Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/3/2006
Publication Date: 6/25/2006
Citation: Dangaran, K.L., Tomasula, P.M. 2006. Predicting biopolymer film function using plasticizer efficiency ratings. IFT 2006 Ann. Meeting Book of Abstracts, 054C-06. Interpretive Summary: n/a
Technical Abstract: Plasticizers affect glass transition temperature (Tg) and tensile strength (TS) of biopolymer films. The effects of plasticizer content on Tg and tensile strength can be correlated to determine plasticizer efficiency ratings, k which can then be used to create predictive models for film function. Predictive models will aid the process of developing applications for biopolymer films. The objective of this study was to determine plasticizer efficiency ratings for tensile strength and Tg in three casein film matrices. Films made from casein precipitated using high-pressure CO2 (CO2CAS), calcium caseinate (CaCAS) or sodium caseinate (NaCAS) were plasticized with propylene glycol (PG), glycerol (Gly) and sorbitol (Sor) at three levels – 10%, 20% and 30%. Tensile strength was measured following ASTM methodology. Tg of the films was measured with a DMTA. The Gordon-Taylor (G-T) equation and the empirical relationship TS = TS0e-kx were used to generate k values using Tg data and tensile strength data, respectively. TEM imaging was also conducted. Test conditions were 53% relative humidity and 25C. Using the G-T equation, the k values for glycerol were determined to be 4.832, 1.896, and 1.951 for NaCAS, CaCAS and CO2CAS films, respectively. A parallel trend among the three caseins was seen for tensile strength k values. NaCAS films had an efficiency rating of 8.205 while CaCAS and CO2CAS film values were 5.890 and 6.005, respectively, when plasticized with glycerol. Efficiency ratings were also determined for PG and Sor. TEM showed differences in microstructure among the films. NaCAS film was homogenous while the CaCAS and CO2CAS films had similarly aggregated structures. It is concluded that k values for tensile and Tg properties are characteristic for a given protein and reflect differences in microstructure. This correlation between definitive imaging results and empirical plasticizer efficiency ratings shows validity of the approach to model biopolymer film function.