Investigation and modeling of moisture sorption behaviour of rice starch/carboxymethyl chitosan blend films

• Main Authors: R. Suriyatem, C. Rachtanapun, P. Raviyan, P. Intipunya, P. Rachtanapun
• Format: Conference Proceeding
• Published: 2018
• Subjects: Engineering; Materials Science
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84939605372&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/54529
• Institution: Chiang Mai University

The biopolymer films from rice starch (RS) and carboxymethyl chitosan (CMCh) were developed by solution casting. The effect of the ratios of rice starch to CMCh (100:0, 88:12, 67:33, 50:50, 33:67, 12:88 and 0:100) on water barrier properties and moisture sorption isotherm of blend films was studied. Water vapor permeability of rice starch film and CMCh film were 4.8 and 9.1 g.mm/m².mHg.day, respectively, while those of the RS/CMCh blend films ranged between 5.0 and 9.1 g.mm/m².mHg.day. The sorption isotherm of RS/CMCh blend films was determined at 25°C. The sorption behaviour of RS/CMCh blend films could be categorized as type II and type III isotherms. The highest equilibrium moisture content (63.5 g water/100 g dry solid) was obtained in the CMCh film at a<inf>w</inf> of 0.87. For further application of sorption isotherm data, the moisture sorption characteristic of the films can be predicted using empirical models. Lewicki, Peleg, Guggenheim-Anderson-deBoer (GAB), Brunauer-Emmett-Teller (BET), and Oswin models were tested to fit the experimental data. The Peleg equation showed the best fit to the experimental data of the RS/CMCh blend films with r² ∼ 0.997 and the lowest % RMS of 6.2-44.3.