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Oil resistant o-rings on the basis of acrylonitrile butadiene rubber (NBR) reinforced by nanoclay were produced via a traditional industrial method in accordance with aviation standard, AMS 7272. The production of nanocomposites comprised the compounding of nanocomposite with optimum mechanical properties and minimum contents of used carbon black and nanoclay, design and manufacturing of the required mold and finally compression molding of the oring. Mechanical and morphological properties of NBR/nanoclay compounds were optimized by introduction of proper contents of a compatibilizer containing a mixture of resorcinol and hexamethylene tetramine through using a master batch production method. The prepared nanocomposites were characterized using X-ray diffraction (XRD) analysis, curing measurements and tensile test analysis. The XRD analysis showed that the compatibilizer facilitates the intercalation of nanoclay silicate layers with the rubber chains which leads to the increase of their basal spacing. The cure characteristics of the nanocomposites showed a decrease of scorch time and increase the cure rate index with the nanoclay loadings. Furthermore, the minimum scorch time and maximum cure rate index could be achieved through using the appropriate content of compatibilizer. The results exhibit that the nanocomposites containing the compatibilizer have higher mechanical properties especially at higher deformations compared to the corresponding uncompatibilized nanocomposites

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The issue of earthquake and its destructive effects is constantly confronting human being communities as an extensive challenge. The ground, upon which we are constructing our buildings, is anything but solid. Hundreds of millions of years ago the continents were joined, but now they are dispersing ever so slowly. The idea that buildings are founded on stationary ground is only an illusion. From the viewpoint of geological time, the earth’s crust is in a continuous dynamic change. The scientific understanding of this process, known as continental drift or tectonic plate movement, which is the basic cause of most earthquakes, dates back only 100 years. Quakes strike at the heart of a community. When they damage buildings, people and animals are injured and killed. Earthquakes destroy the basic necessities of life, demolishing shelter, ruining food and water supplies and disrupting people’s livelihoods. Conversely, buildings that perform well during an earthquake, limit its impact on people and their basic needs. Scientists and building construction experts have strived in order to find the solutions for reducing structures damages which are caused by trembling of the earth and diminishing the casualty rate and also detriments, from some years ago. In our country, Iran, which is located in earthquake zone and has experienced some demolishing quakes before, this matter is more significant and remarkable. Apart from the poorest of communities for whom even partial earthquake protection is unaffordable, most of the disastrous effects of earthquakes are avoidable. Earthquake-resistant construction greatly reduces the rate of victims from a damaging quake, as well as lessening economic losses and disruption to public activities. Seismic retrofitting of existing buildings is of vital and crucial issues of our society. The purpose of rehabilitating is to reduce the vulnerability of a building’s inhabitants and the building itself, its structure, non-structural elements and possibly its contents to earthquake damage. To retrofit a building is to improve its seismic performance. One of the appropriate alternatives for enhancing the structural performance of available buildings is employing composites. These materials can be applied in order to increase the confinement, shear strength and ductility of columns and also enhance in-plane shear wall strength as well as out-of-plane resistance. In addition, with taking advantage of this kind of material, the secondary weight which would be added to the primarily structure is going to be significantly reduced and this would act as an optimum approach for rehabilitating the existing buildings. In this research, firstly the exact definition of composite materials and its components and different kinds are studied. Then, the essence of earthquake and seismic forces in addition to some topics on seismic retrofitting and the essential needs for it are discussed. Eventually, concerning the abilities of composites, employing them as a suitable technique for reconciliation of structural elements of existing buildings, which is one approach of seismic retrofitting, will be proposed with hope for presenting the essential knowledge of appropriate seismic retrofitting with efficient materials to architects and civil engineers in order to diminish the ruins of earthquake effects on structures and as a result, providing the next generations of our country with safer and much more protected circumstances.

