Formation of diblock copolymers at PP/PA6 interfaces and their role in local crystalline organization under fast heating and cooling conditions

Evidences for flow‐assisted interfacial reaction in coextruded PA6/PP/PA6 films

“…We thus have been able to characterize the interfacial reaction rate and to determine experimentally the surface density for multilayer films formed in the lab, but with temperature and time histories comparable to those found in a coextrusion line. For long enough contact times between PA6 and reactive PP mixtures, it has been shown that, as expected, the copolymer surface density saturates to a finite value, just because when the number of copolymers yet formed at the interface is sufficient to fill the surface zone close to the interface with chains all chemically bound to the surface and having their Gaussian equilibrium configuration, the reaction stops, due to the elastic penalty which has to be paid to further introduce new reactive chains inside this layer . The exact value of this surface density at saturation is thus fixed by the molecular parameters of both contacting polymers (molecular weights and average size of the monomers).…”

“…In a first simplified approach, one can assume that in all the zones of the coextrusion line where there is no substantial creation of surface of interface (TCSI close to 1), the grafting reaction takes place in a way quite similar to what happens in annealed samples without flow. The kinetics of the grafting reaction without flow has been investigated , for molecular parameters of PP, PA6, and PPg polymers and concentration of PPg molecules in the PP matrix comparable to those of the present study. The main results of these studies can be summarized as follow.…”

“…I C , I N , I ∞ C , and I ∞ N are respectively the intensities of the carbon and nitrogen peaks for the analyzed sample and for a thick PA6 film. The reproducibility of the Σ determination was ∼±10% .…”

“…First, the surface density of copolymers formed at the PP/PA6 interfaces appeared independent of the exact coextrusion parameters (line velocity, size of the exit slit, air gap length, and draw ratio) provided the final thicknesses of the various layers were maintained fixed. Second, the surface density in copolymer was observed to be smaller than the saturation density of the interface, even for coextrusion parameters such that the open time for the reaction was well above the time necessary to reach saturation when films were formed at rest .…”

Effect of LiCl on the miscibility and crystallization behavior of a hydrophilic PP/PP-g-MAH/PA6 blend

“…In the past decades, a blend of polypropylene (PP) with polyamide-6 (PA6) has been paid more attention [1][2][3][4][5]. PP is one of the most versatile common thermoplastic polymers, owing to its outstanding performance, including low cost and great chemical resistance, but its application is limited by its impact strength.…”