Thermogravimetric analyzer coupled to a mass spectrometer (TGA-MS) was used to study the thermochemical behavior of eight samples. Two varieties of straw (wheat and barley) and two others of binder (lime and plaster) have been employed to design four composites. These composites can be considered as innovative insulation materials for buildings. The thermal degradation of the different specimens was studied from a temperature of 50 to 1000°C using an increased temperature of 20°C/min. This thermal degradation is an important element to evaluate the fire behavior and predict the evolution of smoke emitted during an accidental fire for building application. Using MS analyzer, the ion currents evolutions of 16 molecule groups (shared by a m/z ratio) were followed as functions of temperature. TG curves show that the thermal decomposition of composite samples is more complex (3–4 mass loss steps) than the one of the basic materials (1–2 mass loss stages) and seems to be mostly affected by the binder nature. The highest amount of gas in pyrolysis products is associated to m/z = 28 ratio and presents more than two-thirds of the total quantity. The kinetic parameters were evaluated for the more important mass loss of each sample and their values are in the ranges of 8.29–64.86 kJ/mol, 0.4–3.36 and 1.78×103–1.63×107 min−1 for respectively the activation energy, the reaction order and the pre-exponential factor.
Authors: Chetehouna, Khaled; Belayachi, Naïma; Rengel, Borja; Hoxha, Dashnor; Gillard, Philippe; 24.04.2015
