scholarly journals Nanoparticle amount, and not size, determines chain alignment and nonlinear hardening in polymer nanocomposites

2017 ◽  
Vol 114 (16) ◽  
pp. E3170-E3177 ◽  
Author(s):  
H. Samet Varol ◽  
Fanlong Meng ◽  
Babak Hosseinkhani ◽  
Christian Malm ◽  
Daniel Bonn ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Polymer Nanocomposites ◽  
Nonlinear Elasticity ◽  
Volume Fraction ◽  
Uniaxial Tensile ◽  
Large Strains ◽  
Chain Alignment ◽  
Strain Hardening Behavior ◽  
Polymer Chain Alignment ◽  
Nonlinear Hardening

Polymer nanocomposites—materials in which a polymer matrix is blended with nanoparticles (or fillers)—strengthen under sufficiently large strains. Such strain hardening is critical to their function, especially for materials that bear large cyclic loads such as car tires or bearing sealants. Although the reinforcement (i.e., the increase in the linear elasticity) by the addition of filler particles is phenomenologically understood, considerably less is known about strain hardening (the nonlinear elasticity). Here, we elucidate the molecular origin of strain hardening using uniaxial tensile loading, microspectroscopy of polymer chain alignment, and theory. The strain-hardening behavior and chain alignment are found to depend on the volume fraction, but not on the size of nanofillers. This contrasts with reinforcement, which depends on both volume fraction and size of nanofillers, potentially allowing linear and nonlinear elasticity of nanocomposites to be tuned independently.

Mechanical Properties of Sprayable Fiber Reinforced Strain-Hardening Cement Composite (SHCC)

2013 ◽  
Vol 372 ◽  
pp. 211-214
Author(s):  
Zhong Jie Yu ◽  
Mi Hwa Lee ◽  
Hyun Do Yun
Keyword(s):  
Mechanical Properties ◽  
Strain Hardening ◽  
Volume Fraction ◽  
Crack Opening ◽  
Cement Composite ◽  
Seismic Retrofitting ◽  
Mineral Admixtures ◽  
Uniaxial Tensile ◽  
High Expectations ◽  
The Subject

The use of strain-hardening cement composite (SHCC), which exhibits metal-like deformation behavior and has ability to restrict crack opening, as a retrofit material for seismic retrofitting of existing infrastructures, has been the subject of high expectations. In this work, Three SHCC mixtures including different chemical or mineral admixtures were prepared and evaluated based on the mechanical properties, such as flow, sprayability, compressive and uniaxial tensile performances. All SHCC mixtures were reinforced with polyvinyl alcohol (PVA) fibers at volume fraction of 2.2%. Mechanical properties of each SHCC mixture were measured and evaluated after mixing, pumping, and shotcreting. Experimental results indicated that the compressive strength and elastic modulus of three SHCC mixtures increased almost linearly according to shotcreting procedure from mixer to nozzle. And the uniaxial tensile of SHCC mixture (SHCC-AE) with AE agent was superior to the other SHCC mixtures (SHCC-MC and-N).

Effect of Fiber Type and Fiber Hybrids on Strain-Hardening and Multiple Cracking Properties of the Ultra-High Performance Cementitious Composites under Uniaxial Loads

2016 ◽  
Vol 711 ◽  
pp. 187-194 ◽  
Author(s):  
Li Ping Guo ◽  
Dong Yi Lei
Keyword(s):  
Tensile Strength ◽  
Strain Hardening ◽  
High Performance ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Uniaxial Tensile ◽  
Cementitious Composites ◽  
Multiple Cracking ◽  
Polyethylene Fiber ◽  
Pva Fiber

