scholarly journals Tuning of the elastic modulus of a soft polythiophene through molecular doping

2021 ◽  
Author(s):  
Sepideh Zokaei ◽  
Donghyun Kim ◽  
Emmy Järsvall ◽  
Abigail M. Fenton ◽  
Albree R. Weisen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Side Chains ◽  
Molecular Doping ◽  
Oligoethylene Glycol

Molecular doping of a polythiophene with oligoethylene glycol side chains is found to strongly modulate not only the electrical but also the mechanical properties of the polymer.

Branched Chain Natural Rubber Derivatives Obtained by Reaction with Azodicarboxylates

1957 ◽  
Vol 30 (3) ◽  
pp. 895-902
Author(s):  
S. S. Ivanov ◽  
N. A. Yuzefovich ◽  
A. V. Sidorovich ◽  
E. F. Fedorova
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Natural Rubber ◽  
Side Chains ◽  
Damping Decrement ◽  
Branched Chain

Abstract 1. Ethyl azodicarboxylate (EAD) and ethylene dis-ethyl azodicarboxylate (DEAD) react quantitatively with natural rubber to form branched and cross-linked derivatives, respectively. 2. The mechanical properties of vulcanizates from natural rubber containing side branches (obtained with the aid of EAD) differ greatly from the properties of unbranched vulcanizates. 3. Analysis of the load-extension diagrams shows that the introduction of EAD side chains into natural rubber results in the formation of vulcanizates with high extensions at low loads. Vulcanizates without EAD have steeper load-extension diagrams and lower extensions at break. 4. As the temperature rises from 20 to 100°, the elastic modulus and mechanical losses (or the logarithmic damping decrement) of vulcanizates cross-linked with DEAD decreases greatly (about 4–7 times). Addition of 10 per cent (g-equiv.) of EAD side chains approximately doubles the mechanical losses in comparison with vulcanizates without EAD.

scholarly journals Macromolecular Structure Controlling Micro Mechanical Properties of Vitrinite and Inertinite in Tectonically Deformed Coals—A Case Study in Fengfeng Coal Mine of Taihangshan Fault Zone (North China)

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6618
Author(s):  
Anmin Wang ◽  
Daiyong Cao ◽  
Yingchun Wei ◽  
Zhifei Liu
Keyword(s):  
Mechanical Properties ◽  
Dipole Moment ◽  
Elastic Modulus ◽  
Intermolecular Forces ◽  
Molecular Structures ◽  
Macromolecular Structure ◽  
Side Chains ◽  
13C Nuclear Magnetic Resonance ◽  
Benzene Rings ◽  
Nanoindentation Experiment

In order to study the evolution of the mechanical properties and macromolecular structures in different macerals of tectonically deformed coal (TDC), vitrinite and inertinite samples were handpicked from six block TDCs in the same coal seam with an increasing deformation degree (unaltered, cataclastic, porphyroclast, scaly and powdery coal). The micro mechanical properties were tested by the nanoindentation experiment and the macromolecular structures were measured using 13C nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). The results show that the range of hardness and elastic modulus of inertinite is 0.373–1.517 GPa and 4.339–12.158 GPa, respectively, which is significantly higher than that of vitrinite with values of 0.278–0.456 GPa and 4.857–7.810 GPa, respectively. From unaltered coal to powdery coal, the hardness of vitrinite and inertinite gradually decreases, with the difference between these macerals becomes smaller and the elastic modulus of vitrinite shows an increasing trend, while that of inertinite was more variable. Both the NMR and FITR results reveal that the macromolecular structure of inertinite has similar structural transitions as vitrinite. As the degree of deformation increases, the aliphatic side chains become shorter and the aromaticity is increasing. Macromolecular alterations caused by tectonic stress is expected to produce defects in the TDCs, therefore there should be more interspacing among the macromolecular groups for the extrusion of macromolecules caused by the indenter of the nanoindentation experiment, thereby reducing the hardness. The elastic modulus of coal is believed to be related to intermolecular forces, which are positively correlated to the dipole moment. By calculating the dipole moments of the typical aromatic molecular structures with aliphatic side chains, the detachment of the aliphatic side chains and the growth of benzene rings can both increase the dipole moment, which can promote elastic modulus. In addition, the increasing number of benzene rings can create more π-π bonds between the molecules, which can lead to an increase in the intermolecular forces, further increasing the elastic modulus.

scholarly journals Experimental Analysis of the Mechanical Properties and Resistivity of Tectonic Coal Samples with Different Particle Sizes

