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Journal of Thermal Analysis and Calorimetry
Authors: Sanjiv Arora, Mahesh Kumar, and Mahender Kumar

Abstract

Wood, one of the flammable material, was treated with aqueous solution of guanidine nitrate (GUN) and also with small amount of bases like N,N-dimethylformamide, 4-dimethylaminopyridine, pyridine, and triethylamine in the treating solution. These bases catalyze the impregnation of GUN as indicated by increase in mass gain percentage, elemental analysis, and scanning electron microscopy. To study their thermal behavior, dynamic thermogravimetry (TG) and derivative thermogravimetry (DTG) analysis under nitrogen atmosphere have been applied from ambient temperature to 973 K on all samples, at multiple linear heating rates 2.5, 5, 10, and 20 K min−1. Non-isothermal, “model free” iso-conversional multiple heating rate methods, Ozawa–Flynn–Wall (O–F–W) and modified Coats–Redfern are used to calculate activation energy of samples. The activation energy of samples is found in the range 109–208 kJ mol−1. Thermal parameters like overall pyrolysis duration, maximum mass loss rate, corresponding to DTG peak maximum and percentage char yield calculated at 873 K from TG curves are used to appraise the flammability of samples. Also, flammability of samples is determined by reliable methods namely limiting oxygen index and underwriters laboratories 94 (UL 94) test. The aforesaid study indicates that base catalyzed impregnated samples are less flammable than those impregnated with only GUN and untreated ones.

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Abstract  

Alpha-tocopherol (vitamin E) is the most widely used antioxidant for edible oils. The present investigation presents its effect on the thermal degradation behavior of edible oils (sunflower, soybean, and their blend) through the use of dynamic thermogravimetry. The study is based on the comparison of activation energies of decomposition process which were subsequently calculated using preferred and reliable multiple-heating rate methods viz. Kissinger, Friedman, Ozawa–Flynn–Wall, and Coats–Redfern (modified). It is concluded that the role of alpha-tocopherol as antioxidant at higher temperature is nearly accomplished.

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