Five series of strain hardening ultra-high performance cementitious composites (SHUHPCC) incorporated with different types of fibers and hybrid fibers were produced. Three types of fibers (steel fiber, polyvinyl alcohol fiber and polyethylene fiber) were used as mono or hybrid reinforcement in SHUHPCC with the same volume fraction of 2%. The primary strengths, strain hardening and multiple cracking behaviors of hybrid fiber reinforced SHUHPCC under the uniaxial tensile are investigated. Test results show that the SHUHPCC containing PE fibers exhibited higher strain hardening capacity and lower first cracking strength than composites reinforced with mono PVA fiber or mono steel fiber. The composites containing PVA fibers or steel fibers have higher tensile strength and first cracking strength than the composite reinforced by mono PE fiber. Hybridization reinforcement with different fibers is able to make up defects of mono fiber reinforcement for SHUHPCC. The change laws of tensile strength and uniaxial compression strength of SHUHPCC with mono PE fiber and mono PVA fiber are opposite to each other.

The Behavior of Pseudo Strain-Hardening Cementitious Composite (PSH2C) Using Synthetic Fibers under Uniaxial Tensile Loading

2014 ◽  
Vol 627 ◽  
pp. 449-452 ◽  
Author(s):  
Wan Shin Park ◽  
Young Il Jang ◽  
Hyun Do Yun ◽  
Il Seung Yang ◽  
Bae Su Khil
Keyword(s):  
Strain Hardening ◽  
Volume Fraction ◽  
Tensile Loading ◽  
Fiber Content ◽  
Uniaxial Tensile ◽  
Cement Composites ◽  
Fiber Volume ◽  
Tensile Response ◽  
Pseudo Strain Hardening ◽  
Direct Tensile

The application of pseudo strain-hardening cement composites (PSH2C) to structural systems depends primarily on the tensile response of the materials, which is a direct function of fiber and matrix characteristics, the fiber content or volume fraction. In general, improved response of material is observed with an increase in the fiber volume fraction, as long as the fiber content does not impede mixing. This paper addresses the direct tensile response of pseudo strain hardening cement composites (PSH2C) reinforced with PET fibers, which belongs to a class of discontinuous short fiber reinforced cement based composites characterized by a strain hardening and multiple cracking responses under direct tensile loading. The variables are different types of fibers (PET, PET+PE, PET+PVA).

Effect of network structure from different processing conditions on the mechanical property of semi-crystalline polymers

2014 ◽  
Vol 1619 ◽  
Author(s):  
Xin Dong ◽  
David McDowell ◽  
Karl Jacob
Keyword(s):  
Mechanical Property ◽  
Strain Hardening ◽  
Mechanical Response ◽  
Tensile Deformation ◽  
Processing Condition ◽  
Constant Stress ◽  
Uniaxial Tensile ◽  
Initial Structure ◽  
Stress Strain ◽  
Strain Hardening Behavior

ABSTRACTSemi-crystalline structures were prepared from different processing condition. Biaxial oriented melt were crystallized at 375 K and atmospheric pressure for 10 nanoseconds (ns), to generate a lamellar semi-crystalline structure. Similar structures were also prepared from deformation of a cubic amorphous initial structure isothermally at 375 K. For comparison, two different thermostats, the constant stress (NPT) and constant volume (NVT) conditions were applied to the system during 10 ns of crystallization. The semi-crystalline samples shared common morphological features such as in the crystallinity, crystal orientation, lamellae thickness and density distribution, etc. However, during the subsequent uniaxial tensile deformation test of the samples to strain of 0.5, different stress-strain behaviors were demonstrated. By combining the observations of morphologies during deformation tests and analysis of the stress-strain curves, conclusions were made that the effectiveness of the network had a strong influence on the mechanical property and strain hardening behavior. The oriented network from the constant stress crystallization, owing to the taut chains, gave rise to optimal mechanical response with substantial strain-hardening.

scholarly journals Study on Microstructure Effect of Carbon Black Particles in Filled Rubber Composites

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Li Hong Huang ◽  
Xiaoxiang Yang ◽  
Jianhong Gao
Keyword(s):  
Particle Size ◽  
Carbon Black ◽  
Polymer Nanocomposites ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Uniaxial Tensile ◽  
Particle Volume ◽  
Carbon Particles ◽  
The Difference ◽  
Microstructure Effect

