Systematic investigation of mechanical properties and fracture toughness of epoxy networks: Role of the polyetheramine structural parameters

2018 ◽  
Vol 136 (9) ◽  
pp. 47121 ◽  
Author(s):  
H. Abdollahi ◽  
A. Salimi ◽  
M. Barikani ◽  
A. Samadi ◽  
S. Hosseini Rad ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Structural Parameters ◽  
Systematic Investigation ◽  
Epoxy Networks

scholarly journals A Guide through the Dental Dimethacrylate Polymer Network Structural Characterization and Interpretation of Physico-Mechanical Properties

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4057 ◽  
Author(s):  
Izabela Maria Barszczewska-Rybarek
Keyword(s):  
Mechanical Properties ◽  
Chemical Structure ◽  
Structural Parameters ◽  
Polymer Network ◽  
Polymer Networks ◽  
Impact Resistance ◽  
Organic Matrices ◽  
Dental Restorative

Material characterization by the determination of relationships between structure and properties at different scales is essential for contemporary material engineering. This review article provides a summary of such studies on dimethacrylate polymer networks. These polymers serve as photocuring organic matrices in the composite dental restorative materials. The polymer network structure was discussed from the perspective of the following three aspects: the chemical structure, molecular structure (characterized by the degree of conversion and crosslink density (chemical as well as physical)), and supramolecular structure (characterized by the microgel agglomerate dimensions). Instrumental techniques and methodologies currently used for the determination of particular structural parameters were summarized. The influence of those parameters as well as the role of hydrogen bonding on basic mechanical properties of dimethacrylate polymer networks were finally demonstrated. Mechanical strength, modulus of elasticity, hardness, and impact resistance were discussed. The issue of the relationship between chemical structure and water sorption was also addressed.

scholarly journals The Role of Structure on Mechanical Properties of Nonwoven Fabrics

2001 ◽  
Vol os-10 (2) ◽  
pp. 1558925001OS-01 ◽  
Author(s):  
H.S. Kim ◽  
B. Pourdeyhimi
Keyword(s):  
Mechanical Properties ◽  
Structural Changes ◽  
Maximum Stress ◽  
Structural Parameters ◽  
Bonding Temperature ◽  
Tensile Modulus ◽  
Orientation Distribution ◽  
Nonwoven Fabrics ◽  
Fiber Orientation Distribution

The mechanical properties, namely, tensile modulus, maximum stress in tension and elongation at maximum stress of thermally point-bonded nonwoven fabrics with different bonding temperature have been evaluated. Image acquisition and analysis techniques have been used to quantify structural parameters such as fiber orientation distribution function, bond-region strain, and unit cell strain during controlled-deformation experiments and to identify failure mechanisms. We have shown that an in situ experimental visualization and measurement of the structural changes occurring during controlled-deformation experiments can help establish links between mechanical properties and the structure properties of nonwoven fabrics.

scholarly journals The Role of Synergies of MWCNTs and Carbon Black in the Enhancement of the Electrical and Mechanical Response of Modified Epoxy Resins

2019 ◽  
Vol 9 (18) ◽  
pp. 3757 ◽  
Author(s):  
Georgios Foteinidis ◽  
Kyriaki Tsirka ◽  
Lazaros Tzounis ◽  
Dimitrios Baltzis ◽  
Alkiviadis S. Paipetis
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Carbon Black ◽  
Mechanical Response ◽  
Fracture Mechanisms ◽  
Factors Affecting ◽  
Pull Out ◽  
Carbon Nano Tubes ◽  
Crack Pinning

Nano-reinforced composites are widely studied by the scientific community. The main factors affecting the final nanocomposite performance are the filler type and content, as well as the duration of the dispersion. In this work, we report the effects of Multi-Walled Carbon Nano Tubes (MWCNTs) and milled Carbon Black (CB) dispersion in epoxy resin on the electrical and mechanical properties of the resulting composites. Impedance Spectroscopy (IS) was utilized to assess the dielectric properties of the specimens. The mechanical properties were evaluated by fracture toughness tests, while Scanning Electron Microscopy (SEM) was performed to study the influence of the reinforcement on the failure mechanisms acting on the fracture surfaces of the specimens. IS results for epoxy/CNT systems revealed the creation of a 3D conductive network for concentrations above 0.3 wt. %, while CB did not result in the formation of such a network for filler contents up to 2 wt. %. However, the synergistic effect of CNTs/CB was successfully manifested by both the optimal electrical properties and the 81% enhanced fracture toughness in comparison to the neat resin. Fractography confirmed the aforementioned results and revealed the fracture mechanisms of all systems, such as crack pinning and deflection, and particle pull-out phenomena.

scholarly journals Sintering of Potassium Doped Hydroxy-Fluorapatite Bioceramics

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 858
Author(s):  
Jihen Ben Slimen ◽  
Mustapha Hidouri ◽  
Marwa Ghouma ◽  
Ezzedine Ben Salem ◽  
Sergey V. Dorozhkin
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Relative Density ◽  
Single Phase ◽  
Structural Parameters ◽  
Precipitation Method ◽  
Thermal And Mechanical Properties ◽  
Chemical Formula ◽  
Crystallite Sizes ◽  
Apatitic Phase

