The determination of elastic recovery of impression materials at the setting time

Abstract The paper presents a method for testing the shrinkage of concrete beams with dimensions of 10x10x50cm. Measurements followed from setting into the form until 24 hours after setting. It was used modified TLS system, which originally was meant for the determination of changes in the length of thin-mortar. Simultanously measured were the changes of speed propagation of sound waves by Vikasonic, what allows to specify the setting time of binders. It could be a base for determining the scratch resistance of the concrete in the first 24 hours after casting.

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Dimensional Stability and Accuracy of Silicone – Based Impression Materials Using Different Impression Techniques – A Literature Review

PRILOZI ◽

10.1515/prilozi-2017-0031 ◽

2017 ◽

Vol 38 (2) ◽

pp. 131-138 ◽

Cited By ~ 1

Author(s):

Borjan Naumovski ◽

Biljana Kapushevska

Keyword(s):

Literature Review ◽

Dimensional Stability ◽

Storage Time ◽

Elastic Recovery ◽

Impression Material ◽

Impression Technique ◽

Impression Materials ◽

Scientific Papers ◽

Materials Used ◽

Stability And Accuracy

Abstract A quality-made dental impression is a prerequisite for successful fixed-prosthodontic fabrication and is directly dependent on the dimensional stability, accuracy and flexibility of the elastomeric impression materials, as well as on the appropriately used impression techniques. The purpose of this paper is to provide a literature review of relevant scientific papers which discuss the use of various silicone impression materials, different impression techniques and to evaluate their impact on the dimensional stability and accuracy of the obtained impressions. Scientific papers and studies were selected according to the materials used, the sample size, impression technique, storage time, type of measurements and use of spacer for the period between 2002 and 2016. In the reviewed literature several factors that influence the dimensional stability and accuracy of silicone impression molds, including the choice of the type of viscosity, impression material thickness, impression technique, retention of the impression material on the tray, storage time before the casting, number of castings, hydrophilicity of the material, release of byproducts, contraction after polymerization, thermal contraction and incomplete elastic recovery were presented. The literature review confirmed the lack of standardization of methodologies applied in the research and their great diversity. All findings point to the superiority of the addition silicone compared to the condensation silicone.

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The Setting Time of Polyether Impression Materials after Contact with Conventional and Experimental Gingival Margin Displacement Agents

Journal of Prosthodontics ◽

10.1111/jopr.12471 ◽

2016 ◽

Vol 27 (2) ◽

pp. 182-188 ◽

Cited By ~ 1

Author(s):

Danuta Nowakowska ◽

Zbigniew Raszewski ◽

Marek Ziętek ◽

Jolanta Saczko ◽

Julita Kulbacka ◽

...

Keyword(s):

Setting Time ◽

Gingival Margin ◽

Impression Materials

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Effects of substrate on determination of hardness of thin films by nanoscratch and nanoindentation techniques

Journal of Materials Research ◽

10.1557/jmr.2004.0233 ◽

2004 ◽

Vol 19 (6) ◽

pp. 1791-1802 ◽

Cited By ~ 47

Author(s):

Noureddine Tayebi ◽

Andreas A. Polycarpou ◽

Thomas F. Conry

Keyword(s):

Thin Films ◽

Film Thickness ◽

Elastic Recovery ◽

Empirical Relationship ◽

Residual Deformation ◽

Substrate Effect ◽

Nanoindentation Technique ◽

Film Substrate ◽

Composite Hardness

A comparative study on the effects of the substrate on the determination of hardness of thin films by the use of the nanoscratch and nanoindentation techniques was conducted. Gold films deposited on fused quartz substrates and silicon dioxide films deposited on aluminum substrates with variant film thicknesses were investigated. These two systems correspond to a soft film on a hard substrate and a hard film on a soft substrate, respectively. The effect of substrate interaction on the measurement of hardness using the nanoscratch technique was found to be less pronounced compared to that of the nanoindentation technique due to: (i) the lower normal loads applied to achieve the penetration depths that occur at higher loads when using the nanoindentation method; (ii) the direct imaging of the residual deformation profile that is used in the nanoscratch technique, which allows for the effects of pileup or sink-in to be taken into account, whereas in the nanoindentation technique the contact area is estimated from the load-displacement data, which does not include such effects; and (iii) the account of elastic recovery of the plastically deformed surfaces from scratch tests. The film thickness did not appear to have any effect on the hardness of Au and SiO2 films obtained from nanoscratch data. This observation allowed, for the case of SiO2 films, the determination of the “free substrate effect region” and the derivation of an empirical relationship that relates the composite hardness of the film/substrate system to the contact-depth-to-film-thickness ratio, even when the indenter penetrates into the substrate. Such findings can allow for the determination of the intrinsic hardness of ultrathin hard films (∼1–5 nm thick), where the substrate effect is unavoidable.