The cross sections of blended natural/styrene-butadiene (NSBR) composites filled with different volume fractions of carbon particles were observed using a Quanta 250 scanning electron microscope. In addition, the sizes and distributions of the carbon particles were analyzed using Nano Measurer. A two-dimensional representative volume element model (RVE) for a rubber composite reinforced with circular carbon particles was established, and the uniaxial tensile behaviors of polymer nanocomposites with different particle size distribution patterns were simulated using the ABAQUS software. The results showed the following. (1) For the random models, if the difference of particle size was larger and particle distance was closer, stress distribution would be denser as well as the stress concentration would become greater. However, if the difference of particle size was small, for the case of same particle volume fraction, the particle size has little influence on the macromechanical properties whether the average size is large or small. (2) The correlation between the volume fraction and distribution of the carbon particles revealed that when the volume fraction of carbon black particles was larger than 12%, clusters between carbon particles in the polymer nanocomposites could not be avoided and the modulus of the composites increased with an increase in the cluster number.

Effect of Initial Processing on the Microstructure-Property Relationships in Bake-Hardened C-Mn-Si TRIP Steels

2007 ◽  
Vol 539-543 ◽  
pp. 4315-4320 ◽  
Author(s):  
Ilana B. Timokhina ◽  
Elena V. Pereloma ◽  
Peter D. Hodgson
Keyword(s):  
Strain Hardening ◽  
Volume Fraction ◽  
Bainitic Ferrite ◽  
Tensile Tests ◽  
Trip Steels ◽  
Hardening Behavior ◽  
Transmission Electron ◽  
Before And After ◽  
Initial Processing ◽  
Strain Hardening Behavior

The effect of pre-straining (PS) and bake-hardening (BH) on the microstructure and mechanical properties has been studied in C-Mn-Si TRansformation Induced Plasticity (TRIP) steels after: (i) thermomechanically processing (TMP) and (ii) intercritical annealing. The steels were characterised before and after PS/BH by transmission electron microscopy (TEM), X-ray diffraction (XRD), and tensile tests. The main microstructural differences were the higher volume fraction of bainite and more stable retained austenite in the TMP steel. This led to a difference in the strain-hardening behavior before and after BH treatment. The higher dislocation density in ferrite and formation of microbands in the TMP steel after PS and the formation of Fe3C carbides between the bainitic ferrite laths during BH for both steels also affected the strain-hardening behavior. However, both steels after PS/BH treatment demonstrated an increase in the yield and tensile strength.

Strain Hardening at Large Strains as Predicted by Dislocation Based Polycrystal Plasticity Model

2001 ◽  
Vol 124 (1) ◽  
pp. 71-77 ◽  
Author(s):  
La´szlo´ S. To´th ◽  
Alain Molinari ◽  
Yuri Estrin
Keyword(s):  
Strain Hardening ◽  
Cell Walls ◽  
Path Dependence ◽  
Volume Fraction ◽  
Large Strain ◽  
Large Strains ◽  
Proportional Loading ◽  
Hardening Model ◽  
Polycrystal Plasticity ◽  
Strain Paths

A recent strain hardening model for late deformation stages (Estrin, Y., To´th, L.S., Molinari, A., and Bre´chet, Y., Acta Materialia, 1998, “A dislocation-based model for all hardening stages in large strain deformation,” Vol. 46, pp. 5509-5522) was generalized for the 3D case and for arbitrary strain paths. The model is based on a cellular dislocation arrangement in which a single- phase material is considered as a composite of a hard skeleton of cell walls and soft cell interiors. An important point in the approach is the evolution of the volume fraction of the cell walls which decreases with the deformation and gives rise to a plateau-like behavior (Stage IV) followed by a drop-off (Stage V) of the strain hardening rate observed at large strains. The hardening model was implemented into the viscoplastic self-consistent polycrystal model to predict hardening curves corresponding to different proportional loading paths. The calculated curves were evaluated to elucidate the path dependence of hardening.

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