Different Types Of Nanocomposites Research Articles

Effects of nano zinc oxide and nano chitosan on the taste masking paracetamol granules

Objective The purpose of this study is to investigate the taste masking of Paracetamol granules in the range of 250–850 µm, coated by two nanocomposites prepared from Eudragit® E100, nanozinc oxide, and nanochitosan, respectively, from 1 to 5% by the weight of the granules. Methods In this study, Paracetamol granules were coated in several formulas with two different types of nanocomposites (polymeric and mineral) on two sizes of granules to reduce bitter taste and with the FBC method and pH-sensitive polymers (Eudragit® E100). Results The effect of nanoparticles (Nano zinc oxide and Nanochitosan) on taste-masking Paracetamol was studied with dissolution-coated granules in vitro by simulating in the oral (pH 6.8) range. Based on the results of the studies, the rate of drug release was confirmed by the taste test, and the formulated granule with 5% nano-chitosan (F14) had the best bitter taste mask function of all samples. These results were also confirmed by scanning electron microscopy (SEM) analysis, which showed a smoother and more stable surface than the samples obtained from other formulations. Conclusion In the comparison of the release of two types of nanocomposites in the dissolution test, it was shown that the type B granules of Paracetamol’s 5% nano-chitosan-coated granule (F14) were released 99% less than Paracetamol’s 5% nano-ZnO-coated granule (F11). and Paracetamol’s 1% nano-chitosan-coated granule (F12) was released 91% less than Paracetamol’s 1% nano-ZnO-coated granule (F9). The results showed that nano-chitosan-coated granules have better coverage of bitter taste instead of nano-ZnO.

Bandgap energy controlling and electrochemical performances of quaternary metal oxide combined graphene-TiO2 nanocomposite and its photocatalytic hydrogen evolution

A quaternary metal oxide (BiZnSb2O4) combined graphene-TiO2 nanocomposite could be used to control band gap energy using a heterojunction for high hydrogen production by photocatalytic activity. Here, we designed a BiZnSb2O4 combined graphene-TiO2 heterostructure using a high-power sonic synthesis process. The photocatalyst prepared in this way was coated on a nickel foam in the form of a thin film. Various techniques were then used to characterize the nanoscale composite hybrid. Standard three-probe electrode systems were used for cyclic voltammetry test, LSV, and Tafel data. Finally, we obtained good hydrogen evolution results using three different types of nanocomposites with bandgap energy control. To check photoreaction characteristics of the synthesized sample, more current generation reactions were confirmed in the photocatalyst because light existed in the evaluation of electrochemical characteristics depending on the presence or absence of light. Among these three samples, the BZSB-G-T photocatalyst showed the highest hydrogen production amount (95.5 μmol/g without ultrasonic and 112.6 μmol/g with ultrasonic during 4 h). In addition, BZSB-G-T had a lower band-value energy effect with a heterojunction effect compared to the other two types of photocatalysts owing to its synergetic effects.

Dynamic dielectric properties of isotactic polypropylene-g-maleic anhydride crosslinked by capped-end polyether diamine and filled with native or functionalized nano-graphite particles

Dynamic dielectric properties of an isotactic polypropylene matrix grafted with maleic anhydride (CA 100) and then crosslinked by polyether amine molecules and reinforced with different weight percentages of graphite nanoplatelets (GNPs), KNG180, were studied for the first time and compared to those obtained by DMA (Dynamic Mechanical Analysis). The main objective of this work was to investigate the reinforcement effect of GNPs focusing on the GNPs/matrix interfacial adhesion using dynamic dielectric relaxation spectroscopy in the frequency range from 0.1 Hz to 1 MHz and temperature range from 20 to 140 °C. The obtained interfacial polarization increments \({\Delta \varepsilon }_{\mathrm{MWS}}\) from MWS (Maxwell Wagners Sillars) relaxation showed a threshold value of 3% in weight of KNG180. This analysis suggests that interfacial compatibility between matrix and fillers in the case of nanocomposite KNG180 3 wt% is higher than those of other nanocomposites. A new plasma treatment was used to modify graphite nano-fillers to produce different types of nanocomposites. The 5 wt% plasma treated graphite nanocomposite shows a good dispersion of the nano-fillers but also a high value of \({\Delta \varepsilon }_{\mathrm{MWS}}\), which is an indication of high graphite/graphite interaction. This evolution could show that this material can be close to the formation of an electrical percolation network.

