K.N. Ninan

Bio: K.N. Ninan is an academic researcher from Vikram Sarabhai Space Centre. The author has contributed to research in topics: Thermal decomposition & Thermogravimetry. The author has an hindex of 4, co-authored 4 publications receiving 70 citations.

Pyrolysis Behavior of Hybrid-Rocket Solid Fuels Under Rapid Heating Conditions

Abstract: An experimental investigation of the thermal pyrolysis behavior of several hybrid-rocket solid fuels under rapid heating conditions was conducted to determine pyrolysis laws and to identify and quantify the products of fuel pyrolysis. The study focused on four fuel formulations: pure hydroxyl-terminated polybutadienes (HTPB), 80% HTPB/20% Alex, 80% HTPB/20% Al, and the Joint Industrial Research and Development fuel formulation. A rapid conductive-heating technique was developed and employed to determine Arrhenius-type pyrolysis laws. All four fuels displayed two sets of Arrhenius parameters, depending on the range of surface temperature. For pure HTPB,Ea = 4:91 kcal/mol andA = 11.04mm/s above722K, whileEa = 13:35 kcal/mol andA = 3965mm/s below 722 K. These results agree well with those obtained previously using a lab-scale hybridmotor operating under realistic conditions. The gas chromatograph/mass spectrometer tests of the nonmetalized fuels, using a  ash-heating oven, indicated that the relative concentrations of the pyrolyzed species depended strongly on temperature. For pure HTPB seven major products were identiŽ ed, with 1,3-butadiene representing the dominantproduct at all temperatures tested, up to 1073 K. The measured mole fractions of the pyrolysis products and deduced pyrolysis laws of the fuels studied can be utilized in a comprehensive model simulation for combustion performance predictions.

Thermogravimetric Stability Behavior of Less Common Lignocellulosic Fibers - a Review

Abstract: A review on the thermogravimetric behavior of some less-common natural lignocellulosic fibers is presented. The review was limited to works analyzing results on the weight loss variation with temperature by means of the thermogravimetric (TG) curve and its derivative (DTG) for uncommon fibers such as curaua, rice, wheat straw, henequen, piassava, fique, date palm, buriti, artichoke, grass, okra, sponge gourd, caroa and olive husk. Relevant parameters obtained from corresponding TG/DTG curves were discussed to highlight distinctions and similarities in the thermal stability of these fibers. The concept of fiber thermal degradation is critically examined in view of the decomposition stages associated with the main constituents: water, hemicellulose, lignin and cellulose. The effect of fiber thermal degradation on possible application as polymer composite reinforced is remarked.

Thermal studies on lanthanide nitrate complexes of 4-N-(2'-furfurylidene)aminoantipyrine

Abstract: The kinetics and mechanism of thermal decomposition of nitrate complexes of lanthanides with the Schiff base4-N-(2′-furfurylidene) aminoantipyrine (abbreviated as FAA) have been studied by TG and DTG techniques. The kinetic data for the first stage of decomposition were calculated using the Coats-Redfern equation. The rate-controlling process obeys Mampel model representing random nucleation, with one nucleus on each particle. It is observed that there is no gradation in the values of the kinetic parameters of decomposition of the complexes.

Thermal Degradation of Four Bamboo Species

Abstract: Bamboo, among other natural plants, has a special structure, with different characterization along the culms and between species. In this study, the thermal stabilities of four bamboo species, named Dendrocalamus pendulus (DP), Dendrocalamus asper (DA), Gigantochloa levis (GL), and Gigantochloa scortechinii (GS), were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) under a nitrogen atmosphere. Each species was divided into three different portions: bottom, middle, and top, and fibres were manually extracted from the specified sections of each species. The thermal analysis of extracted bamboo fibres indicated that the thermal degradation behaviour of each bamboo species varied from bottom to top and between species. However, these variations were lower in DA species compared to GS, GL, and DP, because of minor differences between lignocellulosic components of its three portions. The top and middle portions of the four species degraded at a higher temperature range (314 to 379 °C) than the bottom portions. The results of this study suggest that DA and GS species, according to their thermal stabilities, are most suitable for use as reinforcement in composite materials.