Dr.Nadeem Iqbal - Academia.edu (original) (raw)

Papers by Dr.Nadeem Iqbal

International Journal of Engineering and Technology, 2014

In this novel research, aluminum silicate fibers were incorporated into ethylene propylene diene ... more In this novel research, aluminum silicate fibers were incorporated into ethylene propylene diene monomer (EPDM) rubber to fabricate ablative composites, achieve better ablation performance, and thermal endurance for ultrahigh temperature applications. Variant concentrations of ceramic fibers (CFs) were impregnated in the elastomeric matrix. Ablation testing of the composite specimens was carried out according to ASTM E285-08, in which oxyacetylene torch was used as a high temperature source. The obtained results showed that anti-ablation performance of the polymer composites was remarkably augmented with increasing fiber concentration in the polymer matrix. Thermal decomposition of the fabricated composites was diminished with the progressive incorporation of CFs in the EPDM matrix. Ultimate tensile strength, elongation at break, and modulus of elasticity were reduced due to the weak fiber to matrix interaction while Shore A rubber hardness was augmented with increasing fiber to matrix ratio. Voids formation & polymer pyrolysis of the ablated specimens, char reinforcement interaction, CFs dispersion in the polymer matrix, elemental analysis and fiber diameter measurement of the CF, and the compositional analysis of ablative composite were analyzed using scanning electron microscopy coupled with energy dispersive spectroscopy.

Journal of Applied Polymer Science, 2012

To enhance the ablation performance and mechanical strength of silicone rubber (SR), pristine mul... more To enhance the ablation performance and mechanical strength of silicone rubber (SR), pristine multiwalled carbon nanotubes (MWNTs) were dispersed in the polymer matrix using dispersion kneader and two roller mixing mill. Electrical resistivity (100-300 C) was reduced with increasing filler concentration in the host matrix due to the presence and even dispersion of the nanofiller in the rubber matrix. The SR nanocomposite (1 wt % filler contents) has 28% better thermal stability and 100% improvement in the ultimate tensile strength is achieved as compared with the pristine polymer matrix counterpart. Oxy-acetylene torch was used to evaluate the ablation rates, % char yield, and backface temperature evolution at the back facet of nanoablators during the flame exposure for a specific duration. Ablation performance of the fabricated ablative nanocomposites was enhanced with increasing nanotubes concentration in the polymer matrix. Thermal stability and heat quenching ability of the SR nanocomposites were gradually augmented with increasing filler loadings in the host matrix. Porous silica char, polymer pyrolysis, char composition, and uniform dispersion of MWNTs in the rubber matrix were also analyzed using scanning electron microscopy and energy dispersive spectroscopy. V

Desalination and Water Treatment, 2013

Woven Kevlar fabric supported polypropylene (PP)-thermoplastic polyurethane (TPU) blended microfi... more Woven Kevlar fabric supported polypropylene (PP)-thermoplastic polyurethane (TPU) blended microfiltration membranes were synthesized using thermally induced phase separation (TIPS) technique. Microporosity in the fabricated membranes was analyzed using scanning electron microscopy. The PP-TPU blending was confirmed through the Fourier transform infrared spectra of pure resins and blended polymer membranes. Surface roughness, pore geometry, and adhesion between the blended polymer and fabric were influenced with increasing TPU blending concentration in the PP solution. The proposed polymers were found compatible with each other and properly blended to form membranes; most importantly, the TPU helped to transform hydrophobic PP membrane into hydrophilic PP-TPU membrane. Water and methanol flux through the fabricated membranes were measured, and it was found that the permeation through the membranes depended upon the type of membrane.

Nanomaterials, 2016

In order to enhance salt rejection level and high pressure mechanical integrity, functionalized n... more In order to enhance salt rejection level and high pressure mechanical integrity, functionalized nanokaolin decorated multiwall carbon nanotubes (FNKM, 0-5 wt % loading) were incorporated into a cellulose acetate (CA) matrix using high temperature solution mixing methodology. Scanning electron microscopy (SEM), X-ray diffraction technique (XRD), thermo-gravimetric analyzer (TGA) and Fourier transform infrared spectrometer (FTIR) were used to characterize the prepared membranes. The obtained results revealed that with increasing FNKM concentration in the host polymeric matrix, composite membrane's structural, functional, thermal, water permeation/flux and salt rejection characteristics were also modified accordingly. Percent enhancement in salt rejection was increased around threefold by adding 5 wt % FNKM in CA.

In this novel research, aluminum silicate fibers were incorporated into ethylene propylene diene ... more In this novel research, aluminum silicate fibers were incorporated into ethylene propylene diene monomer (EPDM) rubber to fabricate ablative composites, achieve better ablation performance, and thermal endurance for ultrahigh temperature applications. Variant concentrations of ceramic fibers (CFs) were impregnated in the elastomeric matrix. Ablation testing of the composite specimens was carried out according to ASTM E285-08, in which oxyacetylene torch was used as a high temperature source. The obtained results showed that anti-ablation performance of the polymer composites was remarkably augmented with increasing fiber concentration in the polymer matrix. Thermal decomposition of the fabricated composites was diminished with the progressive incorporation of CFs in the EPDM matrix. Ultimate tensile strength, elongation at break, and modulus of elasticity were reduced due to the weak fiber to matrix interaction while Shore A rubber hardness was augmented with increasing fiber to matrix ratio. Voids formation & polymer pyrolysis of the ablated specimens, char reinforcement interaction, CFs dispersion in the polymer matrix, elemental analysis and fiber diameter measurement of the CF, and the compositional analysis of ablative composite were analyzed using scanning electron microscopy coupled with energy dispersive spectroscopy.