Nanocomposites are state-of-the-art in the field of ground improvement- a review

Soil stabilization is the most prevalent technique that provides a stable working platform for the rapidly expanding infrastructure constructions on marginal lands. Sustainable and cost effective methods are crucial for soil stabilization. Nanocomposites are a new ground improvement approach that aims to enhance the geotechnical characteristics of weak soil. Nanocomposites have constituents with at least one dimension in the nanometer scale. The particles in the form of nano powder, nano fiber or nano film are dispersed in a matrix of standard material like clay, sand or silt to form the composite. The commonly used nanomaterials for soil stabilization are SiO2, TiO2, Al2O3, GO, nano clay and carbon nanotubes. These additions have been proven to have a considerable impact on the microstructure, physical, and chemical aspects of soil. This paper examines different types of nanocomposites used for ground treatment encompassing the latest researches, summarizes the key findings and covers various material analysis facilities.

Low percolation behavior of HDPE/CNT nanocomposites for EMI shielding application: Random distribution to segregated structure

In this study, three different types of nanocomposites with random (r-CPC), segregated (s-CPC) and semi-segregated (ss-CPC) distribution of carbon nanotubes in High Density Polyethylene matrix were fabricated using hot compaction method. Microstructure of nanocomposite samples were observed by Scanning Electron Microscopy, which revealed the formation of carbon nanotubes conductive network at the polymer granule interfaces in segregated structure. While, partial formation of segregated structure was shown in semi-segregated samples. A significant reduction of Young modulus and strength of s-CPC6 and ss-CPC6 compared to r-CPC6 nanocomposite has been correlated to weak interface and voids between HDPE granules in segregated structure. DSC results proved that the crystallinity index of HDPE decreases when the distribution of CNTs in polymer matrix changes from segregated to random structure. Electrical conductivity was measured using four-point probe. Segregated structure samples showed electrical conductivity up to 9 and 5 order of magnitude larger than semi-segregated and random structure nanocomposites, respectively. Nanocomposites follow percolation behavior and applying percolation theory showed a decrease in percolation threshold from 7.1 vol% in r-CPC to 0.099 vol% in s-CPC. Finally, Electromagnetic Interference shielding properties were studied and the highest Shielding Effectiveness (SE) was obtained 21.8 dB in segregated sample at 6 wt% CNTs. While, in random structure the highest EMI SE was 9 dB at 20 wt% CNTs. Absorption and reflection were the dominant shielding mechanisms in segregated and random structure nanocomposites, respectively.

Evaluation of diametral tensile and compressive strengths of different types of nanocomposites for dental applications

This study aims to evaluate the diametral tensile strength (DTS) and compressive strength (CS) of restorative composite resins that applied as restorative materials in the field of dentistry. The composites were prepared from different sets of monomers which divided into six groups (A, B, C, D, E, and F) according to the type and ratios of monomers used in preparing the matrix materials, excepted the basic monomer (2, 2 propyl bisphenol glycidyl dimethacrylate (Bis-GMA)) that added at constant ratio (40 wt%), in addition tothe nano-inorganic fillers [SiO2, ZrO2, HA, and Al2O3] which adding individually. Ninety specimens were prepared for diametral tensile strength test, which divided into six groups according to the prepared resin matrix and five sub-divided groups according to types of fillers of prepared composites, and for compressive strength test, the same numbers of specimens were prepared. In the beginning, the diametral tensile strength (DTS) and compressive strength of the prepared matrices were determined and then study the effect of adding the nano-inorganic fillers on the results of these properties for the prepared dental restorations nanocomposites materials. The results show that the composites based on resin matrix of group (D) having the selected monomers (BIS-GMA, meth acrylamide, methacrylic acid, and 1–6 hexanediol methacrylate) that reinforced with silica nanoparticle have higher properties as compared with other types of the prepared nanocomposite, where these values reached to (54 MPa and 174 MPa) for diametral tensile strength and compressive strength, respectively.

