0.05). 2. Autopolymerizing Meta-Fast resin had higher bond strength than heat-cured Meta-Dent, resin(p<0.05). 3. The bond strengths of Biosil and Nobilium to 4-META containging resins were not significally different(p>0.05). 4. Stable adhesion can be achieved when mechanically roughen the metal surface by snadblasting with $50{\mu}m$ aluminum oxide than treating in an oxidizing soluing with potassium manganate(p<0.05). 5. Once the metal surface is contaminated with wax, the bond srtength decreased greatly in spite of wax wash with boiling water. But the bond strength recovered significantly with the use of wax solvent 6. Meta-Dent resin had higher bond strength when roughen the metal surface with $50{\mu}m$ aluminum oxide than with $300{\mu}m$ aluminum oxide(p<0.05). In case of Meta-Fast, resin, the use of $300{\mu}m$aluminum oxide was a little advantageous of bonding, but was statistically insignificant(p>0.05).

• Elastomers and Composites
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• v.33 no.4
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• pp.267-273
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• 1998

Isocyante terminated urethane prepolymers were synthesized by the reaction of 4,4'-dimethyl phenyldiisocyanate(MDI) and ester type polyols such as ethylene glycol/ butanediol adipate(EBA), neopentylglycol/butanediol adipate (NBA) and hexanediol adipate (HA) . All of the NCO-terminated urethane prepolymers are solid at room temperature, but they become mobile enough to be disposed onto a substrate upon heating about $80^{\circ}C$. Subsequently, they are solidified and cured through the reaction with moisture. Tensile behavior of the ore-thane hotmelt exhibits characteristic features depending on the type of polyol. The adhesive strength determined by single lap shear joint is higher in order of HA, NBA and EBA based ore thane hotmelt, which can be correlated with the magnitude of breaking energy of the cured films. The failure mode are cohesive for all cases and the adhesive strength increases as the test is performed faster. This indicates that the strength of the adhesive joint is primarily dependent upon the bulk properties of the adhesives.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.49-54
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• 2020

To attach a stretchable/flexible electrode to something or something to on electrode, conductive adhesives must be stretchable/flexible to suit the properties of the electrode. In particular, conductive adhesive require durability and heat resistance, and unlike conventional adhesives, they should also have conductivity. To this end, Epoxy, which has good strength and adhesion, was selected as an adhesive, and a plasticizer and a reinforcement were mixed instead of a two-liquid material consisting of a conventional theme and a hardener, and a four-liquid material was used to give stretchability/flexibility to high molecules. The conductive filler was selected as silver, a material with low resistance, and for high conductivity, three shapes of Ag particles were used to increase packing density. Conductivity was compared with these developed conductive adhesives and two epoxy-based conductive adhesives being sold in practice, and about 10 times better conductivity results were obtained than products being actually sold. In addition, conductivity, mechanical properties, adhesion and strength were evaluated according to the presence of plasticizers and reinforcement agent. There was also no problem with 60% tensile after 5 minutes of curing at 120℃, and pencil hardness was excellently measured at 6H. As a result of checking the adhesion of electrodes through 3M tape test, all of them showed excellent results regardless of the mixing ratio of binders. After attaching the Cu sheet on top of the electrode through conductive adhesive, the contact resistance was checked and showed excellent performance with 0.3 Ω.

• Journal of Adhesion and Interface
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• v.6 no.1
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• pp.11-18
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• 2005

The capsules were prepared from a phase change material (PCM) of octadecane as a core material and melamine formaldehyde resin as a shell material. The PCM capsule size was varied in the range of $3{\sim}25{\mu}m$. The core contents and sizes of the PCM capsule, were determined by DSC and SEM, respectively. An acrylic coating material which contains butyl acrylate (BA), methyl metacrylate (MMA) and acrylic acid (AA) were synthesized by emulsion polymerization. The films were prepared from the acrylic emulsion and PCM capsules which have various capsule sizes. From the results of SEM experiment, it was observed that the PCM capsules were well dispersed inside the film and the surface of the film became less rough when the PCM capsule size was small. The swelling ratio of the films were not significantly affected by the PCM capsule size. However, the tensile strength and elongation of the films were greatly decreased with increasing the PCM capsule size.

• Journal of Adhesion and Interface
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• v.14 no.4
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• pp.175-182
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• 2013

In this work, we aim to investigate the specific gravity, thermal, and mechanical property changes of solid-state extruded polypropylene (PP)/calcium carbonate composites before and after orientation. For this work, we prepared $PP/CaCO_3$ composites having two different sizes (OM-1 and OM-10). On increasing the filler content, the specific gravity of the composites increases. The specific gravity of the oriented specimen containing filler in PP matrix is found to be much smaller than that of pre-specimen due to the formation of more microvoids. The presence of microvoids in case of oriented composite specimen significantly affected the tensile and flexural properties of the composites. It was observed that the effect of orientation on both flexural strength and modulus is much stronger than the effect of filler contents, regardless of the filler particle size.