Development of a new additive for shrinkage control

J.V. Richard
LPIM, FR

Keywords: composite shrinkage

Summary:

Shrinkage is a critical issue in composite processing. Indeed due to chemical reaction and temperature variations, a thermoset system will shrink when it is cured. For example, unsaturated polyester resin shrinks about 7-10% due to the transformation of Van der Waals bonds into covalent bonds. Usually, Low Profile Additives (LPA) such as poly(vinyl acetate) (PVAc) are used to overcome shrinkage but mechanical properties are damaged. This project aims to develop new additives which lead to limited shrinkage without reducing mechanical properties. Different structures have been developed and tested with a thermoset system. The method to compensate shrinkage is completely different as usual LPAs.