scholarly journals STUDY OF THE INFLUENCE OF THE CROSSLINKING METHODS ON THE PROPERTIES OF POLYETHYLENE

2020 ◽  
Vol 17 (36) ◽  
pp. 7-17
Author(s):  
Mariana Babilone de Souza FERREIRA ◽  
◽  
DOS SANTOS Claudio Gouvêa
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Mechanical Tests ◽  
Temperature Changes ◽  
Gel Content ◽  
Crosslinked Polymer ◽  
Crosslinking Process ◽  
A Chain ◽  
Tga And Dsc

Polyethylene (PE) is considered one of the most versatile thermoplastics available today. However, it exhibits several limitations related to its low melting point, low heat resistance, tendency to crack propagation, and its low resistance to rupture under stress. In order to overcome these deficiencies, several processes for crosslinking PE chains were developed, which makes this material more stable to temperature changes. In this work, methods based on peroxide (PEX-A) and silane (PEX-B) as chemical modification agents for PE chain crosslinking were analyzed, aiming to apply PE in pipes for conduction water. The materials were characterized by infrared spectroscopy (FTIR), gel content, and thermal analysis (TGA and DSC) to achieve those objectives. Also, some mechanical properties such as tensile strength and hardness and the determination of the heat deflection temperature (HDT) were evaluated. Spectra demonstrated the presence of the functional groups characteristic of PE and the incorporation of siloxane groups in PEX-B. Gel content values obtained were above 60% and indicated the formation of crosslinked chains between the molecules of the polymers. The thermal analysis suggests a greater efficiency in forming a chain network by the silane crosslinking process compared to the peroxide process. As for the mechanical tests, they also showed improvement in the mechanical properties of the crosslinked polymer when compared to the respective original PE. Thus, the silane method provided sufficient results to conclude that the properties evaluated are superior compared to the peroxide crosslinking method.

scholarly journals Determination of Physical and Mechanical Properties of Three-layer Boards of Teak (Tectona grandis), Seike (Cedrelinga catenaeformis) and Mascarey (Hieronima alchorneoides), Company PISMADE S.A., Riobamba Canton, Chimborazo Province

2021 ◽  
Author(s):  
J. Criollo Barahona ◽  
D. Román Robalino ◽  
E. Cabezas ◽  
E. Salazar Castañeda
Keyword(s):  
Mechanical Properties ◽  
Compression Test ◽  
Physical And Mechanical Properties ◽  
Tectona Grandis ◽  
Mechanical Tests ◽  
Hyeronima Alchorneoides ◽  
Commercial Use ◽  
Palabras Clave ◽  
Thickness Measurements

The present investigation aims to determine the physical and mechanical properties in three-layer boards of Teak (Tectona grandis), Seike (Cedrelinga catenaeformis) and Mascarey (Hieronima alchorneoides), from the PISMADE S.A. Company, Canton Riobamba, province of Chimborazo. The three specimens used for each of the species in each of the tests performed were worked on using the ASTM D143-94 standard for the tests of parallel compression, perpendicular compression and flexion, and the DIN-52182 standard, with the main variation in thickness measurements caused by the commercial use established by the company. Mechanical tests showed that Seike had the best results, being superior in two tests: perpendicular compression and flexion. Teak tests gave us results that were superior in the perpendicular compression test. Mascarey, unlike the two species mentioned above, had complications during the trials due to problems with the glue between layers. Keywords: physical and mechanical properties of wood, three-layer boards. Resumen La presente investigación pretende: Determinar las propiedades físicas y mecánicas en tableros tricapa de Teca, Seike (Cedrelinga catenaeformis) y Mascarey (Hyeronima alchorneoides), Empresa PISMADE S.A., cantón Riobamba, provincia de Chimborazo; para lo cual se utilizaron 3 probetas por cada una de las especies en cada uno de los ensayos realizados, las mismas fueron trabajadas con base a la Norma ASTM D143-94 para las pruebas de compresión paralela, compresión perpendicular y flexión y la Norma DIN-52182, teniendo como principal variación en las medidas de espesor debido al uso comercial establecido por la empresa. Las pruebas mecánicas mostraron que Seike tuvo los mejores resultados al ser superior en dos ensayos: Compresión perpendicular y flexión. Los ensayos con Teca nos dieron como resultados que es superior en el ensayo de compresión perpendicular. Mascarey a diferencia de las dos especies mencionadas anteriormente tuvo complicaciones con los ensayos debido a problemas con el pegamento entre capas. Palabras clave: propiedades físicas y mecánicas de la madera, tableros tricapa.

