Study On Synthesis Of Phosphorus-containing Hyperbranched Polyamides And Properties Of Its Blends With PA6

Hyperbranched polymers possess highly branched three-dimensional spherical architecture and a large number of terminal groups. Due to their unique structure, they behave different properties from linear polymers, such as good solubility, lower viscosity and high activity. Comparing with dendritic polymers, the synthesis process of hyperbranched polymers is simple and low cost, which is helpful to realize the large-scale industrial applications. Hyperbranched polymers get more and more attentions in last decade. This kind of polymer play a important role in the fields of processing aids, coating and adhesive, nanotechnology, functional membrane materials and drug control and release system.In this paper, tri(3-nitrophenyl) phosphine oxide(TNPPO) was first prepared from triphenylphosphine oxide by mixed acid nitration method, and the yield was 93.4%. Then tri(3-aminophenyl) phosphine oxide(TAPPO) was synthesized by reduction of TNPPO with hydrazine hydrate as reductant, and the yield was 72.5%. The melting point of TNPPO and TAPPO were measured by differential scanning calorimetry (DSC), and their structures were characterized by Fourier transform infrared spectroscopy (FTIR).Phosphorus-containing hyperbranched polyamides (HBPA) were prepared from tri(3-aminophenyl) phosphine oxide(B3) and hexanedioic acid (A2) via A2+B3 solution polymerization. The effects of reaction factors on the intrinsic viscosity of the polymers were investigated, such as the reaction time and temperature, monomer concentration and monomer drop order. The optimum reaction conditions were obtained, in which the reaction time was 8h, the reaction temperature was 130℃, the monomer concentration was 0.20mol/L, and monomers was added at the same time. The influence of monomers ratio on hyperbranched polyamides’terminal groups was characterized by FTIR. The structure of polymerization product was characterized by nuclear magnetic resonance (NMR). Its thermal behaviors were measured by DSC and thermogravimetric analysis (TGA), and solubility was also tested.Blends of polyamide 6 and HBPA were prepared by solution mixing. The non-isothermal crystallization behavior of PA6/HBPA blends was investigated by DSC and the data were analyzed with Ozawa and Mo methods. Blends of polyamide 6 and HBPA were also prepared via melt extrusion. The rheological behaviors, mechanical properties, dynamic mechanical properties, notched impact fracture surface, and flame resistance of blends were investigated by capillary rheometry, mechanical testing machine, DSC, dynamic mechanical analyzer (DMA), scanning electron microscope(SEM) and oxygen index detector, respectively. When the loadings of HBPA were lower than 2%, the tensile strength and the flexural strength of PA6/HBPA blends were increased, and the impact strength was increased from 19.8KJ·m-2 to 24.5 KJ·m-2, and the LOI value increased from 25 to 28. With the content of HBPA increasing, the apparent viscosity of melting blends decreases and the viscous flow activation energy increases, while the mechanical properties of blends have been somewhat reduced.