Macromolecules, Vol.37, No.18, 6814-6822, 2004
Adhesion promotion mechanisms at isotactic polypropylene/polyamide 6 interfaces: Role of the copolymer architecture
The fracture toughness of isotactic polypropylene (iPP)-polyamide 6 (PA6) assemblies, stabilized by diblock copolymers formed in situ during the annealing of the samples, has been investigated as a function of annealing conditions and molecular architecture of the PP part of the copolymer. Comparing the evolutions of the fracture toughness with annealing time annealing temperature and surface density of copolymers for six different architectures, the reinforcement mechanisms could be qualitatively identified. It is thus possible to design an "optimal" copolymer for adhesion reinforcement: it has to have a molecular architecture as close as possible to that of the PP matrix and to be long enough so that it can bridge crystalline lamellae in the PP part of the sample, an effect which is favored when the annealing temperature is above the melting temperature of both parts of the assembly, due to an epitaxial orientation at the PP-PA6 interface.