How do drying methods affect quality of films? Drying of polymer solutions under hot-air flow or infrared heating with comparable evaporation rates

Wrinkles formed during the drying of polymer films by hot-air flow but not when drying by infrared irradiation, even though drying rates were comparable. The top surface was hotter than the bottom during hot-air drying. Conversely, the temperatures of the top and bottom surfaces were very similar when drying by infrared irradiation. We also examined uniform heating with faster and slower drying rates using drying with combined infrared irradiation and air flow (hot or room temperature). Wrinkles formed in both cases. This demonstrated the negative effect of air flow. Features and mechanism of each drying method are discussed.