• 구강회복응용과학지
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• 제22권2호
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• pp.193-202
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• 2006

Objective To evaluate the influence of water storage on the mechanical properties of dental adhesives over 1 and 3 months. Materials and Methods Adhesive resin sheets were prepared by pouring either All-bond 2(AB), Clearfil SE Bond(SE) into a mold measuring $15{\times}15{\times}0.9mm$. After solvent in primer evaporation, the adhesives were light-cured and removed from the mold and divided in two pieces, trimmed to hourglass shape that were used to determine the micro-tensile strength(MTS). Another hourglass shaped metal mold measuring $2.0{\times}1.5mm$ in cross-section area was made to determine the Young's modulus(E). Adhesive specimens for Young's modulus(E) were prepared in the same method. Specimens were stored at $37^{\circ}C$ in distilled water and tested after 1 and 3 months. The data were analyzed by one-way ANOVA and Tukey's test. Results Water storage significantly decreased the micro-tensile strength(MTS) of AB and SE specimens after 1 and 3 months(P<0.05). The Young's modulus(E) were also decreased after water storage for 1 and 3 months, but statistically not significant in each group of AB and SE group respectively. Conclusions Long-term exposure of adhesive resin to water can cause reduction of mechanical properties. It may compromise resin/dentin bonds and affect longevity of restorations.

• 접착 및 계면
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• 제4권3호
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• pp.9-13
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• 2003

본 연구에서는 점착제의 유지력 개선과 pH 조절을 위해 각각 첨가해 주는 가교제와 pH 조절제의 종류 및 첨가량이 수용성 아크릴 점착제의 점착 물성 및 수용성에 미치는 효과를 알아보기 위하여 중합된 점착 시료에 여러 가지의 가교제와 pH 조절를 첨가해 준 후 초기점착력, 유지력 및 점착력 등의 점착 물성과 수용성을 측정하였다. 가교제를 0.2 wt% 미만 첨가해 주었을 때, 초기 점착력은 감소하였고 유지력과 점착력은 증가하였다. 그러나 0.2 wt% 이상 첨가해 주었을 때는 초기 점착력은 증가하였지만 유지력과 점착력은 감소하는 결과를 보였다. 또한 pH 조절제를 첨가해 주었을 때 pH 조절제의 농도가 증가함에 따라 초기점착력과 수용성은 감소하였고 점착력과 유지력은 증가하였으며, LiOH, KOH, NaOH 순으로 점착 물성과 수용성에 미치는 영향이 큰 것으로 나타났다.

• 한국건축시공학회지
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• 제12권5호
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• pp.539-547
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• 2012

To manufacture laminated wood with improved mechanical properties by providing uniform adhesiveness, the adhesive was applied and the plate adhesive was laminated on the wood surface. Then, after laminating the wood on the top part of the adhesivebond, it was heated and dried while the adhesive was stiffened using microwaves, and the test piece was manufactured by compressing it with the press machine for thirty minutes. The temperature and the water content were examined according to the heating time of the wood heated with the microwave, and testing was conducted on the shear strength and flexural strength of the wood. In addition, the microstructure of the adhesive bond between the wood was recorded to confirm the penetrabilityinto the wood structure for the adhesive. After the test was conducted, it was found that the test piece manufactured with wood that has its water content leveled with the microwave heating showed improved shear strength and bending strength compared to the standard test piece. With regard to adhesives, liquefied polyvinyl acetate resin and plate's PVB resin were found to have superior adhesive strength. Also, after filming the cellular microstructure, it was found that when the laminated wood is heated with microwaves, the infiltration of the adhesive into the inside of the wood becomes easy, which makes it effective for improving adhesiveness.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2017년도 춘계공동학술대회
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• pp.111-111
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• 2017

There still exist adhesives that have toxic compounds or consist of those materials in both our life and lots of industries. For instance, formaldehyde adhesive had been still used for woodworking and some medical adhesives had been considered as toxicity problems. In this situation, natural adhesives from raw materials have been suggested as an one of considerable interests. Natural adhesives in recent have been reported fabrication methods via biological materials such as proteins, celluloses, and starches. By-products derived from agricultural something have them richly and each has additional special properties. Using these properties to make natural adhesives, unique adhesives would be attained. In particular, rice-based adhesive is such a good example. Rice-based by-product adhesives have interestingly some pros pertaining to high adhesive strength, excellent water resistance and could dramatically be reduced a formaldehyde a harmful component of plywood. Hence, rice-based adhesive like glues could be applied to lots of industries including agricultural and biological technology. This review paper highlighted some recent development on natural adhesives as a promising biomaterial for agricultural and biological technology fields. The design of agricultural by-product-based natural adhesives were described to demonstrate the application of agricultural and biological technology

• 한국가구학회지
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• 제12권2호
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• pp.1-10
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• 2001

As finger joint method has a high rate of yield and high strength and ease in working, it has been widely used as an end joint method for solid wood and wood based-material. Therefore, we end-joined the material of Pinus densiflora, Quercus variabilis and populus euramericana with polyvinyl acetate adhesive and resorcinol phenol resin adhesive. The effect of difference (0, 0.15, 0.3, 0.45mm) between the dimensions of tip width and root width of the finger (DTRW) on bending strength properties was as follows: 1. In the case of polyvinyl acetate adhesive, DTRW had no effect on bending modulus of elasticity(MOE) and modulus of rupture(MOR) of the three kinds of species, because their bonding layers were destroyed by slippage, not their woody parts. 2. In the case of resorcinol phenol resin adhesive, the material of Quercus variabilis showed an optimal result at 0.15 or 0.3 of DTRW, while the poplar did at 0 of DTRW 3. The differences in efficiency ratio of bending MOR of populus euramericana, Pinus densiflora and Quercus variabilis species according to the kind of adhesive were 13-29%, 23-30% and 45-53%, respectively.

