INVERSE SIZE EXCLUSION CHROMATOGRAPHY- A TECHNIQUE OF PORE CHARACTERISATION OF TEXTILE MATERIALS

Transcription

1 INVERSE SIZE EXCLUSIN CHRMATGRAHY- A TECHNIQUE F RE CHARACTERISATIN F TEXTILE MATERIALS Arunee Kongee a, Thomas Bechtol a, Euar Burtscher b, Markus Scheinecker c a Christain-Doppler Laboratory of Textile an Fibre Chemistry in Cellulosics, Institute of Textile Chemistry an Textile hysics, Leopol-Franzens University Innsbruck, A-6850 Dornbirn, Austria b Institute of Textile Chemistry an Textile hysics, Leopol-Franzens University Innsbruck, A-6850 Dornbirn, Austria c Lenzing AG, A-4860 Lenzing, Austria Abstract Inverse size exclusion chromatography is use to etermine pore parameters such as volume, surface area an mean size, an to follow structural changes in regenerate cellulosic yarns; non-crosslinke type lyocell, CLY1; crosslinke type lyocell, CLY an CLY3; micromoal; CMD an viscose; CV. From the investigation in untreate yarns, CV provie the highest values of pore volume an surface area, but the lowest mean size, whereas the inverse was foun in CLY1. As structures of the yarns change upon treatments, tension treatment in wet state was applie to yarns. With such treatments, the rearrangements in structures occurre an le to changes in pore parameters of materials. ore volumes, surface areas an mean pore sizes of treate yarns tene to ecrease. However, there was no significant change in pore parameters of treate yarns with an without tension. Keywors: inverse size exclusion chromatography, tension treatment, pore volume, pore surface area, mean pore size, structural change Introuction Structural characteristics of textile materials play an important role in etermining the accessibility, uniformity an sorption rate of reactions involve in prouction an treatment. Although, there are many methos available for pore characterisation such as gas asorption [1], X-ray scattering [] an electron microscopy [3], Inverse Size Exclusion Chromatography (ISEC) offers a great avantage over the other techniques as porous materials are analyse in the wet state. Materials with unknown pore characteristics were packe in the column while probe molecules with known molecular sizes were allowe to pass through the column. Resience times of molecules in the column are epenent on sizes of probe as illustrate in Figure 1 (a). (a) (b) A B C Figure 1. (a) Mechanism of size separation in column. (b) Illustration of accessible pore volume, grey circles = probe molecules, black circles = water molecules. From Figure 1 (b), small probe molecules explore pores A, B an C, water in those pores will access them whereas water molecule in any pore accesses cannot access probes which 96

2 is too large to enter the pore. Volume of accesse water will provie accessible pore volume, but this technique is limite by the range of probe sizes available. As accessible pore volumes are etermine by using probes to explore insie pores, probes must not be asorbe on materials to be analyse an must present spherical shapes in water. oly(ethylene glycol); EG an extran are suitable probes for cellulose analyses. (a) (b) Fig.. Molecular structures of stanars use. (a) EG (b) Dextran. Figure shows molecular structure of EG an extran that were use as probes. Size of EG an extran increases with molecular weight with the relationships in equations 1 an [4, 5]. For extran n Experimental Materials Cellulose yarns of normal lyocell, CLY1 of 1.3/40 tex, crosslinke lyocell CLY of 1.3/40 tex an CLY3 of 1.4/38 tex, micromoal (CMD) of 1.3/40 tex an viscose (CV) of 1.3/39 tex were use. Dextran an EG with a series of ifferent molecular weights were use as stanars an Leophen MC (BASF, Germany) was use as e-aerating agent. Methos Tension treatment CLY1, CLY, CLY3, CMD an CV were treate by tension force in wet state as shown in Figure m of each yarn were woun in hanks. A 1 kg weight was suspene on a 30 cm length of the hanks. These hanks were immeiately immerse in water at room temperature for hr, after which the hanks, with the weight attache, were rie in an oven at 105 C for hr. A set of regenerate cellulose yarns without tension was prepare. The hanks, without tension, were wette in water at room temperature, an then rie in an oven at 105 C for 3 hr. 30 cm For EG, ( M) 0. 5 = 0.53 (1) ( M) 0. 4 = 1.74 () Tension treatment in wet state is a common treatment for textile materials an may cause structural changes in the substrate, in aition to changes cause by chemical or other physical treatments [6, 7, 8]. Therefore, it was of interest to us to apply tension treatments to yarns of regenerate cellulose an stuy the change of their structures by etermining pore parameters using ISEC. Figure 3. Tension treatment applie to cellulose yarns. Inverse size exclusion chromatography Treate yarns of CLY1, CLY, CLY3, CMD an CV were cut into cm. They were packe into stainless steel columns of 0.4x5 cm in ry state. Densities of columns were maintaine in the range of g/cm 3. g/l of Leophen MC solution was flushe through columns at a flow rate of 1.0 ml/min for 1 hr. Distille water was replace at the same flow rate for further 1 hr. The operations were performe at room temperature at a flow rate of 0.1 ml/min. 97

