MIT-World Peace University (MIT-WPU) is a top educational institute located in Pune, India. It is recognized within&nbsp;UGC under Government of Maharashtra Act No. XXXV 2017.&nbsp;

It is part of the MIT group of institutions (established in 1983) which covers 10+ campuses across India and has more than 50,000+ students enrolled across various disciplines at a given point of time. The institute houses 15 schools ranging from Engineering &amp; Technology, Design, Pharmacy, Commerce, Governance among others. It offers undergraduate, postgraduate and PhD programs among different disciplines.&nbsp;

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MIT World Peace University

School of Polymer Engineering

Polyethersulfone (PES)-7 wt% graphite- x wt% filler (carbon black (CB), carbon nanofiber (CNF), expanded graphite (ExGr)) hybrid composites are synthesized by solution blending route. The electrical percolation threshold in hybrid composites varies exponentially with the aspect ratio of the second conducting filler. The aspect ratio of the second conducting filler has been found to vary in the order CB &lt; CNF &lt; ExGr. The percolation threshold is identified at 0.05 wt%, 0.4 wt%, 1.3 wt% for ExGr, CNF and CB added PES-7 wt% graphite composites. Through plane thermal conductivity of PES-x wt% graphite-y wt% CB (x=10, 20, 30, 40, 50, 60, y=0, 3, 7) hybrid composites has been found to increase with the addition of CB. Thermal conductivity has been increased to 0.42 W/m-K when 7 wt% CB is added to PES-60 wt% graphite from 0.2 W/m-K. Reduction of interparticular distance with the increased loading of CB facilitates better thermal transport. Aspect ratios of second conducting fillers have been found out from transmission electron microscopy and scanning electron microscopy analysis.

World University root node

Engineering and Technology

Macromolecular Research

Analysis of electrical and thermal conductivities of polyethersulfone-graphite based hybrid nanocomposites

The demand for lightweight, cost-effective electrically conducting polymers and conducting nanocomposites for various applications, such as sensors, actuators, etc., has been skyrocketing in recent years. Electrically conducting polymer composites (CPCs) can be developed by dispersing conducting particles in inherently conducting polymers or insulating polymer matrices. Due to the recent advancements in nanotechnology, it is possible to tailor make composite materials with exceptional electrical, mechanical and thermal properties. The properties of conducting polymer binary composites can be altered by careful selection and dispersion of fillers in the polymer matrix. In a similar way, conducting hybrid polymer composites for a particular application can be synthesized by exploiting the synergism in properties of two or more dispersed phases. It is not merely cost reduction that drives the market of CPCs but also environmentally benign synthesis procedures wherever possible and mass production of the end product with better energy savings has an immense influence on the demand for these materials. The unprecedented growth of nanotechnology offers better control over manipulation of filler size as well as polymers, and hence the composites can be tailor-made. Though there are many nanofillers, such as nanographite, carbon nanofiber, etc., in this chapter, more attention will be given to the electrical properties of multiwalled carbon nanotube (MWCNT) filled polyethersulfone (PES) conducting composites, along with that of PES-graphite-MWCNT hybrid nanocomposites. © 2018 Scrivener Publishing LLC.

Trends and Applications in Advanced Polymeric Materials

Electrical Properties of Conducting Polymer-MWCNT Binary and Hybrid Nanocomposites

The thermal conductivity (k), heat transfer coefficient (HTC) and viscosity of the ethylene glycol/water dispersed with graphite nanoparticles was studied under heating and cooling conditions for temperatures ranging from 0 °C to 75 °C using tubular heat exchanger system built in house. Flow rate was varied from 5 l/h to 25 l/h giving Reynolds number (Re) ranging from 50 to 750. The HTC increased with the increase of Re as well as temperature. The thermal conductivity of the nanofluid was determined at constant low Re (200) for all concentrations and temperatures used in the experiment. The concentration dependence of thermal conductivity was found to be much different than that predicted by models suggested in literature. The viscosity was measured for different concentrations of nanoparticles (0 to 0.8%) as well as temperatures 275 K to 340 K. The temperature dependence of viscosity was found to follow Arrhenius type equation η = ηoexp(E/kbT) with very little change in the activation energy from that of the base fluid. On the other hand the pre-exponential constant increased six folds with the increase in nanoparticle concentration. An empirical relation derived from Brownian motion was found between the product of viscosity and thermal conductivity (Ω = kr · ηr) with respect to concentration of the nanoparticles which was found to be true for whole range of temperature and compositions studied.

