Simple linear ionic polysiloxane showing unexpected nanostructure and mechanical properties

AbstractPolysiloxanes are ubiquitous materials in industry and daily life derived from silicates, an abundant resource. They exhibit various properties, which depend on the main-chain network structure. Linear (1D backbone) polysiloxanes provide amorphous materials. They are recognized as fluid materials in the form of grease or oil with a low glass transition temperature. Herein we report that a simple linear polysiloxane, poly(3-aminopropylmethylsiloxane) hydrochloride, shows an elastic modulus comparable to that of stiff resins such as poly(tetrafluoroethylene). By introducing an ammonium salt at all the units of this polysiloxane, inter- and intramolecular ionic aggregates form, immensely enhancing the elastic modulus. This polysiloxane is highly hygroscopic, and its modulus can be altered reversibly 100 million times between moist and dry atmospheres. In addition, it works as a good adhesive for glass substrates with a shear strength of more than 1 MPa in the dry state. Despite its simple structure with a flexible backbone, this polymer unexpectedly self-assembles to form an ordered lamellar nanostructure in dry conditions. Consequently, this work reveals new functions and possibilities for polysiloxanes materials by densely introducing ionic groups.

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Simple Linear Ionic Polysiloxane Showing Unexpected Nanostructure and Mechanical Properties

10.21203/rs.3.rs-690197/v1 ◽

2021 ◽

Author(s):

Mitsuo Hara ◽

Yuta Iijima ◽

Shusaku Nagano ◽

Takahiro Seki

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Amorphous Materials ◽

Simple Structure ◽

Main Chain ◽

Daily Life ◽

Glass Substrates ◽

Ionic Groups ◽

Dry Conditions ◽

Good Adhesive

Abstract Polysiloxanes are ubiquitous materials in industry and daily life derived from silicates, an abundant resource. They exhibit various properties, which depend on the main-chain network structure. Linear (1D backbone) polysiloxanes provide amorphous materials. They are recognized as fluid materials in the form of grease or oil with a low glass transition temperature. Herein we report that a simple linear polysiloxane, poly(3-aminopropylmethylsiloxane) hydrochloride, shows an elastic modulus comparable to that of stiff resins such as poly(tetrafluoroethylene). By introducing an ammonium salt at all the units of this polysiloxane, inter- and intramolecular ionic aggregates form, immensely enhancing the elastic modulus. This polysiloxane is highly hygroscopic, and its modulus can be altered reversibly 100 million times between moist and dry atmospheres. In addition, it works as a good adhesive for glass substrates with a shear strength of more than 1 MPa in the dry state. Despite its simple structure with a flexible backbone, this polymer unexpectedly self-assembles to form an ordered lamellar nanostructure in dry conditions. Consequently, this work reveals new functions and possibilities for polysiloxanes materials by densely introducing ionic groups.

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FeZrN Films: Magnetic and Mechanical Properties Relative to the Phase-Structural State

Materials ◽

10.3390/ma15010137 ◽

2021 ◽

Vol 15 (1) ◽

pp. 137

Author(s):

Elena N. Sheftel ◽

Valentin A. Tedzhetov ◽

Eugene V. Harin ◽

Philipp V. Kiryukhantsev-Korneev ◽

Galina S. Usmanova ◽

...

Keyword(s):

Mechanical Properties ◽

Magnetic Properties ◽

Elastic Modulus ◽

Elastic Recovery ◽

The Other ◽

Magnetron Deposition ◽

Glass Substrates ◽

Saturation Induction ◽

Low Elastic Modulus ◽

Chemical And Phase Compositions

The paper presents results of investigation of Fe65.3–100Zr34.7–0N7.5–0 films prepared by dc magnetron deposition on glass substrates and subsequent 1-hour annealing at temperatures of 300–600 °C. The influence of the chemical and phase compositions and structure of the films, which were studied by TEM, SEM, XRD, and GDOES, on their mechanical properties determined by nanoindentation and static magnetic properties measured by VSM method is analyzed. The studied films exhibit the hardness within a range of 14–21 GPa, low elastic modulus (the value can reach 156 Gpa), and an elastic recovery of 55–83%. It was shown that the films are strong ferromagnets with the high saturation induction Bs (up to 2.1 T) and low coercive field Hc (as low as 40 A/m). The correlations between the magnetic and mechanical properties, on one hand, and the chemical composition of the films, their phase, and structural states as well, on the other hand, are discussed.