Dielectric Behavior of Nano Lead - Nano Copper oxides Polyvinyl Chloride (PVC) Composites

The dielectric properties of pure PVC and pure PVC filled composites were performed to examine and characterize the structure of polymer composites. At room temperature the values of relative permittivity, loss factor, and ac conductivities were calculated as a function of frequency and it was found that incorporation of both micro and nano PbO and CuO with various wt% to the polymer matrix resulted in enhanced dielectric properties. The electrical response of polymer matrix micro- or nanocomposites show their conductivity and dielectric behavior. So the principal electrical character of polymers is insulating because of their very low concentration of free charge carriers, polymer nanocomposites (also called nanodielectrics) appear to be dielectrics or in other words, materials that will be polarized by applying an external electric field. Nano composites are closely associated with the development of cutting-edge electronic and optoelectronic devices. The nanoscale has been reached on the dimensional scale of electronic devices. The usefulness of polymer/inorganic molecule nanocomposites varies greatly, with various potential applications as well as different types of nanocomposites.

Effective addition of nanoclay in enhancement of mechanical and electromechanical properties of SWCNT reinforced epoxy: Strain sensing and crack-induced piezoresistivity

Many studies were performed to improve CNT dispersion into epoxy using different mechanical dispersion methods as well as CNT functionalization. In this study, a novel method is introduced to enhance CNT dispersion using 2D nanoclay as a secondary filler. Hence, this study was aimed to investigate the effect of nanoclay platelets on electrical, mechanical, and piezoresistive characteristics of the SWCNTs doped epoxy nanocomposites. Two different types of nanocomposites were prepared for comparison including binary (SWCNT/epoxy) and hybrid (SWCNT-nanoclay/epoxy) states. CNT content of 0.1 wt% was used for the binary and hybrid states while two different nanoclay loadings (0.5 wt% and 1.0 wt%) were employed in the hybrid nanocomposites. Tensile and mode I fracture tests were performed for the mechanical and electromechanical characterization using two probe techniques while electron microscopy and X-ray diffraction were used for microstructural analysis. Results showed severe CNT agglomeration in the binary state whilst a homogenous CNT dispersion was achieved in the ternary states. The binary nanocomposite showed weak performance in terms of electrical, mechanical and piezoresistive properties caused by severe CNT aggregates. On the other hand, addition of nanoclay into CNTs doped epoxy manifested a significant increase in the electrical, mechanical and piezoresistive-sensitivity performance of the hybrid nanocomposites compared to the binary one. The best performance was achieved at 0.5 wt% nanoclay loading where electrical conductivity increased by six orders of magnitude, UTS increased by 37%, KIC and GIC increased by 34% and 64%, respectively, with respect to the binary nanocomposite. Crack-pinning and crack deflection were accounted for the fracture toughness increase in ternary composites. Nonlinear piezoresistivity resulting from the predominate effect of tunneling resistance ruled piezoresistivity in the hybrid nanocomposites. A sensitivity of 2.1 and 2.0 at strain of 0.01 were obtained for 0.5 wt% and 1.0 wt% nanoclay contents, respectively, whereas no sensitivity was achieved for the binary composite.

Isolation of Candida species in children and their biofilm-forming ability on nano-composite surfaces

Candida species including Candida albicans, Candida krusei and Candida glabrata are opportunistic microorganisms that inhabit oral cavity. The objective of this study is to determine the effect of dental caries on Candida spp. biofilm-forming ability on nano- composite with the hypothesis that dental caries enhances the colonization of Candida spp. To assess Candida spp. colonisation in the oral cavity of the paediatric patient, samples were obtained from 30 subjects aged five to six years old from Kuantan, Pahang, Malaysia. The samples were collected from buccal mucosa, palate and tooth surfaces using sterile swabs. 10 mL of patient’s saliva suspension was also collected. Following that, the samples were inoculated on CHROMagar and incubated for 24 h at 37 ºC. Candida biofilm of caries isolate C. albicans (HNFC2), and C. albicans ATCC 32354 were developed on three different types of nano-composites. The study showed that no C. albicans was isolated from the caries-free oral cavity while 76% of children with caries possessed Candida spp. 65% of the yeasts were isolated from the tooth surface. Only 35% of the total isolates were obtained from soft tissues, including palatal and buccal mucosa. C. albicans is the most isolated Candida spp. with 82% and 67% of the yeast were obtained from the tooth surface and buccal mucosa, respectively. Besides, HNFC2 significantly colonised the nano- composites more than the ATCC (P < 0.05). In the comparison of the three types of nano- composites, nano-hybrid-based containing pre-polymerised filler (cB) exhibited the least C. albicans HNFC2 cells colonisation with 7.7 x 10³ cells mL-1. In contrast, the nano-composite that contained bulk-filled nanohybrid (cC) was the most colonised with 14.3 x 10³ cells mL-1. In conclusion, dental caries enhances the colonization of Candida spp. in children's oral cavity, and that caries isolate form more biofilm on nano-composites compared to the lab strain C. albicans.

