Composites and nanocomposites
Tohid Abdolahzadeh; Jalil Morshedian; Shervin Ahmadi
Abstract
Researchers have studied the possibility of various polymer composites for radiation shielding applications. Lightness and non-toxicity of these materials are their significant advantages compared to Pb base traditional and common shields. In this research, polyethylene (HDPE)-based composites for shielding ...
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Researchers have studied the possibility of various polymer composites for radiation shielding applications. Lightness and non-toxicity of these materials are their significant advantages compared to Pb base traditional and common shields. In this research, polyethylene (HDPE)-based composites for shielding against X-ray radiations were prepared by utilizing several weight fractions of the nano tungsten oxide, bismuth oxide, and barium sulfate, which were decorated on nanographene oxide (10, 15, 20, and 25 wt%). The linear and mass attenuation coefficient values of samples were investigated experimentally with an X-ray tube at radiology energy ranges and estimated theoretically by using MCNP code (Mont Carlo Nanoparticle program). Results illustrate that by increasing the nanoparticles content, the linear attenuation coefficient parameter and the absorbed dose values increased dramatically. The shielding efficiency of the prepared samples has been shown by measuring the HVL values. Furthermore, the effect of sample thicknesses on the attenuation properties of nanocomposites was studied in this research. The morphological properties of the samples were evaluated with SEM. The collected results showed that the particle size of the nanoparticles used has a uniform dispersion in the polymer matrix. The mechanical properties of nanocomposite samples were characterized by DMTA and tensile test. Nanocomposites containing 20% and 25% of tungsten oxide and bismuth oxide particles reached to 88% and 90% dose absorption, respectively.
Polymer processing
Moammadreza Nakhaei; Ali Ahmadi; Ghasem Naderi
Abstract
Polyamide 6 / nitrile butadiene rubber / nanoclay (PA6/NBR/clay) nanocomposite has gathered wide acceptance in industry. Laser welding, as a fabrication method, is applied to welding of polymer nanocomposites. In this study, the input parameters (clay (Closite 30B) content, laser power, scan velocity ...
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Polyamide 6 / nitrile butadiene rubber / nanoclay (PA6/NBR/clay) nanocomposite has gathered wide acceptance in industry. Laser welding, as a fabrication method, is applied to welding of polymer nanocomposites. In this study, the input parameters (clay (Closite 30B) content, laser power, scan velocity and stand-off-distance) are varied to achieve the best responses (tensile strength of welds). Response surface methodology (RSM) is utilized to investigate the effect of input parameters on mechanical properties. Morphology and tensile properties of nanocomposites were observed with scan electron microscopy (SEM), transmission electron microscopy (TEM) and tensile test. The results demonstrated that increasing the clay content from 1 to 5%wt and stand-off-distance from 4 to 8 mm decreased tensile strength of welds about 15% and 5%, respectively. The tensile strength of PA6/NBR composite is 25.6, whereas the prediction models showed that under optimal conditions of laser power of 105 W, scan velocity of 300 mm/min and stand-off-distance of 4 mm, the maximum tensile strength of PA6/NBR nanocomposite with 1, 3 and 5 % nanoclay are 27.2 MPa, 27.6 MPa and 24.7 MPa, respectively. These tensile strengths are about 99, 89 and 73% of the strength of these nanocomposites before welding.
Characterization
Behjat Tajeddin; Najmaeh Ramedani; Habibolah Mirzaei
Abstract
To apply the nanomaterial as a component in the packaging material structure, in this research, the carboxymethyl cellulose (CMC)/polyvinyl alcohol (PVA) film were prepared with three levels of nanoclay particles (0.5, 1 and 3%) using solution casting evaporation method. The incorporation of nanoclay ...
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To apply the nanomaterial as a component in the packaging material structure, in this research, the carboxymethyl cellulose (CMC)/polyvinyl alcohol (PVA) film were prepared with three levels of nanoclay particles (0.5, 1 and 3%) using solution casting evaporation method. The incorporation of nanoclay on mechanical, water vapor permeability, and oxygen barrier properties of CMC/PVA-based film was investigated. The best result was obtained through the nanocomposite film contain 3% nanoclay. In the next step, the CMC/PVA/nanoclay films were employed for walnut packaging. After 90 days storage in the environmental condition, the optimum result was found through the nanocomposite film with 3% nanoclay in terms of oil content, moisture content, acidity and peroxide indexes of walnuts. According to the overall results, the reinforcement of CMC/PVA film with 3% nanoclay could be introduced as a good candidate for the development of high barrier food packaging material against the diffusion of water vapor and oxygen permeability.
