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Hatui G.,Indian Institute of Technology Kharagpur | Sahoo S.,Indian Institute of Technology Kharagpur | Kumar Das C.,Indian Institute of Technology Kharagpur | Saxena A.K.,DMSRDE | And 2 more authors.
Materials and Design | Year: 2012

Nanocomposites of polybutylene terephthalate (PBT) and liquid crystalline polymer (LCP) with either polyphosphazene or nanosilica, or in combination of both were prepared by melt blending. The compatibility between the polymeric phases (PBT&LCP) was observed to be increased by the addition of polyphosphazene while the nanosilica promoted the LCP domain deformation from spherical to ellipsoidal shape. LCP fibres were produced in presence of both polyphosphazene and nanosilica due to the compatibilization of polyphosphazene and bridging effect of nanosilica through hydrogen bonding. All these above structural changes were confirmed by scanning electron microscope (SEM). Transmission electron microscope (TEM) images showed better dispersion of nanosilica in presence of polyphosphazene than nanosilica alone. There is remarkable increase in storage modulus with the addition of nanosilica, individually and in combination with polyphosphazene. Percentages of crystallinity for the concerned nanocomposites were calculated through X-ray diffraction study (XRD). Tensile strength and Young modulus were increased with addition of nanosilica and polyphosphazene but percentage of elongation at break was higher for polyphosphazene added nanocomposite. This is due to flexible compatibilizing effect of polyphosphazene, which delays the detachment of liquid crystalline polymer (LCP) domain from the polybutylene terephthalate (PBT) matrix and thus detains the fracture. © 2012 Elsevier Ltd.


Bose S.,Indian Institute of Technology Kharagpur | Mukherjee M.,Indian Institute of Technology Kharagpur | Das C.K.,Indian Institute of Technology Kharagpur | Saxena A.K.,DMSRDE
Polymer Composites | Year: 2010

In this article, the chemistry of interfacial adhesion between different additive systems has been dealt with to develop a high performance nanocomposite and in the process, a comprehensive study on the reinforcing effect of nanosilica has been carried out. The base polymer was considered as the blends of Poly ethersulfone (PES) and thermotropic liquid crystalline polymer (TLCP A novel polymeric compatibilizer, polyphosphazene elastomer, has been utilized and the interchain crosslinking has been explained. Results of experimental investigations demonstrate that the nanofillers play an important role in reducing the interfacial tension. However, the presence of Polyphosphazene elastomer, acted as compatibilizer further reducing the interfacial tension through the inter-molecular interaction. The nanocomposites, thus developed, have better thermal stability and improved rheological properties. In addition, it has also been observed that Polyphosphazene elastomer impart flexibility in the composite. POLYM. COMPOS., 31:543-552, 2010. © 2009 Society of Plastics Engineers.


Basuli U.,Indian Institute of Technology Kharagpur | Chaki T.K.,Indian Institute of Technology Kharagpur | Setua D.K.,DMSRDE | Chattopadhyay S.,Indian Institute of Technology Kharagpur
Journal of Thermal Analysis and Calorimetry | Year: 2012

Thermal degradation kinetics of MWNT-reinforced EMA-based nanocomposites having different methyl acrylate (MA) contents (by % mass) ranging from 9 to 30% have been monitored. Kissinger and Flynn-Wall-Ozawa methods for evaluating non-isothermal degradation of polymers have been examined. Overall, the thermal stabilities of the nanocomposites are the function of amount of MWNTs loading and their state of dispersion that depends on the MA content of respective EMAs. Composite samples exhibit higher activation energy (Ea) than the neat EMAs but the Eas of the composites diminish with increased MA contents of the matrices. TG-Mass spectrometry has been used to identify the volatile products resulting from thermal degradation of composites, and a promising mechanism has been proposed over different range of temperatures of degradation. It is proposed that the side-group scission of methoxycarbonyl group initiates thermal decomposition following combination of chain end and random chain scission reactions, ensuing pseudo second-order kinetics. © 2011 Akadémiai Kiadó, Budapest, Hungary.


