Extrusion process definition

Giles, H. F., Jr. Wagner, J. R., Jr. Mount, E. M. Extrusion The Definitive Processing Guide and Handbook - PDL Handbook Series. (2005) William Andrew Publishing, Norwich, NY. 

Technical constraints are often imposed on the design of the monolith geometry by the extrusion process, as well as by the mechanical properties of the extrudate the specific SCR application (e g., high-dust vs. low-dust) is also crucial for the definition of the catalyst geometrical features. Here, attention is paid to the influence that the monolith parameters (wall thickness, channel size, channel shape) have on both DeNOx reaction and SO2 oxidation in order to advance guidelines for optimization of the catalyst geometry. 

After the extrusion process, a posttreatment step is usually necessary to size and shape the strands to the preferred particle length and shape. These types of granule are normally specified by the aspect ratio (also called L/D ratio L = length, D = diameter) or a shape factor F [121], A typical range for the L/D ratio of detergent ingredients is L/D = 1-3 the shape factor characterizes approximation to an ideal spherical particle (Y = 1). Depending on the definition, the shape factor of a nonideal sphere is Y < 1 or Y > 1. 

While these previous studies offered valuable insights, demonstrating the continuous extrusion process of PLA foamed with supercritical CO2, the morphology achieved in foamed PLA failed to satisfy the definition of microcellular foam due to lower cell population density (less than 10 cells/ cm ) with cells being larger than 60 m in average size. Distinctions between these features and microcellular foam... 

H. Giles, J. Wagner, and E. Mount, Extrusion The Definitive Processing Guide, William Andrew, 2005. 

The extrusion process of plastic profile with metal insert is first to heat the polymer pellets mixed in a definite proportion by the extruder and then extrude the fusing polymer melts though the extrusion die to coat onto the moving metal insert. After cooling and shaping in the stock mould, the plastic profile with metal insert shown as Fig.l can be obtained. 

Extrusion A plastic processing technique to produce pipe, film or sheeting. The plastic is fed through a flat or preformed annular die, which gives the object its definitive shape. 

It has been demonstrated that molecular orientation can be achieved starting with a low molecular weight species which is oriented in an elongational flow and subsequently cured under UV-irradiation. The orientation of the monomer is frozen-in by the ultra-fast process of polymerization and crosslinking. Both extrusion and stretching can be carried out at relatively low temperatures and pressures. Polymer filaments produced in this way are definitely anisotropic as is evidenced by their birefringence and by a strong increase of the tensile modulus and a decrease of the thermal expansion coefficient in the axial direction. 

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