Papers by Keyword: Polymer Nanocomposite

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Authors: N. Duangphattra, C. Aramphongphun
Abstract: This research work studies the effects of processing conditions on mechanical properties of polymer nanocomposites. Polypropylene (PP) nanocomposites reinforced with 0.5 and 2.5 %wt multiwall carbon nanotubes (MWCNTs) were prepared via melt compounding and formed by injection molding. 2k Full Factorial design was used to plan the experiments and determine the influences of the processing conditions on mechanical properties and carbon nanotube dispersion in the nanocomposites. These conditions consist of five factors: (a) %wt content of MWCNTs (0.5 and 2.5 %wt), (b) barrel temperature (190 and 220°C), (c) injection velocity (25 and 45 mm/sec), (d) screw rotational speed (75 and 227 rpm) and (e) holding pressure (45 and 65 bar) while injection pressure and cooling time were set at 75 bar and 50 sec, respectively, for all conditions. The samples were examined by Young’s modulus and tensile strength using a Universal Testing Machine (UTM). In addition, Scanning Electron Microscopy (SEM) was applied to study the dispersion of carbon nanotubes in the nanocomposites. The results showed that PP/MWCNT nanocomposites had Young’s modulus of 1,740 MPa and tensile strength of 34.5 MPa while original PP had 1,450 MPa and 28 MPa, respectively. Therefore, the mechanical properties were improved significantly with the content of MWCNTs. Full Factorial experiments investigate that significant factors are %wt, barrel temperature, injection velocity, and screw rotational speed. Moreover, SEM showed that a high content of MWCNTs led to a highly oriented skin layer with well-dispersed MWCNTs.
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Authors: K.R. Gopi, R. Nagarajan
Abstract: Cavitation erosion is predominant in pipelines for liquid transportation, causing damage to pipe wall, impeller and their accessories. The present study is focused on development of cavitation -wear resistant nano-ceramic particle-reinforced polymer matrix material; and on study of its feasibility to be used as lining material in hydraulic transportation. The polymer/nano composite is fabricated using power ultrasound in all three process steps: synthesis of nano-dimensional particles of white fused alumina (WFA) from micron size particles, optimized blending and finally reinforcement into poly methyl methacrylate (PMMA) matrix. The effect of ultrasonic parameters on nanocomposite/ virgin polymers (like polyethylene and polypropylene) is studied by measuring mass loss of the materials and suspension turbidity during exposure time. At low frequency (20-60 kHz), cavitation intensity is predominant; this effect is utilized for fabricating sub-micron particles, and for performing accelerated cavitation erosion tests. At high frequency, acoustic streaming is predominant; this effect is utilized for blending and reinforcing of the nano ceramic particles into polymer matrix. The size and quantity of the particles generated by cavitation erosion was analyzed by Laser Particle Size Analyzer (20 nm-1400 micron range). The nano-composite coupons were analyzed before and after the ultrasonic erosion test using SEM. It is concluded that lowfrequency sonication is a viable option for cavitaton erosion testing of ceramic/polymer composites.
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Authors: Imants Matīss, Ēvalds Pentjušs, Oskars Krievs, Rita Berzina
Abstract: The paper is devoted to investigation of frequency-dependent electric properties of polymer nanocomposites. The experimentally acquired frequency characteristics of complex dielectric permittivity are substituted by equivalent mathematical models of dielectric relaxation. It is shown that such substitution is valid, provided that the selected relaxation model allows shaping the synthesized frequency curves in a sufficient range and the statistical significance of the measurement data is within a satisfactory range.
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Authors: Wan Akmal Izzati, Mohd Shafanizam, Yanuar Z. Arief, Mohamad Zul Hilmey Makmud, Zuraimy Adzis, Nor Asiah Muhamad
Abstract: Polymer nanocomposites have been attracting attention among researchers as electrical insulating application from energy storage to power delivery. However, partial discharge has always been a predecessor to major faults and problems in this field. In addition, there are a lot more to explore as the characteristic of partial discharge in nanocomposites is not clearly understood as well as the electrical properties of the nanocomposites. By adding a few amount of weight percentage (wt%) of the nano fillers, the physical, mechanical and electrical properties of polymers can be greatly enhanced. This is due to its amazing characteristic of having large specific area as a consequential from its nano sized particle that could enhance the electrical properties of the insulator. For instance, nano fillers in nanocomposites such as silica (SiO2), alumina (Al2O3) and titania (TiO2), play big role in providing good approach to increase dielectric breakdown strength and partial discharge resistance of nanocomposites. Such polymer nanocomposites will be reviewed thoroughly in this paper based on previous experimental works and studies. This paper provides reviews from related publications from year 1997 to 2011 including the results of experimental works which have been conducted by the authors with main focus on partial discharge characteristics in polymer nanocomposites, which demonstrates that research and utilization of polymer nanocomposites has well developed from past decades and will possess a high demand in future as electrical insulating material.
