Preparation And Research On Structure And Properties Of MWNTs/Mg(OH)₂ Flame-Retardant Functional PET Fiber

In recent years, with the continuous improvement of living standards and the continued strengthening of consume awareness, the fire resistance of textile products has attracted people's increasing attention. However, the vast majority of textile materials belong to flammable polymers, it not only generates a lot of heat and, but also release many toxic gases during the combustion process, which posed a serious threat on people's lives and property safety. Therefore, it is of great significance to research and develop the flame-retardant fiber materials.Inorganic flame retardant which has been widely used as a high efficiency, good thermal stability, non-toxic, non-corrosive, smoke suppression and the advantages of low cost.Carbon nanotubes (CNTs) with unique structures and excellent physical and chemical properties, which has considered to be an excellent addition phase.As a synthetic fiber with excellent performance, Polyethylene terephthalate(PET) fiber is not only one of the largest output, the most widely used among all chemical fibers, but also appropriate for civilian and industrial use. However, the limiting oxygen index of PET is only 21%, which is easy to melting, decomposition, combustion during heating process, so its applications were limited greatly. Therefore, MWNTs/Mg(OH)2 compound flame retardant were prepared which MWNTs was used as carrier, then applied to PET fiber to improve the thermal stability and flame retardant properties of PET fiber in this topic.In present paper, Multi-walled carbon nanotubes (MWNTs) were surface modified by nitric acid oxidation method firstly, and then used as carrier to prepare the MWNTs/Mg(OH)2 compound flame retardant through reverse precipitation in the liquid phase, MWNTs/Mg(OH)2 flame-retardant PET masterbatch were prepared by using twin-screw extruder, Finally, the MWNTs/Mg(OH)2 flame-retardant PET functional fibers were spun by melt blending technique.The morphology of the samples were observed by Scanning Electron Microscopy(SEM).The structure of specimens were characterized by High-Resolution Transmission Electron Microscopy(HRTEM), X-ray diffraction(XRD) and Infrared Spectrometry(IR). The contents of magnesium cations were measured by AA240-FS atomic absorption spectrometer. The crystallinity and thermal stability of the samples were determined through differential scanning calorimeter(DSC) and thermal gravimetric analysis (TG); and flame retardant properties were tested through the limiting oxygen index meter (LOI).Through studying and discussion, the main conclusions were drawn as follows:(1) By oxidized in nitric acid, it can be introduced -OH,-COOH, and other groups on the surface of MWNTs, which contributed to the chemical grafting and physical coating for MWNTs;(2) The MWNTs after modified by nitric acid can be used as the carrier to prepare MWNTs/Mg(OH)2 compound flame retardant through reverse precipitation in the liquid phase,which could increased the initial thermal decomposition temperature of pure MWNTsï¼›(3)The PET functional masterbatch with good dispersion and flame retardant properties,which can be prepared by melt blending in twin-screw extruder;(4)By melt blend spinning technology,PET functional fiber can be spun with good flame retardant properties.