PSA Composite Fibers and Membranes

prostate specific antigen Composite Fibers and MembranesPolysulfonamide/nano titanium dioxide (prostate specific antigen/nano-TiO2) intricate spinning solutions with various nano-TiO2 portion fractions were fain apply the solution portmanteau word method. The corresponding intricate roles were developed by wet-spinning technology and the building complex membranes were prep atomic number 18d using the digital spin-coating technique. The properties of prostate specific antigen/nano-TiO2 obscure fibers and membranes were investigated by s rumpning electronmicroscope, Fourier transform infrared emission spectroscopy and X-ray diffraction, etc. The effects of nano-TiO2 and its push-down store fractions on the mechanical properties, thermal perceptual constancy and ultraviolet light shield of PSA composites werealso analyzed. The experimental results showed that nano-TiO2 with low mass fractions can be dispersed asin the PSA matrix the blending of nano-TiO2 had no demonstrabl e influence on the molecular structure and the chemical composition of PSA fiber the lechatelierite in PSA fiber was promoted at low nanoparticles mass fractionsbecause it can act as a nucleation agent the mechanical properties and the thermal stability of PSA/nano-TiO2composites can be enhanced obviously by blending nano-TiO2 into PSA matrix. The ultraviolet resistance of PSAcomposites can be improved significantly with the increase nano-TiO2 mass fractions and the 7 wt.% specimenshowed the lowest UV transmittance.Polysulfonamide (PSA) fiber is a new kind of hightemperature resistant material and it has outstandingheat resistance, flame retardancy, and thermal stability,therefore, it can be employ to develop protective products used in aerospace, high-temperature environmentsand civil fields with the flame retardant requirements(Ren, Wang, Zhang, 2007 Wang, 2009). However,raw PSA generally demonstrates poor ultraviolet resistance and the amide groups in polymer molecularchains a re prone to break down under the ultravioletradiation besides, the breaking tenacity of PSA fibersis low these properties lead to some difficulties in itsmanufacturing procedures and limit its exercise indeveloping functional textiles. Therefore, it is a challenging work to improve the mechanical propertiesand ultraviolet resistance of PSA.It has been proved that nano-TiO2 is one of theideal nano-enhanced materials and it has attracted greatscientific attention because of its excellent mechanicalproperties in significantly improved properties of composites (Ali, Shadi, Shirin, Seyedeh, Khademno,2010 Han Yu, 2005). Moreover, nano-TiO2 is goodsemiconductor oxides and it has excellent ultravioletscattering and absorption (Popov, Priezzhev, Lademann, Myllyl, 2005). It is feasible to blend nanoTiO2 into PSA matrix to improve the mechanical properties and ultraviolet resistance of PSA composites.ExperimentalMaterialsThe PSA polymer was used as spinning solution withintrinsic viscosity of 2.02.5 dL/g and relative molecularmass of 462. The rutile titanium dioxide (nano-TiO2)was blended as functional particles with a diameter ranging from 30 to 50 nm and the rutile content of nano-TiO2was nearly 99%. The dimethylacetamide (DMAC) wasselected as dissolvent in this study. The above materialswere provided by Shanghai Tanlon Fiber Co. Ltd. All thechemicals used here were of reagent grade and they wereused without further purification. proviso of PSA/nano-TiO2 compositesA certain amount of nano-TiO2 was predispersed inDMAC using ultrasonic vibration for 30min and thenadded into the PSA solution. The PSA/nano-TiO2composite spinning solutions with various mass fractions of nanoparticles was disposed(p) after mechanical stirring for 1 h and ultrasonic vibration for 2 h. Theexperimental info are shown in plank 1.The pure PSA fibers and PSA/nano-TiO2 composite fibers were developed by a small-scale and singlescrew wet spinning apparatus. Besides, the pure PSAmembrane and P SA/nano-TiO2 composite membraneswere prepared using the SJT-B digital spin-coatinginstrument. The preparation procedures of nanofibersand membranes can be referred to the previous studies(Chen, Xin, Wu, Wang, Du, in press Xin, Chen,Wu, Wang, in press).Test methodsThe dispersion of nanoparticles in PSA compositesS-3400N scanning electron microscope (SEM) with aresolution of 4 nm was used to characterize the dispersion of nano-TiO2 in PSA matrix. The machine wasoperated at 5 kV.FTIR spectroscopyThermo Nicolet AVATAR 370 Fourier transform infrared spectroscopy (FTIR) was