Advanced Materials Research Vols. 150-151

Abstract: In order to improve the mechanical performance of straw fiber reinforced gypsum composite materials, corn straw fiber was modified by alkaline treatment and chemical coating treatment, the influence of different surface modification treatment on mechanical performance of gypsum composite material was studied, and the mechanism of surface modification was discussed. The results indicated that: surface modification treatments could improve the interfacial bonding between straw fiber and desulfurization gypsum, and enhance mechanical performance of composite materials; comparing different treatments, the acrylic chemical coating treatment could enhance the strength of composite materials more outstandingly than other treatments.

Abstract: Pb-Sn-Al (PSA) laminated composite electrode materials were prepared by means of vacuum hot pressing (VHP), through introducing a medium Sn for solving the immiscibility of Pb and Al. Compared to traditional Pb-(1.0%)Ag alloy electrode, zinc eletrodeposition experiments showed that the cell voltage was reduced by at least 120 mv, the polarization potential of electrode was decreased by 13.2%, the current efficiency was higher 1.3% and the surface morphology of cathode zinc was better and smoother as well as zinc crystals smaller and more dense, while the experiment of the resistance test also showed that the resistance was reduced by at least 50%, therefore, Pb-Sn-Al (PSA) laminated composite electrode materials have lower cell voltage, as well as excellent conductivity, which would have good prospect in development and application in zinc hydrometallurgical industry in the future.

Abstract: Although Polyester has outstanding wearability, it only has few reacting functional groups in its surface, so protein can not be grafted firmly on polyester fiber surface. Therefore few reports are about grafting protein on polyester fiber’s surface. In this study, the surface of polyester was encased with hydroxide. Then the polyester fibers could be grafted with milk protein by using a synthetic crosslinkages compound. The structure of grafting milk protein polyester fabric was studied by SEM, and the wearability was measured too. Experimental results showed that milk protein could be grafted firmly on polyester through encasing and crosslinking technology. Milk protein could not be washed in the washing process. With the increase of grafted milk protein rate, the whiteness of polyester almost did not change; the cockle elasticity increased firstly, and then decreased, flexural stiffness and hygroscopicity property increased monotonously, moisture permeability increased firstly and decreased subsequently, and antistatic property increased greatly. Encasing hydroxide and grafting milk protein technology is an effective method to produce high functional polyester fabrics.

Abstract: Due to most of recycled aggregate (RA) possesses higher water absorption, therefore, the process of mixing recycled aggregate concrete (RAC) is more complex than that of normal aggregate concrete (NAC). In this paper, an organosilicone modifier was used to modify RA to reduce its water absorption. Four mixes of concrete were made up with modified RA at a concentration of 1:1, modified RA at a concentration of 1:2, unmodified RA, and NA, respectively. The water absorption unmodified RA and modified RA was compared, and effect of RA surface modification on the microstructure of the interfacial transition zone (ITZ) between the RA and the hardened cement paste was examined. The investigation results show that a higher concentration of modifier is more effective in reducing the water absorption of RA; and there is an optimal value of modifier concentration, and the use of in high concentrations modifier will adversely affect the integrity of interfacial zone.

Abstract: Polyimide-block-polyethylene glycol (PI-b-PEG) copolymers were synthesized and membranes were prepared for sulfur removing from model gasoline by pervaporation. The result of the pervaporation performance using the polyimide (PI) membrane and the PI-b-PEG membranes showed that the polyethylene glycol (PEG) groups were effective to increase the permeation flux with less decreasing of sulfur enrichment factor. And the permeation flux was increased by the increasing of weight content and the decreasing molecular weight of PEG groups. The copolymerization of PI with PEG is an effective method to enlarge the permeation flux of the PI membranes.

