Advanced Materials Research Vols. 150-151

Abstract: This work aims at investigating the effect of thermal aging on tensile properties of three-dimension (3D) and five-direction braided carbon fiber/BMI resin composites prepared by resin transfer molding (RTM) process. The influence of high temperature on the tensile strength and the failure mechanisms of un-aged and aged composites were studied, respectively. As for the thermal aging condition, 180 for 24h was selected. The tensile strength of both un-aged and aged specimens were tested by SHIMADZU universal material testing machine at room temperature. The fracture modes of specimens were observed by scanning electron microscopy (SEM). It was found that the tensile load at break and tensile strength decreased after ageing. From the SEM views of the failed samples, the fracture surface presented hackles which were specific to the debonding of the interface between fibers and matrix. A lot of fibers were pulled-out in the aged state specimen. It can be confirmed that the failure occurred at the fiber/matrix interface and the fiber/matrix interface seemed to be weak in aged carbon fabrics reinforced BMI composites.

Abstract: This research mainly probes into the analysis of performance and assessment that ethyl acrylate polymer is applied to the cement matrix. The result shows that, before and after the purification, ethyl acrylate can increase the flowability of modified mortar, and with the increasing the dosage of polymer, the flowability is getting better. But if the dosage of hydrogen peroxide used to remove the residua alcohol is excessive, it is easy to cause high mortar viscosity, and that is unfavorable to the flowability. According to the setting time of the mortar under normal consistency, the result shows that the ethyl acrylate before the purification, has retarding effects on both initial and final setting time. With the increasing the dosage of polymer, it takes longer for both setting time. Besides, because hydrogen peroxide has accelerative effect, the purified ethyl acrylate can shorten the setting time of initial and final setting time. However, over dosage of hydrogen peroxide can easily lead to poor strength development in later stage. Using purified ethyl acrylate can overcome the shortcoming of lower strength of 3、7- day early stage. when hydrogen peroxide consumption is 0.5% of the total amount of acid and alcohol, the ethyl acrylate has the positive effect on improving the compressive strength. Finally, among the comprehensive assessments of the mortar testing results, EH0.5-0.1 has the significant effect of modification.

Abstract: The decoloration of methyl orange (MO) dyeing wastewater by mineral-catalyzed Fenton-like system of schorl and H2O2 was conducted in this study. The experimental results showed that schorl could efficiently make MO decolor in the presence of H2O2. Through a number of batch decoloration experiments under various conditions, it was found that the MO decoloration ratios increased by increasing the reaction temperature and the optimum addition of schorl and H2O2 was 1g and 1mL, respectively. At pH=2, a maximum of MO decoloration ratio could reach 99%. About 99.61% of MO decoloration ratio could be achieved in presence of schorl and H2O2, which was much higher than that in presence of schorl or H2O2 only, with MO decoloration ratio of 60.88% and 52.8, respectively, which suggested the schorl-catalyzed Fenton-like reaction governed the MO decoloration process. Otherwise, the MO decoloration ratio could be enhanced under the condition of agitation or UV-irradiation. The decoloration mechanism analysis revealed that the MO decoloration process was governed by a mineral-catalyzed Fenton-like reaction. Fe2+/Fe3+dissolved from the surface of schorl catalyzed the decomposition of H2O2 to produce OH radical, which then oxidized the MO.

Abstract: Voids in the mineral aggregate (VMA) is an important volume index for hot mix asphalt (HMA). In the popular HMA design methods such as Superpave system and Marshall Method an accurately calculated VMA is a crucial selection index for the aggregate gradation design. In this article a new formula for calculating VMA is established from the mathematic deduction based on the air voids and traditional VMA formulas. The new built VMA formula can be used to examine the result of the existing empirical equation in the aggregate gradation design process of Superpave. In fact, when the estimated asphalt content is determined according to the initial asphalt content the new formula can completely replace the empirical one for estimating VMA, offering conveniences to calculating.

