Role of Solvent in the Compatibility of a Vinylchloride-Vinylacetate-Maleic Acid Terpolymer and Nitrocellulose Blends

The compatibility of cast films of a vinylchloride-vinylacetate-maleic acid terpolymer (VMCH) and nitrocellulose (NC) blends is injluenced by solvents. Transparent films of VMCH/NC blends are obtained when cast from solvents such as tetrahydrofuran or cyclohexanone, whereas hazy films are obtained when cast from solvents such as acetone or ethylacetate. Visible spectroscopy and phase morphology were used to analyse the compatibility-incompatibility of the blend. Differential scanning calorimetry (DSC) studies demonstrate that the transparent film is compatible, but the hazy film is incompatible. Fourier transform infra-red (FTIR) studies establish that a greater interaction is observed between the polymer pair in case of the compatible blend than in the case of the incompatible blend. A solvent dependency of blend compatibility is reflected in this study. The conformational state of the polymers in solution, which is responsible for the compatibility phenomena, may depend on the donor number and/or Taft-beta value of the solvent. The greater the donor number and/or the Taft-beta value, the higher may be the level of interaction between the solvent and the polymer molecules, which in turn may give a compatible blend after removal of the solvent.