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Processing of reinforced plastics using multi‐screw compounders
Author(s) -
Eise Kurt,
Curry John,
Farrell John
Publication year - 1985
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760250813
Subject(s) - materials science , extrusion , reinforcement , mixing (physics) , compounding , composite material , polymer , plastics extrusion , mechanical engineering , wetting , process engineering , engineering , physics , quantum mechanics
Polymer modification by addition of reinforcing agents represents a popular means of increasing physical property values. The polymer matrix has been forced to accept up to 55 percent by weight of fibrous reinforcement and 80 percent by weight of powdered types in order to meet application requirements. These materials demand sophisticated mixing equipment which must provide extensive intake and conveying capabilities, polymer wetting of reinforcement, and dispersion of reinforcement. This process must also be conducted with controlled shear intensity and excellent temperature and residence time control in order to respect polymer thermal sensitivity and product requirements. The extrusion process is a proven economical method for incorporating reinforcements into polymer resins. Co‐rotating intermeshing twin‐screw extruders are particularly suited for these tasks. Positive conveying, self‐wiping, and shear intensive mixing characteristics provided by the screw mechanism satisfy requirements of reinforcement compounding. This mechanism allows interruption of streamline flow which is needed to disperse both high and low aspect ratio reinforcing agents into a polymer matrix. Mathematical representation of the benefits of twin‐screw extrusion (relative to single‐screw) related to pumping and mixing capability have been developed based on the classical pressure flow continuity equation with proper selection of boundary conditions.