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2303
Author(s):  
Congyu Zhong ◽  
Liwen Cao ◽  
Jishi Geng ◽  
Zhihao Jiang ◽  
Shuai Zhang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniaxial Compressive Strength ◽  
Coalbed Methane ◽  
Coal Sample ◽  
Fine Particles ◽  
Particle Sizes ◽  
Tectonic Coal

Because of its weak cementation and abundant pores and cracks, it is difficult to obtain suitable samples of tectonic coal to test its mechanical properties. Therefore, the research and development of coalbed methane drilling and mining technology are restricted. In this study, tectonic coal samples are remodeled with different particle sizes to test the mechanical parameters and loading resistivity. The research results show that the particle size and gradation of tectonic coal significantly impact its uniaxial compressive strength and elastic modulus and affect changes in resistivity. As the converted particle size increases, the uniaxial compressive strength and elastic modulus decrease first and then tend to remain unchanged. The strength of the single-particle gradation coal sample decreases from 0.867 to 0.433 MPa and the elastic modulus decreases from 59.28 to 41.63 MPa with increasing particle size. The change in resistivity of the coal sample increases with increasing particle size, and the degree of resistivity variation decreases during the coal sample failure stage. In composite-particle gradation, the proportion of fine particles in the tectonic coal sample increases from 33% to 80%. Its strength and elastic modulus increase from 0.996 to 1.31 MPa and 83.96 to 125.4 MPa, respectively, and the resistivity change degree decreases. The proportion of medium particles or coarse particles increases, and the sample strength, elastic modulus, and resistivity changes all decrease.

scholarly journals Experimental and Numerical Analysis of the Mechanical Properties of a Pretreated Shape Memory Alloy Wire in a Self-Centering Steel Brace

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 80
Author(s):  
Bo Zhang ◽  
Sizhi Zeng ◽  
Fenghua Tang ◽  
Shujun Hu ◽  
Qiang Zhou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Loading Rate ◽  
Effective Elastic Modulus ◽  
Maximum Energy ◽  
Numerical Results ◽  
Energy Dissipation Capacity

As a stimulus-sensitive material, the difference in composition, fabrication process, and influencing factors will have a great effect on the mechanical properties of a superelastic Ni-Ti shape memory alloy (SMA) wire, so the seismic performance of the self-centering steel brace with SMA wires may not be accurately obtained. In this paper, the cyclic tensile tests of a kind of SMA wire with a 1 mm diameter and special element composition were tested under multi-working conditions, which were pretreated by first tensioning to the 0.06 strain amplitude for 40 cycles, so the mechanical properties of the pretreated SMA wires can be simulated in detail. The accuracy of the numerical results with the improved model of Graesser’s theory was verified by a comparison to the experimental results. The experimental results show that the number of cycles has no significant effect on the mechanical properties of SMA wires after a certain number of cyclic tensile training. With the loading rate increasing, the pinch effect of the hysteresis curves will be enlarged, while the effective elastic modulus and slope of the transformation stresses in the process of loading and unloading are also increased, and the maximum energy dissipation capacity of the SMA wires appears at a loading rate of 0.675 mm/s. Moreover, with the initial strain increasing, the slope of the transformation stresses in the process of loading is increased, while the effective elastic modulus and slope of the transformation stresses in the process of unloading are decreased, and the maximum energy dissipation capacity appears at the initial strain of 0.0075. In addition, a good agreement between the test and numerical results is obtained by comparing with the hysteresis curves and energy dissipation values, so the numerical model is useful to predict the stress–strain relations at different stages. The test and numerical results will also provide a basis for the design of corresponding self-centering steel dampers.

Mechanical Properties of Secondary Wall and Compound Corner Middle Lamella near the Phenol-Formaldehyde (PF) Adhesive Bond Line Measured by Nanoindentation

2011 ◽  
Vol 236-238 ◽  
pp. 1746-1751 ◽  
Author(s):  
Kun Liang ◽  
Guan Ben Du ◽  
Omid Hosseinaei ◽  
Si Qun Wang ◽  
Hui Wang
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Secondary Wall ◽  
Phenol Formaldehyde ◽  
Middle Lamella ◽  
Adhesive Bond ◽  
Cellular Level ◽  
Bond Line ◽  
Line Region ◽  
Penetration Behavior

