• Title/Summary/Keyword: multi-resin

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Radial flow advancement in multi-layered preform for resin transfer molding

  • Shin, K.S.;Song, Y.S.;Youn, J.R.
    • Korea-Australia Rheology Journal
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    • v.18 no.4
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    • pp.217-224
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    • 2006
  • Rapid flow advancement without void formation is essential in the liquid composite molding (LCM) such as resin transfer molding (RTM) and vacuum assisted resin transfer molding (VARTM). A highly permeable layer in multi-layered preform has an important role in improvement of the flow advancement. In this study, a multi-layered preform which consists of three layers is employed. Radial flow experiment is carried out for the multi-layered preform. A new analytic model for advancement of flow front is proposed and effective permeability is defined. The effective permeability for the multi-layered preform is obtained analytically and compared with experimental results. Compaction test is performed to determine the exact fiber volume traction of each layer in the multi-layered preform. Transverse permeability employed in modeling is measured experimentally unlike the previous studies. Accurate prediction of flow advancement is of great use for saving the processing time and enhancing product properties of the final part.

Fabrication of Waterproof and Moisture-permeable Polyurethane Nanofiber Multi-Membrane (투습방수성 Polyurethane 나노섬유 Multi-Membrane의 제조)

  • Yang, Jeong-Han;Yoon, Nam-Sik;Kim, In-Kyo;Yeum, Jeong-Hyun
    • Textile Coloration and Finishing
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    • v.23 no.2
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    • pp.107-117
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    • 2011
  • Polyurethane (PU) was synthesized by one-shot process and the PU nanofiber was prepared by electrospinning. In this study, electrospun PU multi-membranes were prepared with various coating thickness ratio of base resin to top resin, where the base resin contains melamine curing agent and acid catalyst and the top resin contains water-repellent agent of fluoro-carbon compounds. The PU nanofiber multi-membranes were analyzed by field-emission scanning electron microscopy, differential scanning calorimeter, breathability, tensile strenth, air permeability and water resistance. The results showed that the PU multi-membrane provided excellent waterproof and moisture permeability.

In vitro Measurement of the Mechanical Properties of Resin Infiltrant: Viscosity, Penetration Pattern, Surface Roughness, Microhardness (초기 법랑질 우식 병소에 대한 Resin infiltrant의 점도, 침투 양상, 표면 조도 및 미세경도)

  • Hong, Seung-Hyun;Kim, Min-Jeong;Cho, Hye-Jin;Yu, Mi-Kyung;Lee, Kwang-Won
    • Journal of Dental Rehabilitation and Applied Science
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    • v.27 no.1
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    • pp.81-90
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    • 2011
  • In this study, we observed the penetration of the resin infiltrant into natural initial caries by SEM and CLSM, evaluated the pH and viscosity of resin infiltrant and several adhesives(All-bond 2, Scotchbond Multi-purpose, Clearfil SE bond), and measured the surface roughness and the microhardness on permanent teeth before and after applied resin infiltrant into initial enamel caries. The viscosity(Pa.s) was observed for resin infiltrant($0.173{\pm}0.012$), All-bond 2($0.754{\pm}0.030$), Scotchbond Multi-purpose($1.46{\pm}0.137$), and Clearfil SE bond($1.28{\pm}0.125$). The pH was measured for resin infiltrant (4.7), All-bond 2(7.5), Scotchbond Multi-purpose(8.2), and Clearfil SE bond(4.67). An application procedure of resin infiltrant increased the surface roughness and the microhardness insignificantly(p>0.05), when compared to non-applied specimens.

