Effect of Nanoparticles Surface Bonding and Aspect Ratio on Mechanical Properties of Highly Cross-Linked Epoxy Nanocomposites: Mesoscopic Simulations

The paper aims to study the mechanical properties of epoxy resin filled with clay nanoparticles (NPs), depending on their shapes and content on the surface of a modifying agent capable of forming covalent bonds with a polymer. The cylindrical clay nanoparticles with equal volume and different aspects ratios (disks, barrel, and stick) are addressed. The NPs’ bonding ratio with the polymer (RGC) is determined by the fraction of reactive groups and conversion time and varies from RGC = 0 (non-bonded nanoparticles) to RGC = 0.65 (more than half of the surface groups are linked with the polymer matrix). The performed simulations show the so-called load-bearing chains (LBCs) of chemically cross-linked monomers and modified nanoparticles to determine the mechanical properties of the simulated composites. The introduction of nanoparticles leads to the breaking of such chains, and the chemical cross-linking of NPs with the polymer matrix restores the LBCs and strengthens the composite. At small values of RGC, the largest value of the elastic modulus is found for systems filled with nanoparticles having the smallest surface area, and at high values of RGC, on the contrary, the systems containing disk-shaped particles with the largest surface area have a larger elastic modulus than the others. All calculations are performed within the framework of a mesoscopic model based on accurate mapping of the atomistic structures of the polymer matrix and nanoparticles into coarse-grained representations, which, if necessary, allow reverse data mapping and quantitative assessment of the state of the filled epoxy resin. On the other hand, the obtained data can be used to design the functional materials with specified mechanical properties based on other practically significant polymer matrices and nanofillers.

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Effect of Secondary Carbon Nanofillers on the Electrical, Thermal, and Mechanical Properties of Conductive Hybrid Composites Based on Epoxy Resin and Graphite

Materials ◽

10.3390/ma14154169 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4169

Author(s):

Marcel Zambrzycki ◽

Krystian Sokolowski ◽

Maciej Gubernat ◽

Aneta Fraczek-Szczypta

Keyword(s):

Mechanical Properties ◽

Specific Surface ◽

Epoxy Resin ◽

Surface Area ◽

Specific Surface Area ◽

Hybrid Composites ◽

Department Of Energy ◽

Carbon Nanofillers ◽

The Impact ◽

Secondary Carbon

In this work, we present a comparative study of the impact of secondary carbon nanofillers on the electrical and thermal conductivity, thermal stability, and mechanical properties of hybrid conductive polymer composites (CPC) based on high loadings of synthetic graphite and epoxy resin. Two different carbon nanofillers were chosen for the investigation—low-cost multi-layered graphene nanoplatelets (GN) and carbon black (CB), which were aimed at improving the overall performance of composites. The samples were obtained by a simple, inexpensive, and effective compression molding technique, and were investigated by the means of, i.a., scanning electron microscopy, Raman spectroscopy, electrical conductivity measurements, laser flash analysis, and thermogravimetry. The tests performed revealed that, due to the exceptional electronic transport properties of GN, its relatively low specific surface area, good aspect ratio, and nanometric sizes of particles, a notable improvement in the overall characteristics of the composites (best results for 4 wt % of GN; σ = 266.7 S cm−1; λ = 40.6 W mK−1; fl. strength = 40.1 MPa). In turn, the addition of CB resulted in a limited improvement in mechanical properties, and a deterioration in electrical and thermal properties, mainly due to the too high specific surface area of this nanofiller. The results obtained were compared with US Department of Energy recommendations regarding properties of materials for bipolar plates in fuel cells. As shown, the materials developed significantly exceed the recommended values of the majority of the most important parameters, indicating high potential application of the composites obtained.

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Mechanical Properties and Deformation Mechanisms of Graphene Foams with Bi-Modal Sheet Thickness by Coarse-Grained Molecular Dynamics Simulations

Materials ◽

10.3390/ma14195622 ◽

2021 ◽

Vol 14 (19) ◽

pp. 5622

Author(s):

Shenggui Liu ◽

Mindong Lyu ◽

Chao Wang

Keyword(s):

