scholarly journals Analysis of Additives in Gypsum Coatings Based on Melamine, Polycarbonate Salts, Polycarboxylate, and Polycarboxylic Acids

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1204
Author(s):  
José Antonio Flores Yepes ◽  
Luis Miguel Serna Jara ◽  
Antonio Martínez Gabarrón ◽  
Ana María Codes Alcaraz ◽  
Joaquín Julián Pastor Pérez
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Citric Acid ◽  
Calcium Sulfate ◽  
Surface Hardness ◽  
Mechanical Tests ◽  
Polycarboxylic Acid ◽  
Polycarboxylic Acids ◽  
Compression Resistance ◽  
Hydrated Calcium

In this paper, we evaluate different gypsum coating additives that are available on the market, which are categorized by their chemical bases. The results will serve as a reference for future investigations of new additive bases in order to improve the properties of gypsum. As such, the objective of the this study is to assess the workability, mechanical behavior, and crystalline structure of calcium sulfate combined with different retarding and fluidifying bases, including melamine bases, which have a compressive strength of 19.32 N/mm2 and handling times with polycarbonate salts of up to 117.58 min. The following study presents the results of standard mechanical tests, analyzing semi-hydrated calcium sulfate (without additives) as a reference, along with the addition of melamines, synthetic melanin polymers, polycarbonate salts, polycarboxylates, and a polycarboxylic acid (citric acid). We already know that the addition of these additives will modify the mechanical properties of calcium sulfate, such as the Shore C surface hardness, flexural strength, modulus of elasticity, and compression resistance, which is the object of this study.

Effect of silver nitrate on some mechanical properties of heat polymerizing acrylic resins

2019 ◽  
Vol 14 (1) ◽  
pp. 110
Author(s):  
Assiss. Prof. Dr. Sabiha Mahdi Mahdi ◽  
Dr. Firas Abd K. Abd K.
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Silver Nitrate ◽  
Surface Hardness ◽  
Mechanical Tests ◽  
Hardness Tester ◽  
Acrylic Resins ◽  
The Difference

Aim: The aimed study was to evaluate the influence of silver nitrate on surfacehardness and tensile strength of acrylic resins.Materials and methods: A total of 60 specimens were made from heat polymerizingresins. Two mechanical tests were utilized (surface hardness and tensile strength)and 4 experimental groups according to the concentration of silver nitrate used.The specimens without the use of silver nitrate were considered as control. Fortensile strength, all specimens were subjected to force till fracture. For surfacehardness, the specimens were tested via a durometer hardness tester. Allspecimens data were analyzed via ANOVA and Tukey tests.Results: The addition of silver nitrate to acrylic resins reduced significantly thetensile strength. Statistically, highly significant differences were found among allgroups (P≤0.001). Also, the difference between control and experimental groupswas highly significant (P≤0.001). For surface hardness, the silver nitrate improvedthe surface hardness of acrylics. Highly significant differences were statisticallyobserved between control and 900 ppm group (P≤0.001); and among all groups(P≤0.001)with exception that no significant differences between control and150ppm; and between 150ppm and 900ppm groups(P>0.05).Conclusion: The addition of silver nitrate to acrylics reduced significantly the tensilestrength and improved slightly the surface hardness.

scholarly journals Mechanism of Antiwrinkle Finishing of Cotton Fabrics Using Mixed Polycarboxylic Acids

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Huaifang Wang ◽  
Chuanjie Zhang ◽  
Xudong Chu ◽  
Ping Zhu
Keyword(s):  
Activation Energy ◽  
Citric Acid ◽  
Reaction Rates ◽  
Acid Group ◽  
Hydroxyl Group ◽  
Cotton Fibers ◽  
Curing Process ◽  
Polycarboxylic Acid ◽  
Reaction Rate Constants ◽  
Polycarboxylic Acids

The kinetics, activation energy, and mechanism of esterification of cotton by mixed polycarboxylic acids, namely, 1,2,3,4-butanetetracarboxylic acid (BTCA) and citric acid (CA), were studied during the curing process of cotton fibers in comparison with the esterification by BTCA alone. The reaction rates of these two polycarboxylic acid finishing systems under different temperatures and the dependency of their reaction rate constants on temperature were studied. Consequently, in the temperature range from 120°C to 180°C, the activation energy of the mixed polycarboxylic acids (BTCA+CA) was obtained as Ea=40.7 kJ/mol, which was slightly lower than that for the BTCA finishing system. The reaction occurring between the carboxylic acid group of BTCA and the hydroxyl group of CA was proposed. To confirm and prove the speculation, experiments were conducted to investigate the changes in wrinkle recovery angle and tensile strength retention by changing the concentration of both the single polycarboxylic acid and mixed polycarboxylic acids. The results show that, besides esterification of cotton fibers, citric acid probably functioned as an extender in the curing process, when it was combined with BTCA.

