A comparative study of a modified unsaturated polyester resin with dicyclopentadiene and methyl dicyclopentadiene blends

Abstract

Dicyclopentadiene (DCPD) has been a widely used chemical compound in many sectors of chemical industry and materials engineering, from fragrances to composites, from simple adducts to polymeric materials. Unsaturated polyesters resin (UPR), one of the major sectors of resins in terms of production volumes, have been the downstream market of choice for DCPD application for many years. An innovative distillation production route designed by Orlen Unipetrol can produce DCPD in a high purity, but also production of methyl dicyclopentadiene (MeDCPD). This yet only superficially studied material could be applied in some of the numerous areas where DCPD has already been implanted, particularly in UPR. In this work the properties of two unsaturated polyesters with the same formulation were compared, only the type of DCPD purity was variable. Indeed, a polyester grade DCPD was used as standard against a technical MeDCPD. Overall higher average molecular weights, viscosity and color values were measured in the uncured materials for MeDCPD modified polyesters. In the cured state the latter showed higher stiffness both during tensile and flexural tests. Finally, DCPD UPR had higher glass transition temperatures (Tg), curing exotherms and shrinking, the latter representing a disadvantage for large parts manufacturing. Finally, compositions of both type of polyesters during the first stage of syntheses revealed a highly complex behavior of MeDCPD isomers during their addition on carboxy functional molecules. These reactions should be further studied to understand and control processes where this latter molecule is involved.