used to characterize themolecular structure and chemical composition offibers each spectrum was collected by cumulating 32scans at a resolution of 4 cm_1X-ray diffractionX-ray diffraction (XRD) measurements of the crystalline structure of fibers were recorded on k780FirmV_06 X-ray diffraction using the CuK radiation( = 0.15406 nm). The spectra were obtained at 2hangles range of 5o60owith a scanning hotfoot of 0.8 s/ step.Mechanical properties testYG006 electronic single fiber strength tester was usedto investigate the mechanical properties of fibers. Thesample gage length was 10mm. The elongation speedwas set at 20mm/min. The measurements for eachsample were carried out 10 times and the average wasThe thermal stability testThe thermal stability of fibers was measured by Germany STA PT-1000 Thermal Gravimetric Analyzer(Linseis Inc., New Jersey, USA) the experiment wasconducted under nitrogen atmosphere with a gas flowof 80100ml/min the samples were heated up to700C from the room temperature at a heating rate of20C/min.Ultraviolet resistance testLabsphere UV-1000F Ultraviolet Transmittance Analyzer (Labsphere, Inc., northernmost Sutton, NH, USA) wasused to test the UV transmittance of membranes. Theinstrument parameters were described as below theabsorbance was 02.5A scanning time was about 5 sdata interval was 1 nm and the diameter of beam was10mm. The measurements for each sample were carried out for 10 times and the average was used for theresult discussion.Results and discussionThe distribution of nano-TiO2 in PSA compositesAs demonstrated in Figure 1, 1 wt.% of nano-TiO2 canbe dispersed evenly throughout the PSA matrix and the coat of it of nanoparticles is about 5060 nm with the nanoTiO2 mass fraction increase to 3 wt.%, a little hookup can be observed when the mass fraction of nanoTiO2 increased to 5 or 7 wt.%, its dispersion in PSAbecomes inhomogeneous because of their large specificsurface and high surface polarity, and the aggregationsize is about 100300 nm. It is difficult for nano-TiO2with high mass fractions to distribute uniformly in thePSA blending system.FTIR analysis of PSA/nano-TiO2 composite fibersAs shown in Figure 2, the position and shape of characteristic peaks of PSA composites blending with nanoTiO2 did not change obviously compared with the pristine PSA. The characteristic peaks of PSA compositesexhibiting at about 3338.99 cm_1can be attributed tothe amide NH stretching vibration and the peaks areflattened slightly with the mass fractions of nano-TiO2increased from 1 to 7 wt.%. It ascribes to the quantumsize effect of nanoparticles (Zhang Mou, 2001). Inconclusion, it shows no significant changes to themolecular structure and chemical composition of PSAfibers with the addition of nano-TiO2.XRD analysis of PSA/nano-TiO2 composite fibersAs show in Figure 3, the PSA composite fibers havediffraction peaks at 27.54, 36.15, 41.35, and 54.40,this is because of the blending of nano-TiO2 (Chen,Liu, Zhang, Zhang, Jin, 2003 Xia Wang, 2002).In addition, all the specimens have diffraction peaks atabout 11.85 and 21.25. The sharp diffraction peakscorresponding to 11.85o sharpen that there are crystalline structures in PSA/nano-TiO2 composite fibers(Yang, 2008). Besides, the sharpness of the diffractionpeaks at about 11.85 of composites enhances gradually with the nano-TiO2 mass fractions increased from1 to 5 wt.%. It suggests that t he crystallization in PSAcan be improved with the blending of nano-TiO2,because it can act as a nucleation agent. Moreover, theshape of diffraction peaks exhibiting at 21.25 of PSAcomposites broadens significantly with the increasingnano-TiO2 mass fractions and it proves that the size ofcrystal region becomes smaller (Meng, Hu, Zhu,2007).The mechanical properties of PSA/nano-TiO2 composite fibersAs illustrated in Table 2, the breaking tenacity of PSAcomposite fiber with 1 wt.% nano-TiO2 improvedobviously however, the improving degree of breakingtenacity begins to decrease with the continuousincrease in mass fractions of nano-TiO2 and the valueof the 7 wt.% sample is lower than the pure PSA.This is because nano-TiO2 is an ideal nano-enhancedmaterial the blending of it into PSA can improve themechanical properties of composites to some extent.Moreover, nano-TiO2 with low mass fractions can bedistributed evenly in PSA matrix and it can form agood interface with PSA molecular chains.As can be seen in Table 2, the composite fibers havelow elongation at break which is lower than the rawPSA simultaneously, the initial modulus of compositesincreased significantly, however, the improvementbegins to decrease with the mass fractions of nano-TiO2increased from 1 to 5 wt.