• The Journal of Advanced Prosthodontics
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• v.4 no.1
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• pp.30-36
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• 2012

PURPOSE. The aim of this in-vitro investigation was to describe the effect of reinforcement with different fibers on impact strength of heat polymerized poly-methyl methacrylate (PMMA) denture base resin and to analyze the effect of surface treatment of the fibers on the impact strength. MATERIALS AND METHODS. The specimens were fabricated from the dies formed as per standard ASTM D4812. 2% by weight of glass, polyethylene and polypropylene fibers were incorporated in the PMMA resin. The Izod impact testing was performed on the unnotched specimens and the values obtained were analyzed using appropriate one way ANOVA, followed by unpaired t-test. Fractured ends of the samples were subjected to the SEM analysis. RESULTS. The polypropylene fibers with plasma treatment showed the highest impact strength ($9.229{\times}10^2$ J/m) followed by the plasma treated polyethylene fibers ($9.096{\times}10^2$ J/m), untreated polypropylene fibers ($8.697{\times}10^2$ J/m), untreated polyethylene fibers ($7.580{\times}10^2$ J/m), silane treated glass fibers ($6.448{\times}10^2$ J/m) and untreated glass fibers ($5.764{\times}10^2$ J/m). Also the surface treatment of all the fibers has shown the significant improvement in impact strength. Findings of the SEM analysis justified the improvement in impact strength after surface treatment. CONCLUSION. Reinforcement with the fiber is an effective method to increase the impact strength of PMMA denture base resin. The surface treatment of fibers further increases the impact strength significantly.

• Journal of Technologic Dentistry
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• v.25 no.1
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• pp.71-79
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• 2003

The purpose of this study was to investigate bond strength of denture base resin repaired according to contamination. One commercial denture base resin and two different kinds of relines resin were tested; Lusiton 199(denture base resin), Vertex(reline resin) and TokusoRebase(repair resin). The specimens were processed according to the manufacturer's instructions to cured denture base resin(polymethylmethacrylate; PMMA) and reline resin. Bond strengths were examined by use of a three-point transverse flexural strength test. Data were analyzed with two-factor analysis of variance and Duncan's post-hoc test at $\alpha$=0.05. Generally, the bondstrength of heat-cured resin(Lusiton 199) was higher than the other resins. The contaminations produced an decrease in bond strength. Therefore the contamination, such as saliva or water must be avoided during the laboratory repair procedures.

• Fire Science and Engineering
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• v.34 no.3
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• pp.1-7
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• 2020

Due to the complexity and large size of buildings, plastic resin is widely used as a building material. Accordingly, the occurrence of fires caused by plastics is increasing. Due to the nature of plastic resin fires, the amount of damage to properties and human life caused by combustion products such as smoke are large, and these damages are related to smoke production and smoke generation. Therefore, this study reviews smoke measurement methods and laws on domestic buildings and fire services. Experiments were conducted based on three smoke-related test standards (ISO 5660-1, ISO 12136, ASTM E 662). The experiment results indicate a total smoke production and generation by PP, PVC, and PMMA of 43.27, 32.83, and 12.33 ㎡, and 27.855, 9.599, and 6.975 g, respectively.

• Journal of the Korean institute of surface engineering
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• v.49 no.2
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• pp.178-185
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• 2016

In this study, we have fabricated light guide plates (LGPs) in thin film form for edge type back light unit (BLU) by using UV imprint lithography. In the LGPs, the pattern of functional resins on PC and PMMA substrates were successfully transferred from original master mold through PVC stamp. Optimized pattern arrays with slowly-sloped density were designed to obtain high brightness and uniformity. We could obtain a relatively improved brightness of $950cd/m^2$ and a uniformity of 87.3% by using the NP-S20 functional resins at an input power of 1.3 W because NP-S20 resin could show high formability after UV hardening process. The LGP prepared on polymethylmethacrylate (PMMA) substrate exhibited higher brightness than that on polycarbonate (PC) substrate because PMMA has lower refractive index resulting in more refraction toward the vertical direction.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.190-191
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• 2000

미세가공 기술을 이용한 초소형 렌즈의 제작 및 연구가 매우 활발히 진행되고 있다. 초소형렌즈의 응용 분야는 바코더 스캐너, 레이저 프린터, 프로젝터, 광 기록 장치, 광섬유를 이용한 광통신 등이 있으며 앞으로도 더 많은 응용 분야를 위한 광범위한 설계와 제작 공정들이 연구되어 갈 것이다. 본 논문에서는 아크릴 레진을 이용하여 초소형 렌즈를 제작하는 공정을 개발하여 새로운 재료와 공정에 대한 가능성을 확인한다. (중략)

