Steels for Bridge Structures

Metallurgist - We consider domestic and foreign standards for rolled metals used in bridge building. Domestic standards contain elevated requirements to the reliability of rolled metals in terms of...     

Graft Copolymerization of Acrylamide onto Oil Palm Empty Fruit Bunch (OPEFB) Fiber

Grafting of acrylamide (AAm) onto oil palm empty fruits bunch fiber using hydrogen peroxide as initiator and methyl acrylate as comonomer was investigated. The amount of comonomer needed to make grafting of acrylamide possible was determined. The percentage of poly(acrylamide) and the comonomer in the final graft copolymer was estimated by elemental analysis. Results obtained indicated that methyl acrylate facilitated the incorporation of acrylamide monomer onto OPEFB. The reactivity ratios for both monomers were determined by using Fineman–Ross plot. The effects of reaction temperature and period as well as amount of the initiator, solvent, monomer and comonomer on the percentage of grafting at fixed amount of comonomer (11 mmol) were studied. Maximum percentage of grafting was achieved when the amount of initiator and solvent 3.98×10⁻³ mol and 50 mL respectively. The optimum reaction temperature was 50 ^○C and the reaction period was 90 min. Highest percentage of grafting was 232% when 25.6 mmol of acrylamide was used under these optimum conditions. The presence of functional group in the grafted polymer is characterized by infrared spectroscopy and the surface morphology is observed by scanning electron microscopy. Thermoanalytic investigation on OPEFB and OPEFB-g-PAAM were carried out to evaluate the thermal stability and respective activation energy of the materials.     

Managing a Very Connected World: A Report on APNOMS2015

This article presents a report on APNOMS2015, which was held August 19–21, 2015 in Busan, Korea. The theme of APNOMS2015 was “Managing a Very Connected World.”     

Inhibition of corrosion by a mixture of nonchromate pigments in organic coatings on galvanized steel

We consider several possible substitutes for toxic chromate pigments. Among the most promising compositions for the corrosion inhibition of galvanized steel with a protective organic coating, we should mention a mixture of phosphate- and calcium-containing pigments. As was shown earlier, such a mixture possesses a high efficiency under conditions of the corrosion of zinc and galvanized steel sheet; however, it is less efficient for the protection of carbon steels. This pigment mixture forms an adsorbed phosphate film on the metal and hinders the course of anodic and cathodic reactions. Zinc ions play an important role for obtaining a synergistic protective effect, increasing the coherence and decreasing the porosity of the deposited film. Traditional and local electrochemical methods (EIS and SVE) were used for studying the corrosion of galvanized steel with coatings in acid rain solution. The data obtained corroborated the high anticorrosive efficiency of a pigment mixture in an organic coating on galvanized steel. In addition, we established some specific features of its inhibiting action near defects in the coating.Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 40, No. 3, pp. 74–80, May–June, 2004.     

Managing Clouds, Smart Networks and Services: A Report on APNOMS 2011

This article presents a report on APNOMS 2011, which was held September 21–23, 2011 in Taipei, Taiwan. The theme of APNOMS 2011 was “Managing Clouds, Smart Networks and Services.”     

Reinforcement of graphene nanoplatelets on plasticized poly(lactic acid) nanocomposites: Mechanical,thermal, morphology,and antibacterial properties

Plasticized poly(lactic acid) (PLA)‐based nanocomposites filled with graphene nanoplatelets (xGnP) and containing poly(ethylene glycol) (PEG) and epoxidized palm oil (EPO) with ratio 2 : 1 (2P : 1E) as hybrid plasticizer were prepared by melt blending method. The key objective is to take advantage of plasticization to increase the material ductility while preserving valuable stiffness, strength, and toughness via addition of xGnP. The tensile modulus of PLA/2P : 1E/0.1 wt % xGnP was substantially improved (30%) with strength and elasticity maintained, as compared to plasticized PLA. TGA analysis revealed that the xGnP was capable of acting as barrier to reduce thermal diffusion across the plasticized PLA matrix, and thus enhanced thermal stability of the plasticized PLA. Incorporation of xGnP also enhanced antimicrobial activity of nanocomposites toward Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Listeria monocytogenes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41652.     

Mechanisms of helium porosity formation in vanadium alloys as a function of the chemical composition

Transmission electron microscopy is used to study the effect of doping vanadium with titanium and iron on the formation of helium porosity and gas swelling with ionic embedding of helium at 650°C. It is found that large facetted pores larger than 20 nm form in pure vanadium and vanadium exhibits the largest gas swelling. Doping with any amount of titanium (from 0.1 to 10%) and iron (from 1 to 10%) considerably decreases helium swelling. The titanium concentration has almost no effect on the density of the bubbles. The effect of titanium doping of vanadium on the porosity parameters and swelling is of a nonmonotonic character; in the case of iron doping of vanadium the bubble density increases and the bubble size increases monotonically and swelling occurs with increasing iron concentration. The minimum sizes of the bubbles and swelling are observed in alloy with the maximum titanium content V–10%Ti and the structural alloy V–4%Ti–Cr.     

Synthesis of liquid crystalline rod-coil dimers based on poly(propylene oxide) coil

Summary The synthesis and characterization of 4-[poly(propyleneoxy)propyloxy]-4'-bis[4-decyloxycarbonylbiphenyl-4'-biphenylcarboxylate] with poly(propylene oxide) coil of seven (dimer-7), twelve (dimer-12), seventeen (dimer-17), twenty one (dimer-21) are described. Dimer-7 with short length of poly(propylene oxide) coil exhibits successively smectic C, smectic A and nematic mesophases, while dimer-12 and dimer-17 with longer lengths of coils exhibit a bicontinuous cubic mesophase with Ia3d symmetry. Further increasing the length of coil, as in the case of dimer-21, suppresses liquid crystallinity. Received: 22 February 2000/Revised version: 21 March 2000/Accepted: 29 March 2000     

Study of morphology and gas separation properties of polysulfone/titanium dioxide mixed matrix membranes

Polysulfone (PSf)‐based mixed matrix membranes (MMMs) with the incorporation of titanium dioxide (TiO₂) nanoparticles were prepared. Distribution and agglomeration of TiO₂ in polymer matrix and also surface of membranes were observed by scanning electron microscopy, transmission electron microscopy, and energy dispersive X‐ray. Variation in surface roughness of MMMs with different TiO₂ loadings was analyzed by atomic force microscopy. Physical properties of membranes before and after cross‐linking were identified through thermal gravimetric analysis. At low TiO₂ loadings (≤3 wt%), both CO₂ and CH₄ permeabilities decreased and consequently gas selectivity improved and reached to 36.5 at 3 bar pressure. Interestingly, PSf/TiO₂ 3 wt% membrane did not allow to CH₄ molecules to pass through the membrane and this sample just had CO₂ permeability at 1 bar pressure. Gas permeability increased considerably at high filler contents (≥5 wt%) and CO₂ permeance reached to 37.7 GPU for PSf/TiO₂ 7 wt% at 7 bar pressure. It was detected that, critical nanoparticle aggregation has occurred at higher filler loadings (≥5 wt%), which contributed to formation of macrovoids and defects in MMMs. Accordingly, MMMs with higher gas permeance and lower gas selectivity were prepared in higher TiO₂ contents (≥5 wt%). POLYM. ENG. SCI., 55:367–374, 2015. © 2014 Society of Plastics Engineers