Synthesis and properties of some alkyds of more complex carboxyl functionality

Abstract

Syntheses are described where dimer fatty acid (C36), or anhydrides of trimellitic, or pyromellitic, or dodecenylsuccinic acids are substituted in part for components of a model polymer derived from 1 mole each phthalic anhydride and glycerol, and 0.4 mole of linoleic acid. These polymers are compared at several degrees of polyesterification with respect to endgroup analysis, melt and intrinsic viscosity, and fractionation and emulsification behavior in water-solvent mixtures. The data suggest that predictions of the gel point in terms of functionality concepts are of general value only for defining the reaction degrees where insoluble molecules can first appear. The experimental event of gelatification can be delayed to varying degrees by different types and concentrations of inert solvent. The extent of reaction where molecular complexity can give a gellable polymer in the absence of solvency retardation occurs near the theoretical gel point and can be located by inspection of functions relating either melt or intrinsic viscosity to molecular weight. Significant differences in polymer structure have a very small effect on this parameter, nor is there much evidence to show preferential reactivity of similar functional groups associated with different structures. Other data here cited demonstrate some practically useful facts regarding how composition and molecular weight affect solvency behavior; however, no general correlations were found which relate solubility behavior to quantities here miasured.