Blends of tri-block copolymers and addition curing resins: Influence of block copolymer-resin compatibility on toughness and matrix properties on toughenability

In any sort of rubber toughening of thermosets, there are two principal influences on toughness: Morphology of the elastomer particulate phase and toughenability of the matrix resin. These two factors are difficult to separate experimentally. A new approach is presented which is based on large numbers of data. By analysing property-property-relationships an attempt is made to identify generalizable rules. A tri-block copolymer (PCL-PDMSi-PCL) is analysed in detail: By varying the molecular weights of the compatible and incompatible blocks in two different epoxy resins the influence of morphology on toughness is studied. Linear (Tg and rubbery plateau modulus) and non-linear (yield stress and post-yield behaviour) matrix properties are examined for a larger number of resin/curing agent combinations toughened with three different toughening agents in order to elucidate which matrix property controls toughenability. The same resin/curing agent array was used to study the influence of matrix polarity on morphology and properties for one PCL-PDMSi-PCL tri-block-copolymer.