Biodiesel compatibility with carbon steel and HDPE parts

Compatibility of the new environmentally-friendly alternative of diesel engine fuels, biodiesel, with storage and engine part materials, is still an open issue. In this work, the interaction between three fuels (petroleum diesel and two types of biodiesel — soybean and sunflower) and two materials (carbon steel and high density polyethylene) used in storage and automotive tanks, is analyzed in detail. A wide set of characterization techniques was used to evaluate the changes in both solid and fluid materials, as weight change measurement, optical, scanning electron and atomic force (AFM) microscopies, Raman and FTIR spectroscopies, and differential scanning calorimetry. The AFM technique allowed detecting surface roughness and morphology changes in the metallic material following the trends in the weight losses. In the case of polymeric material, weight gain by fluid absorption occurred, being detected by the spectroscopic techniques. The biodiesel fuels underwent some ageing however this phenomenon did not affect the interaction between the biodiesel fuels and the substrates. The petrodiesel, which did not age, caused more significant degradation of the substrates.     

Long-term effect of diesel degradation on polyoxymethylene at different temperatures

Diesel is an important fuel, partly because of the longevity and cleanliness of diesel engines. Often, polymers are in direct contact with diesel and understanding compatibility is critical. Polyoxymethylene (POM) is a thermoplastic used to manufacture automotive fuel pump gears and rotors due to its low coefficient of friction and thermal and dimensional stability. In this study, tensile tests were performed on plain and glass fiber reinforced (POM and POMGF) after immersion in diesel at different temperatures (−10°C, 23°C, and 60°C) for 1000, 2000, 3000, 5000, and 10 000 hour. A mathematical model was developed using data from just three tensile stress-strain curves obtained at two different fluid temperatures and three different immersion times. Model and experimental results show good agreement with one another for all conditions tested.     

The enhancement of the mechanical properties of a high-density polyethylene

This paper describes the process optimization in injection molding of high-density polyethylene (HDPE). Both conventional injection molding and shear controlled orientation (SCORIM) were employed in processing. The process optimization was based on design of experiments and complemented with analysis of variance. Mechanical characterization was carried out by tensile testing. Wide-angle X-ray diffraction and differential scanning calorimetry were used for the structural characterization of the moldings. High-density polyethylene exhibits 7.2 GPa Young's modulus and 155 MPa of ultimate tensile strength following the application of SCORIM processing. These results account for a fourfold increase in Young's modulus and a fivefold increase in ultimate tensile strength compared to conventional injection molding. The maintenance of toughness while enhancing stiffness and strength of the SCORIM moldings is attributable to an oriented morphology developed during shear flow, i.e., shish-kebab structure. The frequency of shearing action has the strongest influence on the morphology development. It is also demonstrated that the studied parameters are very much interdependent. It is possible to achieve substantial gains in mechanical properties of HDPE in SCORIM processing without causing a substantial increase in cycle time. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2473–2483, 1999     

226Ra, 228Ra and 228Th in scale and sludge samples from the Campos Basin oilfield E&P activities

More than 40 scale and sludge samples from the Campos Basin oilfield were analysed in terms of 226Ra, 228Ra and 228Th. Although the exact origin of the samples was not known, scale samples derived from production pipes and sludge samples from water-oil separation units. Reported values ranged from 0.13 to 331 kBq.kg(-1) for 226Ra, from 0.10 to 245 kBq.kg(-1) for 228Ra and <0.10 to 272 kBq.kg(-1) for 228Th in sludge samples. The concentrations in scales were much more regular than in sludges and ranged from 16.2 to 93.2 kBq.kg(-1) for 226Ra, from 4.0 to 36.9 kBq.kg(-1) for 228Ra and from 4.5 to 18.5 kBq.kg(-1) for 228Th. Based on the Basic Safety Standards recommendations and on the derived results, these activities cannot be regarded as exempted and specific procedures should be designed for their radiological control.     

Paper or plastic revisited: Let's keep them both--Reply to Broderick and Stone (2006); Tennen, Affleck, Coyne, Larsen, and DeLongis (2006); and Takarangi, Garry, and Loftus (2006).