Hardness behaviour of carbon nanotube-aluminium nano-composite using nanoindentation technique

The aim of the current paper is to study the hardness behaviour of carbon nanotube reinforced aluminium (CNT-Al) nano composite material under nanoindentation and Vickers micro hardness techniques. The four different types of nano-composites with 1, 1.5, 2.0 and 2.5 wt% CNT indented by diamond Berkovich indenter in sub microns. The Vickers micro hardness test was performed using a Wilson Wolpert Vickers micro hardness tester. The results showed that the value of hardness increases with the increasing of CNT percentage in Al matrix up to 2 wt%. The highest hardness was obtained from 1.5 wt% CNT-Al nano-composite with the value of 1.90 GPa. From the CNT-Al load-displacement curve a good bonding property was observed between the reinforcement and the matrix material due to the same trend followed with other strong materials such as steel and silicon. However, there is a significant enhancement in the Vickers micro hardness of the 1.5 wt% CNT-Al nano-composite compared to other CNT reinforcement nano-composites. The highest hardness with the value of 102 VH was obtained from 1.5 wt% CNT-Al nano-composite which is three times higher than pure Al.

Fabrication and Characterization of Polysorbate/Ironmolybdophosphate Nanocomposite: Ion Exchange Properties and pH-responsive Drug Carrier System for Methylcobalamin

Background: Nanocomposites are of great interest due to their competency to show multifunctional properties. They have been recently given much attention due to their credibility to offer the synergistic feature of organic material with those of inorganic constituents. Different types of nanocomposites have been prepared to date and are being used for different applications. The delivery of drugs in the human body at a particular site was one of the major problems in the medicinal field. The nanocomposite formulations can be used to provide controlled release and they can be combined with ligands for targeted drug delivery. Applications of the nanocomposites as ion exchangers are also increasing at a faster rate. Due to this, they help in the softening of the water. They can also be easily recharged by washing them with a solution containing a high concentration of sodium ions. In the present paper, we have worked on the synthesis and applications of the polysorbate/ironmolybdophosphate (PS/FMP) nanocomposite. Methods: Polysorbate/ironmolybdophosphate (PS/FMPS) was synthesized by co-precipitation method in the presence of polysorbate. The material was well characterized using X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy, (FTIR) scanning transmission microscopy (SEM), and transmission electron microscopy (TEM). Physicochemical properties of material were studied in detail. Drug delivery behavior of polysorbate/ironmolybdophosphate was investigated by using methylcobalamin as a test drug. Results: The polysorbate/ironmolybdophosphate nanocomposite show enhanced Na+ ion exchange capacity of 2.1 meq/g. It has been revealed that PS/FMP nanocomposite was thermally stable as it retained the ion exchange capacity of 40.4 % at 400°C. An optimum concentration of sodium nitrate (eluent) was found to be 1.0 M for the complete removal of H+ ions from the PS/FMP column. The optimum volume of sodium nitrate (eluent) was found to be 230 mL. The FTIR spectra showed the changes in intensities of characteristic peaks in PS/FMP and in drug loaded on PS/FMP nanocomposite. The characteristic peak at 1043-1061 cm-1 was observed for ionic phosphate stretching, 560-567 cm-1 for iron group and 959 cm-1 due to molybdate present in the material. The additional peak at 3390 cm-1 and 1711 cm-1 were due to -OH and C=O stretching due to the presence of these groups in the structure of polysorbate. The peak present at 430 cm-1 might be due to the presence of Co-O stretching of methylcobalamin. The XRD results confirmed the semicrystalline structure of FMP and PS/FMP. Scanning electron micrographs results revealed the beaded surface of FMP changes to fibrous surface in case of PS/FMP nanocomposite. The TEM images indicate the appearance of smooth surfactant layer on the surface of FMP. The size of the nanocomposite is between 10- 70 nm. The drug loading efficiency and encapsulation efficiency were found to be 35.2%. and 60.4%, respectively. The cumulative drug release of methylcobalamin was studied for the PS/FMP nanocomposite. The order of drug release was found to be pH 9.4 (54.6%) > pH 7.4 (46.4%) > saline (pH 5.7) (36.2%) > pH 2.2 (33.9%). The release at pH 9.4 was higher. As the pH of medium changes from acidic to basic i.e. 2.2 - 9.4, there is an appreciable increase in drug release from the PS/FMP nanocomposite due to the presence of more OH- ions resulting in neutralization of cationic nanocomposite and thus increasing the rate of drug release by ion exchange process and matrix deterioration. : The novel nanocomposite PS/FMP has been synthesized by a simple co-precipitation method. The increase in Na+ ion exchange capacity for nanocomposite is due to the binding of organic part (Polysorbate) with inorganic ironmolybdophosphate. The physiochemical properties of PS/FMP were found to be superior. Fourier transform infrared spectra of PS/FMP and drug loaded PS/FMP confirmed the formation of materials. The SEM results indicated the surface of synthesized FMP is bead-like appearance whereas the beaded surface of FMP changes to fibrous surface on the addition of polysorbate thus indicated the fabrication of nanocomposite. The cumulative drug release of methylcobalamin was studied and the order of drug release was found to be pH 9.4 > pH 7.4 > saline (pH 5.7) > pH 2.2. Thus PS/FMP is a promising multifunctional nanocomposite.

