No abstract

No abstract

As a representative polyoxamide, poly(hexamethylene oxamide) (PA62) has good comprehensive performance. However, the high T m (330 C) creates an obstacle for processing. To improve the processability of PA62, poly(hexamethylene terephthalate/hexamethylene oxamide) alternating copolyamide (alt-PA6T/62) was synthesized by hexamethylene diamine-terminated 6T6-diamine and dibutyl oxalate via solution/solid state polycondensation. Random copolyamide (ran-PA6T/62) was also synthesized for comparison. The structure and properties of the copolymer were analyzed by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Wide-angle X-ray diffraction (WAXD) and the saturated water absorption test. The NMR results confirm the alternating structure of alt-PA6T/62. The DSC and TGA results demonstrate that the novel alternating copolyamide alt-PA6T/62 (T m = 321 C, T 5 = 420 C) exhibited better thermal properties than those of ran-PA6T/62 (T m = 294 C, T 5 = 412 C). The saturated water absorption of alt-PA6T/62 was found to be 3.2 wt%. These results revealed that the novel alt-PA6T/62 had an alternating sequence distribution, showed a high melting point as well as good processability and thermal stability, and possessed low saturated water absorption and excellent dimensional stability.

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.

To modify the properties of poly (hexamethylene oxamide) (PA62), m-xylylene diamine (MXD) was introduced into the polyamide main chain. A series of high molecular weight PA62/MXD2 were synthesized via a two-step method. The chemical structure of polymer was analyzed by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy, and the results confirmed the formation of PA62/MXD2. DSC test showed that the T m of the copolymers were decreased as the molar contents of MXD in the range of 10 to 50 mol %. TGA analysis revealed that the thermal stability of the copolymers compared well with commercial PA6. Wide-angle X-ray diffraction studies suggested the copolymers with MXD content of 0 to 10 mol % possessed high crystallinity. The water uptake measurements were monitored, and the saturated water absorptions were found to be lower than 2.5 wt %. These properties gave them a competitive edge for application where precise dimensional stability and high thermal resistanceproperties are required.

No abstract

As a recently developed biobased polyamide, polyamide 56 (PA56) has great potential in the field of fibers and textiles due to its high strength, high moisture absorption, and easy dyeing. However, the application of PA56 is restricted due to its flammability. Flame‐retardant PA56 copolymers (FRPA56s) have been designed and successfully synthesized by the introduction of 2‐carboxyethyl(phenyl)phosphinic acid (CEPPA) monomer. The thermal properties and thermal stability of FRPA56s have been evaluated using DSC and TGA, respectively. The flammability behavior of the resultant copolymer has been investigated using UL94 vertical burning and cone calorimetry tests. The crystallization temperature (Tc), melting temperature (Tm), and crystallinity (Xc) of FRPA56s are reduced and the degradation pathway for PA56 is changed with the introduction of CEPPA. In addition, FRPA56 containing 7.8 mol% CEPPA may be characterized by a V‐0 rating in the UL94 vertical burning test and its total heat release is reduced 20% than that of PA56, reflecting the high flame‐retardant efficiency of CEPPA. Based on the analysis of the residual char and the gas‐phase pyrolysis products for combustion of FRPA56s, it is concluded that the flame‐retardant modes of action for this material mainly include flame inhibition, dilution effect and charring.

Poly[1,3-bis(aminomethyl)cyclohexaneoxamide] (PBAC2) was synthesized using 1,3-bis(aminomethyl)cyclohexane (BAC) and dibutyl oxalate (DO) via spray/solid-state polycondensation (SSP). The structure of the synthesized polyoxamide was confirmed by 1 H-nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy. The weight average molecular weight (M w ) of the polyoxamides prepared was 1.35 3 10 5 . The polyoxamides showed excellent thermal properties with glass transition temperature (T g ) of 150 8C, melting temperature (T m ) of 318 8C, crystallization temperature(T c ) of 253 8C, and initial degradation temperature (T d ) of 417 8C suggesting higher thermal stability than commercial polyamide 6 (T d 5 378 8C). Kinetic studies of PBAC2 predicted a two-dimensional crystal growth. X-ray diffraction powder diffraction suggested that the polymer has high crystallinity. A saturated water absorption of 2.8 wt % was recorded for the new polyoxamide, giving it a competitive edge for applications in civil aviation, reinforced plastics, and electronics industry where precise dimensional stability and high thermal resistance properties are a priority.