Asish Malas

Carbon black–clay hybrid nanocomposites based upon EPDM elastomer

The present study explored the effect of nanoclay on the properties of the ethylene–propylene–diene rubber (EPDM)/carbon black (CB) composites. The nanocomposites were prepared with 40 wt% loading of fillers, where the nanoclay percentage was kept constant at 3 wt%. As the modified nanoclay contains the polar groups and the EPDM matrix is nonpolar, a polar rubber oil extended carboxylated styrene butadiene rubber (XSBR), was used during the preparation of nanocomposites to improve the compatibility. Primarily the nanoclay was dispersed in XSBR by solution mixing followed by ultrasonication. After that EPDM-based, CB–clay hybrid nanocomposites, were prepared in a laboratory scale two roll mill. The dispersion of the different nanoclay in the EPDM matrix was observed by wide-angle X-ray diffraction (WAXD) and high resolution transmission electron microscopy. It was found that the mechanical properties of the hybrid nanocomposites were highly influenced by the dispersion and exfoliation of the nanoclays in the EPDM matrix. Thermo gravimetric analysis, scanning electron microscopy and dynamic mechanical thermal analysis was carried out for each nanocomposite. Among all the nanocomposites studied, the thermal and mechanical properties of Cloisite 30B filled EPDM/CB nanocomposite were found to be highest.

Synergistic Effect of Expanded Graphite/Carbon Black on the Physical and Thermo-Mechanical Properties of Ethylene Propylene Diene Terpolymer

The present research work explored the effect of expanded graphite (EG) and modified EG (MEG) with and without carbon black (CB) on the mechanical, dynamic mechanical, thermal etc. properties of ethylene propylene diene terpolymer (EPDM). EG-and MEG-filled EPDM nanocomposites were fabricated in the presence and absence of CB by direct mixing on an open two roll mill. The microstructure of the EPDM-based nanocomposites was investigated by wide angle X-ray diffraction (WAXD) and high-resolution transmission electron microscopic (HR-TEM) analyses. EG- and MEG-loaded EPDM nanocomposites in the presence and absence of CB exhibited improved mechanical, dynamic mechanical properties and thermal stability.

Synthesis and Microwave Absorbing Properties of Cu-Doped Nickel Zinc Ferrite/Pb(Zr0.52Ti0.48)O3 Nanocomposites

Nanocomposites based on Cu-doped nickel zinc ferrite and lead zirconium titanate exhibited significant microwave absorbing properties in the X-band (8.2–12.4 GHz) region. Coprecipitation and homogeneous precipitation methods were utilized to synthesize Cu-doped nickel zinc ferrite (Cu0.2Ni0.4Zn0.4Fe2O4) and lead zirconium titanate (Pb(Zr0.52Ti0.48)O3) nanoparticles, respectively. To develop nanocomposites, dispersion of these nanoparticles into epoxy resin (LY665) polymeric matrix was carried out by using mechanical stirrer. Phase analyses of the nanoparticles were done by X-ray diffraction (XRD). Moreover, morphological characterization was done by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Energy dispersive X-ray spectroscopy (EDS) confirmed the chemical constituents present in the nanocomposites. Complex relative permittivity and complex relative permeability values of the nanocomposites were measured in different microwave frequencies in the X-band (8.2–12.4 GHz) region by employing vector network analyzer (model PNA E8364B), and return loss (dB) values were calculated to identify the microwave absorbing performance of the present nanocomposites. Brilliant microwave absorbing properties have been achieved by the nanocomposites with the minimum return loss of −49.53 dB at 8.44 GHz when sample thickness was 3 mm. For the present nanocomposites, mainly dielectric loss was responsible for loss mechanism.

Dual Effect of Polyphosphazene and Halloysite Nanotubes in the Blends of Poly(Phenylene Oxide)/Liquid Crystalline Polymer

The present study investigates the effect of polyphosphazene elastomer and halloysite nano tubular fillers in the blend of poly(phenylene oxide) and liquid crystalline polymer. Fabricated materials were extensively investigated with field emission scanning electron microscope, high resolution transmission electron microscope, thermogravimetric analyzer, rheometer, universal testing machine, and dynamic mechanical thermal analyzer. Significant changes in morphology were observed when fillers were added along with the compatibilizing agent polyphosphazene. Filler-matrix adhesion improves in the presence of polyphosphazene that results in the reduction in the average domain sizes of the dispersed phase where the interfacial phenomena controls the size of the dispersed phase. GRAPHICAL ABSTRACT

Ultrasonic Welding of Amorphous and Semi Crystalline Materials

Ultrasonic welding have been studied using Polycarbonate (amorphous) and Polypropylene (semi-crystalline) in presence and absence of polymeric compatibilizer. A solution phase compatibilization has been used using Polycaprolactone, Polymethylmethacrylate and Maleic anhydride grafted Polypropylene. Cylindrical samples were used in the near and far field ultrasonication in order to achieve the better weldability. The welding strength was increased while utilizing the compatibilizer than that of un-compatibilized samples. Mixture of Polycarbonate and Polymethylmethacrylate on the PC phase enhanced the weld strength tremendously. The XRD analysis revealed the increase in crystallinity during the ultrasonication process resulting the enhanced weldability. The phase fusion is quite prominent from the SEM study of the fractured surface and also from the SEM of the welded portion. The FTIR study indicated the phase interaction through the compatibilizer thus enhancing the ultrasonic weldability of the thermoplastics.