Mechanical Properties ◽

Elastic Recovery ◽

Structural Connectivity ◽

High Stress ◽

Sheet Thickness ◽

Functional Materials ◽

Deformation Mechanisms ◽

Coarse Grained ◽

Graphene Sheets ◽

Graphene Foams

Graphene foams (GrFs) have been widely used as structural and/or functional materials in many practical applications. They are always assembled by thin and thick graphene sheets with multiple thicknesses; however, the effect of this basic structural feature has been poorly understood by existing theoretical models. Here, we propose a coarse-grained bi-modal GrF model composed of a mixture of 1-layer flexible and 8-layer stiff sheets to study the mechanical properties and deformation mechanisms based on the mesoscopic model of graphene sheets (Model. Simul. Mater. Sci. Eng. 2011, 19, 54003). It is found that the modulus increases almost linearly with an increased proportion of 8-layer sheets, which is well explained by the mixture rule; the strength decreases first and reaches the minimum value at a critical proportion of stiff sheets ~30%, which is well explained by the analysis of structural connectivity and deformation energy of bi-modal GrFs. Furthermore, high-stress regions are mainly dispersed in thick sheets, while large-strain areas mainly locate in thin ones. Both of them have a highly uneven distribution in GrFs due to the intrinsic heterogeneity in both structures and the mechanical properties of sheets. Moreover, the elastic recovery ability of GrFs can be enhanced by adding more thick sheets. These results should be helpful for us to understand and further guide the design of advanced GrF-based materials.

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Characterization of Nanoporous Low Dielectric Polysilsesquioxane Thin Films

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.277-279.907 ◽

2005 ◽

Vol 277-279 ◽

pp. 907-911

Author(s):

Jingyu Hyeon Lee ◽

Yi Yeol Lyu ◽

Mong Sup Lee ◽

Jin Heong Yim ◽

Sang Youl Kim

Keyword(s):

Thin Films ◽

Mechanical Properties ◽

Dielectric Constant ◽

Refractive Index ◽

Elastic Modulus ◽

Polymer Matrix ◽

Low Dielectric

Poly(methyl-co-cyclosiloxane bearing silsesquioxane)s (P(M-co-CSSQs)) were prepared. Using poly(e-caprolactone) (PCL) as a template, PCL / P(M-co-CSSQ) nanohybrid films were fabricated. The electrical, morphological, and mechanical properties of the PCL / P(M-co-CSSQ) films were investigated. The dielectric constant of a cured PCL / P(M-co-CSSQ) film at 420°C scaled down from 2.55 to 2.05 and refractive index from 1.41 to 1.33 when 20 vol. % of the PCL was admixed with the polymer matrix. The elastic modulus and hardness of the cured PCL / P(Mco- CSSQ) (2:8, vol./vol.) film were 2.50 and 0.32 GPa, respectively, showing dependency on the PCL content.

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Improving Mechanical Properties of Thermoset Biocomposites by Fiber Coating or Organic Oil Addition

International Journal of Polymer Science ◽

10.1155/2015/840823 ◽

2015 ◽

Vol 2015 ◽

pp. 1-7 ◽

Cited By ~ 8

Author(s):

Truc T. Ngo ◽

James G. Kohl ◽

Tawni Paradise ◽

Autumn Khalily ◽

Duane L. Simonson

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Epoxy Resin ◽

Polymer Matrix ◽

Modulus Of Elasticity ◽

Epoxy Matrix ◽

Linseed Oil ◽

Hemp Fibers ◽

Fiber Coating ◽

Strength And Ductility

Two different thermoset biocomposite systems are experimented in this study with the hope to improve their mechanical properties. Fiberglass and hemp, in form of fabrics, are used to reinforce the thermoset polymer matrix, which includes a traditional epoxy resin and a linseed oil-based bioresin (UVL). The fiber/polymer matrix interface is modified using two different approaches: adding a plant-based oil (pine or linseed) to the polymer matrix or coating the fibers with 3-(aminopropyl)triethoxysilane (APTES) prior to integrating them into the polymer matrix. Epoxy resin is cured using an amine-based initiator, whereas UVL resin is cured under ultraviolet light. Results show that hemp fibers with APTES prime coat used in either epoxy or UVL matrix exhibit some potential improvements in the composite’s mechanical properties including tensile strength, modulus of elasticity, and ductility. It is also found that adding oil to the epoxy matrix reinforced with fiberglass mostly improves the material’s modulus of elasticity while maintaining its tensile strength and ductility. However, adding oil to the epoxy matrix reinforced with hemp doubles the material’s ductility while slightly reducing its tensile strength and modulus of elasticity.