The Processing of Epoxy/1 wt%-graphene Nanocomposites: Effects of Ethanol on Flexural Properties

Four different types of nanocomposites were successfully produced using solution casting technique. Graphene was dispersed in four different ethanol concentrations; 0g, 1g, 2.5g, and 5g. In general, it can be observed that ethanol is an excellent agent for 1 wt% graphene dispersed in the epoxy matrix. The maximum increase in flexural properties, impact strength and microhardness were observed in 1 wt% graphene dispersed in 1g ethanol. The flexural strength and modulus increased by 62% and 61% respectively. The highest impact strength was recorded for 1 wt% graphene dispersed with 1g ethanol, where an improvement of 9.5% was observed. The maximum Vickers microhardness was recorded to improve 3% compared to monolithic epoxy. SEM images revealed that graphene can impede the advancing cracks and significantly change the fracture mode from a straight fracture path to radially emanated path. It is worth to point out that if ethanol is not completely evaporated during processing, it can cause porosity which is unfavourable to the mechanical properties of the nanocomposites.

An Innovative Approach to the Synthesis of PMMA/PEG/Nanobifiller Filled Nanocomposites with Enhanced Mechanical and Thermal Properties

ABSTRACT A facile route was adopted to blend the matrix. The PMMA/PEG blend was reinforced with three types of nanofillers, i.e., pristine MWCNT (P-CNT), amine functionalized MWCNT (PDA-EA-CNT) and nanobifiller i.e. nanodiamond functional MWCNT (PDA-EA-CNT-ND) to yield three different types of nanocomposites i.e. PMMA/PEG/P-CNT, PMMA/PEG/PDA-EA-CNT and PMMA/PEG/PDA-EA-CNT-ND. These nanocomposites were reinforced with nanofiller loading (1 wt. %, 3 wt. %, 5 wt. %, 10 wt. %, 30 wt. % and 50 wt. %) by solution casting method. Structure of composite and nanofillers was confirmed by FTIR. FESEM imaging revealed that nanocomposites have micro porous morphology. At high magnification, distribution of functionalized CNT/ND appears to be protruding out of the polymeric matrix. The TGA result suggests that the thermal stability of the nanocomposites was enhanced in comparison to PMMA due to grafting of filler molecules with PMMA/PEG macromolecules. The DTG results showed that the bifiller nanocomposites (PMMA/PEG/PDA-EA-CNT-ND) exhibited improved thermal stability with Tmax (431°C) as compared to P-CNT and amine functionalized CNT (PMMA/PEG/PDA-EA-CNT) with Tmax of 395°C and 418°C respectively. XRD results showed fine interaction between filler and the polymeric matrix. As the filler loading was increased the composites showed pronounced XRD peak at 25.9°, corresponding to (002) reflection of nanotubes. Significant improvement in the mechanical properties of composites was recorded with the reinforcement of fillers as compared to the neat matrix. The most significant improvement in tensile strength and elastic modulus was observed for the bifiller nanocomposites with 5 wt. % PDA-EA-CNT-ND. They showed a tensile strength and elastic modulus of 29.9 MPa and 1474.31 MPa respectively as compared to amine functionalized CNT with tensile strength (25.7) and elastic modulus (1466.99 MPa)and P-CNT with tensile strength(25 MPa) and elastic modulus (1155.75 MPa).

