Nanostructured Fly Ash Research Articles

Development and characterization of coal fly ash through low-energy ball milling

A paradigm shift from monolithic materials to composite materials has been observed in recent times to achieve the ever changing demands of the manufacturing sector. The composites are being explored in terms of industrial and thermal power plant wastes used as reinforcements. Being a prominent thermal power plant waste, fly ash disposal and utilization is gravitating environmentalists and researchers to propose innovative ideas and feasible implementations. To trace and adjoin an effort to add value to aforementioned cause, an investigation was conducted on fly ash which was milled in tumbler ball mill with predefined input parameters viz. spindle speed, ball-to-powder ratio, and milling time. Low-energy mill has an extensive application in preparation of new materials, their activation and process of synthesis for potential merits like cost-effectiveness, reliability, low maintenance and ease of operation over its contemporary high-energy mill. The modifications in chemical and morphological properties of milled fly ash sample were characterized through X-ray diffraction (XRD) technique, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results inferred that the ball-milling process aimed at reducing crystallite domain size of milled fly ash, and also affected the microstructure, functional groups and led to decline in degree of crystallinity. The milling time was observed as a significant factor to impact extent of these changes. The particles of the raw spherical-shaped fly ash (regularly 5 μm size) were broken down into smaller particles of average crystallite domain size ∼ 30 nm, this change indicated an increase in amorphousness which helped in achieving better compatibility and significantly higher reactivity. The pattern and peaks of XRD for original crystallinites significantly diminished and resulted in broadened peaks. This can be interpreted by the smaller particle size and low degree of crystallinity. The research defined the achievement of nanostructured fly ash with low energy mill technique.

Regression modelling on wear behaviour of nano fly ash–aluminium alloy matrix composites

The demand for particle-reinforced composites has been increasing progressively. Hence, there is an exigency to use low-cost particles or solid waste particles as a reinforcement phase in order to reduce the cost of the composite. Fly ash is a solid waste consisting of various oxides such as silicon dioxide (SiO2), aluminium oxide (Al2O3) and iron (III) oxide (Fe2O3), which will contribute to improving wear resistance. Hence, an attempt is made to use nanostructured fly ash as particle reinforcement to produce high-wear-resistance composite materials. Microsized fly ash was converted to nanostructured material by high-energy ball milling, and the crystallite size was reduced to 27 nm after 30 h of milling. The influence of applied load, sliding speed, sliding time and fly ash reinforcement on dry sliding wear of the metal matrix composites is determined. Wear resistance was increased with increase in fly ash fraction, and beyond 10 wt%, it was decreased. The increased frictional thrust at higher load results in increased debonding and wear rate. The regression model was developed by using the statistical software Minitab R17.1.0 to predict the wear behaviour of the composites under conditions of different normal loads and time periods. The model has been validated, and a good agreement was observed.

Property evaluation of nanostructured fly ash-reinforced acrylonitrile butadiene styrene nanocomposites

Fly ash, a waste generated from thermal power plant, can be used as reinforcing agent for polymer composite applications due to its fine particle size and abundant availability. This article highlights the experimental findings of modification of fly ash to convert its size from micro to nano and its nanocomposites preparation through melt blending technique based on acrylonitrile butadiene styrene (ABS) as matrix material. The nanostructured fly ash (NFA) developed through mechanical milling is characterized to understand its viability toward the filler material in polymer composites. The study showed that the NFA produced after 40 h of milling has a broken rougher surface with improved amorphous nature. Further, a detailed study on the properties of ABS nanocomposites reinforced with NFA has been conducted. ABS/NFA composites at 7 wt% loading have showed better thermomechanical properties. These results are further supported with the fractured surface analysis of nanocomposite using various morphological techniques. The outcome of this study suggests the potential use of nano fly ash to develop sustainable polymer nanocomposites for high-end industrial applications.