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Impact of Moisture Content on the Dynamic Failure Energy Dissipation Characteristics of Sandstone

Shock and Vibration ◽

10.1155/2019/6078342 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10 ◽

Cited By ~ 5

Author(s):

Aihong Lu ◽

Shanchao Hu ◽

Ming Li ◽

Tianzhu Duan ◽

Bing Li ◽

...

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Elastic Modulus ◽

Energy Dissipation ◽

Surface Energy ◽

Moisture Content ◽

Rock Masses ◽

Moisture Contents ◽

Dry Conditions ◽

Moisture Conditions

Rockburst frequently occurs in deep underground engineering, which poses a threat to safety and causes economic losses. Water injection into surrounding rock masses is an effective method for preventing rockburst, and the moisture content of rocks is significant for assessing the probability of rockburst. However, the majority of studies focus on the relationship between the macromechanical properties of rock masses under static loads and the moisture content of rock masses and seldom explore the impact of moisture variation (under dynamic loads) on the mechanical properties and energy dissipation. In this paper, the mechanical properties and energy dissipation of sandstone with different moisture contents have been experimentally investigated by the split Hopkinson pressure bar (SHPB) test. The test results indicate that the peak strength, dynamic elastic modulus, and unloading elastic modulus of sandstone in dry conditions are considerably larger than those in moisture conditions, and the three parameters linearly decrease as the moisture content increases from 0% to 2.58%. The distribution law of sandstone fragments with different moisture contents has been investigated by sieving test fragments with different grain sizes of grading sieves. The results show that the percentage of large grain size fragments incrementally decreases, and the percentage of small grain size fragments incrementally increases with moisture contents from 0% to 2.58%. When the moisture content ranges from 2.01%∼2.58%, the fractal dimension linearly increases, which indicates that the higher the moisture content is, the larger the dimension of the broken sandstone is. The calculation results for energy indicate that the sandstone energy attains the peak value with 0% moisture content. When the moisture content ranges from 2.01%∼2.58%, the reflected energy increases, and the transmitted energy and dissipated energy linearly decrease. In addition, the surface energy of the sandstone with different moisture contents has been investigated by converting fragments into spheres with the corresponding size. The results indicate that the smallest surface area of sandstone is obtained in dry conditions, but its surface energy in dry conditions is larger than that in moisture conditions. When the moisture ranges from 0% to 2.58%, due to 3% illite and 2% chlorite clay minerals reacting with different proportions of moisture, the surface areas of sandstone fragments linearly increase and the surface energy of sandstone linearly decreases.

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A Predictive Model for the Elastic Properties of a Collagen-Hydroxyapatite Porous Scaffold for Multi-Layer Osteochondral Substitutes

International Journal of Applied Mechanics ◽

10.1142/s1758825115500635 ◽

2015 ◽

Vol 07 (04) ◽

pp. 1550063 ◽

Cited By ~ 9

Author(s):

Dario Gastaldi ◽

Gianluca Parisi ◽

Riccardo Lucchini ◽

Roberto Contro ◽

Simone Bignozzi ◽

...

