Characterization of polyethylene terephthalate, cellulose acetate and their blends

Abstract

Surface free energy of a polymer is of great importance in adhesive studies. Acid/base specific interactions play pertinent roles in adhesive bond performance and polymer-polymer miscibility. In this study, the correlation between the surface characteristics of two polymers and their adhesive bond behavior as well as the compatibility of their blend systems are investigated through both the surface characterizations and bulk examinations. Inverse Gas Chromatography (IGC) is employed to determine the surface free energies, the dispersive component and acid/base specific interactions, of polyethylene terephthalate (PET), cellulose acetate (CA) and their blend. Dynamic Contact Angle (DCA) measurements are performed to obtain the surface free energies of PET and CA so that they can be compared to that from IGC. Moreover, the DCA data are used to calculate their spreading coefficients and the adhesive bond behavior between PET and CA is predicted as well. The bulk examinations on specific interactions and the miscibility of the PET/CA , PBT/CA blends are completed through Fourior Transform Infrared-Diffuse Reflectance Spectroscopy (FTIR-DRIFT), Differential Scanning Calorimeter (DSC) and Dynamic Mechanical Analyzer (DMA). Scanning Electron Microscopy (SEM) micrographs of these blends are taken to examine their morphologies. From IGC, it is deterrnined that the surfaces of PET and CA are predominantly basic. The spreading coefficients calculated from DCA data indicate the poor adhesive bond between PET and CA. The bulk examinations reveal that both PET/CA and PBT/CA blends are immiscible systems.