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Research subject: In recent years, there are so many attractions in the field of effective detection and discrimination of volatile organic compounds (VOCs). Detection of VOCs compounds, are very important in many applications and industries such as air pollution control, air quality control, food packaging, food quality control, disease diagnostic, agriculture etc. The sensitivity and selectivity of the prepared sensors to detect of VOCs needs to improve.   
 Research approach: A conductive polymer composite sensitive layer based on poly (lactic acid) as polymer matrix and multiwall carbon nanotubes as conductive filler was prepared to detect of volatile organic compounds (VOCs). For this purpose the porous sensitive layer was prepared by non-solvent induced phase separation (NIPS) method. In this structure, chloroform (low boiling point temperature) was used as the solvent and ethanol (high boiling point temperature) was used as a non-solvent. The sensitive layer was used to detect of toluene, methanol, and chloroform. The structure and morphology of synthesized layer was investigated by means of scanning electron microscopy (SEM) and BET test.
Main results: The investigation indicated that the phase separation method induced the open cell morphology into the conductive composite. The BET results showed that the specific surface area of composite increased to 22.3 m²/gr. The experimental results showed that the response properties of porous layers was improved dramatically in comparison with dense layers. It was related to the increase of specific surface area of polymer composite and therefore the increase of diffusion coefficient of analyte molecules into the polymer matrix. Finally the sensitivity and selectivity of porous sensitive layers was investigated based on Flory-Huggins interaction parameter.
 

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Metformin enhances insulin's effect and increases cells’ sensitivity to insulin. In this paper, nanocomposite was designed and used in the metformin release system, which was able to release the required drug in a controlled manner. In this research, nanoparticles of zinc oxide (ZnO) were prepared via the sol-gel method. The experimental design central composite response surface method was applied for the optimization of the nanoparticles based on varied variables such as the weight of zinc acetate (gr) (X ₁) and the volume of triethanolamine (ml) (X₂). The particle size of the optimized nanoparticle was reported to be 28 ± 21.27 nm; zeta potential and PdI were 25.54 ± 1.64 mV, 0.168 ± 0.05 respectively. The chitosan polymer was used to improve environmental compatibility and increase drug release control; finally, metformin was loaded on the optimized nanocomposite. Structural properties were analyzed using scanning electron microscopy (SEM) X-Ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and Dynamic Light Scattering (DLS). The SEM images showed that the average nanocomposite size was 40 nm. The results of XRD patterns and SEM images were also consistent with each other and the average particle size was the same. Infrared spectrophotometry showed the presence of chitosan used to coat nanoparticles on their surfaces and confirmed the loading of metformin. An in-vitro metformin release from the nanocomposite was conducted in PBS (pH=7.4) and analyzed by a spectrophotometer at 233 nm. Metformin has a high solubility in water, and since it is difficult to prepare a slow release form of high-solubility drugs, the aim of this study was to design a slow-release formulation of metformin with a suitable profile that could control release without explosive release for up to 120 hours.

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Research subject:Well-designed plastic foams, with respect to their cell density and cell size, open-or-close cells, and the cell uniformity, compared to their counterpart unfoamed plastic parts, beside of having the advantages of less material consumption, dimensional stability, better processability, and a higher surface quality, they can have superior mechanical and physical properties, including strength to weight, impact strength, thermal and dielectric properties. The temperature distribution in the different zones of the extruder, the qualities and quantities of the nanoparticle additives and their dispersion in the polymer matrix can have significant effect on the mechanical properties of the produced foams by the extruder.
Research approach: In this study, using an extruder, MA-g-polypropylene microcellular foams, containing 3, 7 and 9 wt% of nano-clay particles, were produced under three temperature arrangements on the extruder and the material and the processing effects on the mechanical properties were investigated.  
Main results: The result of this investigation shows that adding of nanoclay improves the mechanical properties of MA-g-PP.s foams. As an example, the results show that the sample with 7 wt% of surface modified nanoclay, owns about 10% higher impact toughness compared to the samples produced without nanoclay. Also for the same samples a rise of about 5% was recorded in Young's modulus. The microstructural studies of the produced foams by scanning electron microscope (SEM) show that adding of nanoclay can result on more foam uniformity and smaller cell size. In this study, the smallest average cell size (87.5 μm) and the lowest density (0.3 g/cm³) were recorded for a sample with 7wt% nanoclay.