Abstract: The hybrid SBS-g-(DMAEMA-SiO2)/SBS-g-(AA-StSO3Na-SiO2) bipolar membrane, SBS BPM was prepared by SBS (styrene-butadiene-styrene triblock copolymer) grafted with acrylic acid (AA), sodium sulfonic styene(StSO3Na) through free radical grafting reaction, then the grafting copolymer and γ-mercaptopropyltrimethoxysilane (KH-590) were exposed to UV illumination, and the SiO2 doped anode membrane was obtained through sol–gel reaction of trimethoxysilane group, as similar process the cathode membrane was prepared by SBS grafted with dimethyl amino ethyl methacrylate (DMAEMA) and KH-570. The SBS BPM exhibited good mechanical strength (tensile strength, TS is 1.55MPa) and high temperature tolerance (thermal degradation temperature in N2 is in the range of 230–250°C). The ion exchange capacities (IECs) of SBS-g-(DMAEMA-SiO2) and SBS-g-(AA-StSO3 Na-SiO2) were in the region of 1.42–2.82 mmol/g. The SEM images show that the membrane cross- sections are very smooth where no silica particles could be observed. SBS-g-(DMAEMA-SiO2)/ SBS- g-(AA-StSO3Na-SiO2) bipolar membrane was used as the separator in the electrolysis cell for electro- generation of 2,2-dimethyl-3- hydroxypropionic acid(HPAc) and succinic acid in pairs. The yield of HPAc and the corresponding average current efficiency in the anode chamber were 28.2% and 53.8％, respectively. The yield of succinic acid and the average current efficiency in the cathode chamber were 74.1% and 62.5%, respectively.

Abstract: An anisotropic damage constitutive model is developed to describe the damage behavior of C/SiC composites. Different kinematic and isotropic hardening functions were employed in damage yield function to describe accurately the damage nonlinear hardening. The damage variable is defined by the principle of energy equivalence. The degradation of stiffness and the unrecoverable deformation induced by micro-crack propagation were considered in this model. The constants of constitutive model are identified and the damage evolution processes under tensile and shear loading. Uniaxial tension and shear tests have been used to valid the constitutive model to C/SiC composites.

Abstract: The strength and the fouling resistance of PVDF membrane prepared by wet phase inversion process can be improved by an innovation in membrane preparation. The prepared flat-sheet PVDF-fabric composite membrane consists of a fabric layer and a PVDF membrane layer. The fouling resistance of the composite membrane in membrane distillation (MD) desalination was investigated by air gap membrane distillation (AGMD), using simulated saline water and high concentration NaCl solution as the feed solutions respectively. The experimental results showed that the water-and-oil repellent finishing of the fabric support had a significant effect on the bonding strength and the fouling resistance of the composite membrane. With the protection of the fabric layer for the PVDF membrane layer, the composite membrane exhibited better fouling resistance as its fabric surface was in contact with the feed solution in MD process, when the fabric support was finished with 2g/L FK-501.

Abstract: A serial of polyfluorene copolymers have been developed by covalently attaching thiophene units to the side chain of polyfluorene with an alkyl spacer by means of Pd-catalyzed Suzuki coupling reactions. The electrochemical, photophysical and photovoltaic properties of the copolymers were studied. The absorption spectra of the copolymers measured in thin films display two absorption peaks. The power conversion efficiency achieved in the device configuration ITO/PEDT/ PFO-FT-DBT: PCBM (1:2)/Al is 0.83% with open-circuit voltage (Voc) 0.75V. Further investigation of more polyfluorene copolymers with narrow band gap aryl-hetero cycle units on the side chain is in progress.

Abstract: To assess the behavior of concrete beams partially prestressed with external unbonded carbon fiber-reinforced polymer (CFRP) tendons, three specimens prestressed with CFRP tendons and one reference specimen prestressed with external steel tendons were tested to failure under third point loading. It was found that the load-deflection curve of all specimens exhibited three stages, namely, elastic, cracked-elastic and plastic. The transition from the elastic to the cracked-elastic stage was caused by the development of cracks at the bottom of the beam, while the transition from the cracked-elastic to the plastic stage was caused by yielding of the non-prestressed steel. For beams prestressed with external CFRP tendons and that with external steel tendons, the relationships between the stress increment in external tendons and the mid-span deflection of specimens were linear or approximately linear. Although CFRP materials are brittle in nature and behave linearly elastically until failure, proper combination of external CFRP prestress tendons with internal steel reinforcing bars can impart ductility to the beams.