Doctor of Philosophy (Rubber Technology) Master of Technology (Plastic Engineering) Master of Science (Chemistry) Rubber Technology Centre Indian Institute of Technology Kharagpur West Midnapur, West Bengal, INDIA, PIN – 721 302 Contact No.: +91–9733535121 (M), +91–9437436271 (R) Email ID: AKBarick@gmail.com, arunakmr.rt@iitkgp.ac.in Website: http://www.dak.iitkgp.ernet.in/phd/profile.php?roll=07RT9705 Date of Birth: 5th January, 1983
Abstract: The effect of CNFs on hard and soft segments of TPU matrix was evaluated using Fourier transform infrared (FTIR) spectroscope. The dispersion and distribution of the CNFs in the TPU matrix were investigated through wide angle X-ray diffraction (WAXD), field emission scanning electron microscope (FESEM), high resolution transmission electron microscope (HRTEM), polarizing optical microscope (POM), and atomic force microscope (AFM). The thermogravimetric analysis (TGA) showed that the inclusion of CNF improved the thermal stability of virgin TPU. The glass transition temperature (Tg), crystallization, and melting behaviors of the TPU matrix in the presence of dispersed CNF were observed by differential scanning calorimetry (DSC). The dynamic viscoelastic behavior of the nanocomposites was studied by dynamical mechanical thermal analysis (DMTA) and substantial improvement in storage modulus (E′) was achieved with the addition of CNF to TPU matrix. The rheological behavior of TPU nanocomposites were tested by rubber processing analyzer (RPA) in dynamic frequency sweep and the storage modulus (G′) of the nanocomposites was enhanced with increase in CNF loading. The dielectric properties of the nanocomposites exhibited significant improvement with incorporation of CNF. The TPU matrix exhibits remarkable improvement of mechanical properties with addition of CNF.
Abstract: Different formulations of organically modified layered silicate (OMLS) clay based medical grade thermoplastic polyurethane (TPU) nanocomposites were successfully prepared via melt blending followed by compression molding. The effect of incorporation of nanoclay on the spherulitic morphology of the TPU matrix was studied with a polarizing optical microscope (POM). The exfoliation/intercalation of organoclay was attributed to the TPU–organoclay interaction and shear stress during melt mixing. The effects of clay content and degree of clay dispersion on the rheological properties of nanocomposites were studied using a rubber process analyzer (RPA) with the help of dynamic strain, frequency, and temperature sweeps. The dynamic rheological studies show that the complex viscosity (η*) and dynamic storage modulus (G′) of pristine TPU increased significantly with the incorporation of organoclay loading, which is attributed to the formation of an interphase between soft and hard segments of the TPU matrix and effective dispersion of the organoclay.
Abstract: The multi-walled carbon nanotube (MWNT) reinforced thermoplastic polyurethane (TPU) nanocomposites were prepared through melt compounding method followed by compression molding. The spectroscopic study indicated that a strong interfacial interaction was developed between carbon nanotube (CNT) and the TPU matrix in the nanocomposites. The microscopic observation showed that the CNTs were homogeneously dispersed throughout the TPU matrix well apart from a few clusters. The results from thermal analysis indicated that the glass transition temperature (Tg) and storage modulus (E′) of the nanocomposites were increased with increase in CNTs content and their thermal stability were also improved in comparison with pure TPU matrix. The rheological analysis showed the low frequency plateau of shear modulus and the shear thinning behavior of the nanocomposites. The electrical behaviors of the nanocomposites are increased with increase in weight percent (wt%) of CNT loading. The mechanical properties of nanocomposites were substantially improved by the incorporation of CNTs into the TPU matrix.
Abstract: Thermoplastic polyurethane (TPU) nanocomposites based on organophilic-layered silicates were prepared via melt blending. Wide angle X-ray diffraction (WAXD) and transmission electron microscope (TEM) were employed to investigate the state and mechanism of exfoliation of the layered silicate within TPU matrix. The TPU nanocomposites were found to have a partially exfoliated morphology at lower clay loading, whereas the morphology changed to an intercalated nanostructure at higher clay loadings. The effect of the state of dispersion of organoclay on rheological properties of the nanocomposites were carried out by rubber process analyzer (RPA), which exhibited more pronounced shear thinning behavior, and increased storage and loss modulus with the increase in organoclay content. The pseudo-plastic like behavior was observed due to change in liquid-like to solid-like behavior of nanoclay-filled systems.
