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.

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.

scholarly journals Polyamide 12/Multiwalled Carbon Nanotube and Carbon Black Nanocomposites Manufactured by 3D Printing Fused Filament Fabrication: A Comparison of the Electrical, Thermoelectric, and Mechanical Properties

2021 ◽  
Vol 7 (2) ◽  
pp. 38
Author(s):  
Nectarios Vidakis ◽  
Markos Petousis ◽  
Lazaros Tzounis ◽  
Emmanuel Velidakis ◽  
Nikolaos Mountakis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Carbon Black ◽  
Large Scale ◽  
Fracture Mechanisms ◽  
Fused Filament Fabrication ◽  
Melt Mixing ◽  
Multiwalled Carbon ◽  
Electrically Conductive ◽  
Polyamide 12

In this study, nanocomposites with polyamide 12 (PA12) as the polymer matrix and multiwalled carbon nanotubes (MWCNTs) and carbon black (CB) at different loadings (2.5, 5.0, and 10.0 wt.%) as fillers, were produced in 3D printing filament form by melt mixing extrusion process. The filament was then used to build specimens with the fused filament fabrication (FFF) three-dimensional (3D) printing process. The aim was to produce by FFF 3D printing, electrically conductive and thermoelectric functional specimens with enhanced mechanical properties. All nanocomposites’ samples were electrically conductive at filler loadings above the electrical percolation threshold. The highest thermoelectric performance was obtained for the PA12/CNT nanocomposite at 10.0 wt.%. The static tensile and flexural mechanical properties, as well as the Charpy’s impact and Vickers microhardness, were determined. The highest improvement in mechanical properties was observed for the PA12/CNT nanocomposites at 5.0 wt.% filler loading. The fracture mechanisms were identified by fractographic analyses of scanning electron microscopy (SEM) images acquired from fractured surfaces of tensile tested specimens. The nanocomposites produced could find a variety of applications such as; 3D-printed organic thermoelectric materials for plausible large-scale thermal energy harvesting applications, resistors for flexible circuitry, and piezoresistive sensors for strain sensing.

Effect of Cellulose Functionalization on Thermal and Mechanical Properties of Epoxy Resin

2017 ◽  
Vol 757 ◽  
pp. 62-67 ◽  
Author(s):  
Kritsanachai Leelachai ◽  
Supissara Ruksanak ◽  
Tarakol Hongkeab ◽  
Supakeat Kambutong ◽  
Raymond A. Pearson ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Diglycidyl Ether ◽  
Cellulose Content ◽  
Thermal And Mechanical Properties ◽  
Chemical Surface ◽  
Pull Out ◽  
Fiber Bridging ◽  
Surface Modified ◽  
Modified Epoxy

In this study, diglycidyl ether of bisphenol A (DGEBA) cured cycloaliphatic polyamine was modified with functionalized celluloses for improved thermal and mechanical properties. Three different types of surface-modified cellulose, polyacrylamide-g-cellulose (PGC), aminopropoxysilane-g-cellulose (SGC), and carboxymethyl cellulose (CMC), were investigated and used as reinforcing agents in epoxy resins. The storage modulus of these modified epoxy systems was found to significantly increase with addition of cellulose fillers (up to 1 wt. % cellulose content). An improved fracture toughness (KIC) was also observed with increasing cellulose loading content with PGC and SGC. Among the surface-modified celluloses, epoxy modified with SGC was found to have the highest fracture toughness followed by PGC and CMC at 1.0 wt.% cellulose addition due to the chemical surface compatibility. The toughening mechanisms of the cellulose/epoxy composites, measured by scanning electron microscopy (SEM), revealed that fiber-debonding, fiber-bridging, and fiber-pull out were responsible for increased toughness.

