Evaluating the efficacy of a group of nontraditional plasticizers on the glass transition temperature of ethyl cellulose polymer

OBJECTIVE: The aim of this study was to investigate the efficiency of a homologous series of esters of dicarboxylic acid on ethyl cellulose polymer in terms of their glass transition temperatures (T(g)). METHODS: Ethyl cellulose polymer was plasticized with succinates (C-2), glutarates (C-5), adipates (C-6), pimelates (C-7), suberates (C-8), and sebacates (C-10) at different concentration levels. The film formation and physical state of plasticizers within the polymer were investigated and incompatibility of plasticizers was determined by nonhomogeneous system. RESULTS: A decrease in T(g) of the plasticized polymer was used as an indicator of plasticizing efficiency. Experimental T(g) values were correlated with the theoretical ones predicted by Gordon-Taylor equation. Most of the experimental T(g) values did not fit with the predicted ones. For all plasticizers (except succinates) the measured T(g) was lower than calculated indicating negative deviation from the ideal behavior. Anti-plasticization was obtained with lower plasticizers concentration. Fourier transform infrared spectroscopy was used to determine the interactions between the polymer and plasticizers on T(g) values in predicting the efficiency. CONCLUSIONS: The correlation between experimental and calculated T(g) values verifies that physiochemical properties are the primary factors influencing the plasticization efficiency. However, further studies are needed to establish the plasticization efficiency.