A Study on Resin Flow through a Multi-layered Preform in Resin Transfer Molding (수지이송성형시 다층 예비성형체 내부에서의 수지유동 및 투과 계수에 관한 연구)

  • Seong, Dong-Gi;Youn, Jae-Ryoun
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.05a
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    • pp.176-179
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    • 2001
  • When the preform is composed of more than two layers with different in-plane permeability in resin transfer molding, effective average permeability should be determined for the flow analysis in the mold. The most frequently used averaging scheme is the weighted average scheme, but it does not account for the transverse flow between adjacent layers. A new averaging scheme is proposed predicting the effective permeability of the multi-layered preform, which accounts for the transverse flow effect. The new scheme is verified by measuring the effective permeability of the multi-layered preforms and the difference in each flow front position.

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Three-Dimensional Mold Filling Simulation for Multi-layered Preform in Resin Transfer Molding (다층 예비성형체에 대한 삼차원 충진해석)

  • Yang, Mei;Song, Young-Seok;Youn, Jae-Roun
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.04a
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    • pp.137-140
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    • 2005
  • Resin transfer molding (RTM) is one of the most popular processes for producing fiber reinforced polymer composites. In the manufacture of complex thick composite structures, analysis on flow front advancement on the resin impregnating the multi-layered fiber preform is helpful for the optimization of the process. In this study, three-dimensional mold filling simulation of RTM is carried out by using CVFEM (Control Volume Finite Element Method). On the assumption of isothermal flow of Newtonian fluid, Darcy’s law and continuity equation are used as governing equations. Different permeability tensors employed in each layer are obtained by experiments. Numerically predicted flow front is compared with experimental one in order to validate the numerical results. Flow simulations are conducted in the two mold geometries, rectangular plate and hollow cylinder. Permeability tensor of each layer preform in Cartesian coordinate system is transformed to cylinder coordinates system so that the flow within the multi-layered preforms of the hollow cylinder can be calculated exactly. Our emphasis is on the three dimensional flow analysis for circular three-dimensional braided preform, which shows outstanding mechanical properties such as high impact strength and toughness compared with other conventional two-dimensional laminar-structured preforms.

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A study on color characteristics of Multi-color functional Rapid Prototypes Using laser stereolithography (광조형을 이용한 다색 기능성 시작품의 색상특성에 관한 연구)

  • 조진구;정해도;손재혁;임용관
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.05a
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    • pp.824-828
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    • 2000
  • As production cycle has become more and more shorter, the demand of rapid prototyping technology has increased largely. There are many methods for rapid prototyping technology, such as SLA. SLS, FDM. INK JET, LOM and so on. Of all methods, SLA has been most widely used for fabricating precision parts. But products manufactured by this method have limitation of single color and single material. So the principal purpose of this study is to overcome the limit of single color product. If the internal structure of manufactured product is visible with multi-color characteristic, it is possible to check easily the designed model with reality. In order to give multi-color characteristic to the product, photocurable resin mixed with pigment is used in this study. First, transparency of photocurable resin without pigment is evaluated, and then color characteristic and curing characteristic of the mixture is evaluated changing mixing ratio. Through the basic experiments, it becomes possible to fabricate multi-color 3D prototype without assembly.

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Fabrication of Porous Reaction Bonded Silicon Carbide with Multi-Layered Pore Structures (다층 기공구조를 갖는 다공성 반응소결 탄화규소 다공체 제조)

  • Cho, Gyoung-Sun;Kim, Gyu-Mi;Park, Sang-Whan
    • Journal of the Korean Ceramic Society
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    • v.46 no.5
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    • pp.534-539
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    • 2009
  • Reaction Bonded Silicon Carbide(RBSC) has been used for engineering ceramics due to low-temperature fabrication and near-net shape products with excellent structural properties such as thermal shock resistance, corrosion resistance and mechanical strength. Recently, attempts have been made to develop hot gas filter with gradient pore structure by RBSC to overcome weakness of commercial clay-bonded SiC filter such as low fracture toughness and low reliability. In this study a fabrication process of porous RBSC with multi-layer pore structure with gradient pore size was developed. The support layer of the RBSC with multi-layer pore structure was fabricated by conventional Si infiltration process. The intermediate and filter layers consisted of phenolic resin and fine SiC powder were prepared by dip-coating of the support RBSC in slurry of SiC and phenol resin. The temperature of $1550^{\circ}C$ to make Si left in RBSC support layer infiltrate into dip-coated layer to produce SiC by reacting with pyro-carbon from phenol resin.

