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Electrochemical Pretreatment of Polymers with Dilute Nitric Acid Either Alone or in the Presence of Silver Ions 总被引：1，自引：0，他引：1
X-ray Photoelectron spectroscopy (XPS) was used to detect major changes to the surface chemistry of polypropylene (PP), high density polyethylene (HDPE) and styrene-butadiene block copolymer (SBS) caused by electrochemical treatment using dilute nitric acid as electrolyte. Large increases in adhesion levels were observed with PP and HDPE. The method has the potential to be a commercial pretreatment that is inexpensive and safe. Further treatments were carried out in which the complex ion (AgNO3)+ was generated electrochemically. Effective pretreatment was achieved even with dilute solutions (0.001 M w.r.t. silver nitrate). Mechanisms are tentatively proposed for the electrochemical treatment when simply using an electrolyte of dilute nitric acid or where the anolyte consists of a solution of silver nitrate in dilute nitric acid. 相似文献
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S. M. Sayyah M. A. EI-Ahdal Z. A. El-Shafiey M. El-Sockary U. F. Kandil 《Journal of Polymer Research》2000,7(2):97-106
Anionic solution polmerization studies of benzylidene malononitrile, benzylidene ethyl cyanoacetate and their para chloro derivtives in dimethyl formamide (DMF) as a reaction medium using pipridene as initiator under nitrogen atmosphere at 100 °C were carried out. Infrared, 1H NMR and ultraviolet-visible (UV-Vis) spectroscopic studies for the obtained polymers were investigated. The effect of γ-irradiation on PMMA films doped with 1 % of the benzylidene polymers was investigated by uv-vis spectroscopy. A change in the intensity of absorption bands with increasing irradiation dose was recorded. It is suggested that PMMA films doped with this type of benzylidene polymer can be used as dosimeter. 相似文献
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Shear failure is catastrophic and occurs usually without advance warning; thus it is desirable that the beam fails in flexure rather than in shear. Many existing reinforced concrete (RC) members are found to be deficient in shear strength and need to be repaired. Externally bonded reinforcement such as carbon-fiber-reinforced polymer (CFRP) provides an excellent solution in these situations. To investigate the shear behavior of RC beams with externally bonded CFRP shear reinforcement, 11 RC beams without steel shear reinforcement were cast at the concrete laboratory of the New Jersey Institute of Technology. After the beams were kept in the curing room for 28?days, carbon-fiber strips and fabrics made by Sika Corp. were applied on both sides of the beams at various orientations with respect to the axis of the beam. All beams were tested on a 979?kN (220?kips) MTS testing machine. Results of the test demonstrate the feasibility of using an externally applied, epoxy-bonded CFRP system to restore or increase the shear capacity of RC beams. The CFRP system can significantly increase the serviceability, ductility, and ultimate shear strength of a concrete beam; thus, restoring beam shear strength by using CFRP is a highly effective technique. An analysis and design method for shear strengthening of externally bonded CFRP has been proposed. 相似文献
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Analytical and experimental studies were conducted for the purpose of establishing a distinguishing criterion between short and long FRP composite column behaviors. The results of investigating 24 full-scale GFRP composite columns are presented. The experimental studies utilized specimens with commonly used ‘Universal’ and ‘Box’ cross-sections which were manufactured by the pultrusion process using E-glass fibers in various forms as reinforcement and polyester and vinylester as binding matrices. The effective slenderness ratios (L/r) of the investigated columns were 3.79, 32.7, 47.9, 63.1 and 75.4 for the ‘Universal’ section and 9.38, 53.9 and 78.9 for the ‘Box’ section. The specimen lengths were 18 inches (0.46 m), 8 foot (2.44 m), 12 foot (3.66 m), 16 foot (4.88 m) and 19.25 foot (5.87 m). All columns were tested in a vertical position and under compressive axial static loading and the fundamental pinned–pinned end-conditions. The columns’ compressive strains, buckling and crippling loads, lateral displacements, initial curvatures, and modes of failure were documented during the course of this investigation. Orthotropic mechanical properties of the composites were experimentally obtained utilizing 44 coupons cut from the column specimens. Analytically, Euler's formula was employed to obtain critical loads for the slender columns. For short columns, the classical plate theory was used to predict columns’ buckling loads. Based on experimental evaluations and analytical results, a slenderness ratio based criterion was established for distinguishing between short and long composite column behaviors. Further conclusions and design recommendations were made. 相似文献
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