Gelatin

Plasticizer

Engineering

Nanoparticle

Materials science

Surface finish

Chemical engineering

Surface roughness

Contact angle

Nanotechnology

Organic chemistry

Sessile drop technique

Composite material

Chemistry

Wetting

Surface energy

Polymer science

Journal of Food Engineering

The effects on surface properties of films with compositions based on gelatin plasticized with glycerol, without or with montmorillonite (MMT), and plasticized with acetyl tributyl citrate (ATC) was investigated. The water contact angle (WCA), wettability and free surface energy were determined by measuring the WCA using the sessile drop method. The surface topography was measured by AFM. The film plasticized by glycerol presented the smoothest surface, while the film loaded with MMT presented the greatest surface roughness followed by that plasticized by ATC. All films showed a hydrophobic character (WCA>65°), and the same trend was observed for wettability. It is worth mentioning that there was no significant correlation between the values of WAC and roughness. The films showed low polar component values, which corroborate the high WCA values obtained. In conclusion, the MMT load or the use of ATC did not expressively improve the humidity resistance of films based on gelatin.

Wettability of gelatin-based films: The effects of hydrophilic or hydrophobic plasticizers and nanoparticle loads