To modify the properties of poly(hexamethylene oxamide) (PA62), amine-terminated polyoxypropylene glycols (PGs) were introduced into the polyoxamide main chain as soft segments. A series of PA62/PG2 copolymers were synthesized successfully by a two-step method. Fourier transform infrared spectroscopy, solution proton nuclear magnetic resonance spectroscopy ( 1 H-NMR), differential scanning calorimetry, thermogravimetric analysis, and wide-angle X-ray diffraction were used to analyze the structures and to investigate the properties of these copolymers. The saturated water absorption was also evaluated by gravimetric analysis for PA62/PG2 copolymers. The results revealed the incorporation of PG2 effectively modified the properties of PA62 and the copolymers with PG2 content of 10-20 mol% possessed high melting point (2938C-3148C), good thermal stability and low saturated water absorption. POLYM. ENG. SCI., 00:000-000, 2017.T 5 : the decomposition temperature corresponding to 5% mass loss. b T 50 : the decomposition temperature corresponding to 50% mass loss. c T max : the decomposition temperature corresponding to the maximum mass loss rate.

Hydrogen bond interactions are important for nylon fibers, which improve its mechanical properties and crystallization behavior, while hindering the movement and orientation of the molecular chain during the drawn process. In this study, hexamethylene adipamide was used as the second monomer in copolymerization with ε-caprolactam to obtain copolyamide 6/66 (CoPA), and high-tenacity fibers with a maximum value up to 8.0 cN/dtex were achieved by a multi-step drawn and thermal setting process. Results show that the hexamethylene–adipamide ratio affected the draw ratio (DR) of the as-spun fiber, on the tenacity of final high-performance fiber, and on crystalline. Both DR and tenacity showed evident increases with the hexamethylene–adipamide ratio up to 6% in CoPA and then changed smoothly. However, XRD and DSC results illustrate a decreased tendency with regard to crystallinity. The attenuated in-site total reflection Fourier transform infrared (ATR-FTIR) spectra were used to study the hydrogen bond interaction between the C=O group and N–H group and the crystal form of the fiber. Results show that the copolymerization destroyed the regularity of the main chain of CoPA and reduces the interaction of interstrand hydrogen bonds, facilitating the formation of the γ-crystalline form in as-spun fibers, fulfilling the transition from the γ to α crystalline form during the fiber-drawing step because of the release of the C=O group and N–H group from the hydrogen bond interaction at an elevated temperature close to the molten temperature of CoPA, and then reforming during the thermal-setting step which soiled the crystalline and improved the tenacity of the fiber. The copolymerization with a homologous monomer regulates the hydrogen bond interaction, fulfills the high drawn ratio and high tenacity fiber, and provides a new route for high-performance fiber preparation using traditional fiber formation of polymers.

Microcapsules based on the benzyl benzoate core and CaCO 3 shell were synthesized via an interfacial coprecipitation method and used to treat Nylon 6 fabric to impart anti-mite activity. The FTIR, SEM and upright metallurgical microscope results confirmed that the benzyl benzoate was successfully encapsulated with CaCO 3 shell. The morphologies, particle size distribution, encapsulation ratio and encapsulation efficiency of the microcapsules were investigated systematically. The Nylon 6 fabric was treated with the resultant microcapsules via a finishing process and the microcapsules were immobilized on the surface of Nylon 6 fabric with chemical bond by using blocked waterborne PU adhesive.The morphology of the treated fabric was investigated by SEM and the benzyl benzoate content measured by UV-vis spectrophotometer. The mite repellent tests showed that the treated Nylon 6 fabric exhibited excellent anti-mite property and laundering durability, the mite repellent rate was up to 82.3% and still remained 61.8% after 20 times washing.

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Two series of novel alternating copolyoxamides (PAnT-alt-n2 and PAn2-alt-62) are synthesized via solution/solid-state polycondensation (SSP). The alternating structures are analyzed carefully with 1 H NMR and 13 C NMR spectra. The melting behaviors, thermal stabilities, crystal structures and crystallinities are systematically evaluated by DSC, TGA and WAXD. The results reveal that these alternating copolyoxamides possess almost perfect alternating chain structures and have high melting temperature (T m > 270 C), high crystallinity (X c > 32%) and high decomposition temperature (T 5 > 405 C) as well as low saturated water absorption (<3.5 wt%), which suggests that they have high potential as engineering plastic of high heat resistant.