Flexible polymer element as toughening agent in prepregs

A flexible polymer element for a curable composition wherein the flexible polymer element is in solid phase and adapted to undergo at least partial phase transition to fluid phase on contact with a component of the curable composition in which it is soluble at a temperature which is less than the temperature for substantial onset of gelling and/or curing of the curable composition; a method for the preparation thereof, a support structure or carrier for a curable composition comprising the at least one flexible polymer element together with reinforcing fibers, configurations of support structures and carriers, methods for preparation thereof, a curable composition comprising the at least one flexible polymer element or the support structure or carrier and a curable resin matrix, a kit of parts comprising the components thereof and a method for selection thereof, a method for preparation and curing thereof, and a cured composite or resin body obtained thereby, and known and novel uses thereof.