Polymer processing
Mehdi Hajiabdolrasouli; Amir Babaei
Abstract
The effects of three different mixers, two different feeding orders and nanoclay content on the structure development and rheological properties of PE/nanoclay nanocomposite samples were investigated. Fractional Zener and Carreau–Yasuda models were applied to discuss the melt linear viscoelastic ...
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The effects of three different mixers, two different feeding orders and nanoclay content on the structure development and rheological properties of PE/nanoclay nanocomposite samples were investigated. Fractional Zener and Carreau–Yasuda models were applied to discuss the melt linear viscoelastic properties of the samples. Moreover, scaling law for fractal networks was used to quantify clay dispersion depended on the PE matrix structure. The simultaneous feeding resulted in better dispersion and melt intercalation for the nanoclay as compared to the compatibilizer/nanoclay masterbatch feeding. The twin screw extruder (Brabender DSE 25 model) showed greater potential for melt intercalation of PE/nanoclay as compared to the internal mixers (Brabender W50 and Haake Rheomix 3000 batch mixer) . Comparing the thermal Analysis of PE, PE/PE-g-MA and PE/nanoclay samples by DSC technique showed the opposite effect of the compatibilizer and the nanoclay to crystallization behavior of PE. PE/nanoclay cast film samples were produced with three different draw ratios. X-ray diffraction structural analysis in conjunction with the melt linear viscoelastic measurements confirmed that the PE/nanoclay cast film produced at higher draw ratio showed the more effective melt intercalation. Tensile test showed the machine direction modulus and yield strength of both PE and PE/nanoclay cast film samples reduced with increase of draw ratio
Structure and property relationship
Alireza Nikfarjam; Roham Rafiee; Mostafa Taheri
Abstract
Isolated carbon nanotubes (CNTs), CNT films and CNT-polymer nanocomposites are a new generation of materials with outstanding mechanical, thermal, electrical and electromagnetic properties. The main objective of this article is to provide a comprehensive review on the investigations performed in the ...
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Isolated carbon nanotubes (CNTs), CNT films and CNT-polymer nanocomposites are a new generation of materials with outstanding mechanical, thermal, electrical and electromagnetic properties. The main objective of this article is to provide a comprehensive review on the investigations performed in the field of characterizing electrical and electromagnetic properties of isolated CNTs and CNT-reinforced polymers either theoretically or experimentally. The results reported in literature are reviewed and evaluated based on employed and/or developed methods by focusing on the electrical conductivity, permittivity and permeability properties. Available analytical and numerical simulations for predicting electrical properties of CNT-based composites are also reviewed. Besides, equivalent circuit modeling of nanocomposites containing CNTs is presented. The influence of effective parameters on overall electrical and electromagnetic characteristics of CNT-reinforced polymers is discussed based on published data. Therefore, highlighting the recent trends and challenges engaged in new investigations, those aspects which are required to be more deeply explored are introduced.
Polymer processing
Amir Mostafapour; Ghasem Naderi; Mohammad Reza Nakhaei
Abstract
In this study, thermoplastic polyolefin elastomeric (TPO) nanocomposites were fabricated by friction stir processing. The effect of different pin geometries on clay dispersion and mechanical properties of the TPO nanocomposite reinforced with 3% wt nanoclay has been first investigated. The optimum pin ...
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In this study, thermoplastic polyolefin elastomeric (TPO) nanocomposites were fabricated by friction stir processing. The effect of different pin geometries on clay dispersion and mechanical properties of the TPO nanocomposite reinforced with 3% wt nanoclay has been first investigated. The optimum pin geometry namely threaded cylindrical pin was then used to fabricate the nanocomposites containing 3, 5 and 7 wt% nanoclay. The results showed that increase in the clay content increased the tensile strength and tensile modulus of the nanocomposite from 15.8 to 22.76 MPa and 568 to 751 MPa, respectively. The experimental stress – strain curves of nanocomposites were compared with eight constitutive models including Mooney – Rivlin, the second-order polynomial, Neo – Hookean, Yeoh, Arruda – Boyce, Van der Waals and the third- and sixth-order Ogden. The comparisons showed that there was an agreement between the experimental data and the sixth-order Ogden model. Three micromechanical models Halpin – Tsai, inverse rule of mixture and linear rule of mixture were applied to investigate the Young’s modulus of nanocomposites. Because of the significant difference between the Young’s modulus obtained from these models and the ones obtained from experimental data, a modifying factor was used to improve the theoretical predictions obtained from the models.
