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21.
Bionanoparticles of starch obtained by submitting native potato starch granules to acid hydrolysis conditions. The resulted starch nanoparticles were used as core or macro initiator for polymerization of ε‐caprolactone (CL). Starch nanoparticle‐g‐polycaprolactone was synthesized through ring‐opening polymerization (ROP) of CL in the presence of Sn(Oct)2 as initiator. The detailed microstructure of the resulted copolymer was characterized with NMR spectroscopy. Thermal characteristic of the copolymer was investigated using DSC and TGA. By introducing PCL, the range of melting temperature for starch was increased and degradation of copolymer occurred in a broader region. X‐ray diffraction and TEM micrographs confirmed that there was no alteration of starch crystalline structure and morphology of nanoparticles, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
22.
Polyurethane coatings are highly flammable, and because of their widespread applications on different substrates (wood, steel, and building materials), there is a need to increase their fire‐safety properties. Intumescent additives sharply suppress the flammability properties of polyurethane coatings. Two problems accompany intumescent additives: their high loading percentage and incompatibility with polyurethane coatings. In this research, we succeeded in increasing the compatibility by mixing intumescent additives with a butyl acrylate polymer and in lowering the flame‐retardant additive loading (up to 20%) by incorporating newly modified montmorillonite. The flammability properties of the new intumescent coatings were characterized with a cone calorimeter. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
23.
24.
R. M. Hassan 《Journal of Materials Science》1993,28(2):384-388
The kinetics and mechanism of exchange of Ni2+ by H+ ions in ionotropic nickel alginate polymembrane gels of capillary structure have been studied by pH-metric and conductimetric techniques. The rate of exchange conforms to; rate=k
1 [nickel alginate] [H+]- k
–1 [alginic acid] [Ni2+] with k
1=6.34×10–2dm3mol–1s–1 and k
–1=8.83×10–4 s–1 at 20°C, respectively. The activation parameters have been evaluated and a mechanism consistent with the kinetic data is discussed. 相似文献
25.
The performance of a countermeasure technique in the presence of the optimal follower multitone jammer is evaluated for frequency-hopped spread spectrum (FHSS) communications. It is shown that, with a certain probability, the optimal jammer will have dual tones in a frequency channel 相似文献
26.
S. E. Chidiac D. S. Wilkinson F. A. Mirza 《Metallurgical and Materials Transactions B》1992,23(6):841-845
During welding, structures are subjected to localized heating and cooling cycles, as described in Part I.[1] A mathematical
model is proposed to determine the metallurgical changes that occur in austenitic stainless steel due to the welding thermal
cycle. The proposed kinetic model computes the austenite grain growth as a function of time and temperature. It is based on
a Zener pinning grain growth model. The results obtained indicate that the model is in good agreement with the experimental
data reported in the literature. Furthermore, it was observed that rewriting the kinetic constant in the grain growth equation
as a function of the peak temperature led to improved results for the majority of the cases examined. 相似文献
27.
A general-purpose finite-element program has been used to simulate the flow of Newtonian, power-law, and viscoelastic fluids in calendering. The analysis is fully two-dimensional and does not make use of the lubrication approximation. Isothermal and nonisothermal calendering is studied and the results are compared with predictions from the lubrication approximation. The free surface is determined and circulatory flow patterns are predicted in the melt bank. Detailed calculations have been performed for a rigid poly(vinyl chloride) (PVC) resin that exhibits slip at the wall using rheological data for the melt and machine parameters. The results include determination of the shape and location of the free surface, vortex patterns, temperature and pressure distributions, and predictions of roll-separating force, torque, and power consumption. Comparisons are made with experimental data available in the literature. 相似文献
28.
The characteristics of ion beams of hydrogen and nitrogen with different filling pressures emitted from the plasma focus device of 2.3 kJ energy are investigated. CR-39 SSNTDs are employed for the registration of tracks of ions. The exposed detectors are etched in 6N NaOH solution at 70°C and then examined with an optical microscope. The ion flux is estimated to be of the order of 105–6 tracks/cm2. The flux with the radial position does not exhibit any regular pattern of variation. 相似文献
29.
Water Resources Management - Change in the spatiotemporal pattern of precipitation is one the most important effects of climate change. This may result in considerable changes in urban flooding and... 相似文献
30.
Meraj Talha Rauf Hafiz Tayyab Zahoor Saliha Hassan Arslan Lali M. IkramUllah Ali Liaqat Bukhari Syed Ahmad Chan Shoaib Umar 《Neural computing & applications》2021,33(17):10737-10750
Neural Computing and Applications - Lung cancer is a deadly disease if not diagnosed in its early stages. However, early detection of lung cancer is a challenging task due to the shape and size of... 相似文献