High‐flow nylon 6 by in situ polymerization: Synthesis and characterization

A new synthetic strategy for high‐flow nylon 6 was developed in this article. Generation 1, 2, 3 (G1, G2, G3) polyamidoamine (PAMAM) dendrimers reacted with p ‐phthalic acid by equimolar terminal groups in water solution, respectively, and mother salt solution was then prepared. The high‐flow nylon 6 was prepared with suitable quantity of mother salt solution, end‐capping agent, and ϵ‐caprolactam by in situ polymerization. Blue shifts are found for the peaks of NH (γNH and 2δNH) of the high‐flow nylon 6 compared with pure nylon 6 in the IR spectra. Comparing with the pure nylon 6, the high‐flow nylon 6 containing low content of PAMAM units, has high‐flow property and almost the same mechanical property. The high‐flow nylon 6 with low content of PAMAM units has greater melt‐flow index (MFI) (the value of MFI increased by 70–90%). Hardly any decrease in the tensile strength is observed with the elongation at break decreasing by 20–35%. But the izod impact strength of the high‐flow nylon 6 increases. The SEM images show that the high‐flow nylon 6 presents brittle fracture with conglomeration‐like structure, while pure nylon 6 exhibits plastic fracture with island‐like structure. DSC thermograms of nonisothermal crystallization exhibit that the peak of high‐flow nylon 6 broadens compared with pure nylon 6, and the broader peak means the wider processing temperature. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008