International Journal of Materials, Mechanics and Manufacturing

The performedresearch is used to explore the prospectiveinfluence of sodium montmorillonite (Na-M... more The performedresearch is used to explore the prospectiveinfluence of sodium montmorillonite (Na-MMT) on the high temperature ablation, thermal stability/conductivity and mechanical parameters of elastomeric composites. Ablation characteristics viz. (backface temperature rise, insulation index, and ablation rates)were amassed using oxyacetylene flame test. Thermal conductivity, thermal stability, ultimate tensile strength and elastomeric hardness were performed on domestically developed TC apparatus according ASTM E1225-99, TGA, UTM, and rubber hardness meter, respectively. The experimental data explored that with increasing Na-MMT contents in the acrylonitrile butadiene rubber, back-face temperature acclivity, linear ablation resistance, and radial ablation impedance were reduced by a factor of 95, 800, and 88%, correspondingly. Maximum filler content viz. 30% has efficiently improves thermal insulation character, tensile properties and elastomeric hardness of the fabricated specimens. Microscopic results showed microporosity generation during ablation that eventually enhanced the insulation character of the ablative specimens at high temperatures. In the view of the obtained results, well dispersed Na-MMT in NBR matrix is a good combination of high as well as low temperature insulation applications.

International Letters of Natural Sciences

Air pollution in Pakistan is causing damage to health, environment and quality of life. Air pollu... more Air pollution in Pakistan is causing damage to health, environment and quality of life. Air pollution in Pakistan is not effectively monitored due to heavy cost involved in setting up ground stations. However, Satellite remote sensing can effectively monitor the air pollution in terms of Aerosol Optical Depth (AOD) at regional as well as global level. However, algorithms used to derive AOD from different sensors have some inherited differences which can pose challenges in monitoring regional AOD at high temporal resolution using more than one sensor. Therefore, this study focuses on comparison of four major satellite based AOD products namely Moderate Resolution Imaging SpectroRadiometer (MODIS), Multi-angle Imaging SpectroRadiometer (MISR), Ozone Monitoring Instrument multiwavelength (OMI) aerosol product and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) with the ground based AErosol RObotic NETwork (AERONET) AOD which is only available from Lahore and...

ABSTRACT In order to enhance the thermal insulation/stability and mechanical properties of the st... more ABSTRACT In order to enhance the thermal insulation/stability and mechanical properties of the styrene butadiene rubber, four progressive concentrations of activated nanokaolinite were impregnated using conventional dispersion kneader and two roller mixing mill followed by hot isostatic compression molding to fabricate polymer nanocomposites. Nanoclay activation, particle size and crystallinity were confirmed performing FTIR, SEM/EDS, and XRD techniques. Thermal conductivity and thermal impedance of the composite specimens were carried out using ASTM standards. Thermal transport through the polymer nanocomposite was restricted with increasing nanoclay to matrix ratio and as a result thermal conductivity was reduced 41% while thermal impedance was elevated 30%. Thermal stability and endothermic capability were augmented with increasing filler concentration in the host matrix. DSC study reveals that the phase transition temperatures and their corresponding enthalpies were remarkably influenced with the filler incorporation into the polymer matrix. The ultimate tensile strength of the nanocomposites was elevated 83%, elongation at break 24% and modulus of elasticity 67% with the peak layered silicate mineral introduction into the SBR matrix. The morphological and compositional analyses of the thermal transport tested specimens were executed using scanning electron microscopy and energy dispersive spectroscopy, respectively.

Journal of Applied Polymer Science, 2015

Variant concentrations of phenol formaldehyde resin were introduced into Acrylonitrile butadiene ... more Variant concentrations of phenol formaldehyde resin were introduced into Acrylonitrile butadiene rubber (NBR) to investigate the high temperature ablation, thermal and mechanical properties of polymer-polymer composites. Ablation rates, percent char yields and insulation indexes were reduced, while the thermal conduction through the fabricated ablative composites was augmented with increasing phenolic resin blending concentration (PRBC) in the NBR matrix during the oxy-acetylene flame ablation test according to the ASTM E285-08. Thermal decomposition of the composite specimens was revealed thermal stability enhancement with increasing PRBC in the rubber matrix. Tensile strength and Shore A hardness of the ablators were progressed meanwhile the elongation at break suffered with increasing PRBC in the host matrix. Char morphology, polymer pyrolysis, char composition and polymer-polymer char interaction were analyzed using charred sample’s photographs and scanning electron microscopy c...

International Journal of Engineering and Technology, 2014

The effect of variant concentrations of multiwalled carbon nanotubes (MWCNTs) on the thermal tran... more The effect of variant concentrations of multiwalled carbon nanotubes (MWCNTs) on the thermal transport, phase transition temperatures, and mechanical properties of polyisoprene rubber have been studied in the present novel research. MWCNTs were incorporated into the natural rubber (NR) using shear mixing techniques. Microscopy results reveal the uniform dispersion of the nanotubes within the polymer matrix. Thermal conductivity and thermal insulation of the fabricated composites were evaluated according to ASTM standards. Thermal transport through the nanocomposite specimens is restricted by the nanotubes network developed within the polymer matrix. Differential scanning calorimetric study elucidates the reduction of crystallization (T c) and glass transition (T g) temperatures, while melting temperature (T m) enhances with increasing the nanotubes concentration in the rubber matrix. A remarkable enhancement in mechanical properties of MWCNT/NR composites was observed with increasing nanotube to matrix ratio. Index Terms-Multiwalled carbon nanotubes, thermal transport properties, nanocomposite, thermal stability, phase transition temperatures.

