Provided a method to synthesize Nylon-6 oligomers with certain molecular weight and to further synthesize polyesteramides having short Nylon-6 segments connected by ester linkages.Polyamide prepolymer (PrePA) with molecular weight of 524.6 to 808.1 was synthesized by a ring-opening polymerization of -caprolactam in the presence of aminoethanol under the catalysis of H3PO3.The chain extension of the PrePAs was studied using N

N'-carbonylbiscaprolactamat (CBC) and 2

2'-(1

4-phenylene)-bis(2-oxazoline)(PBOX) as combined chain extenders.Through polycondensation of PrePA with adipic acid

polyesteramide prepolymers(PrePEA) with intrinsic viscosity of 0.22~0.30 dL/g were synthesized.Chain extension of the PrePEAs was carried out using PBOX and CBC as combined chain extenders and the chain extended polyesteramide(ExtPEA) with intrinsic viscosity up to 0.74 dL/g was obtained.The ExtPEAs were characterized by FTIR and 1H-NMR spectra

differential scanning calorimetry(DSC)

thermogravimetric analysis (TGA)

wide angle X-ray scattering (WAXS) and tensile test.The DSC study showed that after chain extension the Tm and Hm of the polyesteramides decreased.ExtPEA with [] of 0.72 dL/g had the Tg of 30℃ and Tm of 163℃.WAXS characterization showed that the ExtPEA had similar crystal characteristics to the Nylon-6 crystallites.TGA study showed that the ExtPEA had good thermal stability with initial decomposition temperature over 330℃.Tensile test showed that typical ExtPEA samples had a tensile strength of 14.1 MPa and a strain at break of 68.6%.The ExtPEA has high Tm

good thermal stability and moderate tensile strength

and is suitable for melt processing.Meanwhile

presence of the ester linkages and lower crystallinity in the ExtPEA may lead to improved biodegradability of the ExtPEA compared to the normal nylon-6.