Characterization of composites based on biodegradable poly(vinyl alcohol) and nanostructured fly ash with an emphasis on polymer–filler interaction

A thermal power station fly ash (FA) was mechanochemically activated by high-energy ball milling that yielded nanostructured FA. This nanostructured FA was incorporated into biodegradable poly(vinyl alcohol) (PVA) matrix by solution mixing and ultrasonication. Transmission electron micrographs revealed that the smooth spherical particles of FA were changed into irregular and rough ones; in addition, the particle size of FA was reduced to a few hundred nanometers, and its specific surface area value increased after the high-energy milling process. All these factors, in turn, led to a thermodynamically favorable interaction between the mechanochemically activated FA and PVA as evidenced by Fourier transform infrared spectroscopy. The incorporation of a very small amount of the nanostructured FA led to an increase in crystallinity of the polymer matrix. The glass transition temperature of the PVA matrix increased by about 18°C when 5 wt% of the nanostructured FA was used as the reinforcement.

Ductility and Flame Retardancy Enhancement of PVC by Nanostructured Fly Ash

Fly ash (FA) obtained from a coal-fired local thermal power station was converted into a nanostructured material by mechano-chemical activation using a high energy planetary ball mill. Contact angle measurements and FTIR spectroscopy confirmed the surface modification of mechano-chemically activated FA (MCA-FA). Subsequently, a solution casting method was used to prepare poly(vinyl chloride) (PVC) matrix composites with varying amounts of fresh FA and MCA-FA. Mechanical testing results of the composites revealed that incorporation of fresh FA in PVC resulted in a higher tensile strength with brittle failure; addition of MCA-FA to PVC resulted in higher elongation at break values while retaining the ductility of the PVC. We have proposed a plausible mechanism explaining the influence of fresh FA and MCA-FA on the mechanical behavior of these composites. As fresh FA and MCA-FA contain basic oxide materials, they tend to improve the fire retardancy of PVC even at a very small loading. Overall, the nanostructured MCA-FA could find application as a filler in PVC-based products.

Effect of nanostructured fly ash on mechanical, dynamic mechanical and thermal properties of PP/ABS blends

This study covers the detailed analysis of mechanical, dynamic mechanical, thermal and morphological properties of the nanostructured fly ash (NFA) filled polypropylene (PP)/acrylonitrile butadiene styrene (ABS) blend composites. The melt blended standard samples were molded and considered for characterization studies. The loading of NFA was optimized at 5 wt% based on the mechanical properties of the blend composite. Various models were adopted to assess the mechanical properties of the blend composites. Dynamic mechanical properties were analyzed as a function of temperature. Cole–Cole plots of blend composites revealed the physical compatibilization of NFA and blend phases. Differential scanning calorimetry results showed that NFA particles accelerated the crystallization process and reduced the crystallization time by 12 s. Thermal stability of the PP/ABS blend has found to be improved with the addition of NFA particles and a detailed degradation kinetic study has also been conducted. XRD pattern of the blend composites has also indicated the NFA intervention at the blend interfaces and this further evidenced from SEM and TEM magnified micrographs. The morphological and rheological properties supported the physical interaction of NFA particles within the blend phases and interface. Hence, the study noticed that NFA acted as physical compatibilizer between PP and ABS blend phases.

Influence of planetary ball milling parameters on the mechano-chemical activation of fly ash

This study illustrates the design of statistical analysis by Taguchi methodology to obtain nanostructured fly ash by planetary ball milling. An orthogonal array and analysis of variance were employed to analyze the effect of milling parameters. A class-F fly ash was subjected to planetary ball milling induced mechano-chemical activation aided by a surfactant. Ball milling parameters, such as ball-to-powder weight ratio, type and quantity of surfactant and type of medium were varied as guided by the Taguchi design. The nanostructured fly ash was characterized by dynamic light scattering, BET surface area analysis, X-ray diffraction, FTIR spectroscopy, scanning electron microscopy, field emission scanning electron microscopy and transmission electron microscopy. The ball-to-powder weight ratio and the surfactant type are the major influencing factors on lower crystallite size and average particle size and higher specific surface area. The surface modification of fly ash was confirmed by FTIR spectroscopy. The nano fly ash produced by this method has a wide application potential in polymer industries as reinforcement in composites.