Bose S.,Indian Institute of Technology Kharagpur | Pramanik N.,Indian Institute of Technology Kharagpur | Das C.K.,Indian Institute of Technology Kharagpur | Ranjan A.,DMSRDE | Saxena A.K.,DMSRDE
Materials and Design | Year: 2010

Effect of functionalized polyphosphazene as compatibilizer in melt-compounded polyetherimide (PEI)/liquid crystalline polymer (LCP) blend has been investigated in details. DMTA study showed the variation in glass transition temperature (Tg) in presence of polyphosphazene having different funtionalization. Superior thermal stability of polyphosphazene aided composites is exhibited from thermo-gravimetric analysis. From dielectric measurements it was clear that polyphosphazene-aided PEI/LCP blend can act as low dielectric material as well as high dielectric material depending on the nature of pendant group used. Scanning electronic microscopic observation revealed that the addition of small amount of polyphosphazene results in a decrease in average disperse domain sizes of LCP phase leading to improved filler-matrix adhesion. © 2009 Elsevier Ltd. All rights reserved.


Ramani R.,DMSRDE | Alam S.,DMSRDE
Journal of Physics: Conference Series | Year: 2015

High performance polymer blend of poly(ether ether ketone) (PEEK) and poly(ether imide) (PEI) was examined for their free volume behaviour using positron annihilation lifetime spectroscopy and dynamic mechanical thermal analysis methods. The fractional free volume obtained from PALS shows a negative deviation from linear additivity rule implying good miscibility between PEEK and PEI. The dynamic modulus and loss tangent were obtained for the blends at three different frequencies 1, 10 and 100 Hz at temperatures close to and above their glass transition temperature. Applying Time-Temperature-Superposition (TTS) principle to the DMTA results, master curves were obtained at a reference temperature To and the WLF coefficients c01 and c02 were evaluated. Both the methods give similar results for the dependence of fractional free volume on PEI content in this blend. The results reveal that free volume plays an important role in determining the visco-elastic properties in miscible polymer blends. © Published under licence by IOP Publishing Ltd.


Gupta K.K.,DMSRDE
Man-Made Textiles in India | Year: 2012

For realization of fabric into practice with specific intended purpose, we require certain basic cloth calculations pertaining to no of threads per inch, denier of yarn, weight range of fabric and its cover factor to achieve desired aesthetic properties. 'Mathematical Modeling for Fabric Parameter Setting' is a technical article representing the graphical solution (trend lines) based on these fundamental cloth calculations thereby we can select no of threads per inch (warp and weft) in desired denier of yarn to weave a fabric in specific weight (gsm) range and cover factor. In general, we are familiar with the cloth calculations for the conventional textiles fibre i.e. nylon, polyester, acrylic, cotton, wool, etc, where density ranges from 1.0-1.5 and packing fraction of yarn from 0.55-0.65 with moderate cover factor (16-20). But if we want to design a fabric using nonconventional textile fibre (stainless steel fibre) whose density is 7.8 and packing fraction varying from 0.75-0.85, these calculations do not provide practically acceptable information and resulting fabric based on these information is far away than predicted one. This is because the denier of SS yarn is 5.2 times coarser than cotton with similar construction and diameter. So, we need a model to design a fabric in specific weight range and cover factor. In this article, a modeling has been done to predict the no of threads per inch and its denier for the fabric in weight range of 100, 150 and 200 gsm with cover factor of 12, 14, 16 & 18.


Ramani R.,D.M.S.R.D.E. | Alam S.,D.M.S.R.D.E.
Thermochimica Acta | Year: 2012

Herein, we report the influence of an organophosphonite antioxidant, Irgafos P-EPQ, on the thermal behavior of optimized poly(ether ether ketone)/poly(ether imide) (PEEK/PEI; 50/50) blend. The antioxidant addition was found to limit the rate of thermo-oxidation of the blend to a noticeable extent as revealed from TGA measurements and limiting oxygen index values. The DSC results indicate a decrease in Tg and melting enthalpy of the blend with the antioxidant addition. The DSC results were verified from MDSC and WAXS measurements. It is suggested that addition of 1 wt.% Irgafos P-EPQ to PEEK/PEI blend results to good thermo-oxidative stability. The effective activation energy (Eα) of thermo-oxidation process for 1 wt.% Irgafos P-EPQ incorporated blend decreased steadily than its pure counterpart, in consonance with its improved thermo-oxidative stability. © 2012 Elsevier B.V.