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Effect of Alloying Elements on the Mechanical Properties of Mo3Si

Metals ◽

10.3390/met11010129 ◽

2021 ◽

Vol 11 (1) ◽

pp. 129

Author(s):

Wei Bi ◽

Shunping Sun ◽

Shaoyi Bei ◽

Yong Jiang

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Young’S Modulus ◽

Young's Modulus ◽

Poisson Ratio ◽

Alloying Elements ◽

Covalent Bonds ◽

Excellent Thermal Stability ◽

Nb Doping ◽

Effect Of Alloying

Molybdenum silicides are attractive high-temperature structural materials because of their excellent thermal stability and outstanding oxidation resistance at high temperatures. First-principles calculations were employed to investigate the effect of alloying elements (Cr, Nb, V, W, Al, Ga, and Ge) on the mechanical properties of Mo3Si. The structural stabilities of doped Mo3Si were calculated, showing that the Pm-3n structure was stable at the investigated low-doping concentration. The calculated elastic constants have also evaluated some essential mechanical properties of doped Mo3Si. Cr- and V-doping decreased the elastic modulus, while Al- and Nb-doping slightly increased the shear and Young’s modulus of Mo3Si. Furthermore, V-, Al- and Nb-doping decreased the B/G and Poisson ratio, suggesting that these elements could form strong covalent bonds, and decrease shear deformation and alloy ductility. Based on the three-dimensional contours and two-dimensional projection of the elastic modulus, Cr- and V-doping exhibited a significant influence on the anisotropy of the shear and Young’s modulus. According to charge density and density of states, the electronic structures of alloyed Mo3Si were further analyzed to reveal the doping effects.

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An Investigation of the Microstructures and Mechanical Properties of FeSiBCuAl Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.627.646 ◽

2012 ◽

Vol 627 ◽

pp. 646-650

Author(s):

Hui Chao Cheng ◽

Min Song

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Coarse Grained ◽

Melting Method ◽

Casting Technique ◽

Al Content ◽

Arc Melting ◽

Microstructures And Mechanical Properties ◽

Mould Casting ◽

Copper Mould

Fe76.5-xSi13.5B9Cu1Alxalloys were fabricated by arc melting method plus copper mould casting technique. The effects of Al content on the microstructures and mechanical properties of the alloys were investigated. The results showed that the Al content significantly affects the microstructures and mechanical properties of the alloys. The addition of Al element into the alloy results in a variation from nanostructures to coarse grained structures. At the same time, the hardness and elastic modulus decrease with increasing the Al content.

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Mechanical Properties of Cellulose Nanocrystal (CNC) Bundles: Coarse-Grained Molecular Dynamic Simulation

Journal of Composites Science ◽

10.3390/jcs3020057 ◽

2019 ◽

Vol 3 (2) ◽

pp. 57 ◽

Cited By ~ 5

Author(s):

Majid G. Ramezani ◽

Behnoush Golchinfar

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Molecular Dynamic ◽

Interfacial Energy ◽

Mechanical Performance ◽

Twist Angle ◽

Interfacial Strength ◽

Covalent Bond ◽

Interface Energy ◽

Coarse Grained

Cellulose nanocrystals (CNCs) is a promising biodegradable nanomaterial with outstanding physical, chemical, and mechanical properties for many applications. Although aligned CNCs can self-assemble into bundles, their mechanical performance is reduced by interfacial strength between CNCs and a twisted structure. In this paper, we employ developed coarse-grained (CG) molecular dynamic (MD) simulations to investigate the influence of twist and interface energy on the tensile performance of CNC bundles. CNC bundles of different sizes (number of particles) are tested to also include the effect of size on mechanical performance. The effect of interfacial energy and twist on the mechanical performance shows that elastic modulus, strength, and toughness are more sensitive to twisted angle than interfacial energy. In addition, the effect of size on the bundle and twist on their mechanical performance revealed that both size and twist have a significant effect on the results and can reduce the strength and elastic modulus by 75% as a results of covalent bond dissociation. In addition, a comparison of the broken regions for different values of twist shows that by increasing the twist angle the crack propagates in multiple locations with a twisted shape.