Journal of Materials Science & Technology, 2015

ABSTRACT Graphene has become a worldwide admired material among researchers and scientists equall... more ABSTRACT Graphene has become a worldwide admired material among researchers and scientists equally due to its unique richness in mechanical strength, electrical conductivity, optical and thermal properties. Researchers have explored that the composite materials based on graphene and metal/metal oxide nanostructures possess excellent potential for energy storage technologies. In particular, supercapacitors based on such composite materials have engrossed the extreme interest of researchers for its rapid charging/discharging time, safe operation and longer cyclic constancy. Till now, several fabrication techniques for composite materials and their energy storage applications have been explored. Here, specially, we have concentrated on the hottest research progress for the fabrication of graphene oxide and metal/metal oxide nanocomposites. We also emphasized on the characteristics and properties of supercapacitors fabricated using these composite materials. Moreover, our study is focused on the specific capacitance and cyclic stability of various composites to haul out the most efficient material for supercapacitor applications.

Journal of Thermal Analysis and Calorimetry, 2013

ABSTRACT Pristine multiwalled carbon nanotubes (MWCNTs) were impregnated in acrylonitrile butadie... more ABSTRACT Pristine multiwalled carbon nanotubes (MWCNTs) were impregnated in acrylonitrile butadiene rubber (NBR) using internal dispersion kneader and two roller mixing mill to investigate the effects of various nanotubes concentrations on the thermal transport/stability of rubber nanocomposites. Thermal conductivity (λ N) and thermal impedance (R) measurement experimental setups were established according to ASTM E1225-99 and D5470-03. The 1 mass % addition of MWCNTs in the polymer matrix has enhanced R up to 44 % and reduced λ N of the rubber nanocomposite up to 40 % compare to the base composite formulation. Thermal decomposition and differential thermal analyses of the fabricated composite specimens simulate that the thermal stability and endothermic capability are augmented with increasing the nanotubes contents in the host matrix. The progressive incorporations of carbon nanotubes into the rubber matrix have efficiently influenced the composite specimens regarding glass transition, crystallization, and melting temperatures including their specific enthalpies. Scanning electron microscopy along with the energy dispersive spectroscopy was used to analyze MWCNTs dispersion in NBR matrix, compositional analysis of the nanocomposite, and impregnated nanotubes.

Journal of Reinforced Plastics and Composites, 2013

ABSTRACT In order to analyze the effect of multiwalled carbon nanotubes on the thermal transport/... more ABSTRACT In order to analyze the effect of multiwalled carbon nanotubes on the thermal transport/stability characteristics of styrene butadiene rubber, five diverse loadings of multiwalled carbon nanotubes were impregnated in the rubber matrix using dispersion kneader and two roller mixing mill. Thermal conductivity and thermal impedance of the nanocomposite specimens were evaluated according to ASTM E1225-99 and D5470-03. It was observed that the thermal conductivity was reduced up to 79% while thermal impedance of the polymer nanocomposite was improved up to 390% at 523 K with 1 wt% impregnation of nanotubes into the base composite formulation. Thermal stability of the polymer nanocomposite was augmented up to 6%, with the utmost incorporation of the nanotubes. Glass transition and crystallization temperatures were diminished, while the onset and peak melting temperatures were increased with increasing filler to matrix ratio. The percent crystallinity of the nanocomposites has been augmented up to 5%, with 1 wt% incorporation of multiwalled carbon nanotubes into the host matrix. Scanning electron microscopy along with energy dispersive X-ray spectroscopy was used to examine the multiwalled carbon nanotubes dispersion in the rubber matrix, for surface analysis of the post-thermally tested composite specimens and for their compositional analysis.

Journal of Physics: Conference Series, 2013

ABSTRACT The dielectric, electric and thermal properties of carboxylic functionalized multiwalled... more ABSTRACT The dielectric, electric and thermal properties of carboxylic functionalized multiwalled carbon nanotubes (F-MWCNT) incorporated into the polydimethylsiloxane (PDMS) were evaluated to determine their potential in the field of electronic materials. Carboxylic functionalization of the pristine multi walled carbon tubes (Ps-MWCNT) was confirmed through Fourier transform infrared spectroscopy, X-ray diffraction patterns for both Ps-MWCNTs and F-MWCNTs elaborated that crystalline behavior did not change with carboxylic moieties. Thermogravimetric and differential thermal analyses were performed to elucidate the thermal stability with increasing weight % addition of F-MWCNTs in the polymer matrix. Crystallization/glass transition / melting temperatures were evaluated using differential scanning calorimeter and it was observed that glass transition and crystallization temperatures were diminished while temperatures of first and second melting transitions were progressed with increasing F-MWCNT concentration in the PDMS matrix. Scanning electron microscopy and energy dispersive x-ray spectroscopy were carried out to confirm the morphology, functionalization, and uniform dispersion of F-MWCNTs in the polymer matrix. Electrical resistivity at temperature range (100-300°C), dielectric loss (tanδ) and dielectric parameters (epsilon/ epsilon//) were measured in the frequency range (1MHz-3GHz). The measured data simulate that the aforementioned properties were influenced by increasing filler contents in the polymer matrix because of the high polarization of conductive F-MWCNTs at the reinforcement/polymer interface.