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The effect of various reinforcements on the ablative composites has been discussed in this paper. The ability of phenolic resin to reside a char layer at high temperatures is the main reason to select it as a matrix. Analysis of the physical ablation process of a composite and low thermal conductivity of zirconium oxide is performed to produce Resole/carbon fabrics composites coated with a thin film of zirconium at the back side of the specimens. Different materials, such as carbon fabrics, glass fabrics, and also silica and zirconium powders have been used as reinforcements for synthesis of the composites. The specimens were prepared with three sets of compositions. The first set was produced with 37.5 wt% of Resole and 62.5 wt% of reinforcements. Another set of specimens were produced with 40wt% Resole, 40 wt% of silica and 20 wt% of zirconium. To explore the ablation characteristics of the composites in terms of insulation index, erosion rate and microscopic pattern of ablation, an oxyacetylene torch flame with heat flux of 8.35 Mw/m2 at approximately 3000°C was used. It was found from ablation test that the erosion rates of the Resole/carbon fabric specimens are 20% lower than that of the other specimens. Additionally the high insulation index of the Resole/carbon fabrics coated with zirconium, indicates that these composites are the best ablative materials in the present study. SEM observations show that the thermo mechanical and thermo physical erosion effects are the most important factors that influence the ablation process. The proper adhesion between reinforcements and matrix is important to achieve improved ablative properties.

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The effect of various reinforcements on the ablative composites has been discussed in this paper. The ability of phenolic resin to reside a char layer at high temperatures is the main reason to select it as a matrix. Analysis of the physical ablation process of a composite and low thermal conductivity of zirconium oxide is performed to produce Resole/carbon fabrics composites coated with a thin film of zirconium at the back side of the specimens. Different materials, such as carbon fabrics, glass fabrics, and also silica and zirconium powders have been used as reinforcements for synthesis of the composites. The specimens were prepared with three sets of compositions. The first set was produced with 37.5 wt% of Resole and 62.5 wt% of reinforcements. Another set of specimens were produced with 40wt% Resole, 40 wt% of silica and 20 wt% of zirconium. To explore the ablation characteristics of the composites in terms of insulation index, erosion rate and microscopic pattern of ablation, an oxyacetylene torch flame with heat flux of 8.35 Mw/m2 at approximately 3000°C was used. It was found from ablation test that the erosion rates of the Resole/carbon fabric specimens are 20% lower than that of the other specimens. Additionally the high insulation index of the Resole/carbon fabrics coated with zirconium, indicates that these composites are the best ablative materials in the present study. SEM observations show that the thermo mechanical and thermo physical erosion effects are the most important factors that influence the ablation process. The proper adhesion between reinforcements and matrix is important to achieve improved ablative properties.

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Abstract- In this study thermal properties of Woofd Plastic Composite (WPC) were measured using Differential Scanning Calorimetry (DSC) and Thermogravimetry (TG). The investigated specimens were: high density polyethylene (HDPE), wood particle and WPC. DSC test showed that adding wood particle to HDPE matrix cause a decrease in the area under the DSC curve. The result revealed that WPC have a heat of fusion less than unfilled HDPE and are more stable when temperature increases. The melting point temperature did not changed significantly. The heat of capacity of HDPE, wood particle and WPC were obtained using DSC test. An enhancement in the temperature led to a linear increase in the heat of capacity of wood particle. HDPE and WPC showed similar behavior too. But WPC specimen had a heat of capacity more than wood particle and less than HDPE. The heat capacity of WPC by rule of mixture has a good agreement to experimental results. Adding wood to plastic identify higher WPC thermal stability by TG. The extrusion process was modeled and the throughput temperature was calculated using themal equation. The model was used to carry out high throughput by incresing screw speed. These help to produce defectless extruded WPC in continous production.