Mechanical, dynamic mechanical, and thermal characterization of fly ash and nanostructured fly ash‐waste polyethylene/high‐density polyethylene blend composites

Disposal of polyethylene used as carry bags is the greatest challenge increasing day by day. Composite materials were prepared by mixing Fly ash (FA) and nanostructured fly ash (NFA) from thermal power station as filler and blends of Waste polyethylene (WPE)(carry bags) collected from municipal solid waste (MSW) with virgin high‐density polyethylene (HDPE) as matrix. Different modifications were induced to improve the overall properties of these composites. At first, the WPE/HDPE blend matrix was modified by grafting with maleic anhydride (MA) and the composite prepared with FA/NFA. Then, the WPE/HDPE‐FA/NFA composite as a whole was treated with electron beam irradiation at 250 kGy radiation dose and finally the FA/NFA filler was treated with radiation dose of 250 kGy and the composite prepared. Significant enhancement in tensile strength, flexural strength, flexural modulus, and hardness are observed for MA modified and irradiated composites, the increase being more prominent in irradiated composites. Furthermore, an increase in storage/loss moduli with enhanced thermal stability was observed with the addition of FA/NFA and upon modifications. The analysis of the tensile fractured surfaces by scanning electron microscopy was in well correlation with the mechanical properties obtained. In summary, after analyzing the effects of the three different modifications on mechanical, dynamic mechanical and thermal properties, the irradiation on to the WPE/HDPE‐FA/NFA composites investigated was selected as the most appropriate for future applications. POLYM. COMPOS., 37:3256–3268, 2016. © 2015 Society of Plastics Engineers

Interparticle interactions and lacunarity of mechano-chemically activated fly ash

A class F fly ash was subjected to high-energy ball milling-induced mechano-chemical activation aided by a surfactant. The resultant nanostructured fly ash was characterized by various techniques. X-ray fluorescence results showed that the amount of iron oxide was reduced from 4.39% to 2.75% after pre-treatment of fly ash by magnetic separation. Ethyl acetate as the milling medium, a ball to powder ratio of 12:1 and 2wt% of surfactant reduced the average particle size of fly ash to 329nm and led to a specific surface area of 8.73m2/g. The decrease in crystallite size of mechano-chemically activated fly ash was confirmed from a reduction in peak intensity with a broadened amorphous phase by X-ray diffraction studies. X-ray photoelectron spectroscopic characterization illustrated that peak area of major elements (O, Si and Al) increased after milling. Morphological and FTIR studies revealed that the smooth and inert surface of the fly ash was converted to a rough and more reactive one after mechano-chemical activation. The surface modification of fly ash with the surfactant was determined from FTIR spectroscopy. Also, a fractal approach was used to characterize the lacunarity of the agglomerates in the nanostructured fly ash.

Nanostructured Fly Ash as Reinforcement in a Plastomer-Based Composite: A New Strategy in Value Addition to Thermal Power Station Fly Ash

Class-F fly ash (FA) from a coal-fired thermal power station was subjected to high energy ball milling-induced mechanochemical activation aided by a surfactant. Subsequently, ethylene-octene copolymer/mechanochemically activated FA (EOC/MCA-FA) composites were prepared by solution casting. The surface modification of FA was confirmed from contact angle measurements and FTIR spectroscopy, which accounts for a good interaction between MCA-FA and the polymer matrix. X-ray diffraction reveals that the crystallite size of quartz phase present in FA got reduced, while the relative lattice strain on it increased during milling. Morphological studies revealed that interfacial adhesion between the polymer and MCA-FA is good and this accounts for the improvement in mechanical properties of the composites even at the minimum filler loading. Flame retardance of the matrix polymer is improved by the addition of either fresh FA or MCA-FA. The results imply that FA is a valuable reinforcing filler for ethylene-octene copolymer and its mechanochemical activation is an effective strategy for its future use.