Microstructures and Mechanical Properties of B4C-TiB2 Composite Prepared by Hot Pressure Sintering

2010 ◽  
Vol 434-435 ◽  
pp. 50-53 ◽  
Author(s):  
Xin Yan Yue ◽  
Shu Mao Zhao ◽  
Liang Yu ◽  
Hong Qiang Ru
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Relative Density ◽  
Microstructural Analysis ◽  
Crack Deflection ◽  
Second Phase ◽  
Fine Grain ◽  
Pull Out ◽  
Microstructures And Mechanical Properties

B4C-TiB2 composite was prepared using hot pressure sintering. The microstructures and mechanical properties of the B4C-TiB2 composite were investigated. The B4C-TiB2 composite with 43 mass % TiB2 showed the optimized properties. The relative density, hardness, flexural strength and fracture toughness of that were 98.2 %, 25.9 GPa, 458 MPa and 8.7 MPa•m1/2, respectively. A number of toughening mechanisms, including fine grain, crack deflection and grain pull-out, were observed during microstructural analysis of the composite. The fracture mode of the B4C-TiB2 composite was greatly affected by the existence of the second phase of TiB2.

Mechanical Properties of Toughened Polyester Reinforced with Untreated and Treated Kenaf Hybird Carbon Composite

2017 ◽  
Vol 894 ◽  
pp. 17-20
Author(s):  
Noor Najmi Bonnia ◽  
Aein Afina Redzuan ◽  
Siti Norasmah Surip ◽  
Noor Azlina Hassan
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Impact Strength ◽  
Carbon Black ◽  
Hybrid Composites ◽  
Carbon Composite ◽  
Compression Moulding ◽  
Fracture Toughness Testing ◽  
Rubber Toughened ◽  
Toughness Testing

This research focusing on mechanical properties of rubber toughened polyester filled carbon black (RPCB) reinforced with untreated kenaf (RPCBUK) and treated kenaf (RPCBTK). The samples were fabricated via compression moulding technique in which 3 % of LNR was added as toughening agent in this composite. Percentages of carbon black (CB) is 4 % and kenaf used vary from 5,10,15,20 and 25wt %. The mechanical properties were evaluated by impact and fracture toughness testing. The result for each test was discussed to determine the most optimum loading of kenaf fibre used to produce the best properties of composite. Untreated hybrid composite showed improvement on impact strength as compared to RPCB composite. RPCBTK with 25% of kenaf and RPCBUK with 5% of kenaf loading give the highest impact strength among the hybrid composites, approaching the strength of neat polyester. Same trend shows by fracture toughness testing. The microstructures of the composites’ fracture surface images from scanning electron microscope (SEM) prove the mechanical properties of the hybrid composites.

Effects of Carbon Black on Microstructure and Mechanical Properties of Hot Pressed ZrB2-SiC Ceramics

2010 ◽  
Vol 434-435 ◽  
pp. 185-188 ◽  
Author(s):  
Xin Sun ◽  
Xing Hong Zhang ◽  
Zhi Wang ◽  
Wen Bo Han ◽  
Chang Qing Hong
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Temperature ◽  
Carbon Black ◽  
Potential Method ◽  
Ceramic Composites ◽  
Grain Refining ◽  
Ultra High Temperature Ceramics ◽  
Sic Ceramics ◽  
Microstructure And Mechanical Properties

Abstract. ZrB2-SiC ultra-high temperature ceramics (UHTCs) was hot-pressed at a temperature of 1900°C with the addition of carbon black as a reinforcing phase. Microstructure and mechanical properties were investigated. Analysis revealed that the amount of carbon black had a significant influence on the sinterability and mechanical properties of ZrB2-SiC ceramics. When a small amount ( < 10 vol.%) of carbon black was introduced, it may react with oxide impurities (i.e. ZrO2, B2O3 and SiO2) present on the surface of the starting powder, thus promote the densification and grain refining of ZrB2-SiC ceramics. As a result, the mechanical properties including flexural strength and fracture toughness were improved. However, with the further adoption of carbon black, mechanical properties were not improved much, which could be attributed to the redundant phase at grain boundaries. The results presented here point to a potential method for improving densification, microstructure and mechanical properties of ZrB2-based ceramic composites.

scholarly journals Effect of Different Types of Block Copolymers on Morphology, Mechanical Properties, and Fracture Mechanisms of Bisphenol-F Based Epoxy System

2019 ◽  
Vol 3 (3) ◽  
pp. 68 ◽  
Author(s):  
Bajpai ◽  
Wetzel
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tensile Strength ◽  
Block Copolymers ◽  
Fracture Energy ◽  
Plastic Zone Size ◽  
Fracture Mechanisms ◽  
Epoxy System ◽  
Bisphenol F ◽  
Different Types