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Carbon Nanotube (CNT) dimensions and interphase region are the important parameters that affect on the mechanical behavior of CNT/Polymer composites. In this study, a new analytical model is established to predict the modulus of these structures. Considering the influence of CNT dimensions (diameter and length) an interphase region, the elastic modulus of nanocomposite is determined. In this new model, a nanotube with hollow cylindrical structure is modeled as a transversely isotropic solid nano-fiber. Moreover, interphase region and its van-der Waals interaction is simulated as an isotropic hollow cylindrical solid that its mechanical properties is derived using the continuum mechanics. To predict the modulus of nano-composites, a representative volume element (RVE) containing a transversely isotropic solid nano-fiber, isotropic solid interphase region and the matrix is employed using Halpin-Tsai model. Finally, the results of the proposed analytical model are compared with various available experimental results. The proposed model is simple and the results obtained by the model are in good agreement with available experimental results.

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In this paper, the influence of nanoclay Closite 30B on ballistic impact behavior of 2D woven E- Glass/Epoxy laminated composite has been investigated experimentally. The glass/epoxy/nanoclay laminate nanocomposites have 12 layers and 60% fiber volume fraction is manufactured by VRTM method. Fibers have a plain weave configuration with density of 200gr/m2, while The epoxy resin system is made of a diglycidyl ether of bisphenol A (DGEBA), Epon 828, as the epoxy prepolymer and a polyoxypropylene diamine with average molecular weight of 400 gr/mol, Jeffamine D-400, as the curing agent. The nanoclay Closite 30B is dispersed into the epoxy system in a 0%, 1%, 2%, 3%, 5% and 7% ratio in weight with respect to the matrix. Morphological studies using XRD revealed that nanostructures are mostly in intercalated form rather than exfoliated form. In additional to tensile test, ballistic impact test is carried out on the samples by flat-ended projectile with 14gr mass and 9.77mm diameter in 130m/s, 142m/s and 155m/s velocities. The results have shown that not only the mechanical properties, but also ballistic impact resistance can be improved with adding nanoclay.

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In this paper an analytical model for investigating of the ballistic impact behavior of two dimensional woven E-glass/epoxy composites is presented on the basis dividing the impact duration to several time intervals and calculating the energy absorbed during each time interval. The major components of energy lost by projectile during ballistic impact are identified, namely the cone kinetic energy formed on the back face of the target, the secondary yarns deformation energy, the tensile failure energy of primary yarns, the delamination and matrix cracking energy. It is assumed that the shear plug formation is not observed for glass reinforced composites and the energy lost in overcoming the frictional force between projectile and composite is negligible. Analytical formulations have been presented for calculating energy absorbed by each mechanism in each time interval. Finally, a good correlation has been observed, comparing the analytical model presented in this paper to the experimental results presented by others investigators.

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In this research, a novel method to decrease macro-residual stresses of laminated composites by adding carbon nano-fiber (CNF) is proposed. To this end, using micromechanical and modified micromechanical approaches, coefficient of thermal expansion (CTE) and Young’s modulus of carbon nano-fiber reinforced polymer are calculated. Then using this enhanced matrix, longitudinal and transverse of thermal expansion and Young’s modulus of a CNF/glass/epoxy unidirectional lamina in presence of CNF are obtained. Finally, using the classical lamination theory (CLT), macro-residual stresses for CNF/glass/epoxy laminated composites are obtained. The results explain how CNF can result in reducing macro-residual stresses in nano particle filled laminated composites. The results for both cross ply and angle ply glass/epoxy laminated composites are presented and show that adding CNF through the matrix can decrease macro-residual stresses in each plies up to about 30%. The main reason for the decrease in residual stresses are due to the sever decrease of coefficient of thermal expansion of the unidirectional ply.

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In this paper, a unit cell based micromechanical model is presented to predict the elastic-viscoplastic response of aligned short fiber titanium matrix composites subjected to combined axial loading in the presence of fiber/matrix interfacial damage. The effects of manufacturing process thermal Residual Stress (RS) are also included in the analysis. The representative volume element (RVE) of the short fiber composites consists of c×r×h cells in three dimensions in which a quarter of the short fiber is surrounded by matrix sub-cells. In order to obtain elastic-viscoplastic curves, the fiber is assumed to be linear elastic, while the matrix exhibits elastic-viscoplastic behavior. The Evolving Compliance Interface (ECI) model is employed to analysis interface damage. This model allows debonding to progress via unloading of interfacial stresses even as global loading of the composite continues. Results revealed that for more realistic predictions, in comparison with available experimental and the other models results, both interfacial damage and thermal residual stress effects should be considered in the analysis.