% and the 7 wt.% sample hasthe minimum value of the initial modulus. It suggeststhat the blending of nano-TiO2 with low mass fractionscan improve the mechanical properties of PSA composite fibers to a certain extent.The thermal stability of PSA/nano-TiO2 compositefibersTG curves and derivative thermogravimetric analysis(DTG) curves of PSA/nano-TiO2 composite fibers aredemonstrated in Figures 4 and 5, respectively. Themain parameters of the curves are presented in Table 3.In Figure 4, the thermal annihilation behaviors ofspecimens are divided into three regions.The first region is a level of small mass loss ranging from room temperature to 400C. As depicted inFigure 4, each TG curve has a sharp decrease in thebeginning and then reaches a platform with the temperature heating up to 350C. However, the mass lossof PSA composites blending with nano-TiO2 is alwayslower than the pure PSA during this process. Asshown in Table 3, the T10wt of each PSA composite ishigh, whereas the mass loss of pure PSA reached 10%at 170.19C. This suggests that it is hard for the PSAcomposites to decompose and the thermal stability issignificantly higher than PSA.The second region is a pose of thermal decomposition process ranging from 400 to 600C. Accordingto the analysis of bond nothing (Zhang, Cheng, Zhao, 2000), the CN section of amide in PSA macromolecular chains decomposes at 500600C (Broadbelt, Chu, Klein, 1994a, 1994b) and the mass lossof PSA at this stage is attributed to the gases releasedsuch as SO2,NH3, and CO2. In addition, as illustratedin Table 3, the To of PSA composites blending with 1and 3 wt.% nano-TiO2 can be increased therefore, itsthermal stability can be improved correspondingly.A s exhibited in Figure 4, the mass loss of specimens accelerates steadily with the increasing temperature and each TG curve presents a rapiddecomposition at about 500C. Corresponding to therapid decomposition, there is a peak in DTG curveshown in Figure 5 and the Tmax can be determinedaccording to the value of the maximum peak (Yang,2008).The third region is a high-temperature phase ofcarbon formation ranging from 600 to 700C. Asdemonstrated in Figure 4, the PSA composites dummy upshow a slight decomposition during this stagebesides, the mass loss of pure PSA decreases obviously. As illustrated in Table 3, the residual mass ofcomposites at the terminal temperature is higher thanthe pure PSA.Therefore, it is concluded that the thermal stabilityof PSA composites blending with nano-TiO2 can beimproved significantly.The ultraviolet resistanceAs exhibited in Figure 6, the ultraviolet transmittance of specimens ranging from 390 to 400 nmdecreases gradually with the increase in mass fracti ons of nano-TiO2. This suggests that the nanoTiO2 can improve the ultraviolet resistance of PSAcomposites significantly. This is because the bending index (RI) of nano-TiO2 is extremely high(2.73) and it has excellent ultraviolet scatteringproperties (Liu, Tang, Zhang, Sun, 2007). Inaddition, electrons in nano-TiO2 are transited fromthe valence band to the conduction band under theultraviolet radiation therefore, the nano-TiO2 hasoutstanding ultraviolet absorption properties.ConclusionsThe PSA composite fibers and membranes with different mass fractions of nano-TiO2 were developed.The experimental results can be summarized as follows(1) The nano-TiO2 with low mass fractions (1 or 3wt.%) can be distributed evenly in the PSAblending system however, it is difficult fornano-TiO2 with high mass fractions (5 or 7 wt.%) to disperse homogeneously throughout thePSA matrix.(2) The blending of nano-TiO2 showed no obviouschanges to the molecular structure and chemicalcomposition of PSA compos ite fibers.(3) The crystallization of PSA composite fibers canbe improved by blending with low mass fractions of nano-TiO2, because it can act as anucleation agent.(4) The breaking tenacity and initial modulus of45ance %(a)(b)(c) PSA composite fibers can be improved obviously by blending with low mass fractions ofnano-TiO2 whereas the elongation at breakof PSA composite was decreased with theparticles mass fractions increased from 1 to 7wt.%.(5) The thermal stability of PSA composites can beincreased significantly and the nano-TiO2 hassome influences on the To, T10wt, and Tmax ofPSA composites compared with the pure PSA.(6) The blending of nano-TiO2 can improve theultraviolet resistance of PSA composites signifi-cantly and the 7 wt.% specimen had the lowestUV transmittance.