Melt-mixing in twin-screw extruders is a key process in the development ofpolymer composites. Quantifying the mixing performance of kneading elementsbased on their internal physical processes is a challenging problem. We discussmelt-mixing by novel kneading elements called "pitched-tip kneading disk(ptKD)". The disk-stagger angle and tip angle are the main geometric parametersof the ptKDs. We investigated four typical arrangements of the ptKDs, which areforward and backward disk-staggers combined with forward and backward tips.Numerical simulations under a certain feed rate and screw revolution speed wereperformed, and the mixing process was investigated using Lagrangian statistics.It was found that the four types had different mixing characteristics, andtheir mixing processes were explained by the coupling effect of drag flow withthe disk staggering and pitched-tip and pressure flows, which are controlled byoperational conditions. The use of a pitched-tip effectively to controls thebalance of the pressurization and mixing ability.
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