scholarly journals A Facile Synthesis Route of Hybrid Polyurea-Polyurethane-MWCNTs Nanocomposite Coatings for Ballistic Protection and Experimental Testing in Dynamic Regime

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1618
Author(s):  
Gabriela Toader ◽  
Aurel Diacon ◽  
Edina Rusen ◽  
Florica Rizea ◽  
Mircea Teodorescu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Experimental Testing ◽  
Multiwall Carbon Nanotubes ◽  
Tensile Tests ◽  
Metal Plate ◽  
Dynamic Regime ◽  
Nanocomposite Films ◽  
Uniform Dispersion ◽  
Ballistic Protection ◽  
Aluminum Plates

This study describes a simple, practical, inexpensive, improved, and efficient novel method for obtaining polyurea-polyurethane-multiwall carbon nanotubes (MWCNTs) nanocomposites with enhanced mechanical properties, and their experimental testing in a dynamic regime. SEM and micro-CT investigations validated the homogeneity of the nanocomposite films and uniform dispersion of the nanofiller inside the polymeric matrix. The experimental measurements (TGA, DSC, DMA, and tensile tests) revealed improved thermal and mechanical properties of these new materials. To demonstrate that these nanocomposites are suitable for ballistic protection, impact tests were performed on aluminum plates coated with the polyurea-polyurethane MWCNTs nanocomposites, using a Hopkinson bar set-up. The experimental testing in the dynamic regime of the polyurea- polyurethane-coated aluminum plates confirmed that the nanocomposite layers allow the metal plate to maintain its integrity at a maximum force value that is almost 200% higher than for the uncoated metallic specimens.

Correlation among Microstructure, Texture, and Properties along the Thickness Direction in As-Hot-Rolled and As-Solution-Quenched Al7055 Thick Plates

2021 ◽  
Vol 1026 ◽  
pp. 65-73
Author(s):  
Kai Zhu ◽  
Hong Wei Yan
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Tensile Tests ◽  
Rolled Plate ◽  
Uniaxial Tensile ◽  
Thickness Direction ◽  
Electron Backscattered Diffraction ◽  
Thick Plates ◽  
Aluminum Plates ◽  
Hot Rolled

Both microstructure inhomogeneity and mechanical property diversity along the thickness direction in rolled thick aluminum plates have been considered to have a remarkable impact on the performance and properties of the products made from the plates. In this study, scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) characterizations of microstructure and texture types along the thickness directions of Al7055 thick plate specimens prepared using two conditions, hot-rolling and solution-quenching, were performed. To examine the mechanical properties, uniaxial tensile tests were also carried out on specimens machined from both types of thick plates, using a layered strategy along the thickness direction. The results indicate that both the microstructure and mechanical properties are inhomogeneous under the two conditions. Furthermore, it is evident that there is a hereditary relationship between the mechanical properties of the two plates—areas with higher yield strength in the as-hot-rolled plate correspond to areas with the higher yield strength in the as-solution-quenched plate

Preparation and Property of Waterborne Polyurethane/Cellulose Nanofiber Nanocomposite Films

2020 ◽  
Vol 993 ◽  
pp. 631-637
Author(s):  
Yu Zhe Lin ◽  
Jia Min Zeng ◽  
Jing Hong Ma ◽  
Jing Hua Gong
Keyword(s):  
Mechanical Properties ◽  
Cellulose Nanofibers ◽  
Waterborne Polyurethane ◽  
Tensile Tests ◽  
Environmental Safety ◽  
Nanocomposite Films ◽  
Solution Blending ◽  
Low Weight ◽  
New Type ◽  
Dispersing Medium

Waterborne polyurethane (WPU) is a new type of polyurethane system, which using water instead of organic solvent as dispersing medium. Because of its non-toxicity and environmental safety, WPU is considered as the development direction of coatings and adhesives. However, the mechanical properties of WPU are worse than that of solvent-based polyurethane, therefore, the modification of WPU has received increasingly attention. Meanwhile numerous evidences demonstrate the excellent properties of cellulose nanofibers (CNFs) such as high aspect ratio, low weight and outstanding mechanical strength. Therefore, there is a high expectation for CNFs to be introduced into WPU as reinforcing filler. In this work, a series of CNFs/WPU nanocomposite films were prepared by solution blending. The structure, morphology, thermal behavior and mechanical properties were investigated. SEM results showed that CNFs were evenly dispersed in the WPU matrix. Tensile tests indicated that the modulus and tensile strength of CNFs/WPU nanocomposite films were improved compared with the neat film. While the break elongation of the nanocomposite films decreased with the increase of CNFs content. The synergistic interaction between CNFs and WPU matrix plays an important role in the enhancement of mechanical properties.

