Study On Preparation Of PP/nano-CeO₂ Composite And Its Spinnability

The application of polypropylene fiber became more and more extensive because of its excellent properties such as light density, low thermal conductivity, good mechanical properties, good chemically resistant performance and so on. CeO₂ can be used in many fields, for example it was use as luminescence material, catalyzer, electronic ceramics, glass polishing agent, ultraviolet absorber. The performances of PP and CeO₂ composite fiber will be excellent.In this paper, CeO₂ nanoparticles were doped in polypropylene and composite resins were spun by melting spinning. The structural properties, mechanical properties, crystallization behaviors and dyeing performances of composite fiber were measured.CeO₂ nanoparticles should be modified before it was blended with PP, because inorganic nanoparticles easily aggregate and they have poor compatibilities with polymer. This paper chose four kinds of coupling agents to modify CeO₂ with different proportions. The dispersion of modified CeO₂ nanoparticles in cyclohexane was measured in order to evaluate the dispersion of them in PP melt. The dispersion of CeO₂ nanoparticles in composites was observed with SEM. The results showed that surface modification benefited to the dispersion of CeCO₂ nanoparticles in polypropylene and the effect of No.4 coupling agent with the amount of 8% was the best one. The infrared spectrum of sample modified with No.4 coupling agent showed that new chemical bond between CeO₂ and coupling agent occurred and the effect of them weren't simply physical covered.CeO₂ nanoparticles modified by No.4 coupling agent and un-modified CeO₂ were separately blended with PP in 1% content. The isothermal crystallization rate of PP/nano-CeO₂ composite resin were tested, the results showed that nucleus of composite resin increased dramatically, while crystallization rate decreased. The crystalline morphology of compositeresins in polarized microscope indicated that Maltese Cross phenomena weakened after adding CeO₂ nanoparticles.The flow curves of PP/nano-CeO₂ composite melt showed increased apparent viscosities owing to CeO₂ nanoparticles restricted molecular chain movement, however the apparent viscosity of composite resins with un-modified CeO₂ higher than modified one because coupling agent improved compatibility and dispersion, decreased flow resistant and frictional force.The polypropylene fibers with modified and un-modified cerium dioxide nanoparticles in 1% content were spun by melt spinning, their degree of orientation, crystallinities and mechanical properties decreased compared to the pure polypropylene fiber and composite fiber with modified CeO₂ decreased slightly. The SEM of composite fiber surface indicated that modified CeO₂ uniformly scattered on fiber surface and their sizes were obviously smaller than un-modified one. In addition, composite fibers were dyed with disperse dyes. The K/S value of fibers with cerium oxide increased while the K/S value of fibers with un-modified cerium oxide higher than fibers with modified CeO₂.