Hydrolysis of part of cassava starch into nanocrystals leads to increased reinforcement of nanocomposite films

This article reports on using cassava starch nanocrystals (CSN) to strengthen nanocomposite films from the same matrix. CSN were obtained by acid hydrolysis. Nanocomposite (starch:glycerol:CSN/4.0:2.1:1–10 wt %) were processed by casting and the films were characterized. The CSN (30% yield) presented minimally clustered globular forms, 45 to 178 nm in diameter, with a crystalline index of 46%. Water‐vapor transmission rate, tensile strength, and elastic modulus of the films were influenced by the linear effect of CSN concentration ( R 2  = −0.92, 0.91, 0.99, respectively), while the other parameters resulted in quadratic relations |0.69–0.96|. The film with 10% CSN presented a 43% reduction in water vapor permeability, associated with increases of 200% in traction resistance, and 616% in elasticity modulus, compared with the control. The hydrolysis of part of the cassava starch into nanocrystals resulted in a reduction in permeability and nano reinforcement of the films due to good compatibility and interaction between both, without influencing biodegradability. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45311.