Research On Layered Nanoparticle Modified Polyphenylene Sulfide And Meltblown Nonwoven Materials

Poly(phenylene sulfide)(PPS)fiber is an attractive material because of its excellent properties.Therefore,it is widely used in the field of environmental protection and some special fields.With the increasing application field and demand of PPS fiber,the disadvantages of PPS fiber,such as low electrical conductivity and oxidant easily in high temperature,have been aroused widespread concern by researchers.In order to compensate for these defects,in this paper,two kinds of composites were prepared,using Grignard reagent reduction and surface functionalized graphene sheet(GS)and SiC-coated Organic montmorillonite hybrids(OMMT@SiC)as filler and PPS as polymer matrix.The microstructure,crystallization behavior,mechanical properties,conductive properties and thermal oxidation resistance of composites were studied.Based on the dynamic rheological properties,the appropriate composites were chosen as raw materials for melt-blown,and the modified PPS melt-blown nonwovens with excellent antistatic and thermal oxidation resistance were prepared.The main works and conclusions were listed as following:Firstly,three kinds of Grignard reagents acting as both a reducing agent and a chemical functionalizer were used to reduce and strip the weakly exfoliated graphite oxide(WEGO)in THF.WEGO and GS were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),high-resolution TEM(HRTEM),Fourier transform infrared(FT-IR)spectra,thermogravimetry(TG),X-ray photo electron spectroscopy(XPS),Raman spectroscopy,and electrical conductivity measurement.It was found that Grignard reagents could well remove the oxygen functional groups of WEGO,and the large-area WEGO sheets with weak exfoliation degree could take place with secondary exfoliation.Simultaneously,the GS surface could be covalently grafted with organic groups which restrained GS aggregation during the reduction process.GS reduction with 4 mass equiv of PhMgBr(P-GS-4)showed excellent electrical conductivity of 2.5 × 104 S/m because the ?-?,conjugated system among GS increased the electron transfer.P-GS-4 was used as filler to modify PPS,and the prepared PPS/P-GS-4 composites displayed higher electrical conductivity(10.5 S/m)and better mechanical properties(tensile strength 88.9 MPa and Young's modulus 740 MPa)without much loss in the elongation at break.The reinforcing effects and high electrical conductivity could be explained by both the directional homogeneous dispersion of GS within the PPS matrix and the ?-?conjugated interaction arising from the similar structural characteristics between GS and the PPS matrix.Secondly,SiC-fixed organophilic montmorillonite(OMMT@SiC)hybrid particles with various proportions of SiC were fabricated by electrostatic self-assembly in the presence of CTAB.Then,their PPS composites were prepared by melt-blending method.The results showed that the oxidation resistance and mechanical properties of PPS/OMMT@SiC composites were well enhanced.When SiC content reached 5 wt%,the oxidation induction temperature of PPS/OMMT@SiC composites achieved maximum 513.1 ?,which was 40.9 ? higher than that of the pure PPS.Meanwhile,the oxidation induction time of the obtained composite achieved maximum 25.2 min.These enhancement was attributed to the existence of the SiC,which prevented the aggregation of OMMT and facilitated OMMT to be further exfoliated in PPS matrix.The sulfur atoms of PPS formed the chemical bond with SiC,meanwhile,a part of the surface hydroxyl groups of SiC formed hydrogen bond with PPS,thus weakening the oxidation activity.OMMT and SiC effectively postponed the thermal oxidative degradation of PPS due to the synergistic effects.Thirdly,the spinnability of PPS/P-GS-4 composites and PPS/OMMT@SiC composites were investigated by thermogravimetry(TG)and dynamic rheological analysis.The characterized indicated that the thermal stability of two composites were enhanced in comparasion with pure PPS.Raising the nanoparticle contents had more influence on increasing elasticity than viscosity.Besides,raising the shear rate and temperature,decreasing the nanoparticle contents could reduce the melt viscosity of composites.It was utilized the Han plot,vGP polt and G'-T polt methods to analyze the phase separation in PPS/P-GS-4 and PPS/OMMT@SiC,and got the range of the phase separation temperature.Finally,combining the rheological analysis and melt-blown trials,we got the melt blown spinning parameters.By using a single parameter variation method,the modified PPS melt-blown nonwovens were prepared in according to the different technological conditions and then we analyzed the influence of some parameters on the morphology and properties of modified PPS melt-blown nonwovens such as the diameter of fibers,filter performance,breaking strength,elongation at break.The results showed that the higher pump feed,the smaller fiber diameter and wider fiber diameter distribution.The higher melt blown temperature,the finer fiber diameter and narrower fiber distribution were obtained.When the air flow velocity was higher,fiber would be finer.Die-collector distance had little effect on fiber diameter.With the increase of die temperature and air flow velocity,the filtration efficiency and air permeability increased.The breaking strength tests showed that pump feed had little influence on the breaking strength.Higher die temperature and air flow velocity would increase the breaking strength,while the longer die-collector distance may decrease the breaking strength.The optimum technical condition of preparing modified PPS melt-blown nonwovens was the pump feed rate 98.78 g/min,the air flow velocity 0.9m3/min,the die temperature 305 ? and the die-collector distance 26 cm.In comparation with pure PPS melt-blown nonwoven,the modified PPS melt-blown nonwovens not only had an excellent antistatic property but also had an higher thermal oxidation resistance,and its filtration efficiency of 0.25 nm NaCl particle can be reached to 83.98?84.20%.