• Journal of the Korean Wood Science and Technology
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• v.37 no.3
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• pp.222-230
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• 2009

This study was to investigate the effect of alkali treatment for long kenaf fiber to improve fiber surface characterics by removal of wax, lignin and hemicellulose which affect adversely for matrix union. SEM observation was also studied to check out the interface adhesion improvement by the alkali pre-treatment. From the result, interface coherence increased by 3% alkali pre-treatment and reached a maximum by 5% alkali pre-treatment. However, the 3% the bio-composites treated with 3% alkali was highest tensile and flexural strength than other.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.3
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• pp.231-242
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• 2008

Purpose: The purpose of this study was to investigate the bond strength of the core-veneer interface in all ceramic systems. Material and Methods: The all ceramic systems tested with their respective veneer were IPS Empress 2 with IPS Eris, IPS e.max Press with IPS e.max Ceram and IPS-e.max ZirCAD with IPS e.max Ceram. Cores (N=36, N=12/group, diameter: 10mm, thickness: 3mm) were fabricated according to the manufacturer's instruction and cleaned with ultrasonic cleaner. The veneer(diameter: 3mm, thickness: 2mm) were condensed in stainless steel mold and fired on to the core materials. After firing, they were again ultrasonically cleaned and embedded in acrylic resin. The specimens were stored in distilled water at $37^{\circ}C$ for 1 week. The specimens were placed in a mounting jig and subjected to shear force in a universal testing machine(Z020, Zwick, Germany). Load was applied at close to the core-veneer interface as possible with crosshead speed of 1.00mm/min until failure. Average shear bond strengths(MPa) were analyzed with a one-way analysis of variance and the Tukey test(${\alpha}=.05$). The failed specimens were examinated by scanning electron microscopy(JSM-6360, JEOL, Japan). The pattern of failure was classified as cohesive in core, cohesive in veneer, mixed or adhesive. Results: The mean shear bond strength($MPa{\pm}SD$) were IPS e.max Press $32.85{\pm}6.75MPa$, IPS Empress 2 $29.30{\pm}6.51MPa$, IPS e.max ZirCAD $28.10{\pm}4.28MPa$. IPS Empress 2, IPS e.max Press, IPS e.max ZirCAD were not significantly different from each others. Scanning electron microscopy examination revealed that adhesive failure did not occur in any all ceramic systems. IPS Empress 2 and IPS e.max Press exhibited cohesive failure in both the core and the veneer. IPS e.max ZirCAD exhibited cohesive failure in veneer and mixed failure.

• Composites Research
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• v.12 no.2
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• pp.91-100
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• 1999

The manufacture of high strength polyethylene(HSPE) tape yarns has been accomplished by a solid state processing(SSP) method as the compaction of ultra-high molecular weight polyethylene(UHMWPE) powders and drawing of the compacted film under the melting point without any organic solvents. In this study, the characteristics of HSPE tape yarns produced by SSP which is desirable for production cost and environmental aspect were analyzed. As the results, tensile strengths of HSPE tape yarns increased with increasing the draw ratio and the fracture morphology of highly drawn HSPE tape yarns showed more fibrillar shape than the low drawn one. Interfacial shear strengths of HSPE tape yarns with vinylester resin increased by $O_2$ plasma treatment and maximum interfacial shear strength was obtained in the plasma treatment condition of 100W and 5min. In addition, mechanical properties of HSPE tape yarn reinforced composites were investigated and compared with those of the gel spun HSPE fiber reinforced composites.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.324-325
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• 2012

다이아몬드 마이크로 블레이드의 절삭 효율을 향상시키고 소결 공정 중 윤활제의 유동성과 젖음성이 다이아몬드 마이크로 블레이드의 물성에 미치는 영향을 연구하기 위해 Cu/Sn 금속 결합재에 표면을 부식시킨 $WS_2$와 부식을 시키지 않은 $WS_2$ 윤활제를 각각 동일한 체적 분율로 첨가하였다. 윤활제의 표면 개질에 따른 마이크로 블레이드 결합재의 내마모성과 굽힘 강도 시험을 행하였고, 실착 절삭 시험을 위한 마이크로 블레이드 시편을 제작하여 수명 및 효율을 평가하였다. Cu/Sn 금속 결합재 파면에서의 $WS_2$ 입자 방향 분석을 통해 표면 개질 과정을 거친 $WS_2$가 압축소결 공정 중 압축 방향에 수직하게 위치하려는 경향이 크게 나타났으며, 이는 소결체의 강도와 경도를 향상시켰다. 마이크로 블레이드의 절삭 효율 및 수명을 평가하기 위한 실착 절삭 시험 결과, 윤활제 표면 부식처리는 처리하지 않은 경우에 비하여 절삭성능은 비슷하게 관찰되었으나 결합재와의 계면 결함을 줄이므로써 블레이드의 수명을 연장시킬 수 있었다.

• Composites Research
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• v.33 no.5
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• pp.282-287
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• 2020

In the present study, a high-strength polyethylene terephthalate (PET) sheet was fabricated through a densification process of low melting PET fiber (LMF) combined PET sheet. During the thermal heat treatment process of the combined LMF, individual PET fiber was connected, which in turn leads to the improvement of the interfacial bonding force between the fibers. Also, the densification of the PET sheet leads to reduce macrospore density and in return could enhance the binding force between the overlapped PET networks. Consequently, the asprepared LMF-PET sheet showed about 410% improved tensile strength and the same elongation compared to before compression. Besides, the enhanced bonding force can prevent the shrinkage of the PET fiber network and exhibited excellent dimensional stability.

