Thermal Degradation Kinetics Behavioral Characteristics Research Of Typical Organic Insulation Materlals For Building

In recent years, because the national advocate social background of building energy efficiency, the insulation material has been developed rapidly, Especially organic building insulation materials are widely used in building insulation structure because of its excellent thermal insulation properties and low cost, withstand voltage, water repellency and other characteristics. However, due to organic building insulation materials on fire easily cause a fire and the release of toxic fumes, which often cause huge casualties and property losses. Thus, in order to prevent the occurrence of fire accidents, reduce the risk and severity of fires, in-depth study of the characteristics of these combustible fire building insulation materials is particularly necessary.Molded polystyrene foam(EPS), polyurethane foam(PU), phenolic foam(PF) was selected as the experimental research material.The pyrolysis dynamic behaviors under different experimental conditions were explored by thermogravimetry and different scanning calorimetry(TG-DSC) method, and the atmosphere effects on pyrolysis kinetic parameters and the reaction mechanism function were discussed. The results showed that:(1) Polystyrene foam in the shape of the pyrolysis curves under air and N2 atmosphere similar, and both showed two phases, the second phase of the main stage and almost no weight loss pyrolysis residue. It was found that the pyrolysis curves were delayed and the initial and ending reaction temperatures and the peak temperature under N2 atmosphere were higher than those under air atmosphere, which means pyrolysis is easier to occur with oxygen.Isoconversional be obtained by pyrolysis reaction under air atmosphere activation energy is 144.55kJ/mol, the activation energy increases with an increase in the conversion rate. Under a N2 atmosphere activation energy is 193.34kJ/mol, activation energy in the early stages of pyrolysis has increased slightly, and then little change. Compared to an air atmosphere, a N2 atmosphere is very small changes in the value of the activation energy, more stable. The reaction mechanism function under the two atmospheres were obtained by Coats-Redfern method, which found the pyrolysis behaviors obeyed different mechanism function. the behaviors under air and N2 atmospheres can be described by the nucleating and nuclear growth function A2/3 and the reaction progression function F3, respectively.(2) Polyurethane foam in air and N2 atmosphere pyrolysis curve shape significantly different, each divided into three stages and two stages. The results indicated that the reaction emperature interval is close in the first stage and this stage of the reaction process is similar. The remaining residue respectively 4% and 23%, which means that pyrolysis reaction under air atmosphere is more thorough.Polyurethane foam activation energy in an air atmosphere showed a gradually increasing tendency, when the conversion rate is between 0.1 to 0.5, the activation energy for 79.11kJ/mol, between 0.7 to 0.9, the activation energy for 124.58kJ/mol. The average activation energy of N2 atmosphere is 139.33kJ/mol and the activation energy value gradually increased with the conversion rate. the initial activation energy under the two atmospheres are relatively small, indicating rigid polyurethane foam heat easily heat loss occurs. Coats-Redfern be obtained by pyrolysis mechanism of rigid polyurethane foam under air and N2 atmospheres,and the behaviors can be described by one-dimensional diffusion D1 and dendritic nucleation P-T equation B4, respectively.(3) Phenolic foam pyrolysis curve under air atmosphere with Increased heating rate in migration to the high temperature zone, the pyrolysis process has two phases and the remaining residue is about 21%. The major thermal weight loss occurs in the second phase. There is little loss of quality when the phenolic foam is heated,and long duration of the pyrolysis initial stage. Isoconversional be obtained activation energy for 45.26kJ/mol, the conversion rate from 0.1 to 0.2 in the temperature span, main reaction started relatively late and the remaining material is more.Indicating that the phenolic non-combustible, flame retardant characteristics. The reaction mechanism function under the air can be described by the reaction progression function F3/2.(4) The degree of fire hazard of polyurethane foam is the biggest, followed by molded polystyrene, phenolic minimum.