Melt properties and crystal morphology of polydodecamide plasticized by benzenesulfonamides

The melt of polydodecamide (PA-12) shows a significant viscosity decrease u pon incorporation of benzenesulfonamide plasticizers (BSAs), this effect be ing maximum for a monofunctional BSA with a 12-carbon-atom-long alkyl chain . Nonexhaustive X-ray diffraction analysis developed on isothermally crysta llized samples validated a two-phase model for describing PA-12 plasticized by N-(n-butyl)benzenesulfonamide (BBSA). The massive presence of BBSA betw een the lamellar crystals was established, and lamellar fragmentation was a lso observed. Further, a steady increase in PA-12 crystallinity with an inc reasing BBSA content was evident (and confirmed by DSC) and is consistent w ith the plasticizer easing the mobility of polymer chains during crystalliz ation. Large melting point depressions resulting from both polymer-plastici zer miscibility and lamellar fragmentation were observed with several mono- and bifunctional BSA plasticizers. Phase separation in PA-12 solid state w as only observed at 20 mol % of phi SO2NH2, alhough miscibility occurred in the melt. (C) 2001 John Wiley & Sons, Inc.