The present study describes the influence of potassium and hydroxyl substitutions on the structural, thermal and mechanical properties of fluorapatite bioceramics. A set of non-stoichiometric ion-substituted compounds, with a chemical formula of Ca10−xKx(PO4)6F(2−2x)(OH)x with 0 ≤ x ≤ 1 synthesized by the wet precipitation method, were found to be single-phase apatites crystallizing in the hexagonal P63/m space group. The structural parameters, as well as the crystallite sizes, increased accordingly to the amount of added dopant-ions. The thermal behavior of these compounds, studied within the temperature range 500–1200 °C, indicated a partial decomposition of the apatitic phase and its transformation to tricalcium phosphate β-Ca3(PO4)2 at temperatures exceeding 750 °C. A relative density of the sintered samples achieved the highest value with x = 0.25 and reached about 95% after sintering at 1050 °C for 1 h. The microstructures of the sintered samples were of a trans-granular aspect and experienced an increase in the radius of their pores as x increased. The prepared bioceramic materials were mechanically characterized by means of Young’s modulus, flexural strength and fracture toughness measurements. The overall trend of these parameters evolved comparably to the relative density, and the maximum values obtained for x = 0.25 were measured to be 96 MPa, 47 MPa and 1.14 MPa·m1/2, respectively.

The Mechanical Properties of a Novel Si3N4-Amorphous Si3N4 Composite

1992 ◽  
Vol 287 ◽  
Author(s):  
Ivar E. Reimanis ◽  
J. J. Petrovic ◽  
H. Suematsu ◽  
T. E. Mitchell ◽  
O. S. Leung
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Heat Treating ◽  
Two Phase ◽  
Transmission Electron ◽  
Amorphous Si ◽  
The Relationship ◽  
Amorphous Si3n4

ABSTRACTThe hardness and fracture toughness of a model two-phase composite consisting of crystalline Si3N4 particles in a matrix of amorphous Si3N4 are examined. The composite is created by heat treating high purity, partially amorphous CVD Si3N4 in N2 for various times and temperatures in order to induce crystallization of the a phase. Microindentation tests at temperatures up to 1200 °C are conducted to evaluate the high temperature hardness and fracture toughness. The role of the microstructure is examined using optical and transmission electron microscopy. Finally, the relationship between the microstructure and the mechanical properties is discussed.

scholarly journals The Role of Technological Process in Structural Performances of Quasi-Crystalline Al–Fe–Cr Alloy

2020 ◽  
Vol 21 (4) ◽  
pp. 499-526
Author(s):  
O. V. Byakova ◽  
A. O. Vlasov ◽  
O. A. Scheretskiy ◽  
O. I. Yurkova
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Structural Parameters ◽  
Hot Extrusion ◽  
Cold Spraying ◽  
Processing Route ◽  
Engineering Practice ◽  
Nominal Composition ◽  
Plasticity Characteristic

The present study emphasizes the role of processing strategy in terms of its effect on structural performances, heat-treatment response, and mechanical behaviour of quasi-crystalline Al–Fe–Cr-based alloy with nominal composition Al94Fe3Cr3. Several kinds of semi-products and bulk-shaped materials, all processed with Al94Fe3Cr3 alloy, have been produced using rapid solidification by melt spinning, powder atomization, hot extrusion, and cold-spraying, respectively. All kinds of semi-products and bulk-shaped materials comprised nanosize quasi-crystalline particles of i-phase, all embedded in α-Al matrix, although fraction volume of quasi-crystals and other structural parameters were rather different and dependent on processing route. In particular, cold-spraying technique was believed to give essential advantage in retaining quasi-crystalline particles contained by feedstock powder as compared to currently employed hot extrusion. Crucial role of nanosize quasi-crystalline particles in structural performances and superior combination of high strength and sufficient ductility of ternary Al–Fe–Cr alloy was justified over evolution of mechanical properties under heating. In this aim, evolution of the structure and mechanical properties of each kind of Al94Fe3Cr3 alloy in response to heat treatment was examined and discussed by considering the classical strengthening mechanisms. A set of mechanical characteristics including microhardness, HV, yield stress, σy, Young’s modulus, E, and plasticity characteristic δH/δA was determined by indentation technique and used in consideration. Strength properties (HV, σy, E) and plasticity characteristic (δH/δA) of cold-sprayed Al94Fe3Cr3 alloy were revealed to be much higher than those provided by currently employed hot extrusion. The important point concerns the fact that cold-sprayed Al94Fe3Cr3 alloy kept almost stable values of mechanical properties at least up to 350 °C, suggesting potential application of this material in engineering practice under intermediate temperature.

Microstructural and fractographic characterization of B4C-Al cermets tested under dynamic and static loading

1989 ◽  
Vol 47 ◽  
pp. 562-563
Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Static Loading ◽  
Carbon Deposition ◽  
Full Density ◽  
Unique Combination ◽  
Strong Component ◽  
Reaction Products

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.

Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

1989 ◽  
Vol 47 ◽  
pp. 556-557
Author(s):  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Frictional Stress ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Carbon Coated ◽  
Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

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