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Characterization of Canadian fly ashes and their relative performance in concrete

Canadian Journal of Civil Engineering ◽

10.1139/l87-097 ◽

1987 ◽

Vol 14 (5) ◽

pp. 667-682 ◽

Cited By ~ 18

Author(s):

G. G. Carette ◽

V. M. Malhotra

Keyword(s):

Fly Ash ◽

Setting Time ◽

Air Entrainment ◽

Relative Performance ◽

Hardened Concrete ◽

Freezing And Thawing ◽

Fly Ashes ◽

Wide Range ◽

Pozzolanic Properties

Eleven Canadian fly ashes were characterized and evaluated for their relative performance in concrete. Characterization included the determination of mineralogical composition, chemical composition, physical characteristics, and pozzolanic properties. The relative performance of each fly ash in concrete was evaluated through determination of the following properties of fresh and hardened concrete: slump, air content, bleeding, setting time, strength, modulus of elasticity, drying shrinkage, creep, and freezing-and-thawing resistance.The results indicate a wide range of chemical, physical, and pozzolanic properties for the fly ashes investigated. In spite of this, all the fly ashes studied are shown to be suitable for use in concrete. They affect, however, the properties of fresh and hardened concrete in different ways, and this should be taken into account when proportioning concrete containing these fly ashes. Key words: fly ash, concrete, pozzolanic activity index, bleeding, setting time, air-entrainment, strength, creep, shrinkage, freezing and thawing.

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Determination of optimal system parameters to characterize the wrinkle recovery of fabrics by an integrated shape retention evaluation system

Textile Research Journal ◽

10.1177/0040517519858770 ◽

2019 ◽

Vol 90 (1) ◽

pp. 91-100 ◽

Cited By ~ 4

Author(s):

Yuzheng Lu ◽

Xiaorui Hu ◽

Fengxin Sun ◽

Fujian Peng ◽

Weidong Gao

Keyword(s):

Evaluation System ◽

Elastic Recovery ◽

Orthogonal Experiment ◽

Optimal System ◽

System Parameters ◽

Alternative Approach ◽

Shape Retention ◽

Recovery Angle ◽

Visual Testing

Measurement methods based on the visual testing principle have been widely used for evaluating the wrinkle recovery property of fabrics; however, the cumbersome testing process and poor adaptability for various fabrics are the main shortcomings of these methods. Here, a facile mechanical testing method named the integrated shape retention evaluation system (ISRES) was developed, providing an alternative approach to assess the wrinkle recovery, as well as the compression recovery and elastic recovery of fabrics. The optimal system parameters of the ISRES in measuring the wrinkle recovery angle were determined using an orthogonal experiment design based on correlation analysis between the curve parameters from the force–displacement curves of the ISRES and the wrinkle recovery angles tested by a standard Shirley crease recovery tester. Moreover, the sensitivity of the ISRES for the differences of the wrinkle recovery of fabrics was analyzed. The results showed that the selected optimal system parameters were a good combination, and the ISRES with the optimal system parameters provided a feasible method to differentiate the wrinkle recovery of fabrics.

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The Indentation Elastic Response - Indentation Shape and the Stress Distribution

MRS Proceedings ◽

10.1557/proc-356-699 ◽

1994 ◽

Vol 356 ◽

Author(s):

B. C. Hendrix ◽

Ke-Wei Xu ◽

Jun-Hai Liu ◽

Jia-Wen He

Keyword(s):

Elastic Recovery ◽

Transversely Isotropic ◽

Elastic Response ◽

Consistent Model ◽

Self Consistent ◽

Unique Model ◽

Transversely Isotropic Materials ◽

Fundamental Value ◽

Further Development

AbstractThe unloading of an indentation provides information about the shape of the indentation and the elastic properties of the materials. The assumptions of axisymmetry and material isotropy are critically examined, and a model for transversely isotropic materials is compared to measurements on single crystals. The methods used to infer the area of the indentation from the unloading curve are examined. The area is a fundamental value for the determination of hardness, modulus, and other mechanical properties in the so-called nano-indentor and other continuously monitored indentor techniques. The models of elastic recovery which are currently used are found to lack the flexibility to model the parameters which determine indentation depth. If the current self-consistent model is extended to cover the important aspects of the unloading, the area of the indentation is still not determined uniquely. Guidelines for further development of a unique model are suggested.

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