Preparation of crosslinked polymers with increased modulus by high-pressure polymerization

p-Divinylbenzene has been polymerized by heating at pressures ranging from atmospheric to 2.5 GN/m², and the moduli (Young's, shear, and bulk), density, and residual unsaturation of the products have been determined. The results show a marked effect of polymerization pressure upon density and upon the degree of conversion of the second double bond. Linear relations are indicated between modulus and either density or an intermolecular force function based on a 6–12 potential field. These results and others on the densification of polystyrene are discussed and it is concluded that the moduli of the poly-p-divinylbenzene samples prepared under these conditions are still at a level largely determined by intermolecular forces.