Journal of Applied Polymer Science, 2013

ABSTRACT Variant concentrations of ceramic fibers (CerFs) were incorporated into acrylonitrile bu... more ABSTRACT Variant concentrations of ceramic fibers (CerFs) were incorporated into acrylonitrile butadiene rubber (NBR) to fabricate elastomeric ablative composites for ultrahigh temperature applications. The CerFs introduction into the polymer matrix has enhanced the ablation resistance up to 59% and successfully reduced the backface temperature of the polymer composite up to 110oC during the ultrahigh temperature ablation investigation. Thermal decomposition of the polymer composites was diminished up to 10% with increasing fiber concentration in the rubber matrix. Thermal conductivity was reduced equal to 63% while thermal impedance was enhanced up to 84% with the utmost fiber incorporation into the NBR matrix. The CerFs have adversely affected the mechanical properties of NBR matrix due to their brittle/inert nature and weak interface bonding with the host matrix. Scanning electron microscopy along with the energy dispersive x‐ray spectroscopy was used to examine the ablated specimens and the fiber dispersion within the host matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4392–4400, 2013

Journal of Applied Polymer Science, 2013

ABSTRACT Novel membranes were fabricated with woven Kevlar fabric sandwiched between two isotacti... more ABSTRACT Novel membranes were fabricated with woven Kevlar fabric sandwiched between two isotactic polypropylene layers and with various concentrations of adipic acid as the nucleating agent (NA). A thermally induced phase‐separation dip‐coating method was adopted to generate and control the microporosity in the developed membranes. Scanning electron microscopy and atomic force microscopy were used to directly observe and confirm the morphologies and micropores in the fabricated membranes. We observed that with an increase in the concentration of the NA in the fabricated membranes, both the pore density and pore size decreased. The average pore sizes were observed to be 1.686, 0.925, 0.372 μm, respectively, for 0.3, 0.5, and 0.7 pphr concentrations of the NA, respectively. The flux characteristics of the prepared membranes were also tested at various pressures with water, methanol, ethanol, and isopropyl alcohol as solvents in a custom‐made filtration cell. The results obtained indicate the dependence of the flux on the type of solvent, pressure, and membrane. The flux for the solvents was observed to decrease with increasing concentrations of NA in the prepared membranes and was attributed to the decrease in the pore density and pore size. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2821–2831, 2013

Applied Surface Science, 2013

The present investigation reports the fabrication of thin film composite nanofiltration (TFC-NF) ... more The present investigation reports the fabrication of thin film composite nanofiltration (TFC-NF) membranes using interfacial polymerization technique for desalination. Ethylene diamine (EDA) and terephthaloyl chloride (TPC) were employed as aqueous and organic phase monomers, respectively to develop polyamide thin layer on the surface of Celgard 2400. The prepared membranes were characterized through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The molecular weight cutoff of TFC-NF membranes was estimated to be below 342 Da using dextrose, sucrose and raffinose solutions. A low cost dead end NF Cell was designed and manufactured domestically to conduct permeation experiments. The effect of different reaction conditions including concentration of monomers, residence time in each monomer and curing temperature on the membrane performance (water flux and MgCl 2 rejection) was also studied. The water flux was augmented linearly at higher applied pressure while MgCl 2 rejection was remained constant. The obtained water flux and MgCl 2 rejection were measured 33 L/m 2 h and 90%, respectively at 7 bar applied pressure. Beside this, membrane stability was analyzed, which confirmed the excellent constancy of ethanol and n-hexane fluxes even after an extended period. Hagen-Poiseuille equation was applied to estimate the TFC-NF membrane pore size ∼0.45 nm.

ABSTRACT Pristine multiwalled carbon nanotubes (MWCNTs) along with the silane coupling agent were... more ABSTRACT Pristine multiwalled carbon nanotubes (MWCNTs) along with the silane coupling agent were incorporated into ethylene propylene diene monomer (EPDM) rubber using dispersion kneader and two roller mixing mill to fabricate ablative nanocomposites used in hyperthermal environment encountered by space vehicle or rocket motor. The 1 wt% addition of MWCNTS in the rubber matrix has remarkably reduced the backface temperature elevation up to 40°C during the ablation testing of the ablatives. The linear and mass ablation resistances have been diminished up to 125% and 74%, respectively, while insulation indexes at 110°C backface temperature of the composite specimens have been elevated up to 51% with increasing the MWCNTS incorporation into the EPDM matrix. Thermal stability and heat absorbance capability of the polymer composites were progressed with increasing the filler to matrix ratio. Thermal conductivity/impedance of the ablatives have been conducted according to the ASTM E1225‐99 and D5470‐03, respectively to execute the effect of MWCNTs concentration on the thermal transport characteristics of the tested specimens. Tensile strength of the composite specimen was augmented up to 42% with increasing nanotubes to polymer ratio. Evenly dispersed MWCNTs in the polymer matrix, polymer pyrolysis, and voids formation in the ablated samples can be scrutinized in the scanning electron microscopy images. POLYM. ENG. SCI., 54:255–263, 2014. © 2013 Society of Plastics Engineers

