Expanded polystyrene (EPS) has excellent thermal insulation properties and is widely applied in building energy conservation. However, these thermal insulation materials have caused numerous fires because of flammability. Pyrolysis is necessary to support combustion, and more attention should be paid to the pyrolysis characteristics of EPS. Moreover, pyrolysis is considered to be an effective method for recycling solid waste. Pyrolysis kinetics of EPS were analyzed by thermogravimetric experiments, both in nitrogen and air atmospheres. A new method was proposed to couple the Flynn–Wall–Ozawa model-free method and the model-fitting method called the Coats–Redfern as well as the particle swarm optimization (PSO) global algorithm to establish reaction mechanisms and their corresponding kinetic parameters. It was found that the pyrolysis temperature of EPS was concentrated at 525–800 K. The activation energy of EPS in nitrogen was about 163 kJ/mol, which was higher than that in air (109.63 kJ/mol). Furthermore, coupled with Coats–Redfern method, reaction functions g(α) = 1 − (1 − α)3 and g(α) = 1 − (1 − α)1/4 should be responsible for nitrogen and air reactions, respectively. The PSO algorithm was applied to compute detailed pyrolysis kinetic parameters. Kinetic parameters could be used in further large-scale fire simulation and provide guidance for reactor design.
The influence of alkali lignin (AL) as a carbonization agent on the thermal degradation and flame retardancy of intumescent flame retardant (IFR) coating was investigated under air condition, with ammonium polyphosphate (APP) as an acid source, and melamine (MEL) as a blowing agent. Compared with a traditional APP/pentaerythritol (PER) /MEL IFR system, thermogravimetric analysis (TGA) results showed that APP/AL/MEL IFR system could induce the synergistic effect at a much boarder temperature range, and improve the thermal stabilities of the IFR coating. With the increase of AL loading, cone calorimeter test showed the peak heat release rate of the IFR coatings decreased from 54.86 MJ/m2to 41.06 MJ/m2.
The heat-resistance of PLA is so poor that its application area was limited. It can be widely applied after improvement. In the process of making cotton stalk bast fibers reinforced PLA composites, adding TAIC a type of cross-linking agent in the experiment produces a kind of composites with good heat-resistance. Orthogonal experiment table including length and mass fraction of fibers, molding temperature and addition of TAIC was devised. Then the study focused on the heat-resistance of the composites and the analysis of range and variance were done. The optimal processing condition was obtained: length of fibers was 10mm, mass fraction of fibers was 30%, molding temperature was 175°C and addition of TAIC was 1%. In addition, fibers reinforced PLA composites without TAIC had better heat-resistance than the pure PLA material, the HDT raised 54°C, and the composites added TAIC obtained the best heat-resistance of all. This composite can be extensively used in many fields.
The cotton stalk bast fibers are a new kind of natural cellulose fibers, which have the similar properties as the flax fibers. Polypropylene (PP) is a type of matrix material and commonly used in composites. The cotton stalk bast fibers as reinforced materials and PP as matrix were used to make a new kind of composite in the experiment. The composites were prepared by mixing, molding and cold forming. Orthogonal experiment table including mass fraction of fibers, molding temperature, molding pressure and molding time was devised. Then the flexural strength, tensile strength and impact strength were tested and the analysis of range was done. The optimal processing condition was obtained as follows: mass fraction of fibers was 30%, molding temperature was 190°C, molding pressure was 12MPa and molding time was 480s. The result showed that the cotton stalk bast fibers reinforced PP composites had good mechanical properties.
Response surface analysis was applied to optimize the processing of preparing the heat-resistance of the cotton stalks bast fiber reinforced PLA composite. Effects of all factors were evaluated and three factors were selected, which were addition of TAIC, mass fraction of fibers and length of fibers. Subsequently, response surface analysis based on Box-Behnken experimental design was employed to evaluate the interactive effects of three factors. One mathematical model for the processing of composites as functions was established. The results showed that the optimal processing was that the addition of TAIC was 2.1%, the mass fraction of fibers was 26.7%, the length of fibers was 11.7mm, and the HDT of composite was 161.39°C. Under the optimal conditions, the true value was close to the predicted value.
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