Key Engineering Materials Vol. 815

Abstract: In this paper, acrylic acid was grafted to chitosan in order to change the structure; polymer was obtained from modified chitosan. A series of novel toughened composite NF memebranes were prepared by over-coating the polysulfone ultrafiltration membrane with the polymer of modified chitosan. The chitosan derivatives and the polymer were characterised by infrared spectrophotometer (IR); the structure of the membrane was characrerised by scanning electron microscopy (SEM) and atomic force microscope (AFM). The composite NF membrane’s performances were strictly related to the structure of polymer. The rejection of the membrane was 96.3% with flux as high as 386.46 L m^-2 h^-1 with the 1000 mg/L of NaCl. Tensile strength of membrane increased 46%. The HCl (5%) resistance increased from 20.3 to 36.8h. The NaOH (5%) resistance increased from 18.3 to 31.6h. These results indicated the prepared toughened composite NF memebrane was excellent NF membrane, which had a wide application prospect.

Abstract: In this paper, the carbon fiber and ABS composites were prepared in different carbon fiber power mass percent by the twin screw extruder. The mechanical properties of the ABS/CF composites were studied in different process parameters by injection molding. The influence of mold temperature, melt temperature, packing pressure and injection pressure on the mechanical properties was analyzed in different carbon fiber composites. The results show that with the content of carbon fiber increase, the tensile stress of the composite materials also increase. The effect of different carbon fiber power content on tensile stress is greater compared with process parameters.

Abstract: Various types of hydrogen bonds exist in polyether polyurethane, polyurethane-urea and polyurea (PUA) and can cause microphase separation. The morphology, properties and applications of polyether PUA are determined by the microphase separation. All kinds of hydrogen bonds make it difficult to assignments of Fourier transform infrared spectroscopy (FTIR) peaks of ether linkage, amine and carbonyl group. This affects the calculation of the hydrogen bonding degree of the hard segments for estimating the degree of microphase separation. This paper summarized hydrogen bonding structures between proton donors and proton acceptors. By analyzing the influence of electronic effect, steric effect, various types of hydrogen bonds and the degree of order of hydrogen bonding on infrared peaks, the relationships between hydrogen bonding structures and infrared peaks are established. Lay the theoretical foundation for evaluating the degree of microphase separation by FTIR method.

Abstract: A non-classical mechanical analysis method was used to derive the equivalent torsional stiffness <GI_p> of thick-walled CFRP drive shaft. The equivalent shear modulus calculated by classical lamination theory, finite element analysis method and non-classical mechanical analysis method were compared. Experimental work was carried out on six composite tubes made of same dimensions but different lay-ups. All the results show that the layers with ±45° fiber orientation angle located on the outside of the wall thickness can increase the torsion stiffness of the composite tube. The non-classical mechanical analysis method predicts the torsion stiffness of thick-walled composite tube more precisely than the theory classical lamination, and agree well with experimental results. This method provides a convenient, accurate and fast method for the torsion stiffness.

Abstract: Nano sized of 4wt.% and micro sized of 15wt.% SiC particles reinforced aluminum mental matrix composites fabricated by powder metallurgy vacuum hot pressing sintering were treated by cold-isostatic pressing. The effects of cold isostatic pressing on microstructure, density, hardness and wear resistance were investigated and analyzed. The experimental results showed that in the composites reinforced with hybrid SiC particles after cold isostatic pressing treatment, the agglomeration phenomenon and overlap phenomenon around the micron SiC particles disappeared and the surrounding defects were obviously improved, the grains were flattened, and the material was more densely. The composite is characterized by abrasive wear.

Abstract: In order to study the influence of the blending of chopped basalt fiber on the mechanical properties of concrete, this paper uses basalt fiber content as a variable to simulate the basalt fiber concrete. Simulate its cubic compression, axial compression, splitting tensile, flexural test and working performance, and compare the simulation results with other people's physical and mechanical test data. The results show that the addition of basalt fiber has a great influence on the crack resistance and mechanical properties of concrete.

Abstract: A group of concrete spilitting tensile test was carried out by using the drop test machine Studying on the inertial effect on the dynamic tensile strength of concrete under different working conditions. The result show:with the increase of the drop height and quailty, peak load, loading rate of the concrete are increasing gradually.peak load of the test group is slightly higher than control group, The inertia effect has a certain influence on the dynamic tensile strength of concrete.

Abstract: The heating mechanism of electric and magnetic loss materials under microwave irradiation is expounded. The heating rate, material composition and road performance of four kinds of microwave ice and snow roads including carbon fiber, magnetite ore, steel fiber and ferrite are reviewed. And analyze their respective characteristics and applicable conditions. The problems existing in microwave melting ice and snow technology are discussed, and the application prospects of electromagnetic wave absorbing materials in microwave melting ice and snow road are prospected.

Abstract: In this paper, preliminary research on lightweight aggregate shotcrete is carried out. The main discussion is the pumpability and sprayability of light aggregate injection by single-mixed and complex-doped mineral admixture, and the different dosages and different types are studied. The effect of mineral admixture on the physical and mechanical properties of lightweight aggregate shotcrete. The results show that the small amount of fly ash, silica fume and nano-silica can prevent the segregation and bleeding of the mixture. With the increase of the content of silica fume and nano-silica, the pumpability can be reduced. At the same time, the sprayability is increased. It has also been found that, due to the difference in particle size, the mutual complementation of particles between the complex mineral admixtures in terms of physical and mechanical properties results in a significant increase in sprayability and strength.

Abstract: An experimental researches was performed for carbon black-reinforced cement-matrix composites. The carbon black used was in the form of particles with a nano-size. Results show that when content of the carbon black is between 0.25% and 0.75% by weight of cement, both flexural and compressive strengths of the composite can be enhanced. Flexural strength increases up to 9.69%, and compressive strength increases up to 6.92%, respectively. Moreover, the carbon black-reinforced composite is of high strain-sensing ability. The fractional change in resistance () increases monotonically upon compressive loading, and decreases monotonically upon unloading. These properties indicate that the carbon black-reinforced composite can be used for structural function, while at the same time act as a strain sensor itself. Compared with carbon fiber-reinforced composites, the carbon black-reinforced composite has a low price and is easy for mixing.