Abstract: The present work deals with the preparation of the CNF based TPU nanocomposites by melt blending to explore the effect of state of dispersion and wt.% loading of CNF on material properties. In addition, the morphology, mechanical, thermal, rheological, and electrical properties of the nanocomposites have been evaluated through various characterization techniques with an aim to find the suitability of the nanocomposites for industrial applications. Transmission electron microscopy (TEM) study reveals that the CNFs exhibited a uniformly dispersed in TPU matrix. The thermal stability of the TPU evaluated by thermogravimetric analysis (TGA) showed significant increase with increased CNF content. It is observed that storage modulus (E′) and glass transition temperature (Tg) of the TPU matrix increases by the incorporation of CNF. The melting point (Tm) and the Tg of soft segments observed from the differential scanning calorimetry (DSC) were found to shift towards higher temperature with the inclusion of CNF.
Abstract: Polymer nanocomposites based on the thermoplastic polyurethane (TPU) and organically modified montmorillonite (OMMT) was prepared by melt intercalation technique using a laboratory internal batch mixer followed by compression molding. Varying amount of organically modified nanoclays (1, 3, 5, 7, and 9 wt%) was added to the TPU matrix to examine the influence of organoclay on nanophase morphology and structure–property relationships. The interaction between TPU matrix and nanofiller was studied by infrared spectroscopy. The morphology of nanocomposites was studied by X-ray diffraction, transmission electron microscopy, and atomic force microscopy that shows melt mixing by a batch mixer is an effective method for dispersing OMMT throughout the TPU matrix. Thermogravimetric analysis revealed that incorporation of organoclay enhances the thermal stability of the nanocomposites significantly. Differential scanning calorimetry was employed to measure the melting point and glass transition temperature (Tg) of soft segments. The reinforcing effect of the organoclay was determined by dynamic mechanical analysis and physico–mechanical testing. The effects of nanoclay concentration and processing parameters on the dynamic viscoelastic properties of the nanocomposites were studied by a rubber process analyzer using frequency sweep. A significant increase in the viscosity and storage modulus of the nanocomposites was found with the increasing clay content.
Abstract: Thermoplastic polyurethane (TPU) nanocomposites based on organically modified layered silicate (OMLS) were prepared by melt intercalation process followed by compression molding. Different percentage of organoclays was incorporated into the TPU matrix in order to examine the influence of the nanoscaled fillers on nanostructure morphology and material properties. The microscopic morphology of the nanocomposites was evaluated by wide angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The observation revealed that both nanoclay–polymer interactions and shear stress developed during melt mixing are responsible for the effectively organoclay dispersion in TPU matrix resulting intercalated/exfoliated morphology. Thermal stability of the nanocomposites measured by thermogravimetric analysis (TGA) was improved significantly with the addition of nanoclay. The differential scanning calorimetry (DSC) analysis reveals that melting point of the nanocomposites increased with incorporation of nanoclay. The dynamic mechanical properties of the TPU nanocomposites were analyzed using a dynamic mechanical thermal analyzer (DMTA), which indicates that the storage modulus (E′), loss modulus (E″), and glass transition temperature (Tg) are significantly increased with increasing nanoclay content.