scholarly journals Further Enhancement of Mechanical Properties of Conducting Rubber Composites Based on Multiwalled Carbon Nanotubes and Nitrile Rubber by Solvent Treatment

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1806 ◽  
Author(s):  
Pasi Keinänen ◽  
Amit Das ◽  
Jyrki Vuorinen
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Multiwall Carbon Nanotubes ◽  
Post Treatment ◽  
Nanocomposite Films ◽  
Butadiene Rubber ◽  
Rubber Composites ◽  
Multiwalled Carbon ◽  
Dispersion Agent ◽  
Dispersion Quality

Post-treatment removal of dispersion agents from carbon nanotube/rubber composites can greatly enhance the mechanical properties by increasing the filler–matrix interaction. In this study, multiwall carbon nanotubes (MWNT) were dispersed in water by sonication and nonionic surfactant, octyl-phenol-ethoxylate was used as a dispersion agent. The dispersed MWNTs were incorporated in thermo-reactive acrylonitrile butadiene rubber (NBR) latex and nanocomposite films were prepared by solution casting. As a post-treatment, the surfactant was removed with acetone and films were dried in air. Dispersion quality of the colloid before casting was determined, and mechanical, electrical and thermal properties of the composites before and after the acetone post-treatment were studied. It was found that removal of dispersion agent increased the storage modulus of films between 160–300% in all samples. Relative enhancement was greater in samples with better dispersion quality, whereas thermal conductivity changed more in samples with smaller dispersion quality values. Electrical properties were not notably affected.

Synthesis and Characterization of TiO2Nanoparticles with Polycarbonate and Investigation of its Mechanical Properties

2017 ◽  
Vol 16 (05n06) ◽  
pp. 1750012 ◽  
Author(s):  
Farhad Jahantigh ◽  
Mehdi Nazirzadeh
Keyword(s):  
Mechanical Properties ◽  
Weight Fraction ◽  
Xrd Analysis ◽  
Tensile Tests ◽  
Nanocomposite Films ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Stability Of

In this project, nanocomposite films were prepared with different Titanium dioxide (TiO2) percentages. Properties of polycarbonate (PC) and PC–TiO2nanocomposite films were studied by X-ray diffraction (XRD) analysis and Fourier transform infrared (FTIR) spectroscopy. The structure of samples was studied by XRD. The mechanical properties of PC–TiO2nanocomposite films were investigated by conducting tensile tests and hardness measurements. Thermal stability of the nanocomposites was studied by thermogravimetric analysis (TGA) method. The elastic modulus of the composite increased with increasing weight fraction of nanoparticles. The microhardness value increases with increasing TiO2nanoparticles. The results of tensile testing were in agreement with those of micro-hardness measurements. In addition, TGA curves showed that nanocomposite films have higher resistance to thermal degradation compared to polycarbonate. There are many reports related to the modification of polycarbonate films, but still a systematic study of them is required.

Effects of different gums on tensile properties of cellulose nanofibrils (CNFs)-reinforced starch

2020 ◽  
pp. 096739112092344 ◽  
Author(s):  
Razieh Eslami ◽  
Alireza Azizi ◽  
Mohsen Najafi
Keyword(s):  
Mechanical Properties ◽  
Tensile Properties ◽  
Food Packaging ◽  
Negative Impact ◽  
Cellulose Nanofibrils ◽  
Tensile Tests ◽  
Nanocomposite Films ◽  
Infrared Analysis ◽  
Solution Casting Method ◽  
Starch Films

This research is focused on the development of a new starch-based nanocomposite films reinforced with cellulose nanofibrils (CNFs) for food packaging purposes. A series of starch films were produced by the solution casting method with various concentrations of glycerin, CNF, and citric acid (CA). Mechanical properties of the films were investigated using tensile tests. Based on the results, the best formulation with optimal mechanical properties was introduced by different amounts of various gums to study the effects of the gums on tensile properties of the samples. Fourier-transform infrared analysis was performed to study posttreatment chemical structure of the sample to confirm the cross-linking and esterifying of the nanocomposite films. Results revealed that the tragacanth gum had a negative impact on the mechanical properties, while the frankincense gum (F-gum) and Arabic gum positively influenced the mechanical properties through strengthening the network structure. The sample containing 0.3 g of F-gum (10% w/w, relative to the starch weight) showed the best results compared to the control films.

