Sadia Sagar Iqbal

Synergistic effect of Chitosan-Zinc Oxide Hybrid Nanoparticles on antibiofouling and water disinfection of mixed matrix polyethersulfone nanocomposite membranes

Antifouling polyethersulfone (PES) membranes for water disinfection were fabricated by incorporating varying concentrations of carbohydrate polymer chitosan and Zinc oxide hybrid nanoparticles (CS-ZnO HNPS). The CS-ZnO HNPS were prepared using chemical precipitation method and were characterized using SEM, XRD and FTIR. The membranes were then fabricated by incorporating nanoparticles of CS-ZnO HNPS with three different concentrations of 5%, 10% and 15% w/w in the casting solution of PES through phase inversion method. The influence of nano-sized CS-ZnO HNPS on the properties of PES was characterized to study morphology, contact angle, water retention, surface roughness and permeability flux. The membranes with the maximum concentrations of 15% HNPS resulted in larger mean pore sizes and lowest contact angle value as compare to the pristine PES membrane. The prepared membranes exhibited significant water permeability, hydrophilicity and prevention against microbial fouling. The prepared membranes were observed to have significant antibacterial as well as antifungal properties due to the synergistic effect of chitosan and ZnO against both bacteria of the type of S. Aureus, B. Cereus, E. coli, and fungi such as S. typhi, A. fumigatus and F. solani.

Ablation, thermal stability/transport/phase transition study of carbon nanofiber-reinforced elastomeric nanocomposites

Novelty of presented research is focused on ablation and thermomechanical characteristics of various loadings of carbon nanofibers (CNFs) of polyisoprene elastomer (PR). Conventional method (banbury disperser with open mixing mill) is applied to complete fabrication process of CNF-reinforced elastomeric nanocomposites. Scanning electron micrographs confirm the proper distribution of CNFs within the elastomeric host matrix. The successful incorporation of CNFs into PR has reduced the back-face temperature and increased the ablation resistance CNF/PR elastomeric nanocomposite in front of ultrahigh temperature (oxyacetylene flame exposure). Carbon nanofiber network with the elastomeric chain restricts the thermal transport within the CNF/PR nanocomposite specimens. The synergistic effect of CNFs on crystallization, glass transition, melting temperatures (Tm) of PR elastomeric nanocomposites is studied. Mechanical properties of PR are effectively enhanced by the impregnation of CNFs in the elastomeric nanocomposites.

Thermogravimetric, differential scanning calorimetric, and experimental thermal transport study of functionalized nanokaolinite-doped elastomeric nanocomposites

A simple technique to synthesize and functionalize kaolinite nanoparticles having analogous shape and size in single step using layered silicate microclay as starting material is presented. The morphology, composition, and functionalization study of the activated nanokaolinite were determined by scanning electron microscopy/energy-dispersive spectroscopy, atomic-force microscope, and Fourier transform infrared spectroscopy, correspondingly. Various concentrations of activated nanokaolinite were doped in acrylonitrile butadiene rubber (NBR) by conventional industrial elastomeric mixing techniques to fabricate composite specimens. The accumulated data simulated that the thermal conductivity was diminished 92xa0% by increasing 15xa0mass% filler loading in the polymer matrix. Thermogravimetric analyzer showed that thermal stability and heat-absorbing capability were remarkably augmented by increasing activated nanokaolinite concentration in the NBR base formulation. Differential scanning calorimetric study revealed that glass transition and crystallization temperatures were reduced, whereas first and second melting phase temperatures were enhanced by increasing filler-to-host matrix ratio. Tensile strength, elongation at break, and elastic modulus at 200xa0% elongation were remarkably improved to a level of 144, 66, and 90xa0%, respectively, with increasing filler-to-matrix ratio. Efficient enhancement in elastomeric hardness was also observed.

Ablation and thermo-mechanical tailoring of EPDM rubber using carbon fibers

Abstract Carbon fibers (CFs) are incorporated into ethylene propylene diene monomer (EPDM) rubber to fabricate charring elastomeric ablative composites for ultrahigh temperature applications. Ablation characteristics of the ablative composites were evaluated using ASTM E285-08. Variant content incorporation of short CFs in the basic composite formulation reduced the backface temperature acclivity and the ablation rate rose up to 48% and 78%, correspondingly. Thermal stability and endothermic capability were improved with increasing short fiber contents in the rubber matrix. Experimental thermal conductivity measurement results elucidate that thermal conductivity reduces 60% at 473 K with 6 wt% addition of the fibers. A remarkable improvement was scrutinized in the tensile strength and rubber hardness with increasing fiber to matrix ratio. Scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) analysis of the composite specimens revealed the uniform dispersion of CFs within the host matrix, formation of voids during ablation, char-reinforcement interaction and composition of the charred ablators and the impregnated fibers.

Co-concentration effect of silane with natural extract on biodegradable polymeric films for food packaging

Novel biodegradable films were prepared by blending guar gum, chitosan and poly (vinyl alcohol) having mint (ME) and grapefruit peel (GE) extracts and crosslinked with nontoxic tetraethoxysilane (TEOS). The co-concentration effect of TEOS with natural extracts on the films was studied. FTIR analysis confirmed the presence of incorporated components and the developed interactions among the polymer chains. The surface morphology of the films by SEM showed the hydrophilic character due to porous network structure. The films having both ME and GE with maximum amount of crosslinker (100μL), showed maximum swelling (58g/g) and stability while the optical properties showed increased protection against UV light. This film sample showed compact network structure which enhanced the ultimate tensile strength (40.03MPa) and elongation at break (104.8%). ME/GE conferred the antioxidant properties determined by radical scavenging activity and total phenolic contents (TPC) as ME films have greater TPC compared to GE films. The soil burial test exhibited the degradation of films rapidly (6days) confirming their strong microbial activity in soil. The lower water vapour transmission rate and water vapour permeability showed better shelf life; hence, these biodegradable films are environmental friendly and have potential for food and other packaging.

