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

Abstract

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.

• Adipates
• dicarboxylic acid esters
• glutarates
• pimelates
• sebacates
• suberates
• succinates

Acknowledgments

The authors thank the Barr Pharmaceutical Company for giving the opportunity to work in their preformulation laboratory and are grateful to the R&D formulation group for their help and support.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this paper.