Effect of electron beam irradiation on the mechanical, thermal, and dynamic mechanical properties of flyash and nanostructured fly ash waste polyethylene hybrid composites

AbstractThe effect of electron beam irradiation on the technical properties of fly ash (FA) and nano fly ash (NFA)‐filled waste polyethylene (WPE) composites have been investigated in this article. It is observed that the FA/NFA at 5 wt% imparted enhanced technical properties. The modified composites were prepared by three different methods (1) modification of WPE matrix first by grafting with maleic anhydride (MA) and preparing the composite (2) Preparing WPE‐FA/NFA composites and subjecting to electron beam irradiation. (3) Subjecting the FA/NFA to electron beam radiation first and then preparing composites with WPE. Of the three methods, the composite prepared and then electron beam irradiated gave the best balance in the physico‐mechanical properties. The tensile and flexural strength of WPE increased from 21.2 MPa and 25.4 MPa to 33.0 MPa (57.8%) and 45.8 MPa (72%) respectively at 5 wt% FA‐filled WPE composites, which further increased to 34.5 MPa (65%) and 47.7 MPa (87.8%) respectively with 5 wt% of NFA‐filled WPE composites, after electron beam irradiation. The thermal stability was enhanced upon electron beam irradiation of the composites. The dynamic mechanical properties reveal that the storage modulus reaches the highest value for the irradiated composite corroborating with the flexural modulus throughout the temperature range studied. The fractured surfaces were examined under SEM and were correlated with the mechanical properties. The results indicate that FA/NFA reinforced WPE composites act as an excellent stress raisers preventing crack propagation and enhancing the performance properties on electron beam irradiation. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers

Microstructure and mechanical properties of aluminum–fly ash nano composites made by ultrasonic method

In this paper an attempt has been made to modify the micro sized fly ash into nano structured fly ash using high energy ball mill. Ball milling was carried out for the total duration of 30h. The sample was taken out after every 5h of milling for characterizing. The nano structured fly ash was characterized for its crystallite size and lattice strain by using X-ray diffractometer. It was found that a steady decrease in the crystallite size and increased lattice strain was observed with milling time; the crystallite size at 30h milling time was found to be 23nm. The fresh fly ash particles are mostly spherical in shape; whereas the shape of the 30h milled fly ash particles is irregular and the surface morphology is rough. Al–fly ash nano composites were produced by ultrasonic cavitation route successfully. Scanning electron microscopy images of nano composites reveal a homogeneous distribution of the nano fly ash particles in the AA 2024 matrix. Energy dispersive spectroscopy analysis of nano composites reveals that the fabricated nano composite did not contain any additional contamination from the atmosphere. As the amount of nano fly ash is increasing the hardness of the composite also increasing. The nano fly ash addition leads to improvement in the compression strength of the composites.

Thermal stability of nano structured fly ash synthesized by high energy ball milling

In this paper, an attempt has been made to modify the micro sized fly ash into nano structured fly ash using High Energy Ball Mill. The smooth, glassy and an inert surface of the fly ash can be altered to a rough and more reactive state by this technique. Ball milling was carried out for the total duration of 30 hours. The sample was taken out after every 5 hours of milling for characterizing. The nano structured fly ash was characterized for its crystallite size, lattice strain and percentage of crystallinity by using X-Ray Diffractometer. It was found that for the 30 hrs milling, the crystallite size was reduced from 92 nm to 29 nm and the percentage of crystallinity got reduced from 63% to 38%. The size, shape and texture of the fresh as well as nano structured fly ash were studied using Scanning Electron Microscopy (SEM). The fresh fly ash particles are mostly spherical in shape. The shape of the 30h milled particles is irregular and the surface morphology is rough. Isothermal annealing was carried out on 30 h ball milled fly ash from 100 to 800 0C for various times. The initial grain size of 29 nm for as-milled sample increased to 30.9 nm and 31.7 nm after annealing for 8 h at 100 and 200 0C respectively. Whereas this trend was slightly higher for higher temperatures, this increase was in the order of 29 nm to 33.43 nm, 35.35 nm, 36.53 nm, 37.78 nm, 40.42 nm, 41.93 nm after annealing for 4 h at 300, 400, 500, 600, 700 and 800 0C respectively. Hence, small crystallite size enhancement with good amount of residual strain recovery was observed during the isothermal annealing. Keywords: Nano materials, Particulates and Powders, XRD- analysis; Fly ash.

