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Dispersive Component (dispersive + component)
Selected AbstractsFabrication and characterization of solution cast MWNTs/PEI nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2009Lu Shao Abstract Under mild conditions with the aid of ultrasonic, multi-walled carbon nanotubes (MWNTs) have been functionalized by mixed acid treatment which was proved by FTIR and XPS. According to SEM, acid treatment on MWNTs decreased the thickness of the membrane. However, no devastating damage and fracture happened on MWNTs after acid treatment under mild conditions. Precipitation observation illustrated that the enhanced solubility of MWNTs in water, ethanol, and dimethylformaide (DMF). Further, MWNTs/polyetherimide (PEI) nanocomposite films have been prepared by the simple solution casting method. The dispersion of MWNTs in polyetherimide (PEI) matrix was observed by Atomic Force Microscopy (AFM) which illustrated the improved dispersion for acid treated MWNTs in PEI. The adding of MWNTs in PEI decreased the dispersive component of surface energy and increased the polar component of surface energy, which resulted in the decrement of film surface energy. Differential scanning calorimetry showed that the glass transition temperature of PEI increased by about 4°C after the introduction of MWNTs. This improvement was related to the better affinity between MWNTs and PEI matrix, which also resulted in the improvement of mechanical strength in MWNTs/PEI nanocomposites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Reexamining the quantification of perfusion MRI data in the presence of bolus dispersion,JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2007Linda Ko BSc Abstract Purpose To determine the true impact of dispersion upon cerebral blood flow (CBF) quantification by removing an algorithm implementation-induced systematic error. Materials and Methods The impact of dispersion on the arterial input function (AIF) between measurement and entry into the tissue of interest on CBF estimates was simulated assuming: 1) contralateral circulation flow that introduces a true arterial tissue delay (ATD)-related dispersive component; and 2) the presence of an arterial stenosis that disperses and shifts the AIF peak entering the tissue; increasing the apparent ATD relative to the original AIF. Results Previously reported CBF estimates for the stenosis dispersion model were found to be a mixture of true dispersive effects and an algorithm implementation-induced systematic error. The true CBFMEASURED/CBFNO-DISPERSION ratios for short mean transit times (MTT) (normal) and long MTT (infarcted) tissue were similar for both dispersion models evaluated; this was an unanticipated result. The CBF quantification inaccuracies induced through the dispersion model truly related to ATD were lower than for the local stenosis-based dispersion for small ATD values. Conclusion Correcting the systematic error present in a previous deconvolution study removes the reported ATD-related impact on CBF quantification. The impact of dispersion was smaller than half that reported in previous simulation studies. J. Magn. Reson. Imaging 2007;25:639,643. © 2007 Wiley-Liss, Inc. [source] Some Effects of Corona Plasma Treatment of Polylactide/Montmorillonite Nanocomposite FilmsPLASMA PROCESSES AND POLYMERS, Issue S1 2009Marian, enkiewicz Abstract Influence of the unit energy (Eu) of corona discharge used for modification of pure polylactide (PLA) and polylactide nanocomposite (PLAC) containing 5 wt% of an aluminosilicate nanofiller (Cloisite 30B) on water (,W) and diiodomethane (,D) contact angles as well as on surface free energy (,s) of these polymers was studied. ,W and ,D as advancing contact angles were measured with use of a goniometer while ,s was calculated by the Owens,Wendt method. It was found that ,W increased with the rising Eu while ,D remained approximately constant. Assuming Eu,=,const, it could be stated that the increase in ,s was much more evident for PLA than for PLAC. This increase resulted practically from the change in the polar component of ,s because the dispersive component for the two materials only slightly decreased with increase in Eu. [source] UV curing behaviors and hydrophilic characteristics of UV curable waterborne hyperbranched aliphatic polyesters,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9 2003Anila Asif Abstract A series of waterborne hyperbranched polyesters (WBHPs) endcapped with methacrylic and salt-like groups in different ratios have been investigated as UV curable resins. The kinetic studies of the drying step and UV curing were carried out by FT-IR measurements. The drying of the film of 100,,m thickness was completed in less than 6,hr at 70°C or within 10,hr at 50°C in an oven. The influence of different photoinitiators and their concentrations, extent of unsaturation and acid content of WBHP on final unsaturation conversion was studied. The surface free energy is a critical character, which affects the surface properties of a cured film. So one method based on the measurement of contact angle of a pure liquid on a solid surface was applied to determine the polar and dispersive components of the surface energy of UV cured films. The investigations of surface energy of WBHPs illustrated that those with more acid content and thus higher polar component are more sensitive to water, while those containing less acid content and thus lower polar term are less water sensitive. Moreover, the UV cured films of WBHPs and their blends with commercial waterborne resins (trade name EB 210, EB 2002, EB 11 and IRR 160) have acceptable pendulum hardness varying from 55 to 180,sec. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||