Home About us Contact
|
Home About us Contact | ||
|
|
||
Polystyrene Foam (polystyrene + foam)
Selected AbstractsA model to predict fire resistance of non-load bearing wood-stud wallsFIRE AND MATERIALS, Issue 1 2003H. Takeda Abstract The author has developed a series of computer models to predict the fire resistance of wood-framed walls and floors. The models utilize two-dimensional heat-conduction equations and thermo-physical property data to describe heat transfer through the assemblies. The model for wall assemblies WALL2D, the basic version of the wall model, has already been published in Fire and Materials. Recently, WALL2D has been extended to WALL2DN to analyse heat transfer through insulated walls and walls that experience openings at the joints between adjacent sheets of gypsum board. Since gypsum board shrinks at high temperatures, the joints between adjacent sheets of gypsum board open. Hot fire gases, thereby, enter the openings and heat the edge of the gypsum board and wood studs. The new model WALL2DN simulates the joint opening and describes the resultant effect of openings. The model also calculates heat transfer through insulation in the stud cavity and depicts the effect of insulation on the fire resistance of non-load bearing wall assemblies. Insulation selected in WALL2DN is glass-fibre insulation, rock-fibre insulation, polystyrene foam and polyurethane foam. When walls are exposed to fire, the insulation in the cavity shrinks (and/or melts) and an empty space appears at the interface between insulation and gypsum board. The model simulates this shrinking behaviour of insulation in the cavity. Finally, the model was validated by comparing the predicted results to those from full-scale standard fire-endurance tests. Copyright © 2003 John Wiley & Sons, Ltd. [source] Fast pyrolysis kinetics of expanded polystyrene foamAICHE JOURNAL, Issue 6 2010Pravin Kannan 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. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Dynamics of Foaming of Polystyrene ParticlesMACROMOLECULAR SYMPOSIA, Issue 1 2006Gabriela Salejova Abstract September 24, 2006 Summary: In this work, we address the industrially relevant problem of the foaming of expandable polystyrene (PS) impregnated by pentane as a traditional down-stream processing in the suspension polymerization of styrene. Once the polystyrene foam is formed by means of a proper foaming agent, e.g., pentane or fluoro- or chloro-hydrocarbons, the blowing agent diffuses out from the cellular structure. Environmental efforts call for the reduced consumption of blowing agents. The dynamics of foaming of polystyrene particles was recorded video-microscopically in our laboratory as the sequence of images of expanding particle located in the small pressure cell placed under the microscope with sufficient depth of focus. The amount of pentane sorbed in PS was controlled by the length of the impregnation period and was determined independently by gravimetric measurements. Strong dependence of the structure of the produced foam and of the foaming dynamics on the amount of sorbed pentane, temperature and particle size is reported and explanations for some observed foaming phenomena are provided. [source] Open-celled microcellular thermoplastic foamPOLYMER ENGINEERING & SCIENCE, Issue 3 2001B. A. Rodeheaver A theoritical model of the production of open-cell microcellular foam is presented. This model allows the prediction of the conditions necessary to produce these materials. Experiments verify the model quite well. The results of the batch processing experiments indicate the processing parameters that promote the development of open-celled microcellular polystryene foam. A saturation pressure of 17.2 MPa (2500 psig) provides the nucleation density necessary to form an impinged structure with microcellular bubble density. A foaming temperature of 200°C promotes the formation of both internal and surface porosity. A scaled time between 1 and 2.7 seconds develops a foam structure that intrudes a large volume. Samples foamed at 200°C for 1 and 2 seconds possess pores less than 1 ,m in diameter. These samples represent scaled times of 1 and 2 seconds. Therefore, to produce open-celled microcellular polystyrene foam with batch processing, samples should be saturated at approximately 17.2 MPa (2500 psig) and foamed for a scaled time between 1 and 2 seconds. [source] Modeling of three-dimensional flow and heat transfer in polystyrene foam extrusion diesPOLYMER ENGINEERING & SCIENCE, Issue 6 2008Manoj K. Choudhary A three-dimensional mathematical model was developed to investigate the nonisothermal, non-Newtonian polymer flow through the dies used in the polystyrene foam extrusion process. The model, based on the computational fluid dynamics (CFD) code, Polyflow, allowed for the shear rate and temperature dependence of the shear viscosity of the blowing agent laden polystyrene melt. The model also accounted for viscous heating. The shear viscosity of the polystyrene-blowing agent mixture was measured experimentally at several temperatures. The model was used to calculate pressure, flow, and temperature distributions in two different dies used for industrial-scale extrusion of polystyrene foams. The article presents a selection of computed results to illustrate the effect of die design on uniformity of flow at the die exit, the overall pressure drop in the die, relative magnitudes of pressure drop in the land section versus the rest of the die, and temperature distribution in the die. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers. [source] Effect of die temperature on the morphology of microcellular foamsPOLYMER ENGINEERING & SCIENCE, Issue 6 2003Xiangmin Han A study on the extrusion of microcellular polystyrene foams at different foaming temperatures was carried out using CO2 as the foaming agent. The contraction flow in the extrusion die was simulated with FLUENT computational fluid dynamics code at two temperatures (150°C and 175°C) to predict pressure and temperature profiles in the die. The location of nucleation onset was determined based on the pressure profile and equilibrium solubility. The relative importance of pressure and temperature in determining the nucleation rate was compared using calculations based on classical homogeneous nucleation theory. Experimentally, the effects of die temperature (i.e., the foaming temperature) on the pressure profile in the die, cell size, cell density, and cell morphology were investigated at different screw rotation speeds (10 , 30 rpm). Experimental results were compared with simulations to gain insight into the foaming process. Although the foaming temperature was found to be less significant than the pressure drop or the pressure drop rate in deciding the cell size and cell density, it affects the cell morphology dramatically. Open and closed cell structures can be generated by changing the foaming temperature. Microcellular foams of PS (with cell sizes smaller than 10 ,m and cell densities greater than 10 cells/cm3) are created experimentally when the die temperature is 160°C, the pressure drop through the die is greater than 16 MPa, and the pressure drop rate is higher than 109 Pa/sec. [source] | ||||||||||