Double screw kneader

A poly(L-lactic acid) was fed to a double screw kneader at 200°C. To this, ethylene glycol dimethacrylate as a crosslinking agent and dibutyl peroxide as a radical pol5nnerization initiator were added. Pellets were formed from this mixture. 

PA-66 (60)/PPE (36)/ Double screw kneader/adduct Droscher and Jadamus... 

Figure 10.15. Some mixers and blenders for powders and pastes, (a) Ribbon blender for powders, (b) Flow pattern in a double cone blender rotating on a horizontal axis, (c) Twin shell (Vee-type) agglomerate breaking and liquid injection are shown on the broken line, (d) Twin rotor available with jacket and hollow screws for heat transfer, (e) Batch muller. (f) Twin mullers operated continuously, (g) Double-arm mixer and kneader (Baker-Perkins Inc.), (h) Some types of blades for the double-arm kneader (Baker—Perkins Irtc.).

The cationic copolymerization of trioxane with ethylene oxide, 1,3-dioxolane, and suchlike is initiated either with strong protonic acids or Lewis acids, for example BF3. Molecular weight is controlled by the catalyst concentration and monomer purity, and also by chain transfer agents such as methylal [248], which may lead to more stable end groups. Most processes are run below the melting temperature of the polymer (164-167°C) in precipitating agents or in bulk, and are carried out in kneaders or double-screw reactors [249, 250], but there are also some descriptions of melt processes [251]. 

Kneading is a double-disc screw, that is, an eccentric disc mounted on two shafts rotating in the same direction, the screws are water cooled. Feeding of kneader is continuous. I he water is thus separated from the material. 

Mixing screws — S-shaped kneader, Eagle mixing. Turbine mixing, Cohen double-wave, or Maillefer screws with pin-, blister ring-, fluted-, barrier-screw. Dynamic Extentional Flow Mixer (DEEM), etc. 

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