School of Mechanical Engineering

Fulltext

Journal of Nanofluids (USA)

Investigations on Thermal Conductivity, Heat Transfer Coefficient and Viscosity of Graphite Nanoparticle Dispersed Nanofluid

Unsaturated polyester/benzoxazine copolymer was employed to prepare polyester/benzoxazine/glass fiber compositelaminates and their mechanical, morphological, and thermal properties were investigated. Compared with those of 100UPR/0PBZ/10GFcomposites, the tensile strength and flexural strength of 90UPR/10PBZ/10GF composites with 10 wt % polybenzoxazine content wereincreased by 10 % and 6 %, respectively. The enhancements in mechanical properties are mainly due to the strong interfacial adhesionsbetween glass fiber and UPR/PBZ matrices, which were confirm by the SEM images of fracture surfaces of the composites. Curingbehavior of glass fiber filed composite was investigated by differential scanning calorimetry analysis. All UPR/PBZ/GF compositelaminates are thermally stable up to 270 0C in air. Furthermore, TGA thermograms revealed that the degradation temperatures ofUPR/PBZ/GF composite increased with compare UPR/GF composite. UPR/PBZ/GF composite laminates will have potentialapplications in the areas where require of excellent mechanical properties and high temperature resistance.

International Journal of Science and Research

Studies on Thermal and Mechanical Properties of Glass Fiber-Reinforced Unsaturated Polyester/Benzoxazine Composites

Serials of polystyrene/SiO2 Nano composites (PS/SiO2) with different content of inorganic fillers were successfully prepared by the in situ bulk radical polymerization of styrene under microwave irradiation. The effect of the amount of Nano SiO2 on the properties of the PS/SiO2 Nanocomposites along with the average relative molecular masses (Mn, Mz and Mw) was investigated by thermal analysis and X-Ray Diffraction (XRD). Their structural model was proposed on the basis of the Optical Microscopy, FTIR (Fourier Transform Infrared) analysis, differential scanning calorimetry (DSC), gel permeation chromatography (GPC) and X-Ray Diffraction (XRD). The dispersion of nanoparticles in Polystyrene is observed in the magnified image. The effect of microwave irradiation power on molecular weight of polystyrene was also studied. It was found that, the microwave assisted reaction needs less time as compare to conventional polymerization and found to be in between 10 to 15 min.

Open Journal of Synthesis Theory and Applications

Thermal Stability and Crystallnity study of Polystyrene/SiO2 Nano-Composites Synthesis via Microwave-Assisted In Situ Polymerization

In situ polymerization of pyrrole was executedin the presence of expanded graphite to synthesizepolypyrrole–expanded graphite composites (PPy/EG) bychemical oxidation method. The PPy/EG composites have beenprepared with various compositions (2%, 5%, 7.5%, 10% wt.%) of expanded graphite in pyrrole. Morphology of thecomposites has been examined by scanning electronmicroscopy (SEM). The polypyrrole-expanded graphitecomposites were also examined by X-ray diffractometry (XRD)and Attenuated total reflectance (ATR). The a.c. conductivitybehavior has been analyzed by LCR-Q-Meter-SORTER. Thepresence of expanded graphite in the matrix have an excellenteffect on the observed conductivity values. The results showedthat these composites are of preferably technological andbusinesslike interest.

International Research Journal of Engineering and Technology

Synthesis, characterization and conductivity studies of Polypyrrole-Expanded Graphite–composites

The present article studies the effect of treatment of 0.5, 1.5, and 2.5% titanate-coupling agent (LICA 38) on various properties of fly ash–filled polypropylene (PP) composites. The fly ash content varied from 0 to 30 wt%. The mechanical and thermal properties of the composite material were evaluated, and microstructure investigated through scanning electron microscopy. Experimental results were compared with various existing models. Experimental data for tensile yield strength showed good fit to the existing models. Adhesion parameter or interfacial interaction was also evaluated though Pukanszky model. The values of yield stress and breaking strength of treated fly ash–based composites showed higher values compared to that of untreated fly ash–filled PP composites at corresponding filler content. The overall mechanical properties of fly ash–filled composites are essentially decided by wettability of the filler. It is also found that Vicat softening point improved with the addition of fly ash filler. Morphological studies of the tensile fracture surfaces of the composites revealed that the presence of titanate-coupling agent increased the interfacial interaction between fly ash and PP. It also improved the dispersion of fly ash in PP matrix. Thus, the treatment resulted in improvement in mechanical and thermal properties of the composites as compared to untreated fly ash–filled composites. The overall results showed that fly ash dispersion and interfacial adhesion are greatly affected by the amount of the coupling agent.

