Cashew gum-chitosan blended films: Spectral, mechanical and surface wetting evaluations

Blends of cashew tree gum with chitosan and glycerol as plasticizer were prepared by casting and characterized by Fourier transform infrared spectroscopy (FTIR), mechanical (DMA) and thermogravimetric analysis (TG), scanning electron microscopy (SEM) and surface wettability by static contact angle measurements. FTIR analysis confirmed the consolidation of both polysaccharides and revealed a clearly interaction between the glycerol molecules and hydroxyl groups of chitosan. Chitosan and glycerol improved films mechanical properties and interferes on surface wettability. The unblended cashew gum films presented hydrophilic surfaces (medium measure angle as 40o) and with the addition of chitosan provides a shift towards a more hydrophobic behavior (52o and 75o for additions of 0.5% and 1.0% (w/w) chitosan respectively). Microscopy surface observation confirmed that the presence of glycerol reduced film cracking, changing them from fragile to a more plastic property. The film forming ability of chitosan is also preserved when blending with cashew gum.