International Journal of Engineering and Technology, 2014

In this novel research, aluminum silicate fibers were incorporated into ethylene propylene diene ... more In this novel research, aluminum silicate fibers were incorporated into ethylene propylene diene monomer (EPDM) rubber to fabricate ablative composites, achieve better ablation performance, and thermal endurance for ultrahigh temperature applications. Variant concentrations of ceramic fibers (CFs) were impregnated in the elastomeric matrix. Ablation testing of the composite specimens was carried out according to ASTM E285-08, in which oxyacetylene torch was used as a high temperature source. The obtained results showed that anti-ablation performance of the polymer composites was remarkably augmented with increasing fiber concentration in the polymer matrix. Thermal decomposition of the fabricated composites was diminished with the progressive incorporation of CFs in the EPDM matrix. Ultimate tensile strength, elongation at break, and modulus of elasticity were reduced due to the weak fiber to matrix interaction while Shore A rubber hardness was augmented with increasing fiber to matrix ratio. Voids formation & polymer pyrolysis of the ablated specimens, char reinforcement interaction, CFs dispersion in the polymer matrix, elemental analysis and fiber diameter measurement of the CF, and the compositional analysis of ablative composite were analyzed using scanning electron microscopy coupled with energy dispersive spectroscopy.

Journal of Applied Polymer Science, 2012

To enhance the ablation performance and mechanical strength of silicone rubber (SR), pristine mul... more To enhance the ablation performance and mechanical strength of silicone rubber (SR), pristine multiwalled carbon nanotubes (MWNTs) were dispersed in the polymer matrix using dispersion kneader and two roller mixing mill. Electrical resistivity (100-300 C) was reduced with increasing filler concentration in the host matrix due to the presence and even dispersion of the nanofiller in the rubber matrix. The SR nanocomposite (1 wt % filler contents) has 28% better thermal stability and 100% improvement in the ultimate tensile strength is achieved as compared with the pristine polymer matrix counterpart. Oxy-acetylene torch was used to evaluate the ablation rates, % char yield, and backface temperature evolution at the back facet of nanoablators during the flame exposure for a specific duration. Ablation performance of the fabricated ablative nanocomposites was enhanced with increasing nanotubes concentration in the polymer matrix. Thermal stability and heat quenching ability of the SR nanocomposites were gradually augmented with increasing filler loadings in the host matrix. Porous silica char, polymer pyrolysis, char composition, and uniform dispersion of MWNTs in the rubber matrix were also analyzed using scanning electron microscopy and energy dispersive spectroscopy. V

Desalination and Water Treatment, 2013

Woven Kevlar fabric supported polypropylene (PP)-thermoplastic polyurethane (TPU) blended microfi... more Woven Kevlar fabric supported polypropylene (PP)-thermoplastic polyurethane (TPU) blended microfiltration membranes were synthesized using thermally induced phase separation (TIPS) technique. Microporosity in the fabricated membranes was analyzed using scanning electron microscopy. The PP-TPU blending was confirmed through the Fourier transform infrared spectra of pure resins and blended polymer membranes. Surface roughness, pore geometry, and adhesion between the blended polymer and fabric were influenced with increasing TPU blending concentration in the PP solution. The proposed polymers were found compatible with each other and properly blended to form membranes; most importantly, the TPU helped to transform hydrophobic PP membrane into hydrophilic PP-TPU membrane. Water and methanol flux through the fabricated membranes were measured, and it was found that the permeation through the membranes depended upon the type of membrane.

Nanomaterials, 2016

In order to enhance salt rejection level and high pressure mechanical integrity, functionalized n... more In order to enhance salt rejection level and high pressure mechanical integrity, functionalized nanokaolin decorated multiwall carbon nanotubes (FNKM, 0-5 wt % loading) were incorporated into a cellulose acetate (CA) matrix using high temperature solution mixing methodology. Scanning electron microscopy (SEM), X-ray diffraction technique (XRD), thermo-gravimetric analyzer (TGA) and Fourier transform infrared spectrometer (FTIR) were used to characterize the prepared membranes. The obtained results revealed that with increasing FNKM concentration in the host polymeric matrix, composite membrane's structural, functional, thermal, water permeation/flux and salt rejection characteristics were also modified accordingly. Percent enhancement in salt rejection was increased around threefold by adding 5 wt % FNKM in CA.

In this novel research, aluminum silicate fibers were incorporated into ethylene propylene diene ... more In this novel research, aluminum silicate fibers were incorporated into ethylene propylene diene monomer (EPDM) rubber to fabricate ablative composites, achieve better ablation performance, and thermal endurance for ultrahigh temperature applications. Variant concentrations of ceramic fibers (CFs) were impregnated in the elastomeric matrix. Ablation testing of the composite specimens was carried out according to ASTM E285-08, in which oxyacetylene torch was used as a high temperature source. The obtained results showed that anti-ablation performance of the polymer composites was remarkably augmented with increasing fiber concentration in the polymer matrix. Thermal decomposition of the fabricated composites was diminished with the progressive incorporation of CFs in the EPDM matrix. Ultimate tensile strength, elongation at break, and modulus of elasticity were reduced due to the weak fiber to matrix interaction while Shore A rubber hardness was augmented with increasing fiber to matrix ratio. Voids formation & polymer pyrolysis of the ablated specimens, char reinforcement interaction, CFs dispersion in the polymer matrix, elemental analysis and fiber diameter measurement of the CF, and the compositional analysis of ablative composite were analyzed using scanning electron microscopy coupled with energy dispersive spectroscopy.

