Starch acetate film-forming properties

Tarvainen et al. (2002) studied the film-forming ability of starch acetate (DS 2.8) and the effect of commotfly used plasticizers on the physical properties of starch acetate films. The properties were compared with ethylcellulose films. Mechanical studies, water vapor and drug permeability tests, and thermal analysis by differential scarming calorimetry (DSC) were used to characterize the film-forming ability of starch acetate and efficiency of tested plasticizers. Starch acetate films were foimd to be tougher and stronger than ethylcellulose films at the same plasticizer concentration. Also, in most cases, the water vapor permeability of starch acetate... 

Paralleling their film-forming properties, these amylose triacetates can be molded into strong, tough plastics, but the amylopectin triacetates yield only very brittle products. Similarly, Mullen and Pacsu have shown that whole starch acetate produces clear, transparent, molded pieces which, however, are brittle. 

As amylopectin predominates in all known starches, the poor film-forming properties of whole starch acetates become understandable. Artificial mixtures of amylose and amylopectin triacetates (acetylated fractions A and B) show increasingly poor film-forming properties as the proportion of amylopectin acetate in the mixture is increased. 

The long linear chain structure of amylose is reflected in the film-forming properties of its acetate. Films prepared from acetylated whole starch and amylopectin are quite brittle, whereas those from butanol-precipitated amylose are similar to films from high-grade cellulose acetates (94)-... 

Starch acetates may have low or high DS. The industrial importance of low DS acetates results from their abiUty to stabilize aqueous polymer sols. Low DS acetates inhibit association of amylose polymers and reduce the association of the longer outer chains of amylopectin. These properties are important in food appHcations. Highly derivatized starches (DS 2—3) are useful because of their solubiHty in organic solvents and abiHty to form films and fibers. 

The NCF based thermoplastic starch films have been synthesized using solvent casting method followed by evaporation process. Dispersion of NCF in varied amounts was prepared in water in which TPS is added in respective weight percentage till complete dissolution. Glycerol and acetic acid are added for gelatinization. Average thickness of the films formed is 0.6 mm (Savadekar and Mhaske, 2012). Properties improved as discussed in section 11.1. 

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