Enhancement in Mechanical Properties of Polystyrene Filled with Carbon Nano-Particulates (CNP_S)

The idea of adding reinforcing materials, or fillers, to polymers has been around for many decades. The reason for the creation of polymer composite materials came about due of the need for materials with specific properties for specific applications. For example, composite materials are unique in their ability to allow brittle and ductile materials to become softer and stronger. It is expected that good tribological properties can be obtained for polymers filled with nano-scale fillers. A soft plastic can become harder and stronger by the addition of a light weight high stiffness material. In the present work, the effect of adding different percentages of carbon nano-particulates to polystyrene (PS) on the mechanical properties of nano-composites produced was investigated. Based on the experimental observations, it was found that as the percentage of the carbon nano-particulates (CNPS) increased hardness increased and consequently friction coefficient remarkably decreased.

Respirable nano-particulate generations and their pathogenesis in mining workplaces:a review

There is a growing concern in mining community about the contribution of nano-particulates to miner's health.Despite the health influence of respirable dusts and associated lung diseases have been recognized for decades in the mining industry,the nano-scale particulates accompanying with complicated physiochemical properties and their enor-mous contribution in quantity have been drawing attentions only in recent a few years because of the advancement of nano-science discipline.In this review,we examine the current regulations of dusts exposure and the dominant mass-based monitoring methods to point out the ignorance of nano-particulates in mining industry.The recognized mining-related nano-particulates sources are summarized to identify the mechanically generated finer particulates including particles and aerosols.In addition,the mechanism of adverse health impact on miner with exposure to nano-scale particulates is discussed in a detail to emphasize their substantial detriment as a potential respiratory hazard.Characterization of the complex physiochemical properties of nano-particulates are then summarized and discussed because these properties could be different from regular respirable dusts due to their dramatically increased surface area and particulate counts.The intent of this review is to demonstrate the potential of adverse health effect of nano-particulate on the mine personals throughout the mining cycle and to identify the research gaps of the mine nano-particulate characterization and quantification.We suggest that further understanding of the mining induced nano-particulate properties and their pathogenesis are critical for the future engineering control measure to mitigate the potential health threat for future miners.

Effect of Secondary Processing and Nanoscale Reinforcement on the Mechanical Properties of Al-TiC Composites

Aluminium based composites containing 1, 1.5 and 2wt. % of nano-sized Titanium Carbide particulates (TiC), with an average of 45nm, reinforcement were synthesized using low energy planetary ball mill followed by hot extrusion. Microstructural characterization of the materials revealed uniform distribution of reinforcement, grain refinement and the presence of minimal porosity. Properties characterization revealed that the presence of nano-TiC particulates led to an increase in hardness, elastic modulus, 0.2% yield strength (0.2% offset on a stress-strain curve), and the stress at which a material exhibits a specified permanent deformation, Ultimate Tensile Strength (UTS) and ductility of pure aluminum. Fractography studies revealed that the fracture of pure aluminum occurred in ductile mode due to the incorporation and uniform distribution of nano-TiC particulates. An attempt is made in the present study to correlate the effect of nano-sized TiC particulates as reinforcement and processing type with the micro structural and tensile properties of aluminum composites. The mechanical properties, namely, the UTS, hardness, grain size and distribution of the reinforcement in the base metal were studied in as sintered and extruded conditions. Orowan strengthening criteria was used to predict the yield strength of Al-TiC composites in the present work and experimental results were compared with the theoretical results.

Hollow nano-particles formation for CuO-CeO2-ZrO2 via a supercritical anti-solvent process

Hollow CuO-CeO2-ZrO2nano-particles were prepared with supercritical anti-solvent apparatus by using methanol as sol-vent and supercritical carbon dioxide as anti-solvent. Two key factors （i.e., pressure and temperature） were investigated to explore the effects of catalyst structure and physic-chemical properties （i.e., morphology, reducing property, oxygen storage capacity and specific surface area）. The resulting materials were characterized with X-ray diffraction （XRD）, high resolution transmission electron micros-copy （HRTEM）, Brunauer-Emmett-Teller （BET）,hydrogen temperature programmed reduction （H2-TPR） and oxygen storage capac-ity （OSC） measurement, respectively. The experimental results showed that lower temperatures promoted production of hollow struc-ture nano-particulates. The particle morphology also changed significantly, i.e. the solid construction was first transferred to hollow structure then back to solid construction. The optimal conditions for obtaining hollow nano-particles were determined at 45 °C, 18.0–24.0 MPa.