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The Impact of Hydrogen on Mechanical Properties; A New In Situ Nanoindentation Testing Method

Micromachines ◽

10.3390/mi10020114 ◽

2019 ◽

Vol 10 (2) ◽

pp. 114 ◽

Cited By ~ 2

Author(s):

Christian Müller ◽

Mohammad Zamanzade ◽

Christian Motz

Keyword(s):

Mechanical Properties ◽

Activation Energy ◽

Elastic Modulus ◽

Dislocation Nucleation ◽

Coarse Grained ◽

Testing Method ◽

Nanomechanical Testing ◽

Nanoindentation Testing ◽

The Impact

We have designed a new method for electrochemical hydrogen charging which allows us to charge very thin coarse-grained specimens from the bottom and perform nanomechanical testing on the top. As the average grain diameter is larger than the thickness of the sample, this setup allows us to efficiently evaluate the mechanical properties of multiple single crystals with similar electrochemical conditions. Another important advantage is that the top surface is not affected by corrosion by the electrolyte. The nanoindentation results show that hydrogen reduces the activation energy for homogenous dislocation nucleation by approximately 15–20% in a (001) grain. The elastic modulus also was observed to be reduced by the same amount. The hardness increased by approximately 4%, as determined by load-displacement curves and residual imprint analysis.

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Preparation and Mechanical Characterization of Composite Material of Polymer–Matrix with Starch Reinforced with Coconut Fibers

MRS Proceedings ◽

10.1557/proc-1276-22 ◽

2010 ◽

Vol 1276 ◽

Author(s):

Yaret G. Torres-Hernández- ◽

Alejandro Altamirano-Torres ◽

Francisco Sandoval-Pérez ◽

Enrique Rocha Rangel

Keyword(s):

Mechanical Properties ◽

Composite Material ◽

Epoxy Resin ◽

Polymer Matrix ◽

Vickers Hardness ◽

Mechanical Characterization ◽

Natural Fibers ◽

Hardness Tests ◽

Coconut Fibers

AbstractIn this work the synthesis and mechanical characterization of a polymer matrix composite is reported. An epoxy resin is used as matrix with addition of starch and coconut fibers as reinforcement. Vickers hardness and impact tests are used for mechanical characterization. Starch is used to promote degradability of the polymer matrix with clear benefits for the environment. Natural fibers have been used for reinforcing the composite materials. Natural fibers have several advantages such as price, low density and relatively high mechanical properties, they are also biodegradable and non abrasive In this investigation, the composite material samples are fabricated with epoxy resin, 5, 10, 15 wt % of starch and 5, 10 wt % of coconut fibers with the help of silicon molds which have the dimensions and geometry according to ASTM Standards for make Impact and Vickers hardness tests. The obtained results show that increases in the amount of coconut fibers cause an enhancement of the mechanical properties of the material, due to a good adhesion between the polymeric matrix and the natural fibers.

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Evaluation of flexural modulus, flexural strength and degree of conversion in BISGMA/TEGDMA resin filled with montmorillonite nanoparticles

Journal of Composite Materials ◽

10.1177/0021998316656925 ◽

2016 ◽

Vol 51 (7) ◽

pp. 927-937 ◽

Cited By ~ 11

Author(s):

Luiza MP Campos ◽

Letícia C Boaro ◽

Tamiris MR Santos ◽

Pamela A Marques ◽

Sonia RY Almeida ◽

...

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Flexural Strength ◽

Polymer Matrix ◽

Flexural Modulus ◽

Degree Of Conversion ◽

Bending Test ◽

Similar Degree ◽

Hybrid Filler ◽

Barium Glass

This study had as its main objective to evaluate the flexural properties (strength and modulus) and degree of conversion of a dimethacrylate resin containing different amounts of nanoparticulated clay Montomorillonite (MMT) as filler. A series of composites containing similar amounts (in volume) of barium glass particles was also tested as control data. Eight formulations with polymeric matrix-based BisGMA/TEGDMA (Bisphenol A Bis(2-hydroxy-3 methacryloxypropyl)Ether/Triethyleneglycol Dimethacrylate), four added with MMT and four added with barium glass in the volume concentration of 20, 30, 40 and 50 vol% were studied. The degree of conversion was determined using near-IR spectroscopy. Elastic modulus and flexural strength were determined by the three-point bending test. The dispersion of MMT nanoparticles was determined by means of X-ray diffraction and transmission electron microscopy analysis. The fillers montomorillonite and barium glass interacted with polymer matrix-based BisGMA/TEGDMA in a distinct manner. Although the addition of montomorillonite nanoparticles resulted in similar degree of conversion and higher elastic modulus values at all concentrations tested, only at the 20 vol% the flexural strength was statistically higher, compared to the control groups filled with barium glass. This could be related to the need of concentration optimization of montomorillonite for each type of polymer matrix in order to adjust or improve mechanical properties. The addition of low concentrations (<l 20% vol) of montomorillonite nanoparticles in dental composites resins – such as additive or hybrid filler – should be studied, aiming to the reduction of polymerization shrinkage, better mechanical properties and improvement of a new technology for future applications.

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