On blends of polyamide 6 and a hyperbranched aramid

The hyperbranched (HB) aromatic polyamide synthesised by direct polycondensation of 5-(4-aminobenzoylamino)isophthalic acid (ABZAIA) has been solution and melt- blended with polyamide 6 (PA6) incorporating different end groups. The concentration of p(ABZAIA) in PA6 has been varied from 5 to 30 wt.-% in order to evaluate the influence of hyperbranched polymer content on blend properties. Viscosity and glass transition (T-g) data of the solution blends underlined the full miscibility between the components in the explored composition range. The miscibility was not related to any specific type of PA6 end group, thus suggesting a major role for its amide groups in intern acting (presumably via hydrogen bonding) with HB functional end groups. Well-separated powder particles have been obtained by precipitation from diluted solutions both for the neat polymers and for the blends. Also, in the case of blends prepared by melt mixing Tg linearly increased with the HB polymer content, again confirming full miscibility between the blend components. Blend characterisation, solubility tests and melt rheology supported the idea that p(ABZAIA) forms reactive blends with polyamide 6 by melt mixing. As a consequence of these reactions, the hyperbranched aramid strongly modified the rheological behaviour of PA6.