Abstract: Nanocomposites based on thermoplastic polyurethane (TPU) and organically modified montmorillonite (OMMT) were prepared by melt blending. Organically modified nanoclay was added to the TPU matrix in order to study the influence of the organoclay on nanophase morphology and materials properties. The interaction between TPU matrix and nanofiller was studied by infrared spectroscopy. Morphological characterization of the nanocomposites was carried out using X-ray diffraction, transmission electron microscopy, and scanning electron microscopy techniques. The results showed that melt mixing is an effective process for dispersing OMMT throughout the TPU matrix. Nanocomposites exhibit higher mechanical and thermal properties than pristine TPU. All these properties showed an increasing trend with the increase in OMMT content. Thermogravimetric analysis revealed that incorporation of organoclay enhances the thermal stability of nanocomposites significantly. Differential scanning calorimetry was used to measure the melting point and the glass transition temperature (Tg) of soft segments, which was found to shift toward higher temperature with the inclusion of organoclays. From dynamic mechanical thermal analysis, it is seen that addition of OMMT strongly influenced the storage and loss modulus of the TPU matrix. Dynamic viscoelastic properties of the nanocomposites were explored using rubber process analyzer.
Abstract: Polymer nanocomposites based on thermoplastic polyurethane (TPU) containing organophilic montmorillonite (OMMT) were prepared by melt compounding method followed by compression molding. Different percentage of organically modified nanoclays (1, 3, 5, 7, and 9 wt%) was incorporated into the TPU matrix in order to examine the influence of the nanofillers on nanophase morphology and materials' properties. The microstructure morphology of the nanocomposites was examined by transmission electron microscopy (TEM), energy dispersion X-ray analysis (EDX), wide angle X-ray diffraction (WAXD), and atomic force microscope (AFM). The observation established that the organoclay is homogeneously dispersed and preferentially embedded in the TPU soft segment phase. Significant enhancement in the thermal stability of the nanocomposites was observed with the addition of the OMMT under thermogravimetric analysis (TGA). Dynamic mechanical properties of the TPU nanocomposites were analyzed using a dynamic mechanical thermal analyzer (DMTA), which confirms that the addition of OMMT has a strong influence on the storage and loss modulus of the TPU matrix.
Abstract: Polymer nanocomposites based on organically modified montmorillonite (OMMT), vapor-grown carbon nanofiber (VGCNF), and multi-walled carbon nanotube (MWNT) filled thermoplastic polyurethane (TPU) were prepared by melt blending technique. The nanofillers were added to the TPU matrix in order to study the effect of nanofillers on nanophase morphology and structure–property relationships. The interfacial interactions between TPU matrix and nanofillers were studied by Fourier transform infrared spectroscopy (FTIR). The morphological characterizations of the nanocomposites were carried out by wide angle X-ray diffraction (WAXD), transmission electron microscope (TEM), scanning electron microscope (SEM), atomic force microscope (AFM), and polarizing optical microscope (POM) techniques. The results showed that the melt mixing is an effective process for homogeneous dispersion of the nanofillers throughout the TPU matrix. The thermogravimetric analysis (TGA) revealed that the thermal stability of the TPU nanocomposites was significantly improved by the incorporation of nanofillers. The activation energy (Ea) of the thermal decomposition was calculated by using Kissinger, Flynn–Wall–Ozawa, and modified Coats–Redfern non-isothermal kinetic methods. The differential scanning calorimetry (DSC) result revealed that the melting temperature (Tm), glass transition temperature (Tg), and enthalpy of melting (ΔHm) of both soft and hard segments of TPU matrix were not well affected by the addition of nanofillers. The effects of applied strain amplitude, frequency, and temperature on dynamic mechanical properties of the TPU nanocomposites were analyzed using a dynamic mechanical thermal analysis (DMTA) technique from which it was concluded that the addition of nanofiller noticeably improved the storage modulus (E′) and Tg of the TPU matrix. The effects of clay content and degree of clay dispersion on the dynamic rheological properties of TPU nanocomposites were studied using a rubber process analyzer (RPA) as a function of applied shear strain, angular frequency, and temperature. The complex viscosity (η*) and storage modulus (G′) of TPU nanocomposites increased significantly with insertion of nanofillers. The Han, Cole–Cole, and van Gurp–Palmen plots were employed to investigate the structural differences of heterogeneous TPU nanocomposites. The electrical properties of the nanocomposites were increased with increase in wt% of CNT loading. The mechanical properties of nanocomposites were substantially improved by the incorporation of nanofillers.