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Authors: Wen Xu, Qing Hua Zeng, Ai Bing Yu, Donald R. Paul
Abstract: The properties of interphase in polymer composites are often different from those of bulk polymer matrix, which may include chemical, physical, microstructural, and mechanical properties. The nature of interphase is critical to the overall properties and performance of polymer materials, in particular in nanofiller reinforced composites. Experimental efforts have been made to determine the effective interphase thickness and its properties, for example, by nanoindentation and nanoscratch techniques. Yet, it is very difficult to quantify the interphase and its properties because of its nanoscale nature and the unclear boundary. In this regard, computer simulation, e.g., molecular dynamics, provides an effective tool to characterize such interphase and the properties. In this work, molecular dynamics simulations are applied to quantify the interphase thickness in clay-based polymer nanocomposites. Then, the mechanical properties of the so-called effective nanofiller (i.e., the physical size of nanofiller plus the thickness of interphase) will be determined by a series of simulations.
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Authors: Ignacy Jakubowicz, Nazdaneh Yarahmadi
Abstract: The development of polymer-layered silicate nanocomposites (PNCs) includes a long list of different possible components such as polymers, nano-additives, and co-additives, together with surface chemistry and various processing conditions. This involves the investigation of a large number of parameters that influence PNC performance. Consequently, fairly extensive research and development work is necessary, and this constitutes an obstacle in the commercialization of nanotechnology. This paper, which is based on experience from research and development for an industrial application, presents a procedure composed of high throughput (HT) screening methods for speeding up the development of PNCs.
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Authors: G. Rajasudha, V. Narayanan, A. Stephen
Abstract: Composite polymer electrolytes (CPE) have recently received a great attention due to their potential application in solid state batteries. A novel polyindole based Fe2O3 dispersed CPE containing lithium perchlorate has been prepared by sol-gel method. The crystallinity, morphology and ionic conductivity of composite polymer electrolyte were examined by XRD, scanning electron microscopy, and impedance spectroscopy, respectively. The XRD data reveals that the intensity of the Fe2O3 has decreased when the concentration of the polymer is increased in the composite. This composite polymer electrolyte showed a linear relationship between the ionic conductivity and the reciprocal of the temperature, indicative of the system decoupled from the segmental motion of the polymer. Thus Polyindole-Iron oxide composite polymer electrolyte is a potential candidate for lithium ion electrolyte batteries. The complex impedance data for this has been analyzed in different formalisms such as permittivity (ε) and electric modulus (M). The value of ε' for CPE decreases with frequency, which is a normal dielectric behavior in polymer nanocomposite.
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Authors: Anne Zulfia, Sutopo, Bangkit Indriyana, Muhammad Ekaditya Albar, Saeful Rohman
Abstract: The properties of polypropylene can be improved by addition of multiwall carbon nanotube (MWCNT). This research focuses on material design of composite based on polymer matrix and carbon including MWCNT to improve mechanical and electrical properties of composites according to the requirement for bipolar plate material. It is found that the effect of small addition of MWCNT and Cu have been increasing electrical conductivity up to 15.62 S/cm while tensile and flexural strengths increase to 14.97 MPa and 31.78 MPa respectively.
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Authors: Qing Hua Zeng, Ai Bing Yu, Gao Qing Max Lu
Abstract: Polymer nanocomposites are recognized as the next generation of polymer composites due to their exceptional properties. Understanding the molecular origin of the reinforcement mechanism is crucial to the development of such promising materials. This paper reports our recent molecular dynamic study on clay-based polyurethane nanocomposites. The effect of clay platelets on phase separation behavior of polyurethane, at the clay-polyurethane interface, is quantified in terms of molecular interactions, structure and dynamics. The results show that the nanoconfinement of polyurethane chains in clay gallery impedes the development of phase separation commonly observed in bulk polyurethane. The absence of phase separation of intercalated polyurethane is believed to be related to the competitive interactions among clay platelet, polyurethane and surfactant.
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Authors: Jae Young Lee, Bum Choul Choi, Ji Jung Lee, Sung Won Yang, Hong Ki Lee
Abstract: Palladium (Pd) nanoparticles were incorporated into free-standing polymer films, where isotactic polypropylene (iPP) was used, by a one-step dry process involving simultaneous vaporization, absorption and reduction schemes of palladium(II) bis(acetylacetonate), Pd(acac)2 at 180oC, used as a precursor. iPP film was exposed to the sublimed Pd(acac)2 vapor in a glass vessel with nitrogen atmosphere heated at 180oC. The exposing time was 30 min and the Pd nanoparticle contents in polymer films were estimated from ash contents in a sample of about 5 mg by pyrolysis of the films at 800 oC for 1 h in an electric furnace of the TGA apparatus under dry argon atmosphere. The sensitivity of the TGA apparatus was 0.2 mg, and thus the minimum content to be measured was 0.004 wt% of a 5 mg sample. The reduced Pd nanoparticles were observed by transmission electron microscope (TEM), and it was found that metal nanoparticles were selectively loaded into the amorphous regions between the lamellae of crystalline polymers having higher melting temperatures than the processing temperature (180 oC). In order to measure the thermal degradation rate, TGA data measured by the heating rates of 5, 10, 15 and 20 oC /min at the nitrogen atmosphere of 200 ml/min. The TGA data was introduced to the Ozawa equation and the degradation activation energy was calculated according to the degradation ratio.
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