Fast pyrolysis kinetics of expanded polystyrene foam

Abstract

Fast pyrolysis of polymers, biomass and other substances is of great interest in various applications. For example, in the lost foam casting process, kinetic information about expandable polystyrene (EPS) decomposition under extremely high-heating rate conditions is essential for further process development. A simple laboratory-scale fast pyrolysis technique has been developed and demonstrated for elucidation of EPS decomposition kinetics. Pyrolysis experiments were performed at different reaction temperatures. The cumulative gaseous yields were determined using a flame ionization detector (FID) connected in series with the fast pyrolysis reactor. The governing equations for a semibatch reactor type were modified and applied to obtain kinetic parameters (activation energies and the pre-exponential rate constants) for the EPS decomposition process. V

Polystyrene with trifluoromethyl units: Monomer reactivity ratios, thermal behavior, flammability, and thermal degradation kinetics

“…The lower values of kinetic parameters were calculated by the Kissinger method in the case of PSt and P(St‐ co ‐StCF 3 )–2. In literature the thermal decomposition activation energy of PSt was calculated by various models such as: the Coast‐Redfern ( E = 250.3–251.5 kJ/mol), Friedman‐Ozawa ( E = 201.2 kJ/mol), Anderson and Freeman's ( E = 193–273 kJ/mol), Westerhout et al . 's ( E = 204 kJ/mol), Kannan et al .…”

Effect of strips size and coating thickness on fluidity of A356 aluminium alloy in lost foam casting process

“…5b. Therefore, the overall interfacial heat transfer coefficient h is related to the total thermal resistance by h~1 S R~1 1=h er zL 2 z1=h rm (8) According to equation 8, in the LFC process, as the coating thickness increases, thermal resistance increases. Thermal resistance represents the difficulty of heat extraction from the casting during solidification, which means that at a low thermal resistance, the rate of heat transferring of casting is high.…”

“…6 Coating is a thin layer of refractory material that controls the pattern firmness, surface smoothness, permeability of polymer foam degradation products and, to some extent, the heat transfer and solidification of casting. [6][7][8][9][10][11][12][13][14] Increasing the coating thickness decreases fluidity in mould because of the reduction in the permeability and the possibility of prevention of the escape of foam degradation products in cavity; on the other hand, using the thicker refractory coating causes longer fluidity due to the saving of heat contain and decreasing of the cooling rate of the casting. 15 In the LFC process, mould filling is also dependent on casting geometry.…”

“…

In this research, effects of six different strips size (2,4,6,8,10 and 12 mm thick respectively) and six different coating thicknesses on the fluidity of A356 aluminium alloy in lost foam casting (LFC) process were investigated. It was found that, in each mould, as the strip thickness increases, fluidity length increases.

…”

Influence of process parameters on filling ability of A356 aluminium alloy in expendable pattern shell casting with vacuum and low pressure

“…7,8 Unfortunately, the decomposition of the foam pattern during the pouring process could result in some defects, including pores and slag inclusions, etc., 9 and the pouring temperature of the LFC is usually higher than that of traditional cavity casting in order to improve the filling ability and overcome heat absorption from the decomposition of the foam pattern. As a result, the coarse grains, porosity defects, poorer filling ability and lower mechanical properties of LFC are always a major problem to limit its development.…”