Synthesis and characterization of polyesteramides having short Nylon-6 segments in the main chains through polycondensation and chain extension

A Nylon-6 oligomer (PrePA) was synthesized by ring-opening polymerization from epsilon-caprolactam with 2-amino-ethanol under the catalysis of H(3)PO(3). Polyesteramide prepolymers (PrePEAs) having amide content from 10 to 60 mol% were prepared through melt polycondensation from adipic acid, 1,4-butanediol and the PrePA. Chain extension of PrePEAs was carried out at 200 degrees C using 2,2'-(1,4-phenylene)-bis(2-oxazoline) and carbonylbiscaprolactamate as combined chain extenders. The chain-extended polyesteramides (ExtPEAs) with intrinsic viscosity up to 0.61 dL/g were synthesized. The ExtPEAs were characterized by FT-IR and (1)H NMR spectra, differential scanning calorimetry, wide angle X-ray scattering, thermogravimetric analysis and tensile test. The results showed that the ExtPEAs mainly crystallized in the Nylon-6 crystallites. ExtPEAs had T(g) from -46.71 to 4.28 degrees C, T(m) from 106.69 to 139.92 degrees C, thermal stability with initial decomposition temperature over 339 degrees C, tensile strength up to 30.89 MPa and stain at break higher than 797.1%. These ExtPEAs were strong, thermally stable and tough thermoplastic polymers. (C) 2011 Elsevier Ltd. All rights reserved.