Effect of Alkyl Chain Length in Phthalate Plasticizer via Rheological Investigation of PVC Plastisol Gelation and Fusion

Different plasticizers with variety alkyl chain length are used to investigate of the process-ability and properties of PVC plastisol. The plastisol, which is a relatively stable fluid dispersion of finely PVC resin particles in a liquid plasticizer with a small amount of diluent, is casted into a mold and heated in an oven to gel and fuse. The PVC resin grains become swollen with plasticizer in the gelation stage and then, fuse in such a way become one homogeneous, flexible phase. Plasticizers, with different alkyl chain length have different solvent power, affecting the process of gelation and fusion, and thus, process-ability. This study examines such an effect systematically by using a series of dialkyl phthalates plasticizers which started from Dimethyl Phthalate (DMP) to Dioctyl Phthalate (DOP). The progress of gelation and fusion are followed by the measurements of dynamic moduli in RMS. As it can be anticipated, the shorter the alkyl chain, the higher the solvent power of the plasticizer and lower gelation or fusion temperature obtained.