scholarly journals A Quality Control Scheme for a Commercial Pozzolana Plant: A Case Study of Pozzolana Ghana Ltd

2019 ◽  
Vol 60 (2) ◽  
pp. 74-83
Author(s):  
J. Sarfo-Ansah ◽  
K. A. Boakye ◽  
E. Atiemo ◽  
R. Appiah
Keyword(s):  
Mechanical Properties ◽  
Quality Control ◽  
Compressive Strength ◽  
Process Control ◽  
Statistical Process Control ◽  
Setting Time ◽  
Mechanical Tests ◽  
Statistical Process ◽  
Control Scheme ◽  
Quality Control Scheme

A Quality control scheme was developed for a 200 ton per day commercial pozzolana plant. The scheme was evaluated for the first 34 days of production. Statistical Process Control tech­niques were specifically applied to the mechanical properties of setting times and compressive strength. Results obtained showed that pozzolana samples tested were chemically suitable with total SiO2, Al2O3 and Fe2O3 content ≥ 70%. Mechanical tests performed were mostly under control and when out-of-control, they gave valuable indication to plant malfunction or operator errors which were promptly corrected. The results of mechanical properties tested against the three major brands of cement on the Ghanaian market showed that pozzolana gave highest compressive strengths with Dangote CEM I 42.5R ranging between 21.3 MPa - 36.3 MPa at 7 days and 33.8 MPa - 45.1 MPa at 28 days whilst lowest compressive strengths were obtained with Ghacem CEM II B-L 32.5R cement ranging between 16.3 MPa – 23.6 MPa at 7 days and 23.3 MPa – 30.7 MPa at 28 days. Compressive strengths obtained with Diamond CEM II B-L 42.5N cement were average. A mean compressive strength for all brands of ce­ment of 25.2 MPa and 33.6 MPa at 7 days and 28 days respectively were obtained. Keywords: Pozzolana cement, statistical process control, Shewhart chart, compressive strength, setting time

scholarly journals Estudio comparativo de resistencias a la compresión en hormigones de 24 Mpa empleando agregados finos procedente de los ríos de Manabí

2020 ◽  
Vol 5 (2) ◽  
pp. 45
Author(s):  
Wilter Enrique Ruiz Párraga ◽  
Bolívar Humberto Ortega Bravo ◽  
José Fabián Véliz Párraga ◽  
Juan Carlos Guerra Mera ◽  
Panchana Cedeño Ramona
Keyword(s):  
Compressive Strength ◽  
Mechanical Tests ◽  
Surface Resistivity ◽  
Resistance Test ◽  
Meandering Rivers ◽  
Structural Concrete ◽  
River Sand ◽  
Materials Used ◽  
Compression Resistance ◽  
Cylindrical Test

  Las arenas de río son materiales empleados para las construcciones de viviendas y demás obras pequeñas que se realizan en los sectores alejados de las canteras, pero a su vez están cerca de meandros de ríos para su extracción y empleo. Por el uso que se da a este material, se creyó necesario realizar los ensayos físicos y mecánicos que tiene las arenas de varios ríos de la provincia de Manabí, exclusivamente los que atraviesan los cantones de Paján, Calceta y Olmedo, para posterior a ello realizar las dosificaciones del hormigón según los establece la ACI 211.1 y las normativas ecuatorianas, se realizaron probetas cilíndricas que permaneciendo en curado húmedo por un tiempo de 28 días, para realizar el ensayo de resistencia a la compresión, también se realizó el ensayo de resistividad superficial según lo establece la ASTM C1 202, 2012, para correlacionar los datos y establecer los usos apropiados de las arenas de los ríos en mención, Finalmente se obtuvieron los datos de los ensayos determinando que las arenas de los ríos mencionados no cumplen con las condiciones para su uso en obras que requieran hormigón de tipo estructural.   Palabras claves: Arena de río, resistencia a la compresión, resistividad superficial.   Abstract River sands are materials used for the construction of houses and other small works that are carried out in sectors far from the quarries, but in turn are close to meandering rivers for their extraction and use. Due to the use that is given to this material, it was believed necessary to carry out the physical and mechanical tests that the sands of several rivers in the province of Manabí have, exclusively those that cross the cantons of Paján, Calceta and Olmedo, to later carry out the concrete dosages as established by ACI 211.1 and the Ecuadorian regulations, cylindrical test tubes were made that, remaining in wet curing for a time of 28 days, to carry out the compression resistance test, the surface resistivity test was also carried out according to It  is established by ASTM C1 202, 2012, to correlate the data and establish the appropriate uses of the sands of the rivers in question.Finally, the data of the tests were obtained determining that the sands of the mentioned rivers do not meet the conditions for their use in works that require structural concrete. Keys Words; River sand, compressive strength, surface resistivity

scholarly journals Effect of storage time and chlorhexidine addition on the mechanical properties of glass ionomer cements