3 A series of polymer stanars of 0.1% extran an EG with various molecular weights were injecte using AS-1555 auto-sampler, U-1580 HLC pump, etecte by a ifferential refractometer moel RI-1531 etector (Jasco) an analyse with a software. A schematic illustration of the process is shown in Figure 4. WATER RESERVIR EG 400 EG 8 EG 194 Trithylene glycol Dithylene glycol Ethylene glycol UM INJECTIN Figure 5. Typical chromatograms of EG 400, EG 8, EG 194, TEG 15, DEG 108 an EG 6 on packing material; regenerate cellulose. CLUMN RI DETECTR DATA ACQUISITIN ( T - T ) e o x F Vi = (3) W Figure 4. Instrument of ISEC. Results an iscussion Elution profiles of separate molecules, were obtaine by ISEC. Depening on the variation in their sizes, EG 400, EG 8, EG 194, triethyleneglycol (TEG) 15, iethyleneglycol (DEG) 108 an ethyleneglycol (EG) 6 will be presente as shown in Figure 5. The relationship between log molecular weight of probes an retention time is illustrate in Figure 6. No istinct ifferences in retention times of probes were observe for probes with molecular weight from 1470 to altons (log MW from 3.17 to 6.65) inicating no separation of these probe molecules by cellulosic materials. n the other han, istinct ifferences in retention times were obtaine for probes in the range of molecular weights from 6 to 940 alton (log MW from 1.79 to.97), with the range of retention times obtaine in untreate yarns being 3.97 min while that obtaine for treate yarns being 3.47 min. From the retention times of each probe, accessible pore volumes (V i, ml/g) were etermine using equation (3) [9, 10, 11]. Where T e is elution time of each probe (min), T o is elution time of the biggest probe (min); EG , F is the flow rate of mobile phase = 0.1 ml/min an W is the weight of yarn (g). The resulting accessible pore volumes were plotte against iameter of probes as shown in Figure 7. From Figure 7, it can be seen that accessible pore volume (V i ) is a linear function of iameter ( i ) for probes with size smaller than 6.9 Å. At iameter = 0 Å, total accessible pore volumes of yarns was obtaine by extrapolation [8, 10]. ore parameters of volume, mean size an surface area were obtaine using equations available in literature [1, 13]. Distribution coefficient of probe concentration (K), in external vois an internal pores is the ratio of probe raius () an pore raius (D ) as given in equation (4): K 1- n when «D (4) D 98

