Design of high impact thermal plastic polymer composites with balanced toughness and rigidity: Effect of matrix polymer molecular weight

High impact polymer composites are generally composed of a matrix polymer and an impact modifier. The effect of modifier structure and properties on the balance between the toughness and rigidity of high impact polymer composites has been reported (Li et al., 2019; Li et al., 2020) [1,2]. As the main component, the structure and properties of the matrix polymer can certainly affect this balance. This balance has been assessed using both theory and experiment. A relation between the critical interparticle distance ID, and the brittle strength of the matrix polymer sigma(b,) i.e. IDc similar to sigma(2/3)(b), was identified from both experiment and theory. Based on the relation between sigma(b) and molecular weight, i.e. sigma(b) = A - B/(M) over bar (n), the effect of the matrix polymer molecular weight can be thereby studied quantitatively. It is clear that the higher (M) over bar (n), the higher sigma(b), and the larger IDc is. Larger IDc means lower content of rubber or elastomer modifier is needed to induce the brittle-ductile transition, leading to less loss for the rigidity of impact polymer composites.