2017 ◽  
Vol 16 ◽  
pp. 1-9
Author(s):  
Juliana de Carvalho Machado ◽  
Cristiane Duque ◽  
Josânia Pitzer de Oliveira ◽  
Angela Scarparo Caldo-Teixeira
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Compressive Strength ◽  
Storage Time ◽  
Mechanical Characteristics ◽  
Mechanical Tests ◽  
Glass Ionomer Cements ◽  
Glass Ionomer ◽  
Strength Tests ◽  
Storage Times

Aims: To evaluate the effect of the chlorhexidine (CHX) incorporation and the storage time on the mechanical properties of glass ionomer cements (GICs). Methods: The following GICs were evaluated: Ketac Molar Easymix (KM), Vidrion R (VR) and Vitromolar (VM), containing or not CHX.  GIC liquid was modified by adding 1.25 % CHX digluconate and then manipulated with the power and placed into the stainless steel cylindrical or bar-shaped molds. GICs specimens were stored into water for 1, 7 and 28 days. After these periods, specimens were submitted to flexural, diametral tensile and compressive strength tests, according to ISO standards. Data from mechanical tests were statistically analyzed using 2-way ANOVA and Tukey tests. Results: Overall, the storage time did not influence any of the mechanical properties of the GICs tested. In contrast, the inclusion of CHX reduced significantly these properties for all GICs tested. KM presented the highest values of compressive strength for all storage times. KM + 1.25% CHX had lower compressive strength results than KM, however, it showed similar results when compared to another GICs without CHX. Conclusions: The presence of chlorhexidine, independent of the storage time, interfered on the mechanical characteristics of GIC.

scholarly journals Mechanical Tests and Numerical Simulations for Mining Seafloor Massive Sulfides

2019 ◽  
Vol 7 (8) ◽  
pp. 252 ◽  
Author(s):  
Yu Dai ◽  
Feiyue Ma ◽  
Xiang Zhu ◽  
He Liu ◽  
Zhonghua Huang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Numerical Simulations ◽  
Laboratory Tests ◽  
Mineral Resources ◽  
Friction Angle ◽  
Mechanical Tests ◽  
Massive Sulfides ◽  
Triaxial Compressive Strength ◽  
Ucs Test

With the decrease of primary resources in recent years, deep seabed mineral resources, especially the massive sulfides, are of extensive research significance. In this paper, firstly, the uniaxial compressive strength (UCS) test and triaxial compressive strength (TCS) test on the seafloor massive sulfides (SMS) samples from three different segments are conducted to obtain the key mechanical properties, including the cohesive force, internal friction angle, compressive strength, elastic modulus and Poisson’s ratio. Then, by leveraging the PFC3D code, the uniaxial and triaxial numerical simulations of SMS are performed. During this process, the micro properties in the simulation are altered through a calibration process until they match the macro properties of the SMS samples measured in the laboratory tests. Finally, the micro properties are applied to simulate the cutting process of single cutting pick and two adjacent cutting picks; meanwhile, the cutting force in the fragmentation process of SMS is monitored and collected. This research can provide some guidance for the mining simulation of SMS and effectively predicting the maximum force on the cutting pick.

UHB RIGOR A2

Alloy Digest ◽  
1977 ◽  
Vol 26 (3) ◽  
Keyword(s):  
Wear Resistance ◽  
Compressive Strength ◽  
High Surface ◽  
Surface Hardness ◽  
Heat Treating ◽  
High Dimensional ◽  
Metal Working ◽  
Good Resistance ◽  
High Hardenability ◽  
Compression Resistance

Abstract UHB RIGOR AR is a chromium-molybdenum-vanadium tool steel characterized by high surface hardness, high hardenability, high dimensional stability after hardening and tempering, high compression resistance, good machinability, good resistance to tempering and good wear resistance. Its many uses include metal-working tools, dies for porcelain and gages. This datasheet provides information on composition, physical properties, hardness, elasticity, and compressive strength. It also includes information on forming, heat treating, machining, and joining. Filing Code: TS-315. Producer or source: Uddeholm Aktiebolag.

scholarly journals Microstructure and Mechanical Properties of Composite Resins Subjected to Accelerated Artificial Aging

2013 ◽  
Vol 24 (6) ◽  
pp. 599-604 ◽  
Author(s):  
Andrea Candido dos Reis ◽  
Denise Tornavoi de Castro ◽  
Marco Antonio Schiavon ◽  
Leandro Jardel da Silva ◽  
Jose Augusto Marcondes Agnelli
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Artificial Aging ◽  
Thermal Analyses ◽  
Surface Hardness ◽  
Composite Resins ◽  
Scanning Calorimetry ◽  
Good Thermal Stability ◽  
Microstructure And Mechanical Properties ◽  
Before And After

