Induction of foaming in vacuum drying by needle stimulation and the impact of solution viscosity, vapor pressure, and the type of solute and solvent

Reliable induction of foaming is indispensable for vacuum foam drying. We previously showed that, adequate partial drying followed by puncturing a solution with needle (needle stimulation) resulted in the foaming, even under insufficient where minimal. Herein, characteristics needle-stimulation-induced was investigated, focusing on impact viscosity and vapor pressure. Different combinations solutes (disaccharides, polyvinylpyrrolidones, polyacrylic acid, Eudragit) solvents (methanol, ethanol, isopropanol, water) were used. Needle stimulation conducted after different periods initial drying, probability during restart determined. Each series (polymers disaccharides) respectively indicate solvent-independent correlations between viscosity. The existence lower limit pressure required also implied. A possible mechanism reduced proposed.