Single-screw extruder, blending equipment

The results reported in this paper are characteristic not only of grafting of lA onto PP/PE blends carried out in the Brabender plastograph equipped with a dynamic mixer, but also of lA grafting performed in reactors of other types, particularly in a single-screw extruder. 

The LCP/polymer blends were prepared with a laboratory single screw extruder (D=19 mm, 1 =25 Brabender, Germany), equipped with a die assembly for ribbon... 

The blends were prepared by melt extrusion in a Brabender laboratory single-screw extruder (D = 19 mm, L/D = 25) at 100 rpm with a die temperature of 260°C. The R2/Ny blend was also prepared by melt mixing of homopol5miers in the same Brabender Plasticorder equipped with a mixer head model W 50 EH at 260°C and 100 rpm for 15 min. The mixing time was sufficient to attain a practically constant value of torque. Homopolymers were subjected to the same treatment. 

A report is presented on the development of a 50/1 singlescrew extruder with novel elongational mixing and a comparison of this extruder with a 24/1 single-screw extruder equipped with a Uinon Carbide mixer. Data from trials, which involved flood feeding and starve feeding, conducted on a thermoplastie elastomer, LDPE and blends, proeessed in these maehines are included. 

To a continuing process the pigment dispersions are added directly to the plasticising equipment by volumetric or gravimetric measuring units. Further blending can then be done on a single- or twin-screw extruder. 

Thiele (18) stressed the utility of continuous-single and twin-screw extruders compared with Banbury batch type mixers on the basis of the working volume, that is, small working mass in the extruder channels in continuous process equipment versus a large amount of blended material per cycle in batch type mixers. With a relatively smaller working volume in an extruder, there is more enhanced intimate mixing on the microscopic scale in a shorter period of residence time. 

---