To find out the penetration of PF into the wood cell wall and its effects onthe mechanical properties in the cellular level, the elastic modulus and hardness of secondary wall (S2layer) and compound corner middle lamella (CCML) near PF bond line region were determined by nanoindentation. Compare to the reference cell walls (unaffected by PF), PF penetration into the wood tissues showed improved elastic modulus and hardness. And the mechanical properties decreased slowly with the increasing the distance from the bond line, which are attributed to the effects of PF penetration into S2layer and CCML. The reduced elastic modulus variations were from18.8 to 14.4 GPa for S2layer, and from10.1 to 7.65 GPa for CCML. The hardness was from 0.67 to 0.52 GPa for S2layer, and from 0.65 to 0.52 GPa for CCML. In each test viewpoint place, the average hardness of CCML was almost as high as that of S2layer, but the reduced elastic modulus was about 50% less than that of S2layer. But the increase ratio of mechanical properties was close. All the results showed PF penetrates into the CCML. The penetration behavior and penetration depth from bond line were similar in both S2layer and CCML.

scholarly journals Assessment of the Rheological and Mechanical Properties of Geopolymer Concrete Comprising Fly Ash and Fluid Catalytic Cracking Residue as Aluminosilicate Precursor

2021 ◽  
Vol 11 (7) ◽  
pp. 3032
Author(s):  
Tuan Anh Le ◽  
Sinh Hoang Le ◽  
Thuy Ninh Nguyen ◽  
Khoa Tan Nguyen
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
Flexural Strength ◽  
Catalytic Cracking ◽  
Fluid Catalytic Cracking ◽  
High Alumina ◽  
Geopolymer Concrete ◽  
Sem Images

The use of fluid catalytic cracking (FCC) by-products as aluminosilicate precursors in geopolymer binders has attracted significant interest from researchers in recent years owing to their high alumina and silica contents. Introduced in this study is the use of geopolymer concrete comprising FCC residue combined with fly ash as the requisite source of aluminosilicate. Fly ash was replaced with various FCC residue contents ranging from 0–100% by mass of binder. Results from standard testing methods showed that geopolymer concrete rheological properties such as yield stress and plastic viscosity as well as mechanical properties including compressive strength, flexural strength, and elastic modulus were affected significantly by the FCC residue content. With alkali liquid to geopolymer solid ratios (AL:GS) of 0.4 and 0.5, a reduction in compressive and flexural strength was observed in the case of geopolymer concrete with increasing FCC residue content. On the contrary, geopolymer concrete with increasing FCC residue content exhibited improved strength with an AL:GS ratio of 0.65. Relationships enabling estimation of geopolymer elastic modulus based on compressive strength were investigated. Scanning electron microscope (SEM) images and X-ray diffraction (XRD) patterns revealed that the final product from the geopolymerization process consisting of FCC residue was similar to fly ash-based geopolymer concrete. These observations highlight the potential of FCC residue as an aluminosilicate source for geopolymer products.

Experimental study on mechanical properties of polypropylene nanocomposites reinforced with a hybrid graphene/PP-g-MA/kenaf fiber by response surface methodology

2021 ◽  
pp. 009524432110153
Author(s):  
Jaber Mirzaei ◽  
Abdolhossein Fereidoon ◽  
Ahmad Ghasemi-Ghalebahman
Keyword(s):  
Mechanical Properties ◽  
Response Surface Methodology ◽  
Elastic Modulus ◽  
Response Surface ◽  
Graphene Nanosheets ◽  
Hot Press ◽  
Kenaf Fiber ◽  
Polypropylene Nanocomposites ◽  
Kenaf Fibers ◽  
Internal Mixer

In this study, the mechanical properties of polypropylene (PP)-based nanocomposites reinforced with graphene nanosheets, kenaf fiber, and polypropylene-grafted maleic anhydride (PP-g-MA) were investigated. Response surface methodology (RSM) based on Box–Behnken design (BBD) was used as the experimental design. The blends fabricated in three levels of parameters include 0, 0.75, and 1.5 wt% graphene nanosheets, 0, 7.5, and 15 wt% kenaf fiber, and 0, 3, and 6 wt% PP-g-MA, prepared by an internal mixer and a hot press machine. The fiber length was 5 mm and was being constant for all samples. Tensile, flexural, and impact tests were conducted to determine the blend properties. The purpose of this research is to achieve the highest mechanical properties of the considered nanocomposite blend. The addition of graphene nanosheets to 1 wt% increased the tensile, flexural, and impact strengths by 16%, 24%, and 19%, respectively, and an addition up to 1.5 wt% reduced them. With further addition of graphene nanosheets until 1.5 wt%, the elastic modulus was increased by 70%. Adding the kenaf fiber up to 15 wt% increased the elastic modulus, tensile, flexural, and impact strength by 24%, 84%, 18%, and 11%, respectively. The addition of PP-g-MA has increased the adhesion, dispersion and compatibility of graphene nanosheets and kenaf fibers with matrix. With 6 wt% PP-g-MA, the tensile strength and elastic modulus were increased by 18% and 75%, respectively. The addition of PP-g-MA to 5 wt% increased the flexural and impact strengths by 10% and 5%, respectively. From the entire experimental data, the optimum values for elastic modulus, as well as, tensile, flexural, and impact strengths in the blends were obtained to be 4 GPa, 33.7896 MPa, 57.6306 MPa, and 100.1421 J/m, respectively. Finally, samples were studied by FE-SEM to check the dispersion of graphene nanosheets, PP-g-MA and kenaf fibers in the polymeric matrix.