The effect of adding different types of soft block copolymer on the tensile properties, fracture mechanic properties, and thermo-mechanical properties of bisphenol F based epoxy resin were studied. Two different self-assembling block copolymers, (a) constituting of a center block of poly (butyl acrylate) and two side blocks of poly (methyl) methacrylate-co-polar co-monomer (BCP 1) and (b) poly(ethylene oxide)-b-poly(butylene oxide) (PEO-PBO) diblock copolymer (BCP 2), were used with an epoxy-hardener system. The maximum fracture toughness and fracture energy were measured as KIc = 2.75 MPa·m1/2 and GIc = 2.37 kJ/m2 for the 10 wt % of BCP 1 modified system, which were 366% and 2270% higher in comparison to reference epoxy system, and a 63% reduction in tensile strength was also observed. Similarly, for BCP2 modified systems, the maximum value of KIc = 1.65 MPa·m1/2 and GIc = 1.10 kJ/m2 was obtained for epoxy modified with 12 wt % of BCP2 and a reduction of 32% in tensile strength. The fracture toughness and fracture energy were co-related to the plastic zone size for all the modified systems. Finally, the analysis of the fracture surfaces revealed the toughening micro-mechanisms of the nanocomposites.

Factors Affecting Spherical Nano-Indentation of Thin Film/Substrate Systems

2014 ◽  
Author(s):  
A. Hossain ◽  
A. Mian
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Mechanical Response ◽  
Indentation Test ◽  
Element Analysis ◽  
Factors Affecting ◽  
Nano Indentation ◽  
Fea Modeling ◽  
Soft Biological Materials ◽  
Film Substrate

Great interests have been made over the last few years in the development of techniques to measure the mechanical properties of many engineering materials at the nano scale. In nano-indentation, a hard tip with known mechanical properties is pressed into a sample whose properties are unknown. The load, indentation depth and deformed area resulting from this test are then used to determine the desired mechanical properties, such as hardness and modulus. In this study, the computer-based finite element analysis (FEA) method is used to investigate factors effecting nano-indentation to ensure reliable measurement of thin film properties. First, the FEA method is used to predict the mechanical response of bulk aluminum (Al) using a spherical indenter. The numerical prediction is then compared with existing published results to validate the FEA modeling scheme. Once the model is validated, additional numerical analyses are conducted to investigate the response of Al-film deposited on different substrate materials. New mathematical formulations are proposed to determine the film modulus from nano-indentation test. The film modulus obtained from the new and existing mathematical formulations are also compared. Results obtained from this research can be used to characterize the mechanical properties of soft biological materials such as biofilm or tissue scaffolds.

scholarly journals Microstructure and Mechanical Properties of Si3N4-Fe3Si Composites Prepared by Gas-Pressure Sintering

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1206
Author(s):  
Jiasuo Guan ◽  
Laifei Cheng ◽  
Mingxing Li
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Crack Deflection ◽  
Gas Pressure ◽  
Interface Debonding ◽  
Abnormal Growth ◽  
Pull Out ◽  
Uniform Microstructure ◽  
Microstructure And Mechanical Properties ◽  
Gas Pressure Sintering

Si3N4-Fe3Si composites were prepared using Fe-Si3N4 as the source of Fe3Si by gas-pressure sintering. By adding different amounts of Fe-Si3N4 into the starting powders, Si3N4-Fe3Si composites with various Fe3Si phase contents were obtained. The microstructure and mechanical properties of the composites were investigated. With the increase of Fe-Si3N4 contents, the content and particle size of Fe3Si both increased. When more than 60 wt. % Fe-Si3N4 were added, the abnormal growth of Fe3Si particles occurred and oversized Fe3Si particles appeared, leading to non-uniform microstructures and worse mechanical properties of the composites. It has been found that Fe3Si particles could toughen the composites through particle pull-out, interface debonding, crack deflection, and particle bridging. Uniform microstructure and improved mechanical properties (flexural strength of 354 MPa and fracture toughness of 8.4 MPa·m1/2) can be achieved for FSN40.

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