International Journal of Materials, Mechanics and Manufacturing

The performedresearch is used to explore the prospectiveinfluence of sodium montmorillonite (Na-M... more The performedresearch is used to explore the prospectiveinfluence of sodium montmorillonite (Na-MMT) on the high temperature ablation, thermal stability/conductivity and mechanical parameters of elastomeric composites. Ablation characteristics viz. (backface temperature rise, insulation index, and ablation rates)were amassed using oxyacetylene flame test. Thermal conductivity, thermal stability, ultimate tensile strength and elastomeric hardness were performed on domestically developed TC apparatus according ASTM E1225-99, TGA, UTM, and rubber hardness meter, respectively. The experimental data explored that with increasing Na-MMT contents in the acrylonitrile butadiene rubber, back-face temperature acclivity, linear ablation resistance, and radial ablation impedance were reduced by a factor of 95, 800, and 88%, correspondingly. Maximum filler content viz. 30% has efficiently improves thermal insulation character, tensile properties and elastomeric hardness of the fabricated specimens. Microscopic results showed microporosity generation during ablation that eventually enhanced the insulation character of the ablative specimens at high temperatures. In the view of the obtained results, well dispersed Na-MMT in NBR matrix is a good combination of high as well as low temperature insulation applications.

International Letters of Natural Sciences

Air pollution in Pakistan is causing damage to health, environment and quality of life. Air pollu... more Air pollution in Pakistan is causing damage to health, environment and quality of life. Air pollution in Pakistan is not effectively monitored due to heavy cost involved in setting up ground stations. However, Satellite remote sensing can effectively monitor the air pollution in terms of Aerosol Optical Depth (AOD) at regional as well as global level. However, algorithms used to derive AOD from different sensors have some inherited differences which can pose challenges in monitoring regional AOD at high temporal resolution using more than one sensor. Therefore, this study focuses on comparison of four major satellite based AOD products namely Moderate Resolution Imaging SpectroRadiometer (MODIS), Multi-angle Imaging SpectroRadiometer (MISR), Ozone Monitoring Instrument multiwavelength (OMI) aerosol product and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) with the ground based AErosol RObotic NETwork (AERONET) AOD which is only available from Lahore and...

ABSTRACT In order to enhance the thermal insulation/stability and mechanical properties of the st... more ABSTRACT In order to enhance the thermal insulation/stability and mechanical properties of the styrene butadiene rubber, four progressive concentrations of activated nanokaolinite were impregnated using conventional dispersion kneader and two roller mixing mill followed by hot isostatic compression molding to fabricate polymer nanocomposites. Nanoclay activation, particle size and crystallinity were confirmed performing FTIR, SEM/EDS, and XRD techniques. Thermal conductivity and thermal impedance of the composite specimens were carried out using ASTM standards. Thermal transport through the polymer nanocomposite was restricted with increasing nanoclay to matrix ratio and as a result thermal conductivity was reduced 41% while thermal impedance was elevated 30%. Thermal stability and endothermic capability were augmented with increasing filler concentration in the host matrix. DSC study reveals that the phase transition temperatures and their corresponding enthalpies were remarkably influenced with the filler incorporation into the polymer matrix. The ultimate tensile strength of the nanocomposites was elevated 83%, elongation at break 24% and modulus of elasticity 67% with the peak layered silicate mineral introduction into the SBR matrix. The morphological and compositional analyses of the thermal transport tested specimens were executed using scanning electron microscopy and energy dispersive spectroscopy, respectively.

Journal of Applied Polymer Science, 2015

Variant concentrations of phenol formaldehyde resin were introduced into Acrylonitrile butadiene ... more Variant concentrations of phenol formaldehyde resin were introduced into Acrylonitrile butadiene rubber (NBR) to investigate the high temperature ablation, thermal and mechanical properties of polymer-polymer composites. Ablation rates, percent char yields and insulation indexes were reduced, while the thermal conduction through the fabricated ablative composites was augmented with increasing phenolic resin blending concentration (PRBC) in the NBR matrix during the oxy-acetylene flame ablation test according to the ASTM E285-08. Thermal decomposition of the composite specimens was revealed thermal stability enhancement with increasing PRBC in the rubber matrix. Tensile strength and Shore A hardness of the ablators were progressed meanwhile the elongation at break suffered with increasing PRBC in the host matrix. Char morphology, polymer pyrolysis, char composition and polymer-polymer char interaction were analyzed using charred sample’s photographs and scanning electron microscopy c...

International Journal of Engineering and Technology, 2014

The effect of variant concentrations of multiwalled carbon nanotubes (MWCNTs) on the thermal tran... more The effect of variant concentrations of multiwalled carbon nanotubes (MWCNTs) on the thermal transport, phase transition temperatures, and mechanical properties of polyisoprene rubber have been studied in the present novel research. MWCNTs were incorporated into the natural rubber (NR) using shear mixing techniques. Microscopy results reveal the uniform dispersion of the nanotubes within the polymer matrix. Thermal conductivity and thermal insulation of the fabricated composites were evaluated according to ASTM standards. Thermal transport through the nanocomposite specimens is restricted by the nanotubes network developed within the polymer matrix. Differential scanning calorimetric study elucidates the reduction of crystallization (T c) and glass transition (T g) temperatures, while melting temperature (T m) enhances with increasing the nanotubes concentration in the rubber matrix. A remarkable enhancement in mechanical properties of MWCNT/NR composites was observed with increasing nanotube to matrix ratio. Index Terms-Multiwalled carbon nanotubes, thermal transport properties, nanocomposite, thermal stability, phase transition temperatures.