Nanocomposites in Controlled & Targeted Drug Delivery Systems

In recent years, development of different types of nanocomposites have increased their utilization in the biomedical and pharmaceutical sciences. The nanometer size range and unique composition make nanocomposites a beneficial alternative to any single conventional material. The present chapter provides a general overview of nanocomposites, discusses different types of nanocomposites such as metal, ceramic and polymer nanocomposites. The discussion is further focused on different nanocomposite based controlled and targeted systems developed for delivery of various drugs including anti-cancer, anti-microbial, anti-inflammatory, anti-diabetic and cardiovascular drugs.

Study on Mechanical Characteristics of Nanoclay Reinforced Polymer Composites

The present work is focused on analysis and influence of nanoclay on the mechanical behavior of polymers viz., epoxy and polyester. Different types of nanocomposites are prepared using 5 wt% and 10 wt% nanoclay with 95 wt% and 90 wt% epoxy and polyester respectively. Nanoclay is mixed with the resin using a mechanical stirrer for 2 hours to ensure the proper distribution of the reinforcement. Casting technique is used to prepare the specimens according to ASTM standard. The specimens are tested for tensile strength and hardness. 5 wt% of nanoclay increased the tensile strength of resins, but 10 wt% decreased the tensile strength. Hardness value of epoxy resin increased by increasing the wt% of nanoclay, whereas there is no much change in the hardness value of the polyester resin.

Hierarchical porous nanocomposite architectures from multi-wall carbon nanotube threaded mesoporous NaTi2(PO4)3 nanocrystals for high-performance sodium electrodes

Abstract Rational design and self-assembly of nanostructured electrode materials for high-performance energy-storage devices is highly desirable but still challenging. Herein, we design and synthesize hierarchical porous nanocomposite architectures consisting of mesoporous NaTi 2 (PO 4 ) 3 (MNTP) nanocrystals (NCs) with a pore size of about 10 nm and multi-wall carbon nanotube (MWCNT) networks for high-performance sodium ion batteries (SIBs). Our strategy is based on the hetero-assembly of MWCNTs and nanostructured building units by utilizing the screening effect of electrostatic repulsion in a solution engineered ionic strength using highly soluble ammonium salt to form three-dimensional hierarchical assemblies of MWCNT networks and packed MNTP NCs. Subsequent freeze-drying and calcination convert the assemblies into robust hierarchical porous MWCNTs-threaded particles. Calcination of residual ammonium salt introduces nitrogen into the MWCNTs. Such nanoarchitecture enhances electron/ion conductivity and structural stability as anode materials for SIBs. The nanocomposite has high initial Coulombic efficiency of 99%, high rate capability of 74.0 mAhg −1 at 50C, as well as long-term cycling stability with capacity retention of 74.3 mAhg −1 after 2000 cycles with only 0.012% loss per cycle at 10C. The results provide a general and scalable hetero-assembly approach to different types of nanocomposites for high-performance energy storage devices such as LIBs and SIBs.

Experimental and analytical investigation of water diffusion process in nano-carbon/alumina/silica filled epoxy nanocomposites

This study discusses the water absorption behavior of three different types of nanocomposites. Silica, carbon and alumina nanoparticles are used as fillers incorporated in epoxy resin with different contents of 0.5, 1.5, and 3 wt%. A new nonlinear least-squares regression approach in conjunction with a gradient optimization was developed using symbolic manipulator MAPLE software to find the best fit. The equilibrium moisture content of the nanocomposites is measured as a function of time and the analytical modelling is successfully conducted. Results indicate that the addition of nanoparticles generally lower moisture content in contrast to neat epoxy. Compositions of 1.5 and 3 wt% alumina as well as silica nanocomposites however show a different behaviour. Diffusion coefficients for different types of nanocomposites were computed using Fickian and Langmuir models of diffusion. The least and highest diffusion coefficients correspond to the addition of silica 0.5 wt% and alumina 3 wt%, respectively.