Journal of Thermoplastic Composite Materials

Studies on effect of titanate-coupling Agent (0.5, 1.5 and 2.5%) on the mechanical, thermal and morphological properties of fly ash-filled polypropylene composites

Plug temperature is a key parameter affecting the thickness distribution of thermoplastic components made by plug assist thermoforming. For a specified pair of plug and plastic sheet, the variation in plug temperature can alter the coefficient of friction (COF) between the pair. We show here how the temperature dependence of COF influences the nature and extent of biaxial stretching of the sheet and consequently the thickness distribution of the thermoformed component. In the present study, high impact polystyrene (HIPS) sheets were thermoformed into axisymmetric cups using a plug-assist process in which the aluminum plug temperature (Tplug) was varied from ambient to above the glass transition temperature of HIPS (∼100 °C). Biaxial strain maps on the surfaces of the formed cups were measured and quantified using Grid Strain Analysis (GSA). Thickness distributions of the cups were also measured. Temperature dependent COF between HIPS and aluminum was determined independently using a rotational rheometer. The measured COF was low for T < 100 °C, whereas it increased appreciably at and above 100 °C. We conclude that when Tplug < 100 °C the HIPS sheet slips on the plug during forming, and this results in biaxial stretching of the base and walls of the formed cup. In contrast for Tplug > 100 °C, a significant reduction in the magnitude of slip is expected. Here the sheet is gripped at the clamp and by the plug during forming which causes reduced biaxial stretching of the base and increased uniaxial stretching of the walls of the cup. Simulations of plug-assist thermoforming using a temperature dependent COF showed qualitative agreement with the GSA data thereby supporting our inferences.

International Polymer Processing

Effect of Plug temperature on strain and thickness distribution of components made by Plug Assist Thermoforming

The melt rheology of polypropylene (PP) filled with fly ash (FA) before and after treatment with coconut water (CW) was studied for different concentration of the filler. The fly ash after coconut water treatment clearly showed additional peaks in the infrared (IR) spectra corresponding to the hydroxyl and carbonyl groups indicating good adsorption of CW on FA. The X‐ray diffraction of melt compounded PP filled with CW‐treated (CWT) FA showed large reduction of the main silica peak of FA and considerable broadening of Mullite and hematite peaks suggesting formation of fine particles by this treatment. Scanning electron microscopy (SEM) confirmed the drastic reduction of particle size in these composites. The melt rheological studies for these composites indicated considerable increase in viscosity at low filler loading for CW treated FA. The concentration dependence of melt viscosity did not follow any of the theoretical equations suggested in literature. Although, the behavior was similar to nanoparticle‐filled polymers, there were some differences especially above the critical concentration of 4.5% by volume. The frequency dependence of storage and loss modulus indicated crossover point clearly, which was greatly affected by CW treatment. The Cole–Cole plots of real and imaginary part of melt viscosity brought out the broad distribution of relaxation time for the CW treated FA. The CW treated FA melt compounded with PP gave rise to nanocomposites with uniform dispersion. However, above 4.5% by volume, there appears to be agglomerate formation along with a thin interfacial layer, which assists the melt flow even at high filler loading.

Journal of Applied Polymer Science

Melt rheological studies of polypropylene filled with coconut water treated and untreated fly ash

Solution-blended hybrid composites with carbon black (CB) as the second conducting filler in polyethersulfone (PES)-graphite have been prepared by first dissolving PES in dichloro methane. Addition of 1 wt% CB to solution-blended PES-7 wt% graphite results in decrease in the direct current electrical resistivity by four orders compared to the addition of 0 wt% CB. The particle size of graphite is reduced from few micron to nano level as evidenced by transmission electron microscopy analysis resulting in better dispersion. Without the addition of CB, the binary composite namely PES-7 wt% graphite exhibits finite conductivity due to increase in the contact between graphite particles as a result of reduction in the particle size. Comparison of electrical conductivity of PES-7 wt% graphite-2 wt% CB composites prepared by both solution-blending and powder-mixing routes proves the above-mentioned point. The alternating current behaviour, both conductance and effective dielectric constant studies shows that solution-blended composites exhibit higher value of conductance and effective dielectric constant at 0.01 Hz. This can only be attributed to better graphite dispersion in solution-blended composites. The enhancement is due to only particle size reduction of graphite that decreases the interparticular distance as the solution-blended binary composites with CB act as insulators up to 10 wt%. The charge transport at low concentrations of CB in solution-blended hybrid composites is dominated by the interfacial barriers and capacitance effects, while at higher concentrations it is mainly of hopping type at room temperature. The interfacial capacitance increases from 37.6 pF with 0 wt% CB addition to 96 pF with 2 wt% CB addition in PES-7 wt% graphite. Differential scanning calorimetry result suggests that more than 10°C enhancement in the glass transition temperature of PES is obtained for PES-7 wt% graphite-1 wt% CB.