The improvement of physical and mechanical properties of sealers based on nitrile-butadiene rubber and combination of nano-metal oxides

2020 ◽  
pp. 174-182
Author(s):  
R.F. Khankishiyeva ◽  
◽  
H.N. Akhundzada ◽  
Keyword(s):  
Mechanical Properties ◽  
Metal Oxides ◽  
Chemical Interaction ◽  
Physical And Mechanical Properties ◽  
Mechanical Tests ◽  
Butadiene Rubber ◽  
Nanosized Powders ◽  
Nitrile Butadiene Rubber ◽  
Crosslinking Process ◽  
First Time

The chemical interaction of disulphochloride aromatic compounds with nitrile butadiene rubber (NBR) in the presence of combined nanosized powders of metal oxides (ZnO and Al2O3) was studied for the first time. Vulcanization of the prepared blends has been induced with two methods: by irradiation of gamma rays (D=300 kGy) and by pre-heating in the hydraulicpress and then subsequent irradiation (150 oC x 5', 300 kGy). In order to activate the crosslinking process, a combination of nano-oxides ZnO and Al2O3 were used. The surface of the nanocomposite was studied by using scanning electron microscopy. The mechanical properties of modified blends were studied and then compared with controlling sample (vulcanized with sulphur) and analyzed by the mechanical tests in aggressive environments after thermal aging. The study found that the use of 1,3-disulphochloride benzene with nano oxides produces cured materials with good resistance to aging and provides high service properties in air, seawater, and oil-bearing solution.

First Report of the Research Committee on High-Duty Cast Irons for General Engineering Purposes

1938 ◽  
Vol 140 (1) ◽  
pp. 163-256 ◽  
Author(s):  
J. G. Pearce
Keyword(s):  
Mechanical Properties ◽  
Present State ◽  
State Of The Art ◽  
Mechanical Tests ◽  
Cast Irons ◽  
Research Committee ◽  
The Past ◽  
First Results ◽  
Future Work

The report is presented in three parts. Part I reviews the development of high-duty cast irons during the past fifteen years and relates them to the material traditionally used. This is illustrated by results given in Part II, derived from materials actually supplied by manufacturers and designed to show the present state of the art. When complete, these records will form the basis on which a major portion of the Committee's programme will rest, the service trial of selected materials in appropriate engineering applications. The remaining portion of the programme consists in the preparation of materials covering the whole range of cast irons and the determination of their mechanical properties. The first results of this are given in Part III, and it is intended, when the range is completed, to select materials which show sufficient promise for submission to a complete range of mechanical tests. In the meantime, it is hoped that discussion will assist the Committee in its future work.

Determination of Mechanical Properties of Non-Conventional Reinforcement

2015 ◽  
Vol 662 ◽  
pp. 249-252
Author(s):  
Tomáš Bittner ◽  
Petr Bouška ◽  
Michaela Kostelecká ◽  
Šárka Nenadálová ◽  
Milan Rydval ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Reinforced Concrete ◽  
Modulus Of Elasticity ◽  
Mechanical Tests ◽  
Textile Reinforced Concrete ◽  
Research Project ◽  
Glass Reinforcement

Mechanical tests of samples of basalt and textile glass reinforcement were performed within the solution of the research project GAČR 13-12676S and SGS14/171/OHK1/2T/31. These tests were carried out because of the need to establish elementary mechanical quantities that are tensile strength and modulus of elasticity of non-conventional reinforcement. Both of these quantities are required for further modeling of structures and for designing of the elements made from textile reinforced concrete (TRC) as not being provided by reinforcement manufacturers. The tests were carried out on a total of 12 samples of reinforcement where the first 6 samples were made from textile glass reinforcement (AR-G = Alkali-Resistant Glass) and the remaining 6 samples were prepared from basalt reinforcement. The filament sheaf fibers called roving was used for the production of test specimens.

scholarly journals Determination of Kinetic Parameters of Decomposition of Tetrahydropyrimidine Derivatives

