INTERACTIONS AND PARTITIONING OF DILUENTS PLASTICIZERS IN HYDROXYPROPYL METHYLCELLULOSE AND POLYVINYL-ALCOHOL HOMOPOLYMERS AND BLENDS .1. DIETHYLENE GLYCOL/

The interactions and partitioning of diethylene glycol (DEG) in polyvi nyl alcohol (PVA), hydroxypropyl methylcellulose (HPMC) and their blen ds has been studied. DEG acted as efficient plasticizer for both homop olymers, lowering their T-g and rigidity. Kelly-Bueche-type equations were fitted successfully to the experimental data and yielded an inter action parameter, K-Phi betweenymer. Incorporation of DEG into two-pha se blends of PVA and HPMC with 40, 50 and 60% PVA did not change the s ignificant incompatibility of the two components and plasticized both phases. Composition calculations based on Kelley-Bueche-type expressio ns fitted to the experimental data afforded determination of the parti tion coefficients of DEG into the two phases of the blends. In the cas e of the 50:50 weight % system, it partitioned almost equally into bot h phases. The results are discussed in terms of the DEG affinity to in teract with the two polymers by means of the dispersive, polar and hyd rogen-bonding contribution to the solubility parameters.