Abstract: CNT-reinforced aluminum matrix composites was produced by high-energy ball milling, the effect of rotary speed and milling time on the particle size distribution,the density and hardness of CNT-aluminum matrix composites were studied,it was observed that the rotary speed and milling time have an important effect on the mechanical properties of the CNT-aluminum matrix composites.

Abstract: The polyurethane foam composite was prepared by alkali lignin and renewable polyurethane foam (PUF). The thermal stability as well as compression property was studied. It was obtained from the TG curve and the DTG curve that the initial decomposition temperatures of polyurethane foam composites with 10% renewable PUF and without renewable PUF were 560.25K and 574.13K,respectively, which showed the renewable PUF affacted the thermal stability of the polyurethane foam composite. The compressive strength (σ10)was from 203kPa to 125 kPa , which were affacted by the dose of the renewable PUF.

Abstract: The aim of the project is to study the effect of silane concentrations on the interlaminar fracture toughness, GIC of silk/epoxy composites. Woven silk fibre has been treated with five different silane concentrations and fabricated into a panel with two layers of silk fibre. The processing technique used to prepare the sample is by a vacuum bag in an autoclave. Six sets of panels were fabricated based on different 3-aminopropyl triethoxysilane silane concentrations which include one sets of specimens without treatment for comparison. Mode I test based on double cantilever beam specimens (DCB) method has been used over all the specimens. The results of the GIC were plotted and compared with the untreated composites panel. GIC of the composite has been found to increase when the silane concentrations exceeded certain minimum silane contents of 15 ml. During the test, crack propagation is stable and no fibre bridging occurred between both sides of fracture surfaces. All the failure that occurred were at the fibre-matrix interface. The GIC of woven silk/epoxy composites can be enhanced by surface treatment using coupling agent. Surface treatment has affected the properties of the composite panel by increasing the interlaminar fracture toughness by a maximum of 53% at a 5.8vol% silane concentrations.

Abstract: this paper got the compressive stress-strain fitting curve of crumb rubber plastic concrete, analyzed the influencing factors of elastic modulus of crumb rubber plastic concrete and found the influence law of specimen size and measuring distance to measured value of elastic modulus, through our experiments. The results of our experiments show that the method and operation of experiment strongly influence the measured value of elastic modulus of crumb rubber plastic concrete, but we can use the measures of step loading, screening and fitting curve to get the relatively exact measured value of elastic modulus of plastic concrete. And then, this paper analyzed a 16 sets of uniform experiment results with regression analysis method. As a result, we found the main influencing factors of elastic modulus of crumb rubber concrete are cement mixing amount, crumb rubber mixing amount and product of water-binder ratio and water reducer mixing amount, which the importance of them decreases progressively. Finally, this paper established the prediction equation of elastic modulus of crumb rubber concrete and found the connection of elastic modulus of crumb rubber concrete with specimen size and measuring distance.

Abstract: Performance of Large Stone Porous Asphalt- Rubber Mixture（LSPARM）was studied in laboratory. Hamburg wheel tracking test, low temperature indirect tensile test and bending fatigue test were conducted to evaluate the high temperature performance of resistance to rutting, moisture susceptibility, low temperature performance of resistance to cracking and anti-fatigue performance of LSPARM and the test results were compared with the conventional large stone porous asphalt mixture using one polymer modified asphalt (control mixture). The test results indicate that LSPARM has better performance than the control mixture and it could be used as stress absorbing layers of semi-rigid base asphalt pavement.

Abstract: Selecting Si3N4 as binding agent and Al2O3–Al–Y2O3 as sintering additives, the sintered compact of polycrystalline cubic boron nitride (PcBN) was studied . By modifying the ratio of each component and the parameters of the sintering process, the compact sintered at 4.5 GPa and 1650 °C showed good mechanical properties.The phase constitution, microstructure of the sintered compact were characterized by XRD and SEM respectively. The degree of phase transformation of Si3N4 , the chemical reaction during the sintering process, and the sintering mechanism of the additives were discussed . The best relative density is more than 97 % , the flexural strength is more than 650 MPa, the Vickers hardness Hv is more than 8.7 GPa.