4 8 CLY1 6 CLY CLY3 0.6 CLY1 Log MW of probes CMD CV CLY1 CLY CLY3 CMD CV Accessible pore vol ume (ml/g) CLY Retention time (min) Figure 6 Retention time of probes on cellulosic yarns; (a) before tension treatment, (b) after tension treatment Molecular iameter (Å) Where n is a constant, which is a function of pore configuration. If is the iameter of probe, is the surface area (m /g) an V is pore volume of material (ml/g), istribution coefficient is relate to Σ; surface area (m /ml) as efine in equation (5): K where = 1- Σ (5) V V By multiplying equation (5) by V, equation (6) is obtaine. KV = V - (6) As accessible pore volume of material (V i ) is a function of pore iameter ( i ), the continuous plot between V i an i give pore volume of material (V ) as shown in equation (7). KV = Vi V - (7) Figure 7 Relationship between accessible pore volume an iameter of probe of cellulosic yarns; before tension treatment, after tension treatment By replacing equation (5) in equation (4), the following equation is obtaine. p 1 - = 1- n (8) V D Where n = 1 for slit pore moel [6,13], mean pore size is obtaine as the following equations. As V p an slope ( ) of a linear relationship between V i an D i are obtaine from equation (7), D is obtaine subsequently from equation (10). The calculate values of pore parameter: volume, mean size an surface area of original regenerate yarns an treate- regenerate yarns with an without tension are tabulate in Table 1. V p = (9) D 99

5 Yarn Untreate ore volume (ml/g) Surface area (m /g) Mean pore size (Å) Without tension Treate Treate Treate Un- Un- With treate Without With treate Without tension tension tension tension With tension CLY CLY CLY CMD CV Table 1 ore volume, surface area an mean pore size in regenerate cellulose yarns with an without tension treatment (10) From the results, untreate yarns exhibite ifferences in pore parameters epening on type of material. The values obtaine for pore parameters lie in the range of ml/g for pore volume, m /g for pore surface area an Å for pore size. CLY1 exhibite the lowest pore volume an surface area, but highest mean pore size while the inverse was observe in CV. The pore parameters were also foun to iffer in yarns with tension treatments. Reuce values were foun in all tension treate yarns, except in CV. ercentage of reuction in pore volumes, surface areas an mean pore sizes of materials were observe as 19, 13, 8, 9 an 4% for treate yarns without tension, an 11, 8, 13, 1 an % for the set of yarns treate with tension. By such treatment, it is believe that material structures reorganise, leaing to structural changes. However, in a comparison of yarns treate with tension an without tension, pore parameters were rather similar. This inicates that both treatments cause the similar structural re-organisation in the material. Conclusion D = V ISEC is a technique for etermining pore parameters; volume, surface area an mean size in regenerate cellulosic materials in wet state. By using poly(ethylene glycol) an extran with 100 various sizes, accessible pore volumes in material are accesse. The initial relationship between accessible pore volume an molecular iameter of probe provies pore volume an surface area of material; mean pore size is subsequently obtaine by the relationship of pore volume an surface area. From the investigation, pore parameters of regenerate cellulosic yarns were varie epening on type of materials an also tension treatment. Such changes can result from the ifferent prouction routes an the applie textile chemical treatment. Acknowlegement Great thank is extene to the ÖAD (Österreichischer Austauschienst), Christian- Doppler research society an Lenzing AG for financial support. References [1] orter, B. R., Rollins, M. L., J. Appl. olym. Sci. 197, 16, [] Crawshaw, J., Cameron, R.E., olymer, 000, 41, [3] Dolmetsch, H., Dolmetsch, H., Das apier, 1969,, [4] Haller, W., Macromolecule, 1977, 10, [5] Squire,. G., J. Chromatogr., 1981, 10,

6 [6] Rowlan, S.., Wae, C., Bertoniere, N. R., J. of Appl. olym. Sci., 1984, 9, [7] Li, C., Laisch C. M., Laisch, M. R.. Textile Res. J. 001, 75(5), [8] Breereck, K., Blueher, A. Mellian Textilberichte, 199, 73, [9] Gruber, M. h. D. Dissertation, Universität Stuttgart, [10] Casassa, E. F., Tagami, Y., Macromolecules, 1969, (1), [11] Gorbunov, A. A., Solov eva, L. Ya., esechnik, V. A., J. of Chromatogr., 1988, 448, [1] Stone, J. E., Scallan, A. M., Cellulose Chem. Technology, 1968,, [13] Nelson, R., liver, D. W., J. olym. Sci.: art C, 1971, 36,