Research On Complexationmechanism And Spinning Of Ultra High Molecularpolyamide-6

Different Polyamide 6 (PA6) gels were prepared by dissolving PA6 powder in nitromethane using GaCl3 as complex agent, in formic acid using LiCl as complex agent, in benzyl alcohol solution and in formic acid using CaCl2 as complex agent. Differential Scanning Calorimetry (DSC), FT-IR, X-ray diffraction (XRD) and SEM were used to investigate the structure and properties of those gels. The complexation mechanism of polyamide 6/calcium chloride compound was studied by X-ray photoelectron spectroscopy (XPS) and conductivity measurement. And then we researched the formation and effect of polyamide 6/calcium chloride compound.Results indicated that the forming mechanisms of those gels were different, and there were significant differences among those gels’structure and properties. The gel systems of GaCl3, CaCl2, and LiCl were formed by complexation, but the ability of complexation of three complex agents was different. By the analysis of structure, the benzyl alcohol/PA6 gel system was formed by hydrogen bond, and benzyl alcohol was only as the solvent.Complexation mechanism of polyamide 6/calcium chloride compound was studied. Results indicate that Ca2+ coordinates with O atom of carbonyl group, which weaken the hydrogen bonding between the molecular chains of polyamide 6 and release the free N-H group, so the N-H group coordinates with Cl-1 to form hydrogen bonding. The coordination number between calcium chloride and amide bonds is predicted to be four or six by conductivity measurement. With the increase of PA6 concentration, the interaction of molecules in the gels strengthened and the transformation temperature (Tf) of the gels rose. There are some dissimilarity on the structure and properties and the complexation efficiency of calcium chloride among the gels with different concentration. The Tf was reduced with an increasing of quantity of CaCl2, crystal peaks of PA6 XRD were disappeared. The magnitude of mole ratio and relative viscosity of PA6 had an effect on the properties of flow and spinning of gel. The rheological behavior of PA6/CaCl2/HCOOH gel system was studied, as were the effects of temperature, relative viscosity, complex mole ratio and solution concentration of PA6 onηa-γ? flow curve, non-Newtonian index and structural viscosity index of gel. Results showed that PA6/CaCl2/HCOOH gel behaved to be shear-thinning fluid and showed distinct non-Newtonian behavior. The apparent viscosity of the solution decreased with the elevation of temperature, and increased with the increasing of solution concentration, complex mole ratio or relative viscosity of PA6. The structural viscosity index was increased while increasing relative viscosity or solution concentration, and was decreased while increasing of gel temperature.At last, we studied gel-spinning of partially complexed PA6/CaCl2/HCOOH system. Results indicate that solution of tetrachloroethane and chloroform could be used as the coagulation bath; and Ca2+ complexed with the carbonyl oxygen of the PA6. With the increase of draw ratios, the orientation of fibers was improved, the cross section of PA6 gel fibers became much smoother and compact, and the tensile properties increased. The maximum draw ratio was 12, and the maximum modulus and tensile strength obtained were 70.4GPa and 413.0MPa respectively.