STRUCTURE AND MECHANICAL PROPERTIES OF Nb-Al-N NANOCOMPOSITE FILMS AS A FUNCTION OF THE DEPOSITION PARAMETERS

2015 ◽  
Vol 19 (2) ◽  
pp. 179-187 ◽  
Author(s):  
Volodymyr Ivashchenko ◽  
Vladyslav Rogoz ◽  
Pavlo Skrynskiy ◽  
Czeslaw Kozak ◽  
Marek Opielak
Keyword(s):  
Mechanical Properties ◽  
Nanocomposite Films ◽  
Deposition Parameters

scholarly journals Synthesis, Properties, and Biodegradability of Thermoplastic Elastomers Made from 2-Methyl-1,3-propanediol, Glutaric Acid and Lactide

Life ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 43
Author(s):  
Lamya Zahir ◽  
Takumitsu Kida ◽  
Ryo Tanaka ◽  
Yuushou Nakayama ◽  
Takeshi Shiono ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Glutaric Acid ◽  
Triblock Copolymers ◽  
Tensile Tests ◽  
Thermoplastic Elastomers ◽  
Proteinase K ◽  
Synthesis Properties

An innovative type of biodegradable thermoplastic elastomers with improved mechanical properties from very common and potentially renewable sources, poly(L-lactide)-b-poly(2-methyl-1,3-propylene glutarate)-b-poly(L-lactide) (PLA-b-PMPG-b-PLA)s, has been developed for the first time. PLA-b-PMPG-b-PLAs were synthesized by polycondensation of 2-methyl-1,3-propanediol and glutaric acid and successive ring-opening polymerization of L-lactide, where PMPG is an amorphous central block with low glass transition temperature and PLA is hard semicrystalline terminal blocks. The copolymers showed glass transition temperature at lower than −40 °C and melting temperature at 130–152 °C. The tensile tests of these copolymers were also performed to evaluate their mechanical properties. The degradation of the copolymers and PMPG by enzymes proteinase K and lipase PS were investigated. Microbial biodegradation in seawater was also performed at 27 °C. The triblock copolymers and PMPG homopolymer were found to show 9–15% biodegradation within 28 days, representing their relatively high biodegradability in seawater. The macromolecular structure of the triblock copolymers of PLA and PMPG can be controlled to tune their mechanical and biodegradation properties, demonstrating their potential use in various applications.

Comprehensive study on mechanical properties of coated biaxial warp-knitted fabrics

2021 ◽  
pp. 073168442110204
Author(s):  
Bin Yang ◽  
Yingying Shang ◽  
Zeliang Yu ◽  
Minger Wu ◽  
Youji Tao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Failure Modes ◽  
Least Squares Method ◽  
Tensile Tests ◽  
Tensile Creep ◽  
Base Layer ◽  
Sustained Load ◽  
Uniaxial Tensile ◽  
Membrane Structures ◽  
Knitted Fabrics

In recent years, coated fabrics have become the major material used in membrane structures. Due to the special structure of base layer and mechanical properties, coated biaxial warp-knitted fabrics are increasingly applied in pneumatic structures. In this article, the mechanical properties of coated biaxial warp-knitted fabrics are investigated comprehensively. First, off-axial tensile tests are carried out in seven in-plane directions: 0°, 15°, 30°, 45°, 60°, 75°, and 90°. Based on the stress–strain relationship, tensile strengths are obtained and failure modes are studied. The adaptability of Tsai–Hill criterion is analyzed. Then, the uniaxial tensile creep test is performed under 24-h sustained load and the creep elongation is calculated. Besides, tearing strengths in warp and weft directions are obtained by tearing tests. Finally, the biaxial tensile tests under five different load ratios of 1:1, 2:1, 1:2, 1:0, and 0:1 are carried out, and the elastic constants and Poisson’s ratio are calculated using the least squares method based on linear orthotropic assumption. Moreover, biaxial specimens under four load ratios of 3:1, 1:3, 5:1, and 1:5 are further tensile tested to verify the adaptability of linear orthotropic model. These experimental data offer a deeper and comprehensive understanding of mechanical properties of coated biaxial warp-knitted fabrics and could be conveniently adopted in structural design.

scholarly journals Influence of Hydrostatic Extrusion on the Mechanical Properties of the Model Al-Mg Alloys

2021 ◽  
Author(s):  
Aleksandra Towarek ◽  
Wojciech Jurczak ◽  
Joanna Zdunek ◽  
Mariusz Kulczyk ◽  
Jarosław Mizera
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Tensile Strength ◽  
Microstructural Analysis ◽  
Tensile Tests ◽  
Hydrostatic Extrusion ◽  
Microstructure Formation ◽  
Initial State ◽  
Degree Of Deformation ◽  
Al Mg Alloys

AbstractTwo model aluminium-magnesium alloys, containing 3 and 7.5 wt.% of Mg, were subjected to plastic deformation by means of hydrostatic extrusion (HE). Two degrees of deformation were imposed by two subsequent reductions of the diameter. Microstructural analysis and tensile tests of the materials in the initial state and after deformation were performed. For both materials, HE extrusion resulted in the deformation of the microstructure—formation of the un-equilibrium grain boundaries and partition of the grains. What is more, HE resulted in a significant increase of tensile strength and decrease of the elongation, mostly after the first degree of deformation.

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