Optical Characteristics of Transparent Privacy Film with SiO2/SiON Multi-Layer (SiO2/SiON 다층박막 적용 투명보안필름의 광특성 연구)

  • Sung, Hyeong Seok;Kwon, Jin Gu;Chae, Hee Il;Han, Hyeon Seong;Lee, Seong Eui
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.32 no.4
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    • pp.287-295
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    • 2019
  • Privacy films are typically manufactured by combining black resin and transparent louver-shaped patterns. The use of black resin results in excellent light-shielding. However, black resin can reduce the transmittance of privacy films at the front viewing angle. In this study, we applied $SiO_2/SiON$ multi-layer thin films on a privacy film to maintain transmittance at the front viewing angle and improve light-shielding at the side viewing angle. We determined the optimum combination of thicknesses of the $SiO_2/SiON$ multi-layer stacks to increase the overall transmittance; the light shielding could be maximized at the side viewing angle.

A STUDY ON MICROLEAKAGE OF COMPOSITE RESIN AFTER SURFACE TREATMENT (표면 처리방법에 따른 복합레진의 미세누출에 관한 실험적 연구)

  • Lee, Chang-Woo;Kim, Jung-Wook;Lee, Sang-Hoon
    • Journal of the korean academy of Pediatric Dentistry
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    • v.25 no.1
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    • pp.103-115
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    • 1998
  • Adhesion of composite resin to tooth structure has been of tremendous signgicance in clinical dentistry. Due to the lack of adhesion between composite restorative resins and enamel and dentin, microleakage occurs at the tooth/restoration interface. This may lead to discoloration, secondary caries, marginal breakdown, postoperative sensitivity, and even pulpal pathology. According to extensive use of composite resin, every effort on improving bonding strength and reducing microleakage between a tooth and composite resin has been continued. This study was conducted to determine the difference in microleakage in enamel and dentin treated with air-abrasion, acid etching and combination when restored with composite resin. Class V cavities were prepared on 30 premolars. The specimens were divided into following groups. group 1:air-abrasion+Scotchbond Multi-purpose group 4 :air-abrasion+All-Bond 2 group 2:acid etching+Scotchbond Multi-purpose group 5 :acid etching+All-Bond 2 group 3:combination+Scotchbond Multi-purpose group 6 :combination+All-Bond 2 #combination:air-abrasion + acid etching The specimens were filled with Z-100 after application of Scotchbond Multi-purpose and All-Bond 2. Thermocycling was conducted by alternately dipping the specimens in $5^{\circ}C$ and $55^{\circ}C$ water for 30 seconds 500 times. 1% methylene blue was applied and the specimens were left for 24 hours at $37^{\circ}C$. After washing out the dye, the tooth was sectioned buccolingually along the axis. The sectioned surface was observed with stereoscope for dye penetration. The author has measured the microleakage in teeth prepared with air-abrasion, acid ethching and combination to study the difference in microleakage following different methods of tooth surface treatment and has come to following results. 1. In comparing microleakage between groups, group 1 and 4 showed statistically significant difference from group 2, 3, 5 and 6(p<0.05). There was no significant difference among group 2, 3, 5, 6(p>0.05) nor between group 1 and 4(p>0.05). 2. In comparing microleakage among tooth surface treatment methods, Air-abrasion group showed significantly more microleakage than acid etching group and combination(airabrasion + acid etching) group(p<0.05). Combination(acid etching+air-abrasion)group tended to show lesser microleakage than acid etching group, but this was not statistically significant(p>0.05). 3. In comparing microleakage between bonding agents, there was no statistically significant difference between Scotch bond Multi-purpose and All-Bond 2(p>0.05).

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