Drying Mechanisms in Plasticized Latex Films: Role of Horizontal Drying Fronts

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Science

Background:

• Drying kinetics are crucial for latex-based material processing.
• Particle softness influences drying behavior, but mechanisms are not fully understood.
• Existing models may not fully capture the complex interplay of factors in latex drying.

Purpose of the Study:

• To investigate the drying kinetics of latexes with varying particle softness.
• To correlate global drying rates with the speeds of horizontal drying fronts.
• To analyze particle deformation mechanisms and compare experimental data with the Routh and Russel (RR) model.

Main Methods:

• Gravimetry for global drying rate measurement.
• Video recording and image processing for horizontal drying front speed analysis.
• Piezorheometry for polymer rheological properties and deformation mapping using the RR model.

Main Results:

• Latexes with softer particles exhibited slower drying rates.
• Drying rate was not limited by skin formation in these systems.
• A correlation was found between global drying rates and drying front speeds, linked to water mass transfer coefficients.
• Qualitative agreement was observed between experimental drying front speeds and the RR model, though the fit was not precise.

Conclusions:

• Particle softness significantly impacts latex drying kinetics.
• Water mass transfer is a key factor influencing drying rates and front propagation.
• The RR model provides a qualitative but not a quantitative description of the observed drying front behavior, indicating a need for refined modeling.