Surface Characterization of Glass Fiber by Inverse Gas Chromatography

Journal of Wuhan University of Technology-Mater. Sci Ed. Oct 2008DOI10.1007/sl1595-007-5687-9Surface characterization of Glass Fiberby Inverse Gas ChromatographyHUANG Xiaohua. LI Bin*. SHI Baoli. GUO Xuefei JIA Lina(Heilongjiang Key I aboratory of Flame Retarded Polymeric Materials, College of Science, Northeast Forestry University, Harbin 150040, China)Abstract: The surface properties of glass fiber were quantificationally analyzed by inversegas chromatography (IGC). Five n-alkanes(C, C,, Cs, Co, and Cio) were chosen as apolar probes tocharacterize the dispersive component of surface free energy. Trichloromethane(CHCl,),acetone,and tetrahydrofuran(THF) were chosen as polar probes to detect the Lewis acid-base parameters. It isfound that the dispersive components of free energy are 32.3, 30.5. 27 5, and 26.9 mJ/mf at 70,80. 90, and 100 C, respectively. The Lewis acidic number Ka of the glass fiber is 0.512 4, and thesic number Kh is 2.862. The results mean the glass fiber is a Lewis basicKey words: glass fiber, inverse gas chromatography; acid-base properties; surface free energythe teI IntroduetionThe specific interactions may be in the form of hydrogenbonding, charge transfer complexes, acidGlass fiber is a kind of superexcellence inorganic base type interactions, dipole moments and accep-nonmetallic material. The raw material of glass fiber is tor-donor complexes. Nowadays, the Lewis acid-basethe natural ore. As compared with other materials, glassconcepfor describing surface properties is increasinglyfiber offers high stiffness, high-elastic-modulus, high accepted, which suggests that the totality of specificelectric insulation, high inoxidizability as well as high teractions may be viewed as Lewis acid-base forces'tensile and compressive strengths at substantial cost ad The usual techniques for measuring surface acid-basevantages. These merits make it as reinforcement material parameters are isoelectric point, indicator dye adsorptionin advanced composites 2. Lots of researches on glass x-ray photoelectron, calorimetry and inverse gas chro-fiber reinforcement materials were carried out, such as matography (IGC). Compared with other techniques(egglass-fiber reinforced nylon 66 composites, interfacial contact angle), IGC can characterize the surface proper-component of glass fiber in ternary composites of ties at relative higher temperatures 57. To our knowledge,GF/PC/PP. etc. 34the surface free energies and Lewis acid-base propertiesAmong the properties characterizing materials, of glass fiber at high temperatures are still not measuredrface properties are significant. Surface parameters areIn this study, IGC was used to characterize quan-especially important for composite materials. The inter- tificationally the Lewis acid-base properties and theface properties of reinforcement materials(e g, glass fiber) dispersive component of surface free energy at a broadand bulk materials(eg, polymer) are often explained by temperature range for glass fiberrface theories. The specific properties of materialsdepend strongly on their surface energy and specific 2 Inverse Gas Chromatographyinteraction forces. The surface energy of solid materialsis generally measured by contact angle method. However,IGC is an inversion of conventional gas chroma-ographmain difference between GC and IGC isReveived: Feb. 23, 2006: Accepted: June 13, 2008)that th中国煤化工 uterial acting as theHUANG Xiaohua(黄小华 E-mail: haotianyouji@l63cmstationsCorespongauthorLIBin(XAy:Prof:PhD:E-mai:libinzh62@163.comknown.CNMH Grobe solvents withy…, the column and theFunded by the Key Technologies R&D Programme of Heilongjiangretention times of these probes were measured at infini(No, GB03A203) and Innovative Plan for the Fetched in Talent of NEFU of dilution. The interactions between the probe solvents andthe material were calculated from the retention times, andVol23 No5 HUANG Xiaohua et aL: Surface Characterization of Glass FiberThe dispersive component of surface free energy column, the expression is 4. 7,nto the chromatographicthe surface properties of the material were determined(specific)solvents are injected ir of material stationary phase was measured with△Ga=△Ga+△G(5)n-alkanes as probes. The assumption is that only dispersive interactions exist between n-alkanes and material. rdwhere AG is the dispersive contribution to theis obtained from the net retention volumetotal free energy of adsorption, which is determined withaccording to Eq (In-alkanesAG. results from the distance between theAG,=RTIn(V,)=2N a(r)(n)+K (1) RTIn(v value of polar solvent and the straightwhere A Ga is the total free energy of adsorption of n-allkane lineprobe, R the gas constant, T the temperature of column,Vn the net retention volume, Na the Avogadro number, aThe enthalpy of specific interactions AH ,isthe surface area of n-alkanes, the dispersive surface calculated according to the following expression 58)free energy of n-alkanes, K' is a constant related to the△Ga=△H-T△Sareference gas pressure and the reference surface preswhere AS. is the specific entropy of adsorptionsure. From a plot of 4 Ga vs ar) for the n-alkane AH results from the slope of the plot of AGprobes, the value of r is calculated with