지원사업
학술연구/단체지원/교육 등 연구자 활동을 지속하도록 DBpia가 지원하고 있어요.
커뮤니티
연구자들이 자신의 연구와 전문성을 널리 알리고, 새로운 협력의 기회를 만들 수 있는 네트워킹 공간이에요.
논문 기본 정보
- 자료유형
- 학술저널
- 저자정보
- 발행연도
- 2012.1
- 수록면
- 211 - 219 (9page)
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초록· 키워드
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The purpose of this study is to determine and compare the handling and rheological properties of polyvinylsiloxane impression pastes before mixing and during setting, and to investigate the effect of its constituents on the properties of the materials. Five polyvinylsiloxane impression materials (Examixfine, Extrude, Honigum, Imprint II, and Express) were used. A flow test and a drip test were performed to determine the handling characteristics. The rheological properties of each impression material prior to mixing (shear stress, viscosity) and during setting (storage modulus G', loss modulus G", loss tangent $tan{\delta}$) were measured with a stress-controlled rheometer at $25^{\circ}C$ and $32^{\circ}C$, respectively. Inorganic filler content of each impression material was measured and observed with a SEM. The molecular weight distribution of polymer matrix was determined with a gel permeation chromatography (GPC). Express and Honigum display lower flow compared to the other materials, due to their high yield-stress values. Examixfine exhibits the greatest flow. All materials display pseudoplastic behavior, excluding the Examixfine catalyst. The viscosities at low shear rate are greatest for Express and Honigum; however, under high shear conditions, the viscosities of Extrude and Honigum are the lowest. Following mixing, each material show an increase in G', finally reaching a plateau, and the $tan{\delta}$ rapidly decreases with time. Imprint II shows the highest final G' as well as the most rapid decrease in $tan{\delta}$. Express and Imprint II present the highest filler content and rough filler surface, while Honigum shows the lowest filler content and small filler particles. Most products are composed of polymers over 30 kDa and oligomers less than 1 kDa. Each impression material possesses different rheological properties, which significantly affect the handling characteristics. The yield stress of the impression material minimizes unnecessary flow prior to and after seating. Viscoelastic change during setting of each impression material determines the setting time and the stiffness after setting. These rheological properties of impression materials are affected by the filler content and molecular weight distribution of polymer matrix.
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