Crystallization and morphology of polyamide 1010/single‐walled carbon nanotube nanocomposites under elevated pressure

Abstract

Polyamide 1010/single-walled carbon nanotube (PA1010/SWNT) nanocomposites prepared by melt compounding were treated under a pressure of 2.0 GPa and at three different temperatures (250, 300 and 350 • C) for 30 min. Then, all the samples were naturally cooled to room temperature from the melt prior to release of the applied pressure. The melting temperature and crystallinity of high pressure crystallized samples were shifted to a high value after the treatment temperatures under pressure. The infrared spectrum of the high pressure crystallized samples showed a considerable improvement of crystalline order, a closer packing of the polymer chains due to the shorter N-C bond length, and the presence of a large proportion of free N-H groups resulting from antiparallel chains in flat zigzag conformation. Wide-angle X-ray diffraction measurements indicated that the high pressure gave rise to an increase in crystallite dimensions as well as to a decrease of the distance between the crystal planes bonded by the hydrogen bond (100) planes and by the van der Waals force (010) planes. Scanning electron microscope images showed that denser texture, thicker covering layers on the tubes and regular cubic sugar-like crystals with a lateral length of about 1.5 µm could be detected on the fracture surface of PA1010/SWNT nanocomposites crystallized under pressure.

All Plant Oil Derived Epoxy Thermosets with Excellent Comprehensive Properties

“…Figure shows the XRD patterns of NESO thermosets and the control as well as NYL oligomers. All NYL oligomers are crystalline with obvious characteristic diffraction peaks at 2θ of 8.1°, 19.9°, and 24.0° (Figure a), corresponding to the (002), (100), and (010) planes, respectively . An extra diffraction peak at 21.5° of NYL-1 should be ascribed to the presence of relatively high content of SA residues.…”

“…All NYL oligomers are crystalline with obvious characteristic diffraction peaks at 2θ of 8.1°, 19.9°, and 24.0°( Figure 6a), corresponding to the (002), (100), and (010) planes, respectively. 48 An extra diffraction peak at 21.5°of NYL-1 should be ascribed to the presence of relatively high content of SA residues. The characteristic diffraction peaks of all planes of NYL are present in the diffraction patterns of all NESO thermosets although the peak intensity of (010) plane for NESO-1 is very weak, indicating that the crystallizability of NYL segments remain after incorporation into the NESO thermosets.…”

Structure and properties of bio‐based polyamide 109 treated with superheated water

“…Compared to crystallization of the polymer melt, due to the existence of water molecules, this is more favorable to the growth of lamellae by crystallization from superheated water. Although crystallization of polyamides under ultra‐high pressure also assists thickening of lamellae, the pressure (0.46–0.82 MPa) of the reaction system is much lower than the reported literature values . Hence, the above melting property of PA109 could be mainly influenced by water molecules.…”

Crystallization and polymorphism in polypropylene/polyamide 6/layered silicate ternary nanocomposites

“…The difference between the crystallization behavior of injection‐molded (Table ) and DSC cooled (Table ) samples can be attributed to the effect of crystallization under pressure in polyamide 6. Pressure is known to improve crystallinity and crystallite quality in thermoplastics . Therefore, it is expected that the formation of more ordered α phase be promoted through injection molding.…”