• Journal of the Korean Chemical Society
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• v.52 no.4
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• pp.380-386
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• 2008

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.616-626
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• 1993

Polyurethane(PU) have an excellent flexibility and toughness so that it has been widely used as an elastomer. PMMA was blended with PU to improve the impact property. Five types of PU, having different molecular weight and different polyol types, were prepared and blended with PMMA in order to investigate the effect of molecular weight and polyol type of PU on property of PU-PMMA blend. Tensile strength of PU-PMMA blend was determined by Inston. Differential Scanning Calorymetry(DSC) and Scanning. Elctron Microscopy(SEM) were used to observe morphology change and glass transition temperature changes of PU-PMMA blends. Transparency of PU-PMMA blends was determined by haze meter. But, owing to intrinsic incompatability of PU-PMMA, Low impact strength of PMMA wasn't improved through PU-PMMA blend. therefore, polyurethane dimethacrylate(PUD), having similiar chemical structure to PU and two vinyl group at both ends, was prepared and reacted with methyl methacrylate(MMA) to form crosslinked copolymer Mechanical property of this crosslinked polymer, such as impact strength and transparency, was investigated by Instron, Izod type (Cantilever beam) impact tester and haze meter. Results of these measurements showed that crosslinked copolymer of PUD-MMA was better impact resistance than PMMA and maintained similar transparency to PMMA.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.171-176
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• 2013

The need of volatile organic compound (VOC) free coating material has been increased to solve environmental problems such as the global warming. Nowadays, about 70~80% of coating materials used in the worldwide are a liquid type. Therefore, the development of non-solvent coating material that can minimize VOCs emissions is necessary to solve the global warming problem. In this study, acrylic monomers were added to develop non-solvent paints in order to improve disadvantages of the poor adhesion of a conventional phenolic resin caused by acidification. As a result, the blend resins of 2.818 Mpa phenol- formaldehyde resin/poly methyl methacrylate (PE/PMMA) has the best properties and performances for the adhesives.

• Composites Research
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• v.23 no.6
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• pp.39-46
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• 2010

Acoustic emission (AE) signals are detected during the polymerization shrinkage of composite resin restoration in artificial dental ring according to various interfacial treatment conditions. AE amplitudes and the number of AE hit events were compared through the non-parametric statistics of Mann-Whitney method and Kruskal-Wallis method. The AE amplitudes detected from the PMMA and human tooth ring specimens were not significantly different according to adhesive conditions. The stainless steel ring specimen, meanwhile, had a difference in AE amplitude (p<0.05). The quantity of hit events for the human molar dentin specimens of the good bonding state was much less than that for the steel ring specimen but more than that for the PMMA ring specimen. For the same substrate, the better the bonding state, the less the AE hit events (p<0.05). The degree of marginal disintegration measured by SEM was proportional to the amount of AE hit events detected.

• The Journal of Advanced Prosthodontics
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• v.1 no.1
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• pp.1-5
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• 2009

STATEMENT OF PROBLEM. Poor wettability of denture relining materials may lead to retention problems and patient discomfort. PURPOSE. Purpose of this study is to compare and evaluate wettability of nine denture relining materials using contact angle measurements under air and water storage over time. MATERIAL AND METHODS. Nine denture relining materials were investigated in this study. Two heat-curing polymethyl-methacrylate(PMMA) denture base materials: Vertex RS, Lang, one self-curing polyethyl-methacrylate(PEMA) chairside reline resin: Rebase II, six silicone relining materials: Mucopren soft, Mucosoft, $Mollosil^{{R}}$ plus, Sofreliner Touch, GC $Reline^{TM}$ Ultrasoft, Silagum automix comfort were used in this experiment. Contact angles were measured using high-resolution drop shape analysis system(DSA 10-MK2, KRUESS, Germany) under three conditions(in air after setting, 1 hour water storage, and 24 hours water storage). Nine materials were classified into three groups according to material composition(Group 1: PMMA, Group 2: PEMA, Group 3: Silicone). Mean values of contact angles were compared using independent samples t-test and one-way ANOVA, followed by a Scheffe's post hoc analysis($\alpha$=0.01). RESULTS. Contact angles of materials tested after air and water storage increased in the following order: Group 1(PMMA), Group 2(PEMA), Group 3(Silicone). Heat-cured acrylic denture base resins had more wettability than silicone relining materials. Lang had the highest wettability after 24 hours of water storage. Silicone relining materials had lower wettability due to their hydrophobicity. Wettability of all denture relining materials, except Rebase II and $Mollosil^{{R}}$ plus, increased after 24 hours of water storage. CONCLUSIONS. Conventional heat-cured resin showed the highest wettability, therefore, it can be suggested that heat-cured acrylic resin is material of choice for denture relining materials.