Design, manufacture and analysis of composite epoxy material with embedded silicon carbide (SiC) and alumina (Al2O3) nanoparticles/fibers

Abstract The main objective of the presented study is to improve the performance of composite structures by introducing nanoparticles/fibers in the epoxy resin. The literature on this issue showed shortcomings in the investigations of such materials. Most of the investigations in this field are to enhance the mechanical properties of epoxy materials, which cannot be used alone for high performance structural applications due to their low mechanical properties. In the present work, the epoxy resin was modified with these different types of nanofillers such as silicon carbide (SiC) and alumina (Al2O3) nanoparticles. The nanophased epoxy was used to fabricate different types of nanocomposites as well as nano-hybridized glass fiber reinforced composite laminates. Therefore, nine different advanced materials have been fabricated including two nanocomposite materials (SiC/E and Al2O3/E), two quasi-isotropic nano-hybridized composite laminates (QI-GFR/SiC/E and QI-GFR/Al2O3/E), two unidirectional nano-hybridized composite laminates (UD-GFR/SiC/E and UD-GFR/Al2O3/E), and three control panels manufactured without nanofillers (neat epoxy, QI-GFR/E, UD-GFR/E). The materials were characterized under tension and compression. The results showed improvements in the tensile and compressive properties (strength and modulus) of the fabricated nanocomposites (SiC/E, and Al2O3/E) compared with neat epoxy. The hybridized composite laminate with Al2O3 showed high improvements in its mechanical properties compared to the composite laminates without nanofillers. In contrast, discouraging mechanical properties were observed for SiC hybridized composite laminate. Due to the many variables studied in the present work, the literature list will be long. The investigated parameters include nanofillers, nanocomposites, nano-hybridized advanced composite laminates, mechanical properties, glass transition temperature (Tg), bolted joint parameters and sonication parameters.

Design, Manufacture and Analysis of Composite Epoxy Material with Embedded MWCNT Fibers

Abstract The weight and fuel savings offered by composite materials make them attractive not only to the military, but also to the civilian aircraft, space, and automobile industries. In these industries, bolted and riveted joints are extensively used as a primary method for structural joining. Bolted joints in composite materials have complex failure modes, and hence the demand for improving their performance exists. The main objective of this work is to improve the performance of bolted joints in composite structures by introducing nanoparticles/fibers around the expected failure zone. The literature on this issue showed shortcomings in the investigations of such materials. Most of the investigations in this field aimed to enhance the mechanical properties of epoxy materials, which cannot be used alone for high performance structural applications due to their low mechanical properties. In the present work, epoxy resin was modified with different types of nanofillers including multi walled carbon nanotubes (MWCNT). Nano-phased epoxy was used to fabricate different types of nanocomposites as well as nano-hybridized glass fiber reinforced composite laminates. Therefore, six different advanced materials were fabricated including a nanocomposite material (MWCNT/E), a quasi-isotropic nano-hybridized composite laminate (QI-GFR/MWCNT/E), a unidirectional nano-hybridized composite laminate (UD-GFR/MWCNT/E) and a control panel manufactured without nano-fillers (neat epoxy, QI-GFR/E, UD-GFR/E). The materials were characterized by tension and compression tests. The obtained properties are essential for the validation of respective finite element analysis. The results showed improvements in the tensile and compressive properties (strength and modulus) of the fabricated nanocomposites (MWCNT/E) compared with neat epoxy. The hybridized composite laminate with MWCNT showed high improvements in their mechanical properties compared to the composite laminates without nanofillers.

Effect of one-step polishing system on the color stability of nanocomposites

ObjectivesThis study was to compare the effect of three different one-step polishing systems on the color stability of three different types of nanocomposites after immersion in coffee for one day and seven days and determine which nanocomposite material has the best color stability following polishing with each of the one-step polishing system. MethodsThe nanocomposites tested were Tetric EvoCeram, Grandio and Herculite Précis. A total of 120 discs (40/nanocomposite, 8mm×2mm) were fabricated. Ten specimens for each nanocomposite cured under Mylar strips served as the control. The other specimens were polished with OptraPol, OneGloss and Occlubrush immersed in coffee (Nescafé) up to seven days. Color measurements were made with a spectrophotometer at baseline and after one and seven days. Two way repeated measure ANOVA, two way ANOVA and Bonferroni tests were used for statistical analyses (P<0.05). ResultsThe immersion time was a significant factor in the discoloration of the nanocomposites. The effect of three one-step polishing systems on the color stability was also significant. The color change values of the materials cured against Mylar strips were the greatest. The lowest mean color change values were from the Occlubrush polished groups. The effect of the three different types of nanocomposite on the color change was significant. The highest color change values were with Tetric EvoCeram groups. The lowest color change values were with Herculite Précis groups. ConclusionThe color change of nanocomposite resins is affected by the type of composite, polishing procedure and the period of immersion in the staining agent.