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91.
Zareen Akhter Muhammad Saif ullah Khan Mubasher A. Bashir 《Journal of Inorganic and Organometallic Polymers》2004,14(4):253-267
Some ferrocene containing aromatic azo polyesters were prepared by condensing 1,1-ferrocenedicarbonyl chloride with different azo groups containing aromatic diols, which were synthesized by diazotization coupling reaction from aromatic diamines. The polymeric products were separated as two portions on the basis of their solubility and subsequently characterized by their elemental analysis and FTIR spectral studies. Thermal properties of the products were measured by differential scanning calorimetry and thermogravimetry and the activation energies of pyrolysis were calculated using Horowitz and Metzger's method. The molecular weights of the soluble portions were determined by gel permeation chromatography (GPC) and these portions were also characterized by their inherent viscosities and UV-Vis spectroscopic studies. 相似文献
92.
A partex surface was modified by a UV‐curing system with epoxy acrylate (EB‐600). A set of formulations was prepared with oligomer and the trifunctional monomer trimethylol propane triacrylate in different combinations of percentages (1–5%) of sand to study the role of sand in various physical properties of UV‐cured thin films, as well as partex surfaces. Increased pendulum hardness (PH), gloss, adhesion, and abrasion values were obtained by the addition of sand into the partex surfaces. The best results were obtained with the formulation containing 3% sand. An enhanced PH and a decreased percentage of gel content of the UV‐cured film was observed with an increase of the sand concentration. A simulated weathering test was performed with partex surfaces cured by a formulation containing 3% sand in the base coat. The losses of the physical properties were found to be lower over the surface treated with the formulation containing sand. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2385–2392, 2002 相似文献
93.
Md. Majibur Rahman Khan Hideaki Morikawa Mikihiko Miura Yoshie Fujimori Masanobu Nagura 《Carbon》2007,45(5):1035-1042
Carbon fibers were prepared from silk fibers after an iodine treatment and the carbon yield, fiber morphology, structure and mechanical properties were investigated. A single or multi-step carbonization process was used for the preparation. In the single step process, silk fibroin (SF) fibers were heated from 25 to 800 °C with a heating rate of 5 °C min−1 under Ar atmosphere. However, the carbon fiber obtained was partially melted and was too fragile to handle. For better performance, SF fibers were treated with iodine vapor at 100 °C for 12 h and untreated and iodinated SF fibers were heated from 25 to 800 °C by a multi-step carbonization process, which was defined based on the optimum thermal degradation rate of silk. In this multi-step process, the carbon fibers obtained from iodinated SF were structurally intact and stable in appearance, and the carbon yield achieved was ca. 36 wt.%, much higher than the value for untreated SF. X-ray diffraction, Raman spectroscopy and transmission electron microscopic observation revealed that the obtained carbon fibers from both untreated and iodinated SFs had a basically amorphous structure. The strength of carbon fibers prepared from iodinated SF using the multi-step carbonization was considerably increased compared to that of untreated SF. According to viscoelastic measurement, by heating above 280 °C the iodine introduced intermolecular cross-linking of the SF, and its melt flow was inhibited which produced a higher yield and better performance of the carbon fiber. 相似文献
94.
To improve the physicomechanical properties of jute yarn, grafting with 1,6‐hexanediol diacrylate (HDDA) monomer was performed by a UV radiation technique. A series of HDDA solutions of various concentrations in methanol were prepared. A small quantity of photoinitiator (Darocur‐1664) was also added to HDDA solutions. To optimize the conditions for grafting, the effects of monomer concentration, soaking time, and radiation doses were studied by varying the number of soaking times along with variation of monomer concentrations and UV radiation intensities. The extent of polymer loading and the mechanical properties like tensile strength (TS), elongation at break (Eb), and tensile modulus of both treated and untreated jute were investigated. The highest tensile strength, polymer loading, and modulus were achieved with 5% HDDA concentration, 5 min soaking time, and the 4th pass of UV radiation. This set of conditions was selected as optimum and produced enhanced tensile strength (67%), modulus (108%), and polymer loading (11%) over those of virgin fiber. To further improve the mechanical properties the jute yarns were pretreated with alkali (5% NaOH) solution and after that the alkali‐treated yarn were treated under UV radiation of various intensities. The pretreated samples were grafted with optimized monomer concentration (5% HDDA). Increased properties of alkali + UV‐pretreated and grafted samples such as polymer loading (12%), tensile strength (103%), elongation at break (46%), and modulus (114%) were achieved over those of virgin jute yarn. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 18–24, 2004 相似文献
95.