The aim of this study was to investigate the influence of accelerated artificial aging (AAA) on the microstructure and mechanical properties of the Filtek Z250, Filtek Supreme, 4 Seasons, Herculite, P60, Tetric Ceram, Charisma and Filtek Z100. composite resins. The composites were characterized by Fourier-transform Infrared spectroscopy (FTIR) and thermal analyses (Differential Scanning Calorimetry - DSC and Thermogravimetry - TG). The microstructure of the materials was examined by scanning electron microscopy. Surface hardness and compressive strength data of the resins were recorded and the mean values were analyzed statistically by ANOVA and Tukey's test (α=0.05). The results showed significant differences among the commercial brands for surface hardness (F=86.74, p<0.0001) and compressive strength (F=40.31, p<0.0001), but AAA did not affect the properties (surface hardness: F=0.39, p=0.53; compressive strength: F=2.82, p=0.09) of any of the composite resins. FTIR, DSC and TG analyses showed that resin polymerization was complete, and there were no differences between the spectra and thermal curve profiles of the materials obtained before and after AAA. TG confirmed the absence of volatile compounds and evidenced good thermal stability up to 200 °C, and similar amounts of residues were found in all resins evaluated before and after AAA. The AAA treatment did not significantly affect resin surface. Therefore, regardless of the resin brand, AAA did not influence the microstructure or the mechanical properties.

Temperature Effect on the Mechanical Properties of Very High Performance Concrete

2018 ◽  
Vol 34 ◽  
pp. 29-39
Author(s):  
Mebarek Belaoura ◽  
Dalila Chiheb ◽  
Mohamed Nadjib Oudjit ◽  
Abderrahim Bali
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Exothermic Reaction ◽  
Physical And Mechanical Properties ◽  
Mass Effect ◽  
Mechanical Tests ◽  
Conventional Concrete ◽  
Very High

This study aims at a better understanding of the behaviour of very high performance concretes (VHPC) subjected to high temperatures. The temperature increase within the concrete originating from the hydratation exothermic reaction of cement is emphasized by the mass effect of the structures and can lead to thermal variations of around 50°C between the heart and the structures walls. These thermal considerations are not without consequence on durability and the physical and mechanical properties of very high performance concrete, such as the compressive strength. This work is an experimental research that shows the effects of temperature on the mechanical properties of very high performance concrete (VHPC) and compares them with those of conventional concrete and HPC. Test specimens in usual concrete, HPC and VHPC are made, preserved till maturity of the concrete, and then subjected to a heating-cooling cycle from room temperature to 500°C at heating rate 0.1°C/min. Mechanical tests on the hot concrete and cooling (air and water) were realized. The results show that the mechanical characteristics of VHPC (density, compressive strength, tensile strength and elastic modulus) decrease with increasing temperature, but their strength remains higher than that of conventional concrete.

scholarly journals The Effects of Processing Parameters on the Structure and Mechanical Properties of Structural Pm Steels Containing Mn, Cr and Mo/ Wpływ Parametrów Wytwarzania Na Strukturę I Własności Mechaniczne Spiekanych Stali Konstrukcyjnych Zawierających Mn, Cr I Mo

2014 ◽  
Vol 59 (4) ◽  
pp. 1499-1505 ◽  
Author(s):  
M. Sulowski
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Sintering Temperature ◽  
Rupture Strength ◽  
Surface Hardness ◽  
Processing Parameters ◽  
Mechanical Tests ◽  
Pure Hydrogen ◽  
Low Carbon ◽  
Offset Yield Strength

Abstract The effects of processing parameters on the microstructure and mechanical properties of Fe-Mn-Cr- Mo-C PM steels are described. Pre-alloyed Astaloy CrM and Astaloy CrL, low-carbon ferromanganese and graphite powders were used as the starting materials. After pressing in rigid die, the compacts were conventionally and high temperature sintered at 1120 and 1250°C, respectively. Sintering was carried out for 60 minutes in atmospheres with different H2/N2 ratios. Cooling rate from sintering temperature was 65°C min-1 (convective cooling). The specimens were subsequently tempered at 200°C for 60 minutes in air. All specimens were tested for tensile strength (UTS), elongation (A), offset yield strength (R0:2), transverse rupture strength (TRS), impact toughness and apparent surface hardness (HV 30). After mechanical tests the microstructure of Fe-Mn-Cr-Mo-C PM steels was studied by optical microscopy. These investigations have shown that, by sintering in inexpensive and safe nitrogen-rich atmospheres, it is possible to achieve mechanical properties similar to those of specimens sintered in pure hydrogen and hydrogen-rich atmospheres.

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