Preparation And Properties Of Waterborne Cationic Polyurethane/ Polypyrrole/ Natural Fiber Conductive Composites

To explore the preparation of polypyrrole(PPy)/natural fiber conductive composite, waterborne cationic polyurethane surfactant(CPUS) was used as dopant. CPUS was prepared by prepolymerization method and was modified by γ-amino propyl triethoxy silane(KH550). Conductive fiber was synthesized when polyurethane was grafted with polypyrrole and natural fiber. And then conductive papers were prepared by the papermaking process. The main content of this paper was as follows:(1) A series of waterborne cationic polyurethane surfactants was prepared through changing the content of N-Methyldiethanolamine(MDEA) and its structure was investigated by fourier transform infrared spectrometer(FTIR) and nuclear magnetic resonance(NMR). The effects of MDEA concentration on the surface tension, critical micelle concentration(cmc), rheology property, micelle size, micropolarity and aggregation behaviors of CPUS were studied by dynamic light scattering(DLS), surface tension analysis, viscosity tester and fluorescence analysis. Transmission electron microscope(TEM) result showed that CPUS micelles displayed as core-shell spheres. The results showed that the average micelle particle size and polydispersity index of CPUS solution decreased with increasing MDEA concentration. While the surface tension and critical micelle concentration decreased first and then increased, the lowest of which were 39.54 m N/m and 1.99 g/L. When the CPUS concentration was lower than cmc, the light scattering intensity was very low and changed slowly with CPUS concentration. However, the light scattering intensity displayed a gradually increasing tendency when the CPUS concentration was greater than cmc. Meanwhile, the aggregation number of CPUS micelles increased greatly. The viscosity of CPUS solution increased with increasing MDEA concentration, as well as the interactions among micelles increased, while the pseudoplastic behavior was weakened. In addition, fluorescence spectrometry showed that I1/I3 values decreased from 1.8 to 1.3 and I338/I334 increased from 0.5 to 1.7, suggesting that the microenvironment among micelles changed greatly and more and more pyrene probe entered into CPUS micelles. Furthermore, the micelle micropolarity and the difficulty with micelle formation decreased first and then increased as increasing MDEA concentration.(2) A series of waterborne cationic polyurethane surfactants modified by KH550(KCPUS) was obtained by changing the content of KH550 and its structure was investigated by FTIR and NMR. The effects of KH550 concentration on the surface tension, critical micelle concentration, rheology property, micelle size, micropolarity and aggregation behaviors of KCPUS were studied by DLS, surface tension analysis, viscosity tester and fluorescence analysis. TEM result showed that KCPUS micelles had adhesion and displayed as core-shell spheres. The results showed that the average micelle particle size and polydispersity index of KCPUS solution decreased first and then increased with increasing KH550 concentration. While the surface tension and critical micelle concentration decreased, the lowest of which were 39.68 m N/m and 1.32 g/L. When the KCPUS concentration was lower than cmc, the light scattering intensity was very low and changed slowly with KCPUS concentration. However, the light scattering intensity displayed a gradually increasing tendency when the CPUS concentration was greater than cmc. Meanwhile, the aggregation number of KCPUS micelles increased greatly. The viscosity of KCPUS solution increased with increasing KH550 concentration In addition, fluorescence spectrometry showed that I1/I3 values decreased from 1.8 to 1.14 and I338/I334 increased from 0.45 to 1.64, suggesting that the microenvironment among micelles changed greatly and more and more pyrene probe entered into KCPUS micelles(3) FTIR, raman spectroscopy, elemental analysis and x-ray photoelectron spectroscopy(XPS) results showed that the polypyrrole molecular chains were doped with CPUS2 and KCPUS2. The adsorption behavior of polyurethane surfactants on fibers indicated that by increasing the charge density of polyurethane, the adsorption amount on fibers at saturation level was decreased. Scanning electron microscope(SEM) and atomic force microscope(AFM) results showed the surface of conductive paper was endowed with polypyrrole compared with natural paper. Thermogravimetric results indicated that the thermal stability of conductive paper was improved slightly. The conductivity of CF3 and KCF3 were better and the resistivity of them were 63 k??cm and 5.6 k??cm. The mechanical property of conductive paper showed that tensile index was declined greatly after modification.