Tuning the interlaminar shear strength and thermo-mechanical properties of glass fiber composites by incorporation of (3-mercaptopropyl) trimethoxysilane-functionalized carbon black

The incorporation of functionalized nanoscale fillers into traditional glass fiber/unsaturated polyester (GF/UPE) composites provides a more robust mechanical attributes. The current study demonstrates the potential of 3-mercaptopropyl trimethoxysilane (MPTS)-functionalized carbon black (f-CB) for enhancing the thermo-mechanical properties of GF composites. The composites infused with 1, 3 and 5xa0wt% of pristine and MPTS-functionalized CB were fabricated by hand lay-up and hot press processing. Tensile testing, interlaminar shear strength (ILSS) testing and dynamic mechanical analysis were used to evaluate the performance of nanocomposites. Fourier transform infrared spectroscopy validated the MPTS functionalization of CB. Pristine CB-loaded nanocomposites exhibited marginal improvement in ultimate tensile strength (UTS), ILSS and thermo-mechanical properties. However, with the addition of f-CB, the improvement in all the studied properties was more substantial. The inclusion of 5xa0wt% f-CB increased the elastic modulus and UTS by 16 and 22%, respectively, whereas the ILSS was enhanced by 36%, in comparison to the neat GF composite. The scanning electron microscope analysis of fractured ILSS samples revealed better fiber-matrix adhesion and compatibility in f-CB-loaded nanocomposites. At the same filler weight percentage, the storage modulus at 25xa0°C was ~xa019% higher than that of neat composite. The f-CB inclusion resulted in increment of Tg by ~xa013xa0°C over the Tg of neat GF/UPE composite (~xa0109xa0°C). These improvements were due to the chemical connection of f-CB to the UPE matrix and GF surface. With such improvements in thermal and mechanical properties, these nanocomposites can replace the conventional GF composites with prominent improvements in performance.

Synergistic Effect of Functionalized Nanokaolin Decorated MWCNTs on the Performance of Cellulose Acetate (CA) Membranes Spectacular

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.

Controlled release of cephradine by biopolymers based target specific crosslinked hydrogels

The novel silane crosslinked (TEOS) hydrogels based on eco-friendly biodegradable chitosan/guargum were prepared by blending with PEG to develop pH sensitive hydrogels (CGP) and achieved its hydrophilicity and target specificity for controlled release of drug. The crosslinker amount was varied to analyze its effect on the hydrogel properties and were characterized using FTIR, SEM, TGA, swelling studies (water, buffer and ionic solution) and in-vitro release of cephradine (CED). FTIR confirmed the presence of characteristic peaks and crosslinking between the components while SEM images showed the formation of clear micro- and macro-pores. The swelling behavior in water showed that compared to the controlled hydrogel, the crosslinked hydrogels revealed more swelling but a decrease in swelling with further increase in the amount of crosslinker was observed. The hydrogels showed low swelling at basic and neutral pH while maximum swelling was observed at acidic pH. This pH response made these hydrogels an ideal candidate for injectable controlled release. The CED was loaded on hydrogels and its release mechanism was studied in PBS, SGF and SIF which revealed that out of all hydrogels (CGP100, CGP150, CGP200 and CGP250), CGP100 has shown CED release of 85% in 130u202fmin in PBS and 82.4% in SIF.

Tuning of Thermo-Mechanical Performance: Modified Multiwalled Carbon Nanotubes Reinforced SBR/NBR/SR Nanocomposites

The present study aimed to identify the potential of modified nanoreinforcement (multiwalled carbon nanotubes; m-MWCNTs) to attenuate the thermal transport/decomposition/transition and mechanical aspects of three different polymeric matrices. In order to develop strong interfacial interaction between the host matrix and the incorporated nanotubes, 3-aminopropyletrimethoxy silane (APTMS) was used to m-MWCNTs. IR spectra confirmed the silane chemical moiety attachment on the upper surface of the MWCNTs. Conventional elastomeric mixing techniques were adopted to disperse m-MWCNTs within the three polymeric matrices (Acrylonitrile butadiene rubber, Silicone rubber, and Styrene Butadiene rubber) separately. SEM images assured the uniform dispersion of m-MWCNTs within the host polymeric matrices. Experimental evaluation of thermal conductivity revealed the reduction of thermal transport through the developed composite specimens by increasing the host polymer matrix to nanofiller concentration (m-MWCNTs). The utmost insulation effect was perceived in the F-MWCNTs incorporated silicone rubber nanocomposite comparatively. Glass transition/crystallization temperatures of the nanocomposites were lessened however melting temperatures were enhanced by impregnating nanotubes into the host polymeric matrices. Maximum thermal stability improvement due to the addition of m-MWCNTs was observed in the silicone elastomeric nanocomposite as compared to the other two systems. Proper dispersion and compatibility of m-MWCNTs with the polymeric matrices effectively enhanced the ultimate tensile strength (UTS)/elongation at break along hardness of rubber of the nanocomposites. The insulation character of m-MWCNTs/silicone rubber system was found best among the explored nanocomposite formulations.

Exfoliated Sodium Montmorillonite Reinforced Elastomeric Nanocomposites: Ablation, Thermal Transport/Decomposition/Transitions and Mechanical Aspects)

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.