Advanced Materials Research Vols. 79-82

Abstract: Nowadays, natural fiber-reinforced green composites are increasingly being used in the industrial field. The strength of natural fibers is often evaluated on the assumption that the fibers’ cross-sectional shape is circle, but this is rather observed as an ellipse. In the present study, therefore, we propose a new method to calculate the cross-sectional area of natural fibers by measuring their projection widths. In addition, we propose a strength distribution function with taking account of variation in cross-sectional area, based on Weibull distribution, and discuss the validity of the proposed distribution function.

Abstract: In this paper, Nanoslurry-ZrO2 were added into alumina powders to improve the bending strength of macroporous Al2O3 Ceramic sintered at 1550°C, 1600°C, 1650°C corresponding for3h each in air, respectively. The results show that the bending strength of porous alumina ceramic was simultaneously greatly influenced by various ZrO2 contents. When ZrO2 content is 2wt%, the maximum bending strength value of sample heated at 1650°C was observed, which achieves to 50 MPa. And the maximum bending strength value of any sample also exists at 1650oC. By SEM analysis, many fine ZrO2 particles with high activity surface form a neck bonding which is beneficial to the improvements of bending strength.

Abstract: Advanced wastewater treatment requires highly efficient substrates, able to insure in a single step process the water discharge requirements. The paper the results obtained in the simultaneous removal of heavy metals and dyes, using a composite powder of fly ash and activated carbon. The results show that adding a small amount of activated carbon in a powder mixture with modified fly ash is highly effective in removing cadmium from wastewaters also containing dyes (methylen blue or methyl orange). Chemisorption is the likely mechanism governing this process.

Abstract: In a wastewater resulted from the dyes finishing industry there are amounts of dyes (very common Methyl Orange) and heavy metals resulted mainly from the organo-metallic dyes. Heavy metals (Cd2+ and Cu2+) advanced removal is usually proposed via adsorption and the use of modified fly ash as adsorbent represents a sustainable solution. The paper presents the results obtained in investigating the effect of methyl orange adsorbed onto the fly ash with modified surface, on the removal efficiency of cadmium and copper ionic species, considering the final application: a single step treatment process applied for wastewaters containing both heavy metals and dyes. The adsorption mechanisms are discussed based on the kinetic results and on the Langmuir model.

Abstract: An thin reagent containing optochemical film sensor for detecting and measuring free chlorine in water is described. The film sensor has been manufactured by immobilisation indicator of 3,5-dimethyl-4-hydroxybenzaldazine in a permeable transparent polymeric membrane. A linear calibration for free available chlorine can be obtained in the range between 0.05 and 3ppm. The limit of quantitation is 0.3 ppm, and the accuracy exceeds 7%. It takes about 150s to measure the relatively low occupational exposure concentration of 0.1ppm. The interference of combined chlorine has been studied. The sensor has no response to combined chlorine. And the stability of the sensors and the effect of external parameters like relative humidity (RH), temperature on the sensor response have been investigated. The sensor response is affected by varying the temperature; however, humidity in the range between 0 and 90% RH does not affect sensor response. The 3,5-dimethyl-4-hydroxybenzaldazine remained stable inside the polymeric film and no chemical reaction, crystallization or leaching occurred during 6 months of observation. Proper choice of indicator dye and polymeric material and successful application of kinetic evaluation method for the exposure experiments determine the desired features of the sensor. Introduction

Abstract: The morphology and diameter of Cu and La2O3-Ce2O3 nanoparticles were observed and measured by TEM. The tribological properties of the lubricating oils containing nanoparticles were examined by MRS-1J four-ball tribotester. A 300-hour contrastive experiment was carried out in KDE5000E diesel engine.The results show that lubricating oils containing nanoparticles have optimal tribological properties, when WCu:WLa2O3-Ce2O3=2:1,WCu+ La2O3-Ce2O3=0.8%. Wear values of friction pair using 40CD oil with Cu and La2O3-Ce2O3 nanoparticles decrease by 88.6%-100%,compared with using 40CD oil. The consumptions of diesel oil reduce by 9.29%.

Abstract: A new type of piezoelectric composite ultrasonic transducer with high frequency in radial vibration is studied. A high-frequency acoustic transducer has been designed and prepared with pzt-5-type piezoelectric ceramic cylinder. When the piezoelectric ceramic cylinder vibrates along the direction of its radial direction, the working frequency is high. It is composed of a piezoelectric ceramic tube and a steel bracket which is inserted in the inner of the ceramic tube. Use the finite element method by ANSYS for analyzing the radial vibration of a piezoelectric tube. On that basis, through managing ANSYS simulation the vibration mode of transducer system is obtained, and analyzed the working frequency of transducer. According to the simulation, the high-frequency cylindrical acoustic transducer has been produced. Comparing the products and the traditional cylindrical transducers, the products haven’t only a good all-round circle directional, but it also has a high working frequency (300 kHz).

Abstract: In this study, array type fiber-PZT senor systems were newly developed with capabilities of detecting both damage location and monitoring of gas or liquid leakage by applying time-frequency analyses. The system consists of two piezoelectric transducers for the signal receiver and generator applications and three optical fibers for wave propagation. The results showed developed fiber-PZT array sensor can accurately measure the position of crack and its intensity. Also the fluid leakage of methyl alcohol as test specimen, on the plate structure has also been investigated employing the fiber-PZT sensors. The ultrasonic wave optical fiber sensor can be used effectively to monitor changes in structural and chemical properties.

Abstract: The relationship between the axial inserted yarns and the mechanical properties of the multi-angled filament wound pipes was studied by experimental investigation in this paper. Firstly, the glassfiber/epoxy pipes with different process parameters were fabricated on the specially-designed filament winding equipment under varying conditions. Then the specimens were made in terms of standard sizes and tested under axial tensile load and axial compressive load, respectively. Furthermore, the axial tensile strength and the axial compressive strength were obtained from the test data, which showed that the above two values of the specimens with the axial yarns were larger than that without the axial yarns. That is to say, the incorporation of the axial reinforcement was found to result in increased strength.

Abstract: Biodegradable novel poly(D,L-lactide)-based shape memory polymers (SMPs) were prepared from poly(D,L-lactide) (PDLLA) Diols, hexamethylene diisocyanate(HDI) and butanediamine(BDA) via two steps polymerization reaction. Its thermal, mechanical properties and shape-memory behaviors were investigated by means of differential scanning calorimetry, stress-strain measurements and bending test. The glass transition temperature of the SMPs changes with composition from 38 to 45°C which close to body temperature in a predictable manner. These type SMPs can achieve the high modulus and tensile strength, and their elongation at break can be greater than 500% at lower hard segment content. All SMPs display excellent shape-memory properties. When a deformation temperature 20°C above Tg was chosen, the ratio of the shape-memory fixation approximately 100%, and the recovery ratio was 95-100%. Meanwhile, the recovery time is relevant to the recovery temperature, the recovery time decrease with increasing the recovery temperature. By adjusting the composition of SMPs, the recovery temperature could be adjusted to the neighborhood of the body temperature and it can be designed as potential biomaterials for use in biomedical fields.