gholamreza pircheraghi

Lead-acid batteries are a significant part of the global battery market; however, due to limited life of these batteries, we are faced with major environmental challenges associated with lead-acid battery waste. One of their main components is the separator. In addition to polyethylene and silica, the separator of these batteries also contains lead compounds. In this research, lead-acid battery separator and polyethylene were used as a matrix for preparing a composite that could improve polyethylene's mechanical properties due to the presence of silica. Samples of HDPE and LLDPE with 5% to 15% lead-acid battery separator were prepared and their mechanical and thermal properties were evaluated and compared. By analyzing the DSC results, the type of polyethylene in the battery separator, HDPE, was determined. By adding the battery separator to HDPE matrix, elastic modulus increased by about 22% and bending modulus by about 55%. For LLDPE elastic modulus increased by approximately 35%. The yield strength of the sample, with HDPE matrix containing 15% separator has increased from 25.1 MPa to 28 MPa, and for the sample, with LLDPE matrix containing 15% separator, yield strength increased from 11.9 MPa to 13.7 MPa. Hardness and modulus for 15% of the separator are at maximum value. Consequently, 15 wt.% separator is an optimal value to improve samples' mechanical properties.

Engineering education is based on the technical methods in the present form. Information revolution causes to access the technical education materials as a widely spread form by the students. These materials are more effective than the traditional engineering education. Thus, it is necessary to change the engineering education methods from the classical form. General workshop is a first-year course for the engineering students and it is an introduction on the engineering regulations. Nowadays, this course is run to teach the practical training. However, this goal cannot be achieved because of the short period of the course, various topics of the course and improper education methods. In this paper, this course is revised based on the teaching of engineering concepts to the students. Various engineering concepts are explained which can be educated in this course without considerable changes in practice but with magnificent change in the course prospective. It is expected that this new design helps the students more to be familiar with the engineering concepts and methods.

Considering the working conditions of down hole mud motors, enhancing the mechanical and thermal strengths of their elastomeric parts is crucial. Some attempts have been done to increase the motor performance through geometrical changes, but lack of material improvement is significant in previous studies. In this study, NBR/nanoclay composite was prepared through melt intercalation in an internal mixer. In order to evaluate the mud motor performance with regard to down hole working conditions, different mechanical and thermal tests were done. Moreover, tensile test results showed that the stiffness and toughness of prepared composites are increased simultaneously. While, tensile fatigue test results revealed the enhanced fatigue life of NBR/nanoclay composite samples in comparison with neat NBR sample. Dynamic mechanical analysis also showed a decrease in the damping factor, tan δ of composite samples compared to neat elastomer, indicating the less dissipation heat production in each cycle and hence increasing fatigue life of the samples. Based on the results of this study, it is confirmed that the incorporation of right selected nanoclay into NBR matrix offers increased mechanical and thermal strengths and barrier properties over conventional virgin elastomer. Therefore increasing the working life and performance of the motor is achievable through replacing its elastomeric stator lining with the NBR/nanoclay composite.

Nowadays filtration process is increasingly used in various areas such as water purification, food industries, filtering the air dust and other separation applications. In this work, the HDPE microporous filters have been fabricated at different pressure and time conditions via sintering process and then were characterized by different techniques. It can be expected that microstructure and mechanical properties of the samples could be controlled by changing the fabrication parameters like temperature, pressure, time of the process and also by changing the properties of the resin such as powder shape, particle size and rheological properties. In the first step, by using DSC, MFI, rheology test and optical microscope, the most suitable polymeric powder for sintering process was chosen. The sintering temperature was fixed in the vicinity of melting temperature of the used HDPE powder, based on DSC result. In order to evaluate mechanical properties and porosity of the samples, the results obtained from the shear punch test, acetone drop permeability, gas permeability, transition optical microscopy and SEM, have been used; then the effect of pressure and time parameters on the characteristics of the product has been studied. Finally, it was concluded that it is possible to make microporous filters with suitable mechanical properties, using sintering process at controlled pressure and temperature conditions.It can be seen that by increasing time and pressure, on the one hand the mechanical properties of the products increase, and on the other hand, their porosity and the gas permeability of the vents decrease.

Carbon nanotubes (CNTs) are a new class of nanomaterials that have gained special attention due to their unique properties such as excellent electrical and mechanical properties. Nanocomposite hydrogels, a novel category of hydrogels, have received great attention both in industry and scientific research because of their exceptional structural and mechanical properties. A nanocomposite aqueous dispersion based on poly(acrylamide-co-acrylic acid) and modified carbon nanotube was synthesized through in situ radical polymerization. Water can be a good candidate instead of toxic organic solvents for preparation of poly(AA-co-AM)/CNT nanocomposite aqueous dispersions. The rheological properties of the nanocomposites were significantly improved compared to those of pure copolymer samples. Modification of carbon nanotubes by acid was conducted to introduce hydroxyl and carboxyl groups on their surface in order to achieve a better dispersion behavior and suitable interactions between the nanoparticles and polymer matrix. Once the oxidation step was finished, amide functional groups were inserted into the CNT particles through amidation reaction. The surface modification reactions of CNT were tracked by FTIR and Raman spectroscopy techniques. FTIR and Raman spectra were utilized in order to investigate the dispersion behavior of nanoparticles and to confirm the formation of linkages between the nanoparticles and polymer matrix, respectively. In addition, the rheological features including viscoelastic behavior of samples, the sol-gel transition phenomenon, dynamic oscillatory frequency sweep and steady shear measurements were studied. Finally, the relationship between the improved rheological properties (modulus and viscosity) and the dispersion microstructures caused by dispersion of nanoparticles, formation of networks and interfacial interactions between Poly(AA-co-AM) macromolecular chains and CNT nanoparticles were determined.