• 접착 및 계면
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• 제9권4호
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• pp.12-16
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• 2008

핫멜트 접착제는 상온에서 고체상태로 존재하나 열에 의하여 활성화되어 지압 정도의 압력으로 접착이 가능하다. 또한 접착속도가 빠르고 공정의 자동화가 가능하며 친환경적인 장점을 가지고 있다. 본 연구에서는 SBS와 석유수지의 종류 및 이들의 조성비가 핫멜트 접착제의 물성에 미치는 영향을 알아보았다. 핫멜트 접착제의 스타이렌 함량 및 $C_9$계 석유수지의 함량이 증가함에 따라 점도, 인장강도, 접착력 및 내열성 등이 증가하는 경향을 나타내었다.

• Structural Engineering and Mechanics
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• 제83권5호
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• pp.693-707
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• 2022

Bonded joints have proven their performance against conventional joining processes such as welding, riveting and bolting. The single-lap joint is the most widely used to characterize adhesive joints in tensile-shear loadings. However, the high stress concentrations in the adhesive joint due to the non-linearity of the applied loads generate a bending moment in the joint, resulting in high stresses at the adhesive edges. Geometric optimization of the bonded joint to reduce this high stress concentration prompted various researchers to perform geometric modifications of the adhesive and adherends at their free edges. Modifying both edges of the adhesive (spew) and the adherends (bevel) has proven to be an effective solution to reduce stresses at both edges and improve stress transfer at the inner part of the adhesive layer. The majority of research aimed at improving the geometry of the plate and adhesive edges has not considered the effect of temperature and water absorption in evaluating the strength of the joint. The objective of this work is to analyze, by the finite element method, the stress distribution in an adhesive joint between two 2024-T3 aluminum plates. The effects of the adhesive fillet and adherend bevel on the bonded joint stresses were taken into account. On the other hand, degradation of the mechanical properties of the adhesive following its exposure to moisture and temperature was found. The results clearly showed that the modification of the edges of the adhesive and of the bonding agent have an important role in the durability of the bond. Although the modification of the adhesive and bonding edges significantly improves the joint strength, the simultaneous exposure of the joint to temperature and moisture generates high stress concentrations in the adhesive joint that, in most cases, can easily reach the failure point of the material even at low applied stresses.

• Journal of Welding and Joining
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• 제24권5호
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• pp.43-48
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• 2006

This paper is concerned with a fracture strength study of composite adhesive lap joints. The tests were carried out on specimen joints manufactured hybrid stacked composites such as the polyester and bamboo natural fiber layer. The main objective of the work was to test the fracture strength using hybrid stacked composites with a polyester and bamboo natural fiber layer. Tensile and peel strength of hybrid stacked composites are tested before appling adhesive bonding. From results, Natural fiber reinforced composites have lower tensile strength than the original polyester. and The load directional orientation and small amount and low thickness of bamboo natural fiber layer have a good effect on the tensile and peel strength of natural fiber reinforced composites. The failure strength of these materials applied adhesive bonding is also affected by fiber orientation and thickness of bamboo natural fiber layer. There for, Fiber orientation of bamboo natural fiber layer have a great effect on the tensile-shear strength of natural fiber reinforced composites including adhesive bonded joints.

• 접착 및 계면
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• 제3권1호
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• pp.43-51
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• 2002

Advanced adhesive technologies and demanding applications of adhesive joints can no longer be developed successfully by the traditional "trial and error" approach. Appropriate technical solutions require reference to a reliable basis of well-established scientific knowledge about the elementary mechanisms of adhesion (i.e. the 'fundamental adhesion') as they are responsible for the capability of the compound w transmit mechanical force between the adhesive and the substrate surface (i.e. the 'practical adhesion'). Adhesion mechanisms also influence the formation of polymer structure in the adhesive and the resulting macromolecular dynamics in the interphase that is formed in the adhesive near to the substrate. These manifold molecular factors rule the macroscopic behaviour of an adhesive bond line in terms of mechanical and other physical properties as well as in terms of durability. This paper reviews the level of refinement that understanding of fundamental adhesion has achieved up to now.

• 폴리머
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• 제39권2호
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• pp.281-286
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• 2015

UV경화형 2-ethylhexyl acrylate(2-EHA)/acrylic acid(AA) 점착제의 점착특성에 대한 경화제 함량의 영향에 대해 조사하였다. 0.01 wt%의 극소량의 MMT가 도입된 아크릴 단량체 혼합물에 각각 0, 0.05, 0.1, 0.3 wt%의 1,6-hexanediol diacrylate(HDDA)를 경화제로 첨가하고 UV조사를 실시하여 점착제를 제조하였다. MMT 도입이 공중합체의 경화 거동과 점착제의 표면 특성에 미치는 영향은 매우 낮았으나, 점착특성의 경우 MMT의 도입으로 분자 사슬의 유연성이 제한되면서 응집파괴(cohesive failure)가 억제되는 것을 확인하였다. 그러나 0.3 wt%의 경화제가 도입된 점착제는 사슬 경직성이 크게 증가하면서 MMT의 첨가가 오히려 점착특성을 저하시키는 것으로 추측되었다. 결과를 토대로 2-EHA/AA 점착제의 경우 0.05 wt%의 낮은 함량의 경화제와 극소량의 MMT의 도입이 박리 시 응집파괴 없이 균형적인 점착특성을 부여하는 것으로 판단된다.