Papers by Keyword: Microcomposite

Abstract: The present study deals with the effect of the Diatomite (D) microcomposite with and without chemical modification in a polypropylene (iPP) blend. The objective is to achieve a material with a better performance at a lower cost and more accessible and more suitable processing. The chemical surface modification of Diatomite (MD) was achieved using a crosslinking system based on a mixture of sulfur, accelerator, and peroxide. The iPP/Diatomite composite was prepared by batch melt mixing in a Brabender Plasti-Corde under intense shearing at high temperatures and varying the Diatomite content from 0 to 15 wt%. The rheological behavior was examined by monitoring the Brabender Plasti-Corde torque/time rheographs. Different techniques were used to characterize the sample: Fourier transform infrared spectroscopy (FTIR), WAXS, SEM, and DSC. In addition, tensile strength tests and impact strength mechanical tests were conducted to study the performance. It was found that chemical modification strongly affected rheological behavior and generated a new rheological characteristic compared to the composites without modification. This has induced a new structure form that has improved mechanical properties. Moreover, the chemical modification used and due to its simplicity, can be successfully used on an industrial scale with the appropriate process.

Abstract: The abrasive wear of pure UHMWPE as well as one filled with nanoand microparticles (fibers) were investigated. It was found that abrasive wear resistance of microcomposites (containing AlO(OH) and Al₂O₃ microparticles) can grow up by 16-18 times in comparison with pure UHMWPE depending on the strength and size of the filler as well as abrasive grit. Nanofillers (AlO(OH) and carbon nanofibers (CNF) as well as SiO₂ and Cu nanoparticles) as opposed to microfillers can improve abrasive wear resistance of UHMWPE in a significantly less degree (up to 50 %). Abrasive wear resistance of nanocomposites weakly depends on the type of filler and is defined by the polymeric matrix (permolecular) and counter-face abrasive grit. The comparative analysis of the wear mechanisms of UHMWPE based micro-and nanocomposites under abrasive wear (fixed abrasive particles) and dry sliding friction is carried out.

Abstract: The tribotechnical properties of ultra-high molecular weight polyethylene (UHMWPE) based composite filled with hydroxyapatite (HA) microparticles under dry sliding and lubrication of distilled water and plasma blood wear investigated with block-on-ring. It was shown that modification of UHMWPE by HA microparticles of 20 wt.% results in decrease of wear intensity at dry sliding up to 4 times. The under lubrication, wear intensity of pure UHMWPE and microcomposite are deceased up to 50–70% as compared with under dry sliding. Permolecular structure of pure UHMWPE and microcomposite are spherulitic structure and the HA microparticles were dispersed in the UHMWPE matrix.

Abstract: The present study investigates the preparation of ferulic acid (FA) sustained-release cellulose acetate (CA) microparticles, in which a third component, polyvinylpyrrolidone (PVP), was included into the microcomposites for an improved sustained drug release profile. An electrospraying process was exploited for the fabrication of multiple-component microparticles. Under an applied voltage of 18 kV, FA/PVP/CA composite microparticles were successfully generated. Field emission scanning electron microscopic observations demonstrated that these microparticles had an indented surface morphology with an average diameter of 1.71 ± 0.56 μm. The drug presented in the polymeric microparticles in an amorphous state due to the favorable secondary interactions among the components, as verified by the X-ray diffraction (XRD) patterns and attenuated total reflectance Fourier transform spectra. The triple-component microparticles could provide a fine sustained release profiles with full release completeness and small tailing-off release time period. The electrospraying process is a useful tool for developing sustained release microparticles and multiple-component co-existence in the microparticles can be taken to adjust the sustained drug release profiles.

Abstract: The paper deals with the determination of the characteristic strength and as well as the Weibull moduli and of the Si3N4+SiC micro/nanocomposite determined by the four-point bending test and the contact test using opposite spheres both applied to specimens of different size, respectively. Material failure in the bending and contact modes is caused by the presence of processing defects as fracture origins, and by the formation of cone cracks, respectively, where a stable growth of the cone cracks initiated during contact loading is assumed to be a reason of , . A microstructural analysis of the processing flaws, and a mathematical analysis of the propagation of the cone cracks regarding different dimensions of a specimen are also presented.

Abstract: A brief update (2001 till the present) is presented on published records on nano- and microcomposites involving inorganic compounds as dispersed and matrix or support phase in powder or thin film/coating form. Properties and applications of the currently reported composite materials are also discussed. The status of this field of research is highlighted in a short analysis.

Abstract: The multilayer construction of metal-matrix Cu-Nb microcomposite wire wound Zylon-epoxy composite reinforced inductor is analyzed. Inductor geometry was verified analytically to find the maximal available value of a magnetic field. For comparison, the soft copper wire wound inductor was made by the same geometry and technology and both inductors were investigated at room and liquid nitrogen temperatures. Experimental results were compared with calculated data. The acceptable agreement of calculated and measured data for soft copper wire wound inductor and the significant decrease of amplitude and distortions of sinus shape pulse due to weak heat dissipation of metal-matrix Cu-Nb wire wound inductor took place.