scholarly journals Influence of Alumina Nanofibers Sintered by the Spark Plasma Method on Nickel Mechanical Properties

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 548 ◽  
Author(s):  
Leonid Agureev ◽  
Valeriy Kostikov ◽  
Zhanna Eremeeva ◽  
Svetlana Savushkina ◽  
Boris Ivanov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Strength Properties ◽  
Alumina Nanoparticles ◽  
Metal Powders ◽  
Wide Range ◽  
The Matrix ◽  
Spark Plasma ◽  
Average Size

The article presents the study of alumina nanoparticles’ (nanofibers) concentration effect on the strength properties of pure nickel. The samples were obtained by spark plasma sintering of previously mechanically activated metal powders. The dependence of the grain size and the relative density of compacts on the number of nanofibers was investigated. It was found that with an increase in the concentration of nanofibers, the average size of the matrix particles decreased. The effects of the nanoparticle concentration (0.01–0.1 wt.%) on the elastic modulus and tensile strength were determined for materials at 25 °C, 400 °C, and 750 °C. It was shown that with an increase in the concentration of nanofibers, a 10–40% increase in the elastic modulus and ultimate tensile strength occurred. A comparison of the mechanical properties of nickel in a wide range of temperatures, obtained in this work with materials made by various technologies, is carried out. A description of nanofibers’ mechanisms of influence on the structure and mechanical properties of nickel is given. The possible impact of impurity phases on the properties of nickel is estimated. The tendency of changes in the mechanical properties of nickel, depending on the concentration of nanofibers, is shown.

scholarly journals Numerical Studies of the Effects of Water Capsules on Self-Healing Efficiency and Mechanical Properties in Cementitious Materials

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Haoliang Huang ◽  
Guang Ye
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Cementitious Materials ◽  
Self Healing ◽  
Negative Effects ◽  
Numerical Studies ◽  
Healing Efficiency ◽  
The Impact ◽  
Positive Effect

In this research, self-healing due to further hydration of unhydrated cement particles is taken as an example for investigating the effects of capsules on the self-healing efficiency and mechanical properties of cementitious materials. The efficiency of supply of water by using capsules as a function of capsule dosages and sizes was determined numerically. By knowing the amount of water supplied via capsules, the efficiency of self-healing due to further hydration of unhydrated cement was quantified. In addition, the impact of capsules on mechanical properties was investigated numerically. The amount of released water increases with the dosage of capsules at different slops as the size of capsules varies. Concerning the best efficiency of self-healing, the optimizing size of capsules is 6.5 mm for capsule dosages of 3%, 5%, and 7%, respectively. Both elastic modulus and tensile strength of cementitious materials decrease with the increase of capsule. The decreasing tendency of tensile strength is larger than that of elastic modulus. However, it was found that the increase of positive effect (the capacity of inducing self-healing) of capsules is larger than that of negative effects (decreasing mechanical properties) when the dosage of capsules increases.

Graphite/Bio-Based Epoxy Composites: The Mechanical Properties Interface

2015 ◽  
Vol 799-800 ◽  
pp. 115-119 ◽  
Author(s):  
Anika Zafiah M. Rus ◽  
Nur Munirah Abdullah ◽  
M.F.L. Abdullah ◽  
M. Izzul Faiz Idris
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Filler Content ◽  
Weight Percent ◽  
Epoxy Composites ◽  
Elongation At Break ◽  
Graphite Content ◽  
Dispersion Condition ◽  
Strong Interfacial Bonding

Graphite reinforced bio-based epoxy composites with different particulate fractions of graphite were investigated for mechanical properties such as tensile strength, elastic modulus and elongation at break. The graphite content was varied from 5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, 25 wt.%, 30 wt.% by weight percent in the composites. The results showed that the mechanical properties of the composites mainly depend on dispersion condition of the treated graphite filler, aggregate structure and strong interfacial bonding between treated graphite in the bio-based epoxy matrix. The composites showed improved tensile strength and elastic modulus with increase treated graphite weight loading. This also revealed the composites with increasing filler content was decreasing the elongation at break.

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