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Elastic Properties ◽

Porous Scaffold ◽

Single Layer ◽

Porous Scaffolds ◽

Sufficient Information ◽

Structure Property ◽

Flat Punch ◽

Dry Conditions

Damaged articular cartilage can be substituted by porous scaffolds exhibiting tailored mechanical properties and with a suited layer-based design. Reliable predictive models are able to provide a structure–property relationship in the design phase is still an open issue which is of prominent relevance. In this paper, a bottom-up homogenization approach is presented having the purpose to determine the elastic properties of each single layer of a osteochondral porous three-layers scaffold: a top cartilage chondral layer and two mineralized layers: an intermediate and a subchondral bone layer. For the cartilage top layer, dry and wet conditions are considered; while, for intermediate and bone layers only dry conditions are considered. The homogenization model is based on the porosity of each layer and on the elastic properties of the constituent materials, i.e., water, hydroxyapatite (HA) and collagen. The elastic moduli predicted for the mineralized layers are compared with available literature results. The model results obtained on the cartilage layers are validated through flat punch micro-indentation tests carried out on wet and dry samples. The results have shown that the elastic modulus of the mineralized layers is of the order of magnitude of few GPa; whereas, the elastic modulus of the cartilage layer which exhibits porosity higher than 90% is as low as 50 kPa and 300 kPa in wet and dry conditions, respectively. The above results show that the knowledge of the mechanical properties of the basic constituents which are universally known and the porosity of the layers are sufficient information to obtain a reliable prediction of the elastic properties of both mineralized layers and of cartilage layers.

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

Energies ◽

10.3390/en14082303 ◽

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.

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

Processes ◽

10.3390/pr9010080 ◽

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.

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Internal constraints and arrested relaxation in main-chain nematic elastomers

Nature Communications ◽

10.1038/s41467-021-21036-3 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Takuya Ohzono ◽

Kaoru Katoh ◽

Hiroyuki Minamikawa ◽

Mohand O. Saed ◽

Eugene M. Terentjev

Keyword(s):

Mechanical Properties ◽

Main Chain ◽

Polymer Networks ◽

Nematic Order ◽

Nematic Elastomers ◽

Nematic Director ◽

Highly Nonlinear ◽

Nonlinear Mechanical ◽

Liquid Crystal Elastomers ◽

Memory Applications

AbstractNematic liquid crystal elastomers (N-LCE) exhibit intriguing mechanical properties, such as reversible actuation and soft elasticity, which manifests as a wide plateau of low nearly-constant stress upon stretching. N-LCE also have a characteristically slow stress relaxation, which sometimes prevents their shape recovery. To understand how the inherent nematic order retards and arrests the equilibration, here we examine hysteretic stress-strain characteristics in a series of specifically designed main-chain N-LCE, investigating both macroscopic mechanical properties and the microscopic nematic director distribution under applied strains. The hysteretic features are attributed to the dynamics of thermodynamically unfavoured hairpins, the sharp folds on anisotropic polymer strands, the creation and transition of which are restricted by the nematic order. These findings provide a new avenue for tuning the hysteretic nature of N-LCE at both macro- and microscopic levels via different designs of polymer networks, toward materials with highly nonlinear mechanical properties and shape-memory applications.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.236-238.1746 ◽

2011 ◽

Vol 236-238 ◽

pp. 1746-1751 ◽

Cited By ~ 7

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.

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

Applied Sciences ◽

10.3390/app11073032 ◽

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.

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Effects of water absorption on the mechanical properties of hybrid natural fibre/phenol formaldehyde composites

Scientific Reports ◽

10.1038/s41598-021-92457-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sekar Sanjeevi ◽

Vigneshwaran Shanmugam ◽

Suresh Kumar ◽

Velmurugan Ganesan ◽

Gabriel Sas ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Impact Strength ◽

Water Absorption ◽

Hybrid Composites ◽

Phenol Formaldehyde ◽

Natural Fibre ◽

The Other ◽

Fibre Reinforcement ◽

Dry Conditions

AbstractThis investigation is carried out to understand the effects of water absorption on the mechanical properties of hybrid phenol formaldehyde (PF) composite fabricated with Areca Fine Fibres (AFFs) and Calotropis Gigantea Fibre (CGF). Hybrid CGF/AFF/PF composites were manufactured using the hand layup technique at varying weight percentages of fibre reinforcement (25, 35 and 45%). Hybrid composite having 35 wt.% showed better mechanical properties (tensile strength ca. 59 MPa, flexural strength ca. 73 MPa and impact strength 1.43 kJ/m2) under wet and dry conditions as compared to the other hybrid composites. In general, the inclusion of the fibres enhanced the mechanical properties of neat PF. Increase in the fibre content increased the water absorption, however, after 120 h of immersion, all the composites attained an equilibrium state.

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