Chain extension of oligoamide or polyamide in an extruder

Polycondensates with too short chains can be chain-extended with repair mol ecules. In this report, the molecular weight and, thereby, the melt viscosi ty of polyamides is enhanced in the extruder by two chemically very differe nt types of repair molecules. Firstly, the chains were extended linearly wi th a bisoxaline which is a well-known strategy. Secondly, polyamide chains were bundled by grafting onto a functionalized backbone chain, i.e., malein ated polystyrene (SMA). This less known route leads to branched rather than linear chain extension. Despite the fact that the melts of branched chains are less viscous than those of linear chains. at the same molecular weight , the viscosity of polyamides was markedly increased by grafting onto SMA. Grafting of oligoamide and polyamide chains was studied, as well as graftin g of the monomer of the polyamide in combination with its polycondensation.