Incorporation of a semi-aromatic nylon salt into polyamide 6 by solid-state or melt polymerization

Morphology and local chain structure of polyamide 6 modified in the solid state with a semi-aromatic nylon salt

“…A semi-aromatic equimolar nylon salt (DyI) of 1,5-diamino-2-methylpentane (Dytek A) and isophthalic acid (IPA) was prepared as described before [2] and mixed in hexafluoroisopropanol with PA6 in a weight percentage of 20% and 30% with respect to the total weight of the composition. These mixtures are named (PA6/DyI) 20 and (PA6/DyI) 30 , respectively.…”

“…These mixtures are named (PA6/DyI) 20 and (PA6/DyI) 30 , respectively. After the removal of the solvent solid-state modification was performed as described before [2]. For an overview of the built-in composition, molecular characterization and thermal properties of these polyamides see Table 1, where Table 1 Built-in composition, molecular weight, melting and crystallization temperatures, and enthalpy of the transitions obtained from the second DSC heating and cooling runs of the homo-and copolyamides.…”

“…1,5-Diamino-2-methylpentane (Dytek A, 99% Sigma-Aldrich), isophthalic acid (IPA, 99% Sigma-Aldrich), chloroform-d (99.8 atom % D), trifluoroacetic acid-d (99.5 atom % D, Sigma-Aldrich), ethanol and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP, Biosolve) were used as received unless stated otherwise [2].…”

“…As an alternative technique, solid-state modification (SSM) [1] can be used where the incorporation of other monomers or polymers into PA6 can be achieved well above the glass transition temperature, but below the melting temperature of PA6. In this way, the crystalline phase of PA6 is not affected during the chemical modification and remains intact while the amorphous phase is modified, resulting in a blocky chemical microstructure [2].…”

“…Synthetic routes for the incorporation of a semi-aromatic nylon salt into the PA6 backbone resulting in different chemical compositions and the formation of a non-random microstructure by solid-state modification were explained in detail elsewhere [2]. Comparison of these copolyamides prepared by SSM with the corresponding melt-polymerized copolymers revealed that up to high concentrations of comonomers crystallization rates, crystallinity and melting temperatures of the PA6 blocks were almost retained after SSM, whereas a significant decrease in these properties was seen after melt copolymerizations with similar amounts of the comonomer.…”