The authors review commentaries by J. E. Broderick and A. A. Stone (2006)(see record 2006-03820-007); H. Tennen, G. Affleck, J. C. Coyne, R. J. Larsen, and A. DeLongis (2006)(see record 2006-03820-008); and M. K. T. Takarangi, M. Garry, and E. F. Loftus (2006)(see record 2006-03820-009) on their original article (A. S. Green, E. Rafaeli, N. Bolger, P. Shrout, & H. T. Reis, 2006)(see record 2006-03820-006). The authors were pleased to find more agreement than disagreement regarding the choice of methods for conducting diary studies. It is clear that continued critical evaluation of all diary methods, both paper and plastic, is warranted. However, on the basis of their initial findings, the authors conclude that paper diaries are still likely to have a valuable place in researchers' toolboxes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dynamic mechanical properties of hydroxyapatite-reinforced and porous starch-based degradable biomaterials

It has been shown that blends of starch with a poly(ethylene-vinyl-alcohol) copolymer, EVOH, designated as SEVA-C, present an interesting combination of mechanical, degradation and biocompatible properties, specially when filled with hydroxyapatite (HA). Consequently, they may find a range of applications in the biomaterials field. This work evaluated the influence of HA fillers and of blowing agents (used to produce porous architectures) over the viscoelastic properties of SEVA-C polymers, as seen by dynamic mechanical analysis (DMA), in order to speculate on their performances when withstanding cyclic loading in the body. The composite materials presented a promising performance under dynamic mechanical solicitation conditions. Two relaxations were found being attributed to the starch and EVOH phases. The EVOH relaxation process may be very useful in vivo improving the implants performance under cyclic loading. DMA results also showed that it is possible to produce SEVA-C compact surface/porous core architectures with a mechanical performance similar to that of SEVA-C dense materials. This may allow for the use of these materials as bone replacements or scaffolds that must withstand loads when implanted.     

Swelling phenomena of emulsion liquid membranes with dithio-DEHPA as carrier

The purpose of this paper is to investigate the swelling of emulsion liquid membranes using dithio-DEHPA as carrier. The application of interest was the removal of zinc from a synthetic aqueous solution which simulates a zinc plant effluent. The effect of several variables such as the concentration of carrier in the membrane, stirring speed and permeation time on the swelling of the emulsion is reported. Experimental results show that occlusion depends mainly on the amount of carrier in the membrane and can be significant when the concentration of carrier is lower than 6.0%. The interfacial tension analysis confirms that the size of globules is influenced by the concentration of carrier in the membrane. Stirring speed and permeation time are related to the water transport and must be kept at low values.     

Hysterosalpingo contrast sonography (HyCoSy) with SH U 454 (Echovist) for the assessment of tubal patency

A total of 88 Fallopian tubes from 44 patients was examined with hysterosalpingo contrast sonography (HyCoSy), hysterosalpingogram (HSG), and laparoscopic chromopertubation (LC) in order to assess their relative accuracy for measuring tubal patency. HyCoSy was done by transvaginal ultrasound and the contrast was SH U 454 (Echovist). The flow of multiple fractions of the contrast medium through each Fallopian tube was observed in real time in appropriate imaging planes by means of a transvaginal probe. Compared with laparoscopic results, we found a sensitivity of 85.2%, a specificity of 85.2%, a positive predictive value (PPV) of 71.9%, a negative predictive value (NPV) of 92.9% and concordance (HyCoSy/LC) of 85.2%, while the corresponding values for HSG were sensitivity = 85.2%, specificity = 83.6%, PPV = 69.7%, NPV = 92.7% and concordance (HSG/LC) of 84.1%. Compared with HSG results, HyCoSy obtained a co-positivity of 66.7%, a co-negativity of 81.8% and a concordance of 76.1%. In conclusion, HyCoSy with SH U 454 proved to be a reliable and safe modality for evaluating tubal patency; it is suitable as an outpatient diagnostic procedure to be used before more invasive procedures.     

Starch–chitosan hydrogels prepared by reductive alkylation cross-linking

Starch-chitosan hydrogels were produced by oxidation of soluble starch to produce polyaldehyde and subsequently cross-linked with chitosan via reductive alkylation. The swelling ratio of starch-chitosan membranes was increased gradually with increasing starch ratio, but it was always lower than the native chitosan. In dry state, starch-chitosan membranes with low starch ratio (0.16, 0.38) showed similar tensile strength values to those of native chitosan while these values decreased with increasing starch ratios (0.73-1.36). Membranes in physiological buffer solution (PBS) gave a tensile modulus between 2.8 and 1.0 MPa, decreasing with increasing starch ratio (0.16-1.36 (Wstarch/Wchitosan)). When the membranes were incubated in PBS only, a moderate weight loss was observed for the first two weeks. Original weights of low starch weight ratio membranes (0-0.38) were at near 85%, while high ratio samples (0.73-1.55) were kept around 70% after three months. However, for the membranes incubated in alpha-amylase solution, very fast weight loss was observed. For low starch ratio membranes (0.16, 0.38, 0.73), the residual original weights were measured to be 11%, 6%, 20%, while for high ratio membranes (1.04 and 1.36) these were 45% and 30%, respectively, after two months of enzyme incubation. Scanning electron microscopy analysis of alpha-amylase degraded membranes exhibited rough surface morphology.