Effect of stearic acid and sodium stearate on cast cornstarch films

Abstract

Stearic acid and sodium stearate were used as lipids to form inclusion complexes with cornstarch through a cooking process, respectively. The complexing index and the surface tension of the cooked pastes were measured. The films of the pastes were formed by casting, paper-sizing, and paper-coating methods. X-ray diffraction and scanning electron microscopy were used to characterize the crystal and surface structures. Such properties of the complex films as the moisture absorption, friction coefficient, and tensile properties were tested. The results reveal that the two lipids could form an inclusion complex with amylose in the cornstarch more or less as a result of forming V-type crystals that restrained the crystallite size of the B-type crystal in the starch film. The addition of lipids reduced the sensitivity of the complex films to environmental moisture, decreased the friction coefficient of the films, and visibly increased the smoothness of the surfaces of the films. When the lipids were added in the starch at a weight content of 1%, the elongation at break of the complex film increased and the strength decreased slightly, and above a 1% content of the lipids, the tensile properties of the starch film were greatly deteriorated.

High‐performance starch/clay bionanocomposite for textile warp sizing

“…Here the V‐type crystallization was believed to be resulted from associated natural lipids in the corn starch . This indicated that the free aliphatic amine DMA18 was released during the preparation of HOMMT, leading to formation of an inclusion complex of amylose , which promoted the formation of single helices in starch while restricted its double helix structure of B‐type. It was worth mentioning that the peak observed at 2 θ = 26.1° in the XRD curves of nanocomposite was caused by the existence of impurities (SiO 2 ) in the MMT.…”

“…The relevant peaks of the nanocomposites with different contents of HOMMT changed obviously. The typical B-type crystallization peak at 2h 5 17.18 [27] had a decreasing trend and the typical feature corresponding to V-type crystallization at 2h 5 19.98 [28,29] increased with the content of HOMMT increasing. Here the V-type crystallization was believed to be resulted from associated natural lipids in the corn starch [29].…”

Effect of the ways of adding stearic acid on properties of sweet potato starch and sweet‐potato‐starch‐based films

“…Nobrega et al report that the SA can cause a decrease in the water vapor permeability (WVP) values of cassava‐based films. In a series of recent papers , the effects of fatty acids on the mechanical, barrier, and other properties of starch‐based films have been explored. However, the effects based on different ways of adding SA on the properties of starch‐based films, to the best of our knowledge, have not been investigated, and some questions remain unclear concerning the effects of the ways of adding SA on the properties of films.…”