Advanced Materials Research Vol. 502

Abstract: Steel tube and filled concrete of square CFT (concrete filled steel tubular structures) columns under eccentric load are in complicated stress condition, the influence of every kind of factors on mechanics performance is difficult to ascertain accurately. On the other hand, neural network is good at obtaining the relationship between input and output variables by self-studying, self-organizing, self-adapting and nonlinear mapping. Therefore, it is suitable that use neural network to calculating the bearing capacity of square CFT columns. In this paper a four-layer back-propagation model of network is trained according to experimental data of square CFT columns under eccentric load, a neural network model for eccentrically loaded square CFT columns is set up. The model is verified by six groups of experimental data, the results show the predicted values are in good agreement with test values, precision in calculation is good enough to be used as an auxiliary method for structure design.

Abstract: The mono polyethylene glycol maleate (MPEGM) was prepared by direct esterification of maleic anhydride (MAH) and polyethylene glycol (PEG). The yields of monoester (YM) could reached to 96% when the molar ratio of MAH and PEG was 1.2 using 2 wt% p-toluene sulphonic acid (PTSA) as catalyst at 95°C for 3 h. The amphoteric retaning agent (ARA) with excellent retanning properties was synthesized by copolymerization when the molar ratio of methacrylic acid (MA), MPEGM and dimethyl diallyl ammonium chloride (DMDAAC) was 3 : 1 : 0.2 using 3 wt% ammonium persulfate (APS) as initiator at 90°C for 4 h. The applied results showed that retanned leather by ARA had excellent selective filling and can improve remarkable the flexiblity and elasticity. The chemical structure of the ARA was characterized by FTIR.

Abstract: A graft copolymer was synthesized by copolymerization of degraded starch and acrylamide using horseradish peroxidase (HRP)/H2O2/acetylacetone (ACAC) as initiator. The structure of the copolymer was confirmed by FTIR and NMR. The copolymer can be used as retannage in leather making substitute for chrome retannage and contribute to decreasing pollution. The applied results show that the retanned leather possesses merits of excellent soft feeling, good elasticity and uniform thickness.

Abstract: A novel amphoteric polycarboxylate superplasticizer (APCs) was prepared by solution copolymerization from acrylic acid (AA), allyl polyethylene glycol (APEG), diallyldimethyl ammonium chloride (DMDAAC). Effects of DMDAAC dosage and monomers ratio on performance of APCs were investigated by tested of zeta potential of cement particles and adsorption on cement. Results indicated that introducing of cationic monomer can increase the saturation adsorption amount and dispersibility of APCS. When the molar ratio of AA and APEG and DMDAAC is 5:1:0.5, the dispersibility of APcs has the best adsorptivity and disersibility. The synergistic effects of Zeta potential and steric repulsion of the cement particles surface is the main mechanism for dispersion.

Abstract: This paper studies the carbon fiber weight influencing on the thermal conductivity of carbon fiber reinforced cement-based composites. Experiment results show that the thermal conductivity decreases with the increase of carbon fiber weight. It is because that the air bubble results from the proceeding when the carbon fiber adds into cement-based composites. When the carbon fiber weight is less than 1.0%(by mass), the thermal conductivity decreases significantly. And when the weight is more than 1.0%, the decreasing tendency starts to slow down. Based on the experiment data, the functional relationship between the thermal conductivity and carbon fiber weight is obtained by using the fitting method.

Abstract: This study establishes a 3-D finite element model for the numerical simulation of laser transformation hardening on inner wall of pump barrel through a finite element code-SYSWELD. The change of thermal mechanical parameters with temperature is considered. The temperature field, metallurgy transformation and distribution of residual stress are predicted. The effect of scanning velocity on the temperature, martensite fraction and distribution of residual stress are studied. The results show that peak temperature in the hardened zone reaches to 1067.0°C and the maximum heating and cooling rate of hardened zone are 1.24×104°C/s and 3.68×103°C/s. After treatment, martensite can be obtained as a main phase in the hardened zone whose fraction increases with the decrease of scanning velocity. Compressive stress could be acquired in the hardened zone while the peak of tensile stress exists in the HAZ.

Abstract: Through suspension polymerization , the influences of different crosslinking agent, initiator, disperser and reaction temperature on oil absorption rate of cetane methacrylate highly oil absorptive resin were studied. The oil absorption ability of the resin for different oil was investigated. The results show the oil absorption capacity of synthesized resins was good with crosslinker divinylbenzene(DVB), initiator benzoyl peroxide(BPO) and disperser polyvinyl alcohol(PVA). Suitable process conditions were: crosslinker DVB 1.0%, initiator BPO 1.2%, disperser PVA 0.8%, reaction temperature 70°C, and oil absorptive power of obtained resin is about 36.6g.g-1 for CC14.

Abstract: Surface modification of Poly(ρ-phenylene terephthalamide) (PPTA) fiber has been considered an effcient way to increase the interfical bonding of the fiber/epoxy composites. In this article, the hydrogen peroxide solutions (H2O2) was used to treat the PPTA fiber based on an orthogonal experimental design. The optimum conditions of H2O2 treatment were concentration of 40%, treating temperature 40°C and treating time 60min. The morphology of the modified fiber were characterized by scanning electron microscope (SEM). The interfacial properties of aramid fiber/epoxy composites were investigated by the single fiber pull-out test (SFP. The results showed that the interfacial shear strength (IFSS) of aramid/epoxy composites was remarkbly improved which was attributed to the fact that some polar groups were introduced into the molecular structure of aramid fibers and the physical structure of the treated fibers was not etched obviously.

Abstract: In this article, a new process was used to make flame resistant polyacrylonitrile (PAN) fibers by surface modification. The effects of the treating conditions during the copper ion treatment, aqueous mixture of hydrazine hydrate treatment and high temperature treatment on the mechanical properties and flammability of the resultant flame resistant fibers were studied. The results showed that the optimum reactiong conditions were: the addition of hydrazine hydrate 20mL, drying time 3min, heating temperature 160°C and heating time 180min.Under these conditions, the flame-retardant PAN fiber with good mechanical properties could be obtained.

Abstract: The grain sizes and precipitates in hot-rolled bands of the non-oriented electrical steel containing Cu were quantitatively studied while the effect of hot-band annealing on microstructure was evaluated by hot-band annealing at different temperatures. The average sizes of recrystallized grains after coiling at 650°C are in the range of 24~29μm. After hot-band annealing at 850°C for 1h, grains coarsened dramatically. The volume fractions of precipitates in hot-rolled bands after coiling at 650°C for different time are 15~18%. After hot-band annealing, precipitates coarsened and distributed sparsely, and the volume fraction of them decreased to less than 10%.