Heating extruders

L. S. Socha, D. F. Thompson, and P. S. Weber. Reduced Energy and Power Consumption for Electrically Heated Extruded Metal Converters, SAE 930383, Society of Automotive Engineers, Warrendale, Pa., 1993. 

The copolymers are used in the manufacture of filaments. These may be extruded from steam-heated extruders with a screw compression ratio of 5 1 and a length/diameter of 10 1. The filaments are extruded downwards (about 40 at a time) into a quench bath and then round drawing rollers which cause a three- to four-fold extension of the filaments and an increase in strength from about 10000 to 36 000 Ibf/in (70-250 MPa). The filaments are used for deck chair fabrics, car... 

The first evidence for the formation of compounds having a silicon-silicon double bond first appeared in 1969 when it was formed that disilebicyclo [2.2.2] octadienes on heating extruded tetramethyldisilene. 

Silaphosphetanes can be synthesized. They result from the intramolecular cyclization of /3-chlorosilylphosphine using n-butyllithium (Scheme 100). Like the germoxetanes they exist as a monomer-dimer equilibrium, insert sulfur and benzaldehyde, and on heating extrude the silaphosphimine intermediate which then either dimerizes or inserts the original silaphosphetane (Scheme 101) (79JOM(182)9). 

Menges and his successor Professor Michaelis conducted pyrolysis at RWTH-Aachen in an externally heated extruder, up to 430°C, a temperature maximum dictated by materials selection considerations. Early extruder pyrolysis systems were developed by Union Carbide and Japan Steel Works [14],... 

Blow-fill technology is an aseptic process whereby the container is formed from thermoplastic granules, filled with sterile solution and sealed, all within one automatic operation. The bulk solution should have a low bioburden and is delivered to the machine through a filling system that has been previously sanitized and steam sterilized in situ. Concern has been expressed that the machine itself may generate particles. The plastic granules are composed usually of polyethylene, polypropylene or one of their copolymers and are heat extruded at 200°C into a tube. The two halves of a mould close around this tube and seal the base. The required quantity of sterile fluid is filled into the container, which is then sealed. Products packed in this way include intravenous solutions, and small volume parenteral, ophthalmic and nebulizer solutions. The... 

When photocuring of the composition is desirable immediately after extrusion, i.e., before the thermoplastic polymer cools and solidifies, UV irradiation of the heated extrudate can take place directly at the die orifice. 

In conclusion, a starchy material is converted into thermoplastic starch (often called TPS) by melting in closed devices such as heated extruders or other closed devices capable of... 

Forming represents a relatively low cost method, utilizing male or female molds, to which a heated extruded polymeric slab is attached, so that the... 

Plastic moves from the hopper onto the feeding portion of the reciprocating extruder screw. The flights of the rotating screw cause the material to move through a heated extruder barrel where it softens (is made fluid) so that it can be fed into the shot chamber (front of screw). This motion generates pressure (usually 50-300 psi [0.35-2.07 MPa]), which causes the screw to retract. When the preset limit switch (or a position transducer, on newer machines), is reached the shot size is met and the screw stops rotating. At a preset time the screw acts as a ram to push the melt into the mold. Injection takes place... 

In conclusion, a starchy material is converted into thermoplastic starch (TPS) by melting in closed devices such as heated extruders or other closed devices capable of maintaining temperature, pressure and shear conditions. Starch that has undergone a thermoplastic transformation does not show the typical melting peaks of native starch at specific water content, under differential scanning calorimetry (DSC) analysis in sealed vials, and can be defined as thermoplastic starch. 

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