M. A. Javed M. Saleem N. Shakir S. A. Khan 《European Journal of Lipid Science and Technology》1984,86(4):160-161
Physico-chemical properties of the seed oils of three species of Rosaceae family, namely Prunus armeniaca (apricot), Prunus cerasifera (prune), and Prunus persica (peach) have been determined. Fatty acid composition of the oils and amino acids composition of seed cake proteins have also been determined and their utility in every day life has been discussed. 相似文献
96.
The experimental results presented in this paper indicate that the cement/aggregate ratio, the water/cement ratio, the size of aggregate, and the rate of cooling have significant influence on the modulus of rupture of sulfur-infiltrated concrete (SIC). Using sand only as aggregate and 65% cement, SIC of over 3500 psi in flexural tension was obtained from the test of 1″ × 1″ × 4″ specimens. 相似文献
97.
Experiments have been performed to investigate the mechanical response of unfilled polycarbonate vis‐à‐vis the influence of prior deformation on stress relaxation and creep. Piecewise linear deformation histories, which involve strain‐controlled tensile loading of a specimen to a maximum load and partial unloading to a target strain/stress point as prologue to a relaxation test, have been shown to qualitatively influence the recorded stress‐time behavior. In particular, the stress magnitude during relaxation first increases and is then followed by a decrease. Analogously, in creep tests during unloading, the strain might decrease and then increase. Time characteristics for this U‐turn in the deformation response are influenced by the placement of the test. The influence of prior specimen conditioning on this phenomenon is investigated by comparing test data from virgin samples to that of specimens having high (~85%) inelastic strain from prior tensile elongation. Findings suggest that the observed persistence in the occurrence of this reversal effect for both types of specimens is evidence of the need to incorporate this behavior into the fold of material modeling. Additionally, this novel relaxation and creep behavior has been observed in other amorphous (poly(phenylene oxide)) and crystalline (high‐density polyethylene) polymers. Polym. Eng. Sci. 44:1783–1791, 2004. © 2004 Society of Plastics Engineers. 相似文献
98.
The present investigation pertains to modeling of seawater desalination system. A simulation model was developed and verified for a small-scale reverse osmosis system. The proposed model combines material balances on the feed tank, membrane module andproduct tank with membrane mass transfer models. Finally a comprehensive simulation model has been developed incorporating the effect of mass transfer inhibition The model is non-linear differential equation representing the feed concentration as a function of operating time and space. The solution of the simultaneous differential equations was obtained using the fourth order Runge-Kutta method, due to self starting and stability. The model was verified using the experimental data from the literature [17,24]. Parameter sensitivity was carried out to select the proper step size. The simulation was run for over 1000 11 enabling a prediction of operational performance at high overall system recoveries. 相似文献
99.
S. M. Khan A. Aziz Khan M. A. Beg 《European Journal of Lipid Science and Technology》1969,71(6):451-454
The kinetics of oxidation of isobutyric and isovaleric acids by chromic acid in sulphuric acid medium have been studied. The end product acetic acid is supposed to be derived from the ketones which are the initial oxidation products of the corresponding branched chain fatty acids. The influence of acetic acid on the oxidation velocity has been examined and a marked effect on the rate constants with increasing acetic acid concentration has been observed. A mechanism involving the electrophilic attack of the oxidant on the tertiary carbon atom of the fatty acid to yield a carbonium ion has been postulated. 相似文献
100.
Due to the advancement of low power miniature electronic devices, there is growing interest of physiological data sensing and recording using wireless body sensor networks. The paper presents the design of a portable physiological data logger that includes rechargeable battery, wireless radio frequency and Bluetooth connectivity, and graphical display with touch screen capability. The target application is video capsule endoscopy. Image data are logged in micro SD cards which can be easily transferred to PC or Smartphone using SD card reader, USB interface or Bluetooth wireless link. The hardware design is general and can be used in various medical or industrial applications by changing only the firmware of the microcontroller. The design is prototyped in 109 × 107 × 20 mm printed circuit board (PCB). Tests with animal tissues have been conducted to demonstrate the performance advantages of the data logger. A demonstration of wireless heart pulse monitoring and data logging is also presented. 相似文献