Journal of Materials Science & Technology, 2015

ABSTRACT Graphene has become a worldwide admired material among researchers and scientists equall... more ABSTRACT Graphene has become a worldwide admired material among researchers and scientists equally due to its unique richness in mechanical strength, electrical conductivity, optical and thermal properties. Researchers have explored that the composite materials based on graphene and metal/metal oxide nanostructures possess excellent potential for energy storage technologies. In particular, supercapacitors based on such composite materials have engrossed the extreme interest of researchers for its rapid charging/discharging time, safe operation and longer cyclic constancy. Till now, several fabrication techniques for composite materials and their energy storage applications have been explored. Here, specially, we have concentrated on the hottest research progress for the fabrication of graphene oxide and metal/metal oxide nanocomposites. We also emphasized on the characteristics and properties of supercapacitors fabricated using these composite materials. Moreover, our study is focused on the specific capacitance and cyclic stability of various composites to haul out the most efficient material for supercapacitor applications.

Journal of Thermal Analysis and Calorimetry, 2013

ABSTRACT Pristine multiwalled carbon nanotubes (MWCNTs) were impregnated in acrylonitrile butadie... more ABSTRACT Pristine multiwalled carbon nanotubes (MWCNTs) were impregnated in acrylonitrile butadiene rubber (NBR) using internal dispersion kneader and two roller mixing mill to investigate the effects of various nanotubes concentrations on the thermal transport/stability of rubber nanocomposites. Thermal conductivity (λ N) and thermal impedance (R) measurement experimental setups were established according to ASTM E1225-99 and D5470-03. The 1 mass % addition of MWCNTs in the polymer matrix has enhanced R up to 44 % and reduced λ N of the rubber nanocomposite up to 40 % compare to the base composite formulation. Thermal decomposition and differential thermal analyses of the fabricated composite specimens simulate that the thermal stability and endothermic capability are augmented with increasing the nanotubes contents in the host matrix. The progressive incorporations of carbon nanotubes into the rubber matrix have efficiently influenced the composite specimens regarding glass transition, crystallization, and melting temperatures including their specific enthalpies. Scanning electron microscopy along with the energy dispersive spectroscopy was used to analyze MWCNTs dispersion in NBR matrix, compositional analysis of the nanocomposite, and impregnated nanotubes.

Journal of Reinforced Plastics and Composites, 2013

ABSTRACT In order to analyze the effect of multiwalled carbon nanotubes on the thermal transport/... more ABSTRACT In order to analyze the effect of multiwalled carbon nanotubes on the thermal transport/stability characteristics of styrene butadiene rubber, five diverse loadings of multiwalled carbon nanotubes were impregnated in the rubber matrix using dispersion kneader and two roller mixing mill. Thermal conductivity and thermal impedance of the nanocomposite specimens were evaluated according to ASTM E1225-99 and D5470-03. It was observed that the thermal conductivity was reduced up to 79% while thermal impedance of the polymer nanocomposite was improved up to 390% at 523 K with 1 wt% impregnation of nanotubes into the base composite formulation. Thermal stability of the polymer nanocomposite was augmented up to 6%, with the utmost incorporation of the nanotubes. Glass transition and crystallization temperatures were diminished, while the onset and peak melting temperatures were increased with increasing filler to matrix ratio. The percent crystallinity of the nanocomposites has been augmented up to 5%, with 1 wt% incorporation of multiwalled carbon nanotubes into the host matrix. Scanning electron microscopy along with energy dispersive X-ray spectroscopy was used to examine the multiwalled carbon nanotubes dispersion in the rubber matrix, for surface analysis of the post-thermally tested composite specimens and for their compositional analysis.

Journal of Physics: Conference Series, 2013

ABSTRACT The dielectric, electric and thermal properties of carboxylic functionalized multiwalled... more ABSTRACT The dielectric, electric and thermal properties of carboxylic functionalized multiwalled carbon nanotubes (F-MWCNT) incorporated into the polydimethylsiloxane (PDMS) were evaluated to determine their potential in the field of electronic materials. Carboxylic functionalization of the pristine multi walled carbon tubes (Ps-MWCNT) was confirmed through Fourier transform infrared spectroscopy, X-ray diffraction patterns for both Ps-MWCNTs and F-MWCNTs elaborated that crystalline behavior did not change with carboxylic moieties. Thermogravimetric and differential thermal analyses were performed to elucidate the thermal stability with increasing weight % addition of F-MWCNTs in the polymer matrix. Crystallization/glass transition / melting temperatures were evaluated using differential scanning calorimeter and it was observed that glass transition and crystallization temperatures were diminished while temperatures of first and second melting transitions were progressed with increasing F-MWCNT concentration in the PDMS matrix. Scanning electron microscopy and energy dispersive x-ray spectroscopy were carried out to confirm the morphology, functionalization, and uniform dispersion of F-MWCNTs in the polymer matrix. Electrical resistivity at temperature range (100-300°C), dielectric loss (tanδ) and dielectric parameters (epsilon/ epsilon//) were measured in the frequency range (1MHz-3GHz). The measured data simulate that the aforementioned properties were influenced by increasing filler contents in the polymer matrix because of the high polarization of conductive F-MWCNTs at the reinforcement/polymer interface.