2013 ◽  
Vol 18 ◽  
pp. 23-32
Author(s):  
Kapil Bhesaniya ◽  
Ashish Patel ◽  
Shipra Baluja
Keyword(s):  
Thermal Analysis ◽  
Kinetic Parameters ◽  
Frequency Factor ◽  
Entropy Change ◽  
Structural Determination ◽  
Mass Spectral Data ◽  
Mass Spectral ◽  
Tga And Dsc ◽  
Thermal Stability Of

Some new tetrahydropyrimidine derivatives have been synthesized and their structural determination was done by IR, NMR and mass spectral data. Thermal analysis of these synthesized dihydropyrimidinthiones has been carried out by TGA and DSC techniques. From the thermograms, various kinetic parameters such as order of degradation (n), energy of activation (E), frequency factor (A) and entropy change (ΔS) have been evaluated. Further, thermal stability of tetrahydropyrimidine have been determined which is found to depend on the type of substituent present in the compounds.

Human Prothrombin Activation: Determination of Plasma and Serum Levels of Prothrombin Fragment 3 by Radioimmunoassay

1979 ◽  
Author(s):  
Daniel Walz ◽  
Thomas Brown
Keyword(s):  
Blood Clotting ◽  
Factor Xa ◽  
Heart Association ◽  
Serum Levels ◽  
Cross Reactivity ◽  
Assay Procedure ◽  
A Chain ◽  
Prothrombin Activation ◽  
Theoretical Amount

Human prothrombin activation is unique in that, in addition to the release of fragment 1.2 (FI.2) from the NH-terminus of prothrombin by factor Xa during the generation of thrombin, an additional 13 residue polypeptide, fragment 3 (F3), is autocatalytically removed from the amino-terminus of the thrombin A chain. We have developed a rapid radioimmunoassay for human F3 which incorporates short incubation times and the use of a preprecipitated second antibody; the assay can be performed in three hours. Specificity studies in buffer systems show prothrombin and prethrombin 1 cross-reacting at a level of 0.001; purified thrombin does not cross-react. In the presence of 5% BSA, prothrombin displays considerably less cross-reactivity. No immunoreactive material to F3 antibodies could be detected in 400 μL of plasma. Serum, obtained from whole blood clotting, contained measurable quantities of F3 (40-100 ng/mL). This amount in serum represents only 5-10% of the theoretical amount available should all of the fragment be hydrolytically cleaved during the conversion of prothrombin to thrombin. This assay procedure is currently being utilized to monitor the activation of purified human prothrombin in the absence and presence of selected plasma inhibitors. (Supported in part by NIH 05384-17 and the Michigan Heart Association).

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.

Basic set of experiments for determination of mechanical properties of sand

2014 ◽  
Vol 62 (1) ◽  
pp. 129-137
Author(s):  
A. Sawicki ◽  
J. Mierczyński
Keyword(s):  
Mechanical Properties ◽  
Soil Mechanics ◽  
Physical And Mechanical Properties ◽  
Local Strain ◽  
Initial State ◽  
Laboratory Equipment ◽  
Additional Information ◽  
Basic Set ◽  
Initial Anisotropy

Abstract A basic set of experiments for the determination of mechanical properties of sands is described. This includes the determination of basic physical and mechanical properties, as conventionally applied in soil mechanics, as well as some additional experiments, which provide further information on mechanical properties of granular soils. These additional experiments allow for determination of steady state and instability lines, stress-strain relations for isotropic loading and pure shearing, and simple cyclic shearing tests. Unconventional oedometric experiments are also presented. Necessary laboratory equipment is described, which includes a triaxial apparatus equipped with local strain gauges, an oedometer capable of measuring lateral stresses and a simple cyclic shearing apparatus. The above experiments provide additional information on soil’s properties, which is useful in studying the following phenomena: pre-failure deformations of sand including cyclic loading compaction, pore-pressure generation and liquefaction, both static and caused by cyclic loadings, the effect of sand initial anisotropy and various instabilities. An important feature of the experiments described is that they make it possible to determine the initial state of sand, defined as either contractive or dilative. Experimental results for the “Gdynia” model sand are shown.

Sign in / Sign up

Export Citation Format

Share Document