the slope. ITThe net retention volume Vn is calculated according to eqg)(z)The Lewis acid number Ka and Lewis base numberK, are calculated according to Eq (7)'V. =(t-to)△H=KXDN+KxANwhere I, is the retention time of probe solvent, to thehere DN and AN are the Gutmann's Donor andretention time of non-interacting probe, Fthe flow rate of modified Acceptor number of polar solvents, respectivelycarrier gas, C the correction factor, allowing for the vaporpressure of water at the temperature of bubble flow meter Plotting -AH: /AN"vs DN/AN', gives Ka as the slope,used to determine the flow rate of carrier gas by the fol- and Ko as the interceptlowingexpressionC=1-PH, 0/Po(3)3 Experimentalwhere Plo is the saturated vapor pressure of waterat ambient temperature, Po the atmospheric pressure, /is 3.1 MaterialsGlass fiber was purchased from Jushi group Co, Ltd.the James-Martin compression correction term deter- China. For the IGC analysis, the apolar n-alkanes probesmined as follows:were n-hexane(C6), n-heptane(C,), and n-octane( Cs).(4) n-nonane(C9), n-decane(C1o). The polar probes were2(P/P)-1trichloromethane(CHCl3), acetone(Acet)and tetrahy-where Pi is the inlet pressure of carrier gas.drofuran(THF). They were analytical grade solvents andThe Lewis acid-base properties are calculated from purchased from Tianjin Kermel Chemical Reagents De-velopment Center, China. n-pentane was used as theAGa,the contribution to the free energy of adsorption by non-interacting probe, which was analytical grade solLewis acid-base(specific) interactions when polar vents and purchased from Tianjin Kermel ChemicalReagents Development Center, China. The characteris-tics of probe solvents are listed in Table 1Tabl 1 Characteristics of the probe solaProbe(A2(mJ·m23y5)/(kJ·mol)/kJ·mol)51.51847021.3TH中国煤化工CNMHGCHCI2270.0Acet16.510.5THF402521321864Journal of Wuhan University of Technology-Mater. Sci Ed. Oct 20083. 2 IGC instrumentwhich shows the dispersive component of surface freeThe instrument was a GC-900A gas chromatograph energies decreasing with the increasing temperature(Shanghai TianPu Analytical Instrument Ltd, China)Table 2 Dispersive component of surface freeequipped with a flame ionization detector(FID). Nitro-energy r(mJ.m)of glass fibergen was used as the carrier gas. The flow rate wasTemperature/k343.2353.2363.237327.0 mL/min, measured from the end of the column with asoap bubble flow meter. The injector and FID wereGlass fiber32.326.9heated to 130 C. The probe solvents were injectedFig 3 is the plot of dispersive surface free energy vsmanually,using a 1.0 HL Hamilton syringe. The injection the temperature. Generally, dispersive surface free envolumes were 0.6 HL. The column was a stainless steel ergy of solid materials decreases when temperature inube(0.5 m in length, 4.24 mm i.d. ) It was washed with creases. Therefore, result in Fig 3 is with the lawacetone prior to use Glass fiber was sheared by scissors toshort fibers with length of 1-2 mm. 2.099 5 g glass fiberwas packed into the column by tweezers, and the twoends of the column were plugged with silane-treatedglass wool. The column was stabilized at 140 C andfast carrier nitrogen gas flow rate 20 mL/min for 10 h 2prior to use The IGC experiments were performed at 70,80,90,andl00℃3732K4 Results and Diseussion363.2K353.2K343.2KFig. I shows the plot of InVn vs the inverse of thecolumn temperature for n-alkanes and polar probes inIGC experiment. From the values of net retention vol-Fig 2 Surface free energy offor n-alkanes in Igcumes of the probes, the surface properties of glass fiberare determinedTHEFig.3 Plot of r, vs temperature for glass fiber000/7/Kig.I Plot of Invn vs 1 000/T for the probes4.2 Lewis acid-base parameters K, andK, of glass fiber4.I Dispersive component of surface freeFig 4 shows the calculation of free energy of ad-energy y of glass fibersorption by Lewis acid-base interactions AG: for theAccording to Eq. ( D), the dispersive component of polar probes adsorbed on glass fiber at 90 C Table 4surface free energy y, of the glass fiber is calculated lists中国煤化工 at the overall tfrom A Ga(RTn Vn)of n-alkanes for every temperature. pratCNMHGFig 2 shows the plots of (RTInVn)vs a(ni)for n-alkanesAccording to Eq (6), the enthalpy of specific inter-at different temperatures. The results are listed in Table 2, actions AHa for every polar probe are calculated fromol.23 No 5 HUANG Xiaohua et al: Surface Characterization of Glass Fiber.the free energy of specific interactions listed in Table 3. 5 ConelusionsThe results are listed in Table 4The surface properties, dispersive component ofsurface free energy and Lewis acid-base of a glass fiberwere quantificationally determined by IGC methods inthis work. The dispersive component of surface free en-ergies decrease from 32.3 mJ/m at 70 C to 26.9 mJ/at 100 C. The Lewis acidic number K and the basicnumber ks of the glass fiber are 0.512 4 and 2.862,re-spectively. The result indicates the glass fiber is a Lewisbasic polymer35ReferencesFig4 Free energy of adsorption vs a(r) for n-alkanes and [1] H Zhou. W P Zhang. Development of Fiberglass Industrialpolar probes at 363.2 KFabrics[J]. Fiber Glass, 2006(1): 33-36Table 3 Free energy of adsorption by Lewis acid-base[2] LC Wei. 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