Polymer synthesis and structure-property analysis, synthesis of various nanomaterials, surface modifications, polymer nanocomposites, polymer formulation and melt processing, polymer nanofibers and blends, super hydrophobic and super hydrophilic materials, especially polyurethanes, water dispersible polyurethanes, emulsion polymerizations for coating and painting, also for fire retardant, adhesives, textiles, antibacterial, biodegradable, biological and packaging applications.
Design of Poly(cyclotriphosphazene)-Functionalized Zirconium Phosphate Nanoplatelets To Simultaneously Enhance the Dynamic Mechanical and Flame Retardancy Properties of Polyamide 6 Kuruma Malkappa, Jayita Bandyopadhyay, Suprakas Sinha Ray ACS Omega, 2020 To obtain polyamide 6 (PA6) composites with improved flame retardancy and thermomechanical properties, highly cross-linked supramolecular poly(cyclotriphosphazene)-functionalized α-zirconium phosphate (f-ZrP) nanoplatelets were synthesized and melt-blended with PA6 in a twin-screw extruder. The performance enhancements of composites were investigated through measuring the dynamic mechanical property and observing cone calorimeter data, toxic gas evolution, and UL-94 rating. The thermomechanical performance of PA6 was increased by 37.2% after composite formation with f-ZrP. As for the fire retardancy performance, compared to neat PA6, the composite containing 10 wt % f-ZrP showed 41.7 and 30.4% decrease in the peak heat and total heat release rates, respectively, and the UL-94 rating of the composite was V-0. Moreover, the thermogravimetric analysis combined with infrared spectroscopy revealed that the addition of f-ZrP to the PA6 led to decrease in the evolution of the volatile compounds and toxic gases, with the formation of highly cross-linked P–N-containing dense char with microspheres, providing a strong barrier to the inhibition of the heat and flammable volatile components transferring between the flame zone area and substrate during the combustion test. Finally, based on the obtained results, the possible mechanisms for improved mechanical and fire retardancy properties of the composites were proposed.
Thermal Stability, Pyrolysis Behavior, and Fire-Retardant Performance of Melamine Cyanurate@Poly(cyclotriphosphazene- co-4,4′-sulfonyl diphenol) Hybrid Nanosheet-Containing Polyamide 6 Composites Kuruma Malkappa, Suprakas Sinha Ray ACS Omega, 2019 A novel halogen-free highly cross-linked supramolecular poly(cyclotriphosphazene-co-4,4′-sulfonyl diphenol) (PZS)-functionalized melamine cyanurate (MCA) (MCA@PZS) hybrid nanosheet fire-retardant (FR) was synthesized and thoroughly characterized using scanning electron microscopy, Fourier-transform infrared (FTIR), X-ray diffraction, and X-ray photoelectron spectroscopy analyses. The polyamide 6 (PA6) composites comprising MCA, PZS, and the MCA@PZS hybrids were prepared via the melt-blending technique. The thermogravimetric analysis combined with FTIR and mass spectroscopy revealed that during thermal degradation, the PA6/MCA@PZS composites released less toxic gases and small organic volatile compounds than the neat PA6 and composites containing MCA or PZS solely. Moreover, compared to neat PA6, the PA6 composite with a 5 wt % MCA@PZS hybrid exhibited enhanced fire retardation properties, with a 29.4 and 32.1% decrease in the peak heat and total heat release rates, respectively. Besides, the PA6 composites with MCA@PZS-5% content achieved a V-0 rating in the UL-94 test. Finally, based on the obtained results from gaseous and condensed phases, the possible mechanism responsible for improved FR properties of the PA6/MCA@PZS composites was proposed.
Ferrocene grafted hydroxyl terminated polybutadiene: A binder for propellant with improved burn rate Billa Narasimha Rao, Kuruma Malkappa, Nagendra Kumar, Tushar Jana Polymer, 2019 In this work, iron containing hydroxyl terminated polybutadiene (Fe-HTPB) based binder cum burn rate catalyst has been developed without altering the crucial physical properties of HTPB. Ferrocene, the source of Fe in the Fe-HTPB, has been grafted at the terminal carbons of HTPB to ensure no alternation in microstructure of HTPB which in turn helped in retaining physical properties of pristine HTPB. The structure and the presence of ferrocene as the end cap groups of the Fe-HTPB were confirmed by solid-state NMR and MALDI-TOF-MS analysis. Control over the viscosity and Fe content of the Fe-HTPB was achieved by varying the grafting reaction recipes and conditions. The Fe content, as measured by inductively coupled plasma - atomic emission spectroscopy (ICP-AES) in the Fe-HTPB varied from 0.06% to 0.165% (by weight) and found to be responsible for increasing viscosity of Fe-HTPB from 5857 mPa S to 11,890 mPa S. Non aluminized composite solid propellants (CSPs) with 86% (wt%) ammonium perchlorate loading were prepared using Fe-HTPB as a binder for studying the burn rate efficiency. Burn rates of CSPs made from Fe-HTPB binders were found to be enhanced by ∼125% compared to CSPs of pristine HTPB. At 40 bar pressure, the burn rate of CSPs made from Fe-HTPB and pristine HTPB binders are 20.56 and 9.07 mm/s burn rate, respectively. In addition, all the CSPs made from Fe-HTPB were found to be very stable as their pressure index is less than 0.5.