Synthesis and Characterization of Nano-Structured Fly Ash: A Waste from Thermal Power Plant

In this work an attempt has been made to modify micro-sized fly ash into nano-structured fly ash using high-energy ball milling. The smooth, glassy, and inert surface of the fly ash can be altered to a rough and more reactive surface by this technique. Ball milling was carried out for a total duration of 30 h. A sample was removed after every 5 h of milling for characterization. The nano-structured fly ash was characterized for its crystallite size, lattice strain, and percentage crystallinity by X-ray diffraction. A steady decrease in crystallite size and increased lattice strain were observed with milling time; the crystallite size at 30 h milling time was found to be 23 nm, 21 nm, and 16 nm for quartz, mullite, and haematite, respectively. The percentage crystallinity was reduced from 63 to 38 per cent. The size, shape, and texture of the fresh and nano-structured fly ash were studied using scanning electron microscopy. The fresh fly ash particles were mostly spherical in shape. The particles milled for 30 h were irregular and their surface morphology was rough.

Nanostructured fly ash–styrene butadiene rubber hybrid nanocomposites

AbstractHybrid nanocomposites of styrene butadiene rubber (SBR) with nanostructured fly‐ash (NFA) were prepared in the laboratory by melt blending technique in an internal mixer. Curatives were added on a laboratory two‐roll mill. Curing characteristics as well as physico‐mechanical properties of the composites were evaluated. A comparison on SBR composites filled with fresh fly‐ash (FFA); carbon black (CB) and precipitated silica (PS) has been reported. In general, SBR‐NFA composites exhibit higher state of cure and higher strength properties as compared with HAF black‐filled and fresh fly‐ash‐filled SBR composites at equivalent loadings. This may be attributed to the higher reinforcing ability of NFA. This fact has also been supported by the swelling studies and Kraus' plot. Tear strength and abrasion resistance of the SBR‐NFA composites were superior to FFA‐filled and precipitated silica‐filled vulcanizates, but were inferior to carbon black‐ filled SBR vulcanizates. The SBR‐NFA composites showed lower hardness as compared with both the carbon black‐filled and silica‐filled composites. Transmission electron microscopy and scanning probe microscopy studies revealed that the NFA particles are well dispersed in the SBR matrix. These results were further supported by fracture surface analysis under the SEM, which revealed the role of NFA in the prevention of fracture propagation. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Preparation and Characterization of Nano structured Materials from Fly Ash: A Waste from Thermal Power Stations, by High Energy Ball Milling

The Class F fly ash has been subjected to high energy ball milling and has been converted into nanostructured material. The nano structured fly ash has been characterized for its particle size by using particle size analyzer, specific surface area with the help of BET surface area apparatus, structure by X-ray diffraction studies and FTIR, SEM and TEM have been used to study particle aggregation and shape of the particles. On ball milling, the particle size got reduced from 60 μm to 148 nm by 405 times and the surface area increased from 0.249 m2/gm to 25.53 m2/gm i.e. by more than 100%. Measurement of surface free energy as well as work of adhesion found that it increased with increased duration of ball milling. The crystallite was reduced from 36.22 nm to 23.01 nm for quartz and from 33.72 nm to 16.38 nm for mullite during ball milling to 60 h. % crystallinity reduced from 35% to 16% during 60 h of ball milling because of destruction of quartz and hematite crystals and the nano structured fly ash is found to be more amorphous. Surface of the nano structured fly ash has become more active as is evident from the FTIR studies. Morphological studies revealed that the surface of the nano structured fly ash is more uneven and rough and shape is irregular, as compared to fresh fly ash which are mostly spherical in shape.