In situ synthesis of polyamide 6/MWNTs nanocomposites by anionic ring opening polymerization

Abstract

In situ anionic ring opening polymerization is used to prepare monomer casting polyamide 6 (MCPA6)/carbon nanotubes (CNTs) nanocomposites, whereby water is used as auxiliary dispersing agent of hydroxyl functionalized multiwalled carbon nanotubes (MWNTs-OH) and e-caprolactam (CL) monomer. The MWNTs-OH were dispersed homogenously in MCPA6 matrix when being observed through transmission electron microcopy. The well dispersed MWNTs-OH existed at the center of many radial texture phases in MCPA6 matrix. Polarizing microscope analysis showed that these radial texture phases were MCPA6 spherulitic crystallities.Differential scanning calorimetry analysis revealed that the crystallization temperature of the MCPA6/MWNTs-OH nanocomposites had been improved by adding only 0.2 wt % MWNTs-OH when compared with pure MCPA6. The influence of MWNTs-OH on the thermal stability of MCPA6 under nitrogen and air environments was also investigated by thermal gravimetric analysis (TGA).

Synthesis and properties of homogeneously dispersed polyamide 6/MWNTs nanocomposites via simultaneous in situ anionic ring‐opening polymerization and compatibilization

“…Radial textures with black spots at their centers were homogeneously dispersed in the MCPA6 matrix, as shown in Figure 4(a). These radial textures were attributed to the spherulitic morphology of MCPA6 crystals, which had been confirmed by us 29. Figure 4(b) showed that the black spots were well dispersed MWNTs.…”

“…MWNTs did not exhibit large weight loss until 550°C. Comparatively, for MWNTs‐NCO and MWNTs‐PA6, major decomposition took place at a temperature that ranged from 200 to 500°C corresponding to the surface grown TDI and PA6 28, 29. If the mass loss of the MWNT‐OH at 550°C is used as the reference, the amount of TDI and PA6 covalently attached to MWNTs determined by TGA is about 8.0 and 21.5 wt %, respectively, as shown in Figure 2.…”

“…These radial textures were attributed to the spherulitic morphology of MCPA6 crystals, which had been confirmed by us. 29 Figure 4(b) showed that the black spots were well dispersed MWNTs. These results indicate that the dispersion of MWNTs in MCPA6 matrix is homogeneous.…”

Anionic nylon 6/TiO2 composite materials: Effects of TiO2 filler on the thermal and mechanical behavior of the composites

“…According to Figure 5, the thermal decomposition of neat nylon 6 and its composite materials with different untreated and treated TiO 2 loadings is characterized by presence of two DTG peaks, indicating that there exist two stages of weight loss T max1 and T max2 , respectively. It is seen from Figure 5 that the first step ( T max1 ) is most evident on the derivative curve and can be probably attributed to the fact that a few of unreacted ε‐caprolactam monomer or oligomers which still remained in the neat nylon 6 and nylon 6 matrix due to strong hydrogen bonding between ε‐caprolactam and nylon 6 induce the decomposition of polymer at a lower temperature, under nitrogen atmosphere [39, 40] . The second step arises from the decomposition of neat nylon 6 and nylon 6 matrix [39, 40].…”

“…It is seen from Figure 5 that the first step ( T max1 ) is most evident on the derivative curve and can be probably attributed to the fact that a few of unreacted ε‐caprolactam monomer or oligomers which still remained in the neat nylon 6 and nylon 6 matrix due to strong hydrogen bonding between ε‐caprolactam and nylon 6 induce the decomposition of polymer at a lower temperature, under nitrogen atmosphere [39, 40] . The second step arises from the decomposition of neat nylon 6 and nylon 6 matrix [39, 40]. With increasing the concentration of untreated TiO 2 particles the T peak2 of the nylon 6 composites decreases very slightly, while in case surface‐treated TiO 2 particles T peak2 of the nylon 6 composites slightly increases.…”