Journal of Applied Polymer Science, 2013

ABSTRACT Variant concentrations of ceramic fibers (CerFs) were incorporated into acrylonitrile bu... more ABSTRACT Variant concentrations of ceramic fibers (CerFs) were incorporated into acrylonitrile butadiene rubber (NBR) to fabricate elastomeric ablative composites for ultrahigh temperature applications. The CerFs introduction into the polymer matrix has enhanced the ablation resistance up to 59% and successfully reduced the backface temperature of the polymer composite up to 110oC during the ultrahigh temperature ablation investigation. Thermal decomposition of the polymer composites was diminished up to 10% with increasing fiber concentration in the rubber matrix. Thermal conductivity was reduced equal to 63% while thermal impedance was enhanced up to 84% with the utmost fiber incorporation into the NBR matrix. The CerFs have adversely affected the mechanical properties of NBR matrix due to their brittle/inert nature and weak interface bonding with the host matrix. Scanning electron microscopy along with the energy dispersive x‐ray spectroscopy was used to examine the ablated specimens and the fiber dispersion within the host matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4392–4400, 2013

Journal of Applied Polymer Science, 2013

ABSTRACT Novel membranes were fabricated with woven Kevlar fabric sandwiched between two isotacti... more ABSTRACT Novel membranes were fabricated with woven Kevlar fabric sandwiched between two isotactic polypropylene layers and with various concentrations of adipic acid as the nucleating agent (NA). A thermally induced phase‐separation dip‐coating method was adopted to generate and control the microporosity in the developed membranes. Scanning electron microscopy and atomic force microscopy were used to directly observe and confirm the morphologies and micropores in the fabricated membranes. We observed that with an increase in the concentration of the NA in the fabricated membranes, both the pore density and pore size decreased. The average pore sizes were observed to be 1.686, 0.925, 0.372 μm, respectively, for 0.3, 0.5, and 0.7 pphr concentrations of the NA, respectively. The flux characteristics of the prepared membranes were also tested at various pressures with water, methanol, ethanol, and isopropyl alcohol as solvents in a custom‐made filtration cell. The results obtained indicate the dependence of the flux on the type of solvent, pressure, and membrane. The flux for the solvents was observed to decrease with increasing concentrations of NA in the prepared membranes and was attributed to the decrease in the pore density and pore size. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2821–2831, 2013

Applied Surface Science, 2013

The present investigation reports the fabrication of thin film composite nanofiltration (TFC-NF) ... more The present investigation reports the fabrication of thin film composite nanofiltration (TFC-NF) membranes using interfacial polymerization technique for desalination. Ethylene diamine (EDA) and terephthaloyl chloride (TPC) were employed as aqueous and organic phase monomers, respectively to develop polyamide thin layer on the surface of Celgard 2400. The prepared membranes were characterized through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The molecular weight cutoff of TFC-NF membranes was estimated to be below 342 Da using dextrose, sucrose and raffinose solutions. A low cost dead end NF Cell was designed and manufactured domestically to conduct permeation experiments. The effect of different reaction conditions including concentration of monomers, residence time in each monomer and curing temperature on the membrane performance (water flux and MgCl 2 rejection) was also studied. The water flux was augmented linearly at higher applied pressure while MgCl 2 rejection was remained constant. The obtained water flux and MgCl 2 rejection were measured 33 L/m 2 h and 90%, respectively at 7 bar applied pressure. Beside this, membrane stability was analyzed, which confirmed the excellent constancy of ethanol and n-hexane fluxes even after an extended period. Hagen-Poiseuille equation was applied to estimate the TFC-NF membrane pore size ∼0.45 nm.

ABSTRACT Pristine multiwalled carbon nanotubes (MWCNTs) along with the silane coupling agent were... more ABSTRACT Pristine multiwalled carbon nanotubes (MWCNTs) along with the silane coupling agent were incorporated into ethylene propylene diene monomer (EPDM) rubber using dispersion kneader and two roller mixing mill to fabricate ablative nanocomposites used in hyperthermal environment encountered by space vehicle or rocket motor. The 1 wt% addition of MWCNTS in the rubber matrix has remarkably reduced the backface temperature elevation up to 40°C during the ablation testing of the ablatives. The linear and mass ablation resistances have been diminished up to 125% and 74%, respectively, while insulation indexes at 110°C backface temperature of the composite specimens have been elevated up to 51% with increasing the MWCNTS incorporation into the EPDM matrix. Thermal stability and heat absorbance capability of the polymer composites were progressed with increasing the filler to matrix ratio. Thermal conductivity/impedance of the ablatives have been conducted according to the ASTM E1225‐99 and D5470‐03, respectively to execute the effect of MWCNTs concentration on the thermal transport characteristics of the tested specimens. Tensile strength of the composite specimen was augmented up to 42% with increasing nanotubes to polymer ratio. Evenly dispersed MWCNTs in the polymer matrix, polymer pyrolysis, and voids formation in the ablated samples can be scrutinized in the scanning electron microscopy images. POLYM. ENG. SCI., 54:255–263, 2014. © 2013 Society of Plastics Engineers