Twin-screw extruder extrusion process

With the pressurized hydrolysis technology, water under high temperature and high pressure is applied to hydrolyze and break the crosslinks of the paint film, and then a kneading extruder is used to convert the decomposed film into particles and disperse them in the TP resin. Two types of the processing system have been developed. One is the autoclave reaction and screw extrusion processing system (batch system), and the other is the twin screw reactive extrusion processing system (continuous system). 

Figure 3 outlines the twin-screw reactive extrusion processing system. The crushed bumper is introduced to a twin-screw extruder whose... 

In injection molding and extrusion, use of strand pellet PES resin is certainly justified from a practical and economical point of view. The strand-cut pellet PES, strand extruded on single or twin-screw extruder using processing conditions listed in Table 7, were satisfactory in appearance and internal structure. 

Blends of polypropylene (PP) and liquid crystalline polymer (LCP) processed without melting the LCP were compared with conventional melt processed blends. In a first stage, PP was blended with 20 wt% of LCP in a twin-screw extruder with the take-up speed varied to achieve blends with different LCP fiber dimensions. In the second stage, these blends were processed both below and above the Tm of the LCP by extrusion and injection molding. 

Post-consumer PMMA plastics can be depolymerised back into their starting components. Degradative extrusion in twin-screw extruders can be used for this process. 10 refs. Translation of Kunststoffe, 87, No.2, Feb.1997, p.183-8... 

Homopolymers and copolymers from amido-sulfonic acid or salt containing monomers can be prepared by reactive extrusion, preferably in a twin screw extruder [1660]. The process produces a solid polymer. Copolymers of acrylamide, N-vinyl-2-pyrrolidone, and sodium-2-acrylamido-2-methyl-propane sulfonate have been proposed to be active as fluid loss agents. Another component of the formulations is the sodium salt of naphthalene formaldehyde sulfonate [207]. The fluid loss additive is mixed with hydraulic cements in suitable amounts. 

Fig. 2.15. Reactors for producing these materials include batch, continuously vented, tray reactors, twin-screw extruders, and vented single-screw extruders. These production devices will not be covered in this text because they are of more interest to the manufacturing engineer than the extrusion process engineer.

SAN can be modified, for example by grafting. For example, maleic anhydride (MA) can be grafted onto SAN. This process occurs preferably in a twin-screw extruder by reactive extrusion. An advantage of reactive extrusion is the absence of solvent as the reaction... 

Extrusion. The main applications of this method include the production of film, sheet, pipe, and tubing. PB is usually extruded by using the same equipment (single- cu twin-screw extruders) as that used foi PP and HDPE, at melt and die temperatures of 170- 190°C. PMP is processed on extruders with a high length-to-diameter ratio at temperatures of 240-300°C. 

The twin-screw injection molding extruder is an injection molding machine that is capable of both blending/compounding and extrusion in one step. Because it is a one step process, the fibers never go through the entire extrusion process as well as the pelletization that limits the fiber size, but are blended into the molten plastic before injection. The screw part of this machine is based on a non-intermeshing, counterrotating twin-screw extruder (Chapter 5). One of the screws in this machine is capable of axial movement and has a non-return valve on the end. This action enables the screw to inject and mold parts. 

The extrusion of foamed products with twin screw extruders has been reviewed (375). The machinery, tools and processes for the production of foam core pipe, sheet and profile have been listed and the market reviewed (124,333). Technical details of PVC-U foam sheet extrusion lines, including dies and calibrators, have been given (258). 

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