Semisolid mixing combines aspects of both solid and liquid mixing due to the intermediate nature of semisolids (e.g., creams, pastes, gels):
Convective Mixing:
Similar to solid mixing, involving bulk movement but adapted to the higher viscosity of semisolids.
Shear Mixing:
Applying shear forces using equipment like planetary mixers, sigma blade mixers, or kneaders.
This is critical to overcoming the high resistance to flow in semisolids.
Extensional Flow:
Stretching the material to enhance mixing, particularly important in high-viscosity materials.
Homogenization:
Often used to break down particle agglomerates and improve uniformity. This might involve high-pressure homogenizers or mills.
Semisolid Mixing Equipment
Planetary Mixers: Use rotating blades and a rotating container for thorough mixing.
Sigma Blade Mixers: Use two large blades that move in a sigma shape to knead and mix.
Extruders: Force materials through a narrow die to achieve mixing and shaping.