title: Heterogeneities in gelatin film formation using single-sided NMR.
abstract: Gelatin solutions were prepared in D(2)O. The drying process of cast solutions was followed with a single-sided nuclear magnetic resonance (NMR) scanner until complete solidification occurred. Spin-spin relaxation times (T(2)) were measured at different layers with microscopic resolution and were correlated with the drying process during film formation. Additionally, the evaporation of the gelatin solution was observed optically from the reduction of the sample thickness, revealing that at the macroscopic level, the rate of evaporation is not uniform throughout the experiment. A crossover in the spatial evolution of the drying process is observed from the NMR results. At the early stages, the gel appears to be drier in the upper layers near the evaporation front, while this tendency is inverted at the later stages, when drying is faster from the bottom. XRD (X-ray diffraction) data showed that a structural heterogeneity persists in the final film.
authors.affiliation: Department of Technical Physics II/Polymer Physics, Institute of Physics, Faculty of Mathematics and Natural Science, Ilmenau University of Technology, P.O. Box 10 05 65, D-98684 Ilmenau, Germany. sushanta.ghoshal@tu-ilmenau.de
authors.forename: Sushanta
authors.initials: S
authors.lastname: Ghoshal
authors.forename: Carlos
authors.initials: C
authors.lastname: Mattea
authors.forename: Paul
authors.initials: P
authors.lastname: Denner
authors.forename: Siegfried
authors.initials: S
authors.lastname: Stapf
mesh_terms: D003890:Desiccation; D005780:Gelatin / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D012997:Solvents / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D012997:Solvents; C015233:gelatin film; D005780:Gelatin