• Restorative Dentistry and Endodontics
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• v.30 no.4
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• pp.319-326
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• 2005

This study compared the microtensile bond strength $({\mu}TBS)$ of single step adhesives to different dentin depths. Superficial or deep dentin was exposed in 30 molar teeth by sectioning immediately under the DEJ or 1.5mm area from central pit, respectively. After polishing with 600-grit SiC paper, the dentin surfaces were assigned to three groups: AQ group-AQ Bond, L-Pop group-Adper Prompt L-Pop, Xeno group-Xeno III. The bonded specimens were sectioned into sticks and subjected to ${\mu}TBS$ testing with a crosshead speed of 1mm/minute. The results of this study were as follows; The ${\mu}TBS$ to superficial dentin was higher than that to deep dentin in all group. The ${\mu}TBS$ of Xeno group was significantly higher than that of L-Pop group and AQ group in both superficial and deep dentin (p<0.05).

• Composites Research
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• v.21 no.4
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• pp.7-14
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• 2008

Prediction of the load-bearing capacity of an adhesive-bonded Joint is of practical importance for engineers. This paper introduces interface fracture mechanics approach to predict the load-bearing capacity of composite metal bonded joints. The adhesion strength of composite/steel bonding is evaluated in terms of the energy release rate of an interfacial crack and the fracture toughness of the interface. Virtual track closure technique (VCCT) is used to calculate energy release rates, and hi-material end-notched flexure (ENF) specimens are devised to measure the interfacial fracture toughness. Bi-material ENF specimens gave consistent mode II fracture toughness $(G_{IIc})$ values of the composite/steel interface regardless of the thickness of specimens. The critical energy release rates of double-lap joints showed a good agreement with the measured fracture toughness. Therefore. the energy-based interfacial fracture characterization can be a practical engineering tool for predicting the load-bearing capacity of bonded joints.

• The korean journal of orthodontics
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• v.29 no.5 s.76
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• pp.599-611
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• 1999

The purpose of this study was to evaluate shear, tensile and shear/tensile combined bond strengths(SBS, TBS, S/TBS) in various orthodontic brackets bonded to human teeth with chemically cured adhesive (Ortho-one, Bisco, USA). Five types of metal brackets with various bracket base configurations (Micro-Loc base(Tomy, Japan), Chessboard base(Daesung, Korea), Non-Etched Foil Mesh base(Dentarum, Germany), Micro-Etched Foil Mesh base(Ortho Organiners, USA), Integral base(Unitek, USA)) were used in this study. Shear, tensile and shear/tensile combined bond strengths according to the direction of force were measured by universal testing machine. The bracket base surface after bond strength test were examined by stereoscope and scanning electron microscope. The assessment of resin remnant on bracket base surface was carried out by ARI(adhesive remnant index). The results obtained were summarized as follows, 1. In all brackets, SBS was in the greatest value(p<0.05), TBS was in 50% level and S/TBS was in 30% level of SBS. 2. In bond strength, Micro-Loc base bracket showed the maximum bond strength($SBS:22.86{\pm}1.37kgf,\;TBS:11.37{\pm}0.42kgf,\;S/TBS:6.69{\pm}0.34kgf$) and Integral base bracket showed the minimum bond strength($SBS:10.52{\pm}1.27kgf,\;TBS:4.27{\pm}1.08kgf,\;S/TBS:2.94{\pm}0.58kgf) (p<0.05). 3. In bond strength per unit area, Integral base bracket showed the minimum value, Micro-Loc base and Chessboard base brackets were in similar value(p>0.05). Non-Etched Foil Mesh base and Micro-Etched Foil Mesh base bracket were similar in SBS and TBS(p>0.05), but Micro-Etched Foil Mesh base bracket was greater than Non-Etched Foil Mesh base bracket in S/TBS(p<0.05). 4. Bond failure sites were mainly between bracket base and adhesive, therefore ARI scores were low.

• Restorative Dentistry and Endodontics
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• v.35 no.2
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• pp.106-115
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• 2010

The purpose of this study was to evaluate the microtensile bond strength (${\mu}TBS$), failure modes and bonding interfaces of self-etching and three self-adhesive resin cements to dentin and indirect composite resin. Cylindrical composite blocks (Tescera, Bisco Inc.) were luted with resin cements (PA: Panavia F 2.0, Kuraray Medical Inc., RE: RelyX Unicem Clicker, 3M ESPE., MA: Maxem, Kerr Co., BI: BisCem, Bisco Inc.) on the prepared occlusal dentin surfaces of 20 extracted molars. After storage in distilled water for 24 h, $1.0\;mm\;{\times}\;1.0\;mm$ composite-dentin beams were prepared. ${\mu}TBS$ was tested at a cross-head speed of 0.5 mm/min. Data were analyzed with one-way ANOVA and Tukey's HSD test. Dentin sides of all fractured specimens and interfaces of resin cements-dentin or resin cements-composite were examined at FESEM (Field Emission-Scanning Electron Microscope). In conclusion, PA and RE showed higher bond strength and closer adaptation than MA and BI when indirect composite blocks were luted to dentin using a self-etching and three self-adhesive resin cements.

• Journal of Adhesion and Interface
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• v.1 no.1
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• pp.30-37
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• 2000

This study focused on the direct blending of bonding agents (resorcinol, hexamethylenetetramine, NaOH) into rubber compound to simplify the composite manufacturing process. The mechanism of direct blending system was studied by comparing the following two cases. The one is direct blending of bonding agents into rubber compound and then allows the reaction (Case I). The other is mixing of reactant obtained by reaction of bonding agents (Case II). According to the morphology analysis, the Case II showed the clean interfacial area between bonding agents and matrix rubber, while the Case I created the new interphase under proper processing condition. Also, the optimum adhesion strength between SBR and nylon cord could be obtained with bonding agents whose molar ratios of resprcinol/hexamethylenetetramine was 1.2/1 in the recipes.