Mechanical Properties Of Nanomaterials Research Articles

Evaluation of Elastic Modulus and Hardness of Polylactic Acid-Based Biocomposite by Nano-Indentation

This study focuses on the micromechanical properties of polylactic acid (PLA) reinforced with kenaf fiber (KF) and organo-montmorillonite (OMMT) hybrid biocomposite by using nanoindenter. Nanoindenter is an analytical device that can record small load and depth with high accuracy and precision which can be used to determine the modulus, hardness and other mechanical properties of nanomaterials. The result shows that the optimum properties of the hardness and elastic modulus were dominated by PLA-KF-OMMT hybrid composite.

Statistics for Quantifying the Mechanical Properties of Nanomaterials

In the paper, the up-to-date advances in the statistical analysis of nano-mechanical measurements are briefly reviewed. It is shown that, by means of statistical methods such as a minimum information criterion, a better statistical model can be selected for quantifying the intrinsic mechanical properties of nanomaterials or extracting the optimal information from those imperfect experimental data obtained with recently available nano-mechanical testing techniques.

“Mechanical Behavior of Nanostructured Materials”

The symposium, ‘‘Mechanical Behavior of Nanostructured Materials,’’ was held during the 2009 TMS Annual Meeting from February 15 to 19 in San Francisco, California. The symposium focused on understanding the mechanical behavior of ultra-fine-grained and nanostructured materials in the form of bulk, thin films, and nanowires. There is a good mixture of advanced experimental as well as theoretical and computational presentations in the symposium. Topics presented include the following: (1) synthesis and microstructural characterization of nanomaterials; (2) nanomechanics; (3) fatigue and fracture of nanomaterials; (4) deformation, plasticity, and creep in nanomaterials; (5) mechanical and thermal stability; (6) advanced characterization techniques including in-situ techniques and advances in nanomechanical testing techniques; and (7) theoretical, computational, and analytical modeling of mechanical properties of nanomaterials. Numerous articles in this special issue report the important results and perspectives presented in this symposium.

Catalyst-Free Synthesis and Structural and Mechanical Characterization of Single Crystalline Ca2B2O5·H2O Nanobelts and Stacking Faulted Ca2B2O5 Nanogrooves

Single crystalline Ca(2)B(2)O(5).H(2)O (CBOH) nanobelts were synthesized for the first time using a facile catalyst-free hydrothermal method at low temperature. After being annealed at 400 degrees C for 10 h, the CBOH nanobelts transformed into curve-shaped Ca(2)B(2)O(5)(CBO) nanogrooves with ordered stacking fault arrays along the [110] direction. The single crystalline CBOH nanobelts and the stacking faulted CBO nanogrooves provided a unique platform for investigating the effects of hydrated H(2)O and stacking faults on the mechanical properties of nanomaterials. Nanoindentation tests were performed directly on individual CBOH nanobelts and CBO nanogrooves to probe their mechanical properties. It was found that the CBOH nanobelts, with the presence of hydrated H(2)O, achieved 28.7% increase in elastic modulus, whereas the stacking faulted CBO nanogrooves, with the absence of hydrated H(2)O, exhibited 99% loss in elastic modulus, compared to bulk CBO.

Functional nanomaterial-based amplified bio-detection strategies

In the development of bio-detection assays that could be useful in a variety of applications such as medical diagnostic and biowarfare agent detection, improving assay sensitivity might be the foremost important task. To address this assay sensitivity issue, researchers have synthesized highly functional nanomaterials and used their structures and functions to amplify detection signals often without using enzymatic amplification that is essential in the polymerase chain reaction (PCR). Here, we review various amplification methods that facilitate ultrahigh assay sensitivity using functional nanomaterials. We describe the basic principles, advantages, limitations and perspectives of amplified bio-detection strategies based on optical, electrical, magnetic or mechanical properties of nanomaterials.

Mechanical Properties of Nanomaterials Examined with a NI-AFM

The mechanical properties and strain rate sensitivity of nanocrystalline nickel was studied as a function of grain size at different temperatures in tensile tests and with a nanoindenter in order to examine the different deformation mechanisms of nanocrystalline materials. The effect of lateral boundaries and hydrogen on the nucleation of dislocations was studied in detail. For the first time it was possible to observe the reduction of the dislocation nucleation stress on a nanoscale. In addition the experiments yielded, depending on temperature and strain rate, the strain rate sensitivity, the activation volume and the creep exponents as a function of stress and grain size. From the creep experiments the transition between grain boundary sliding and dislocation climb as a function of temperature was obtained. The strain rate jump tests gave extremely small activation volumes, nearly a factor of 100 smaller than in conventional nickel as a function of grain size. To help in understanding this behaviour the strain rate sensitivity of single grains was tested with a nanoindenter. The results clearly showed that the primary interaction of dislocations with grain boundaries is the reason for the observed strong rate effects and small activation volumes.

Scale effect and geometric shapes of grains

The rule-of-mixture approach has become one of the widely spread ways to investigate the mechanical properties of nano-materials and nano-structures, and it is very important for the simulation results to exactly compute phase volume fractions. The nanocrystalline (NC) materials are treated as three-phase composites consisting of grain core phase, grain boundary (GB) phase and triple junction phase, and a two-dimensional three-phase mixture regular polygon model is established to investigate the scale effect of mechanical properties of NC materials due to the geometrical polyhedron characteristics of crystal grain. For different multi-sided geometrical shapes of grains, the corresponding regular polygon model is adopted to obtain more precise phase volume fractions and exactly predict the mechanical properties of NC materials.

Physical, chemical, and mechanical properties of nanostructured materials

Nanocrystalline materials have special physical, chemical, and mechanical properties. To a significant extent, these properties are attributed to a high density of grain boundaries and other defects in nanocrystalline compounds. We study the microstructure and mechanical properties of nanomaterials (Al, Al-alloys, Cu, Ni, Ti, and stainless steel) and nanocomposites (Al2O3/Ni-P) by the methods of transparent and scanning electron microscopy, X-ray diffraction analysis, and microhardness and tensile tests. The experimental methods include the procedures of measuring the electric and corrosion resistances. The materials are prepared by using contemporary methods, namely, by hydrostatic extrusion (nanometals) and by sintering ceramic powders covered with Ni-P nanoparticles under high pressure by using the procedure of nonelectric chemical metallization (Al2O3/Ni-P nanocomposites).

Biological applications of localised surface plasmonic phenomenae

Researchers and industrialists have taken advantage of the unusual optical, magnetic, electronic, catalytic, and mechanical properties of nanomaterials. Nanoparticles and nanoscale materials have proven to be useful for biological uses. Nanoscale materials hold a particular interest to those in the biological sciences because they are on the same size scale as biological macromolecules, proteins and nucleic acids. The interactions between biomolecules and nanomaterials have formed the basis for a number of applications including detection, biosensing, cellular and in situ hybridisation labelling, cell tagging and sorting, point-of-care diagnostics, kinetic and binding studies, imaging enhancers, and even as potential therapeutic agents. Noble metal nanoparticles are especially interesting because of their unusual optical properties which arise from their ability to support surface plasmons. In this review the authors focus on biological applications and technologies that utilise two types of related plasmonic phenomonae: localised surface plasmon resonance (LSPR) spectroscopy and surface-enhanced Raman spectroscopy (SERS). The background necessary to understand the application of LSPR and SERS to biological problems is presented and illustrative examples of resonant Rayleigh scattering, refractive index sensing, and SERS-based detection and labelling are discussed.