Roy D.,DMSRDE | Tiwari N.,DMSRDE | Mukhopadhyay K.,DMSRDE | Saxena A.K.,DMSRDE
Polymer (United Kingdom) | Year: 2014

The surface of multi wall carbon nanotubes (MWCNTs) was first covalently functionalized with oleyl amine and then non-covalently wrapped with polycarbosilane (PCS). The hybrid functional groups were chosen to introduce different features in the MWCNTs properties. For covalent functionalization a long chain unsaturated aliphatic amine was used to simultaneously achieve the dissociation of MWCNT bundles along with the dispersion and interaction with the host matrix using the amide functionality and double bond. On the other hand, a thermally stable polymer was selected which can interact with both resin and glass fabric to promote interfacial adhesion. This hybrid doubly modified MWCNT is thus possesses duel advantages in glass fiber based epoxy composite. The pristine, covalent, noncovalent and covalent-noncovalent doubly modified MWCNT systems were used to study the viscoelastic behavior and interactions of functionalized MWCNTs in the matrix above and below the glass transition temperature of the matrix. The PCS coating on the MWCNTs is amorphous and thermally insulating whereas the nanotube is highly graphitized and thermally conducting. This contrasting behavior provides us to insight into the temperature dependant resin microstructure and curing thermodynamics of epoxy resin in the presence of MWCNTs. © 2013 Elsevier Ltd. All rights reserved.


Ramani R.,D.M.S.R.D.E. | Srivastava J.,D.M.S.R.D.E. | Alam S.,D.M.S.R.D.E.
Thermochimica Acta | Year: 2010

We report here the investigations on the thermal and thermo-oxidative degradation kinetics of a technologically important conducting polymer poly(3-hexyl thiophene) (P3HT) as measured in nitrogen and air medium, respectively. The derivative thermogravimetric results clearly indicate single stage decomposition for thermal degradation while triple stage decomposition is observed for thermo-oxidative degradation. The Vyazovkin model-free kinetics method was applied to calculate the effective activation energy (Eα) of the degradation process as a function of conversion. The Eα values are higher in nitrogen than in air medium. In nitrogen medium, the Eα value remains almost constant up to an extent of conversion, α = 90%. Interestingly, in air medium, the Eα shows an initial minimum, then increase and exhibits a maximum at α = 45%, decreases steadily and plateaus thereafter. This reveals that the degradation mechanism of P3HT in air medium is complex. The model-free isothermal predictions could be of use in correlating the service temperature of this conducting polymer. © 2009 Elsevier B.V. All rights reserved.


Ramani R.,D.M.S.R.D.E. | Alam S.,D.M.S.R.D.E.
Thermochimica Acta | Year: 2010

We report here the investigations on the thermal and thermo-oxidative degradation kinetics of a miscible high performance polymer blend poly(ether ether ketone)/poly(ether imide) (PEEK/PEI) with various compositions, measured in argon and air medium, respectively. The derivative thermogravimetric results indicate two-stage decomposition for both thermal and thermo-oxidative degradation for the entire composition of PEEK/PEI blend. Interestingly, the PEI addition is found to enhance the thermo-oxidation rate of PEEK. The effective activation energy (Eα) as a function of conversion (α) is found for both the processes using model-free kinetics. The model-free kinetics results reveal that the blend with 50% PEI content show high E α value and the differential scanning calorimetry results corroboratively show a significant change in crystallinity for this PEI composition. Based on these results, the blend with composition 50/50 (PEEK/PEI) is suggested to have optimum thermal stability. © 2010 Elsevier B.V.

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