Comparative effect of grain size and texture on the corrosion behaviour of commercially pure titanium processed by equal channel angular pressing

The effect of grain size and texture on the corrosion properties of commercially pure titanium was investigated. Equal channel angular pressing (ECAP) was used to produce different grain size and various crystallographic orientations. Electrochemical impedance spectroscopy was employed to measure the corresponding surfaces’ general corrosion resistance. Samples with the (0 0 0 2) planes parallel to the surface were found to offer the highest corrosion resistance, regardless of their grain size.     

Synthesis and characterization of novel polyurethanes based on aminolysis of poly(ethylene terephthalate) wastes,and evaluation of their thermal and mechanical properties

BACKGROUND: Much research is currently directed towards recycling post‐consumer poly(ethylene terephthalate) (PET) products for both environmental and economic reasons. Aminolysis of PET wastes using different amines, such as allylamine, morpholine, hydrazine and polyamines, leads to different reaction products as diamides of terephthalic acid, which do not possess any potential for further chemical reactions. In the past, the use of ethanolamine has been investigated for the aminolytic degradation of PET waste in the presence of different simple chemicals such as sodium acetate as catalysts. The product obtained, bis(2‐hydroxyethylene) terephthalamide (BHETA), has potential for further reactions to obtain useful products. Nevertheless, there has been no report on using recycled BHETA from PET to synthesize polyurethanes. RESULTS: In this research the product of aminolysis of PET waste, BHETA, was prepared. Then novel polyurethanes were synthesized based on the BHETA prepared, 1,4‐butanediol, ether‐type polyol and various molar ratios of hexamethylene diisocyanate. To evaluate the effect of BHETA, the properties of the polyurethanes without and with BHETA were compared. Fourier transform infrared spectra, thermal transitions, degradation, swelling ratio and chemical resistance of the synthesized polyurethanes were investigated. Also, the polyurethanes were applied as adhesives on various substrates. Comparison of the maximum bond strength of the synthesized polyurethane to that of commercial adhesives shows an about 2.2‐fold increase. CONCLUSION: It is possible to synthesize new polyurethanes with interesting properties using BHETA as an aminolysis product of PET waste. These kinds of materials have potential for many applications, such as adhesives and coatings. Copyright © 2008 Society of Chemical Industry     

Correlation between irregular surface geometry and certain electrochemical quantities in poly-ortho-aminophenol

The relationship between the fractal dimension of poly-ortho-aminophenol film and its thickness in the presence of different anions was studied using the peak current scaling in cyclic voltammetry (CV). There is a meaningful relation between the inner and outer cutoff (minimum and maximum length scale of the surface seen by the diffusing species, respectively) distinction in the polymer sensed by anions and the film charge transport resistance. The constant phase element exponent at low frequency was found to depend on the thickness of the poly-ortho-aminophenol film and on the applied potential during the impedance measurements. The constant phase element exponent dependence on the thickness of the film is explained by the film morphology and its dependence on the applied potential is interpreted by a change in the charge transport mechanism in the poly-ortho-aminophenol films.     

CHARACTERIZATION OF SOLVENT-INSOLUBLE ORGANIC MATTER ASSOCIATED WITH MINERAL MATTER FROM OIL SANDS∗

ABSTRACT

Considerable quantities of insoluble organic matter (IOM) are known to be associated with certain solid fractions found in oil sands. This organic matter is believed to be partly responsible for the intractability of the sludge generated by the hot water process used for the extraction of bitumen from Alberta oil sands. In previous investigations we had attempted to enrich the insoluble organic matter by dissolving the minerals in concentrated HCl/HF mixtures. As a result of this severe acid treatment the inorganic material is decomposed, but the organic constituents are also likely to undergo significant changes. In the present work we have used a milder HCl/HF treatment for mineral dissolution. The results from the current investigation are compared with the results of the previous study to assess the chemical alterations of the organic matter resulting from the two treatments.

The fractions obtained from the mild acid treatment were analyzed using solid state ¹³C NMR spectroscopy and elemental analysis. Latter results have been discussed in terms of a van Krevelen diagram which is derived by plotting the atomic H/C ratios against O/C. The NMR data were used to calculate the aromaticities of the various organic fractions. Based on the elemental compositions and the NMR data, it is suggested that the IOM associated with the sludge solids is derived from terrestrial sources.     

一种用于从水中分离挥发性有机化合物的疏水性渗透汽化中空纤维复合膜

研制出一种名为VOC-SEP200新型中空纤维疏水性复合膜,并考察了这种复合膜从水中分离BTEX(苯、甲苯、乙苯和二甲苯)的性能．这4种芳香碳氢化合物是工业有机废水中的一组有代表性的污染物,本研究的最终目的是想从现实的工业废水中回收这些化合物．采用料液在纤维中孔流动的方式,系统考察了进料液流速、操作压力、温度和进料液浓度对膜分离效率及膜性能的影响．结果显示,随着进料液流速的提高,BTEX的通量随之增大．这是由于随着进料液流速的提高,浓度极化的影响会减少,同时BTEX和水的分离因子会有显著增大．结果还显示,膜的性能随膜横向的驱动力降低而提高,其最佳的渗透压范围是10．7～13．3kPa(即80～100mmHg),此时BTEX通量达到最大平稳值,同时水的通量最小．提高渗透压可减少操作费用,同时可增强分离效果,和预期的情况一样,BTEX和水的渗透通量都随着温度和进料浓度的提高而增大,但再进一步提高浓度和温度,则对水通量不产生影响．水通量在初始阶段的增加可以归因于膜的溶胀,水通量不再随温度和浓度的进一步升高而增加,可以归因于水分子的聚集与膜的溶胀达到了平衡,     

Heavy metals concentrations in dairy cow feedstuffs from the south of Iran

ABSTRACT

Levels of lead, cadmium, mercury, copper and zinc elements in feedstuffs were measured by inductively coupled plasma-optical emission spectrometry. A total of 216 feedstuffs samples including corn silage, alfalfa hay, wheat straw, full ration pellet, wheat bran and barley were collected from polluted and unpolluted regions during four seasons and prepared with wet digestion. Lead and mercury concentrations did not differ significantly in various feedstuffs, but cadmium level was significantly the highest in barley samples (p < 0.05). All feed material samples had lead, cadmium and mercury concentrations well below the maximum levels allowed by the European Union. The lowest and highest levels of both copper and zinc were found in wheat straw and wheat bran, respectively, but their maximum content did not exceed the legal limits. In contrast to the sampling area, season significantly (P < 0.05) affected heavy metal levels, except for zinc, in feedstuffs.