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In this paper, the influence of nanoclay Closite 30B on ballistic impact behavior of 2D woven E- Glass/Epoxy laminated composite has been investigated experimentally. The glass/epoxy/nanoclay hybrid laminate nanocomposites are manufactured by layup method under pressure. The nanoclay particles are Closite 30B and are dispersed into the epoxy system in a 0%, 3%, 5%, 7% and 7% ratio in weight with respect to the matrix. In additional to tensile test, ballistic impact test is carried out on the samples by flat-ended projectile with 8.9gr mass and 10mm diameter in 134m/s and 169m/s velocities. The results have shown that not only the mechanical properties, but also ballistic impact resistance can be improved with adding nanoclay.

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Abstract-In this study,nanocomposites based on polypropylene and polyethylene containing 0 to 7phr of nanoclay and 3phr of maleated polypropylene (PP-g-MA) and maleated polyethylene (PE-g-MA) as compatibilizer were prepared by melt compounding followed by injection molding.Morphology of the mixtures was carried out through Field Emission Scanning Electron Microscopy (FESEM). Mechanical properties of different samples were examined empirically by tension and izodimpact tests.Test results show that the addition of clay particles to the PP and LLDPE, increases the tensile strength, yield strength, tensile modulus and decreases impact strength and elongation at break compared to pure polymer.Themixture design method and Minitab16 software were utilized for designing the tests, statistical analyses, and optimization the mechanical properties of the mixtures.Results showed that the in compounds based on polypropylene and polyethylene, respectively, compounds includes 3.96 and 2.12percent clay has the best mechanical properties.blends base on PP have better tensile modulus and LLDPE blends have better impact strength.

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In this paper, the influence of nanoclay Closite 30B on ballistic impact behavior of 2D woven E- Glass/Epoxy laminated composite has been investigated Theoretical and experimentally. The structure of the hybrid nanocomposite is glass/epoxy/nanoclay laminate and is manufactured by hand layup method under pressure. The nanoclay is dispersed into the epoxy system in a 0%, 3%, 5%, 7% and 7% ratio in weight with respect to the matrix. Comparison of theoretical results and results of the ballistic impact test are shown a good correlation. The results have shown that optimal to increase in energy absorption is 10% in 3% nanoclay content. Howevere, in the impact velocities far than ballistic impact, maximum increasing in energy absorption is 20% in 10% nanoclay content.

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The influence of maleic anhydride-polypropylene (MAPP) (0, 2, 3 and 5%) as a compatibilizer on the wettability of polypropylene/wood flour/glass fiber hybrid composites was studied by using the contact angle determination technique. Sample slats with a cross section of 10×70 mm were made by a twin screw extruder. Specimens were conditioned at room temperature and the angles between the water droplets and surfaces of the hybrid composites were measured. Results revealed that the wettability of the composites was significantly decreased as the MAPP was increased to 3%. However, no significant decreasing effect was observed at MAPP contents above 3%.

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Graphene/Polypropylene nanocomposite is a new material and limited research is performed on mechanical properties of such material. A random distribution of the nano particles in the matrix has a special importance in having proper mechanical properties for Graphene/Polypropylene nanocomposites. To have a uniform distribution of the nano graphene in the polypropylene, a method developed by Kalaitzidou, et al. for distribution of exfoliated graphite in polypropylene is used in this research. In this paper, Polypropylene is coated with graphene and then the nanocomposite specimens are made using melt-blending and injection molding. Polypropylene reinforced with 0.5, 1.0 and 2.0 wt% graphene sheets were prepared and their tensile properties are investigated. Good enhancement of Young’s modulus and yield stress at very low graphene contents are achieved. The results indicate that the mentioned method is suitable for fabrication of graphene/polypropylene nanocomposites, which yields a good dispersion of graphene in the polypropylene.