The fractionated crystallization of high density polyethylene dispersed in a poly(ethylene terephthalate) matrix at composition of 15 wt-% was studied. The effect of the molecular weight of polyethylene with and without compatibilization was particularly addressed regarding its influence on the morphology of the blends. For non-compatibilized blends, the dramatic influence of the molecular weight of the polyethylene on the viscosity ratio and therefore on the dispersion is reflected on the relative intensities of the twin crystallization peaks of polyethylene that are developed upon cooling. These peaks reflect two sets of particles that are nucleated by more or less active heterogeneities. The influence of the addition of an ethylene-glycidyl methacrylate copolymer on the morphology and on the crystallization of the blends was also investigated. For a high molecular weight polyethylene, the compatibilizer shows less efficiency as far as dispersion is concerned. 相似文献
A detailed numerical study has been conducted in order to analyse the combined buoyancy effects of thermal and mass diffusion on the turbulent mixed convection tube flows. Numerical results for air-water system are presented under different conditions. A low Reynolds number k-ε turbulent model is used with combined heat and mass transfer analysis in a vertical heated tube. The local heat fluxes, Nusselt and Sherwood numbers are reported to obtain an understanding of the physical phenomena. Predicted results show that a better heat transfer results for a higher gas flow Reynolds number Re, a higher heat flux qw or a lower inlet water flow Γ0. Additionally, the results indicate that the convection of heat by the flowing water film becomes the main mechanism for heat removal from the wall. 相似文献
This study aims to improve the performances of a solar still single slope using metal oxide nanofluid (Al2O3–water, Cu2O–water, and TiO2–water). The numerical study was carried out for the climatic conditions of Agadir, Morocco, with different concentrations of nanofluids inside a basin equipped with an absorber plate with two different absorptivities. The numerical study is based on thermal balance equations applied on different solar system components and solved using the Runge Kutta method. The numerical model is validated by comparing our results with the literature available data. A comparison study of the effect of these nanofluids on solar still productivity is done. The results show that the productivity of the solar still using nanoparticles Cu2O, TiO2, and Al2O3 are 7.38, 7.1, and 7.064 kg m−2 day−1, respectively. It is obtained that the maximum efficiency of the solar still is found to be 55.27% by using cuprous oxide nanoparticles. Furthermore, an enhancement in solar still productivity of 6.36%, 19.54%, and 33.25% is obtained by dispersing 1%, 3%, and 5% volume fraction of Cu2O nanoparticles in pure water, respectively compared to the conventional solar. Moreover, the impact of the absorptivity of the absorber plate on the solar still effectiveness is investigated. Two types of coatings are considered to change the absorber plate absorptivity. The results indicate that the efficiencies of the solar system are 58.81% and 51.77% using an absorber plate with 0.95 and 0.85 of absorptivity, respectively. 相似文献
This paper deals with immiscible blends of poly(ethylene terephthalate) obtained by melt blending with polycarbonate. A large survey of the current knowledge in the field of these blends is presented. Resolved and unresolved issues concerning the effect of exchange reactions on the miscibility of the components are addressed. The experimental part of the paper focuses on the rheological behavior of PET/PC blends. Blends containing various polymer ratios were obtained by melt blending with and without transesterification catalysts. Oscillatory shear flow in the melt was used to characterize the rheology of the various samples. A plot of the oscillatory data, similar to the Van Gurp Palmen plot, is used to point out the broadening of the co‐continuity window when in situ compatibilization takes place.
Analog Integrated Circuits and Signal Processing - The next generation of non-volatile memory elements have been attracting significant attention for future emerging memory applications in recent... 相似文献
Journal of Superconductivity and Novel Magnetism - A nanostructured nickel–iron alloy having the Ni40Fe60 composition was prepared through the mechanical alloying of the elemental powders in... 相似文献
Microsystem Technologies - The near-field measurement is based generally on the use of purely passive miniature sensors, dedicated to the capture of a component of the electromagnetic field. The... 相似文献