Stanisław Rabiej, Włodzimierz Biniaś, Dorota Biniaś Akademia Techniczno Humanistyczna ul. Willowa, 243-309 Bielsko-Biała The Transition Phase in Polyethylenes – WAXS and Raman Investigations Abstract The existence of the third, transition component, apart from the crystalline and amorphous phases, in polyethylenes has already been proved in several papers. In this work, the WAXS patterns of polyethylenes with various branch contents were analysed, aiming at the best method of accounting for the third phase in the procedure of decomposition of the patterns into crystalline peaks and amorphous scattering. It appeared that the best result was obtained when we assumed that the intermediate phase is represented by two peaks located close to the crystalline reflections (110) and (200), on the left sides of these reflections. The calculations performed have shown that both the density and the mass fraction of this intermediate third phase decrease continuously with increasing 1-octene content. A comparison of the mass fractions of the three phases has shown that the total mass fractions of the crystalline and transition phases determined with the WAXS and Raman methods coincide very well; however, the values obtained for each individual phase do not agree with one another. Key words: WAXS, Raman spectroscopy, transition phase, crystallinity, polyethylene. Introduction The analysis of Wide Angle X-ray Scattering (WAXS) curves for various polyethylenes (this name covers polyethylene and ethylene-1-alkene copolymers of different degrees of branching) leads to the conclusion that the proper description of their structure needs the introduction of a transition phase – an intermediate component in addition to the crystalline and amorphous phases. Such a conclusion has already been presented in several papers [1-4]. It was shown [4], that for a polyethylene in a solid state, both the angular position 2θ of the amorphous halo as well as its width at half height are considerably higher than the values expected from the extrapolation of the respective data for this polymer in a molten state. This fact suggests that the amorphous halo of a polyethylene in a solid state is a sum of scattering from a completely amorphous, liquid-like phase and from the intermediate, better-ordered regions that originate during crystallization. So, in analysing the WAXS profiles, we have to determine how to account for this third component in the deconvolution of the diffractogram. In this work, a series of ethylene-1-octene homogeneous copolymers with a 1-octene content ranging from 0.8 to 11.27 mol% and a linear polyethylene standard were investigated. In contrast to other similar investigations, the WAXS patterns were analysed in a broad 2θ range: 4°–60°, covering not only the highest (200) and (110) peaks but all the peaks characteristic of the crystalline phase, located at higher 2θ angles. The mass fractions of all three phases were calculated with the WAXS method and compared with those obtained from the analysis of the Raman spectra of the investigated polymers, which was performed using the method developed by Strobl and Hagedorn [5]. Experimental Material The measurements were carried out for 8 homogeneous ethylene-1-octene copolymers synthesized at DSM Research (the Netherlands) using a metalocene catalyst system. The number of CH3 groups per 1000 carbon atoms in the main chain (CH3/1000 – degree of branching) and mole % of 1-octene provided by the producer are given in Table 1. The melting temperatures were determined by independent DSC measurements. Additionally, the samples of linear polyethylene (LPE) and a commercial high-density polyethylene (HDPE) were investigated as the reference samples. Before the measurements, all the samples were melted at a temperature higher than their respective melting temperatures to erase their thermal history and cooled at the same rate of 10 °C/min to room temperature. The crystallinity of the samples was determined using the wide-angle X-ray diffraction (WAXS) and Raman spectroscopic methods. WAXS method Diffraction patterns were recorded in a symmetrical reflection mode using a URD-6 Seifert diffractometer and a copper target X-ray tube (λ = 1.54 Å) operated at 40 kV and 30 mA. Cu Kα radiation was monochromized with a graphite monochromizer. WAXS curves were recorded in the 2θ range 4°-60°, with a step of 0.1°. The samples had the shape of circular plates with a radius of 1 cm and a thickness of 1 mm. Raman spectroscopic method The Raman spectra of the investigated samples were recorded in the range of 3700-100 cm-1 with a resolution of 4 cm-1, using the MICROSTAGE adapter of the Raman module of the Magna–IR 860 FTIR spectrometer (Nicolet) equipped with a YAG laser. The wavelength was 1064 nm, the diameter of the beam was 50 μm and its power 0.6 W. Each spectrum was obtained as the average of 2000 scans. Results and discussion The analysis and decomposition of the WAXS curves into component peaks and all the calculations were performed using WAXSFIT [6], a new version of Table1. Samples characteristics. CH3/1000 is a number of CH3 groups per 1000 atoms in the main chain of a copolymer. Sample LPE EO1 EO2 EO3 EO4 EO5 EO6 EO7 EO8 CH3/1000 0 3.9 8.4 19.2 23.3 23.6 27.7 35.9 42.1 Mole % of 1-octene 0 0.8 1.77 4.34 5.42 5.5 6.64 9.15 11.27 Melting Temperature [oC] 132 130 119 101 96.3 94.1 92.3 69.5 60.5 Rabiej S., Biniaś W., Biniaś D.; The Transition Phase in Polyethylenes – WAXS and Raman Investigations. FIBRES & TEXTILES in Eastern Europe January / December / B 2008, Vol. 16, No. 6 (71) pp. 57-62. 57 the Optifit [7] computer program. In the first stage, a linear background was determined based on the intensity level at small and large Results angles and and subtracted discussion from the diffraction curves. Next, the curves of all the samples were normalResults and andized discussion to the same of value integralcurves inten- into compo The analysis decomposition the ofWAXS sity scattered by a sample over the whole calculations were performed using WAXSFIT [6], a new version of range of scattering angles recorded in The analysis and decomposition of the WAXS curves into component and all thebased the stage, experiment. Finally, the peaks diffraction program. In the first a linear background was determined curves wereversion resolvedthe into crystalline calculations were performed small using and WAXSFIT [6], aand new Optifit [7] computer large angles subtractedoffrom the diffraction curves. N peaks and amorphous scattering. To this program. In the first stage, a samples linear background wasadetermined based on intensity level at sca were normalized to the same value of integral intensity aim, theoretical curve wasthe constructed, composed of functions related to indismall and large angles and subtracted diffractionangles curves. Next, the curves of all theFinal the whole from rangethe of scattering recorded in the experiment. vidual crystalline peaks and amorphous samples were normalized to were the same valueinto ofhalos. integral by over To resolved crystalline peaksscattered andcurve amorphous scattering. Theintensity theoretical wasa sample fitted theexperiment. experimental using arelated multic-tocurves the whole range of scattering curve angleswas recorded intothe the diffraction constructed, composed Finally, ofone functions individua riterial optimization procedure and a hywere resolved into crystalline peaks and amorphous scattering. To this aim, a theoretical amorphous halos.brid The theoretical wasa fitted system [8] that curve combines geneticto the exp curve was constructed, composed of functions related to individual crystalline peaks and algorithm and the classical optimization multicriterial Figure 1. WAXS pattern of linear polyethylene standard resolved into crystalline peaks and optimization procedure and a hybrid system [8] th method of Powell. Both crystalline peaks amorphous scattering. amorphous halos. The theoretical was classical fitted tooptimization the experimental one using a Both algorithmcurve and the method of Powell. and amorphous halos were represented multicriterial optimization procedure hybrid system [8] combines a genetic by a represented linear combination of Gauss and amorphousand halosa were by athat linear combination of Gauss a Lorentz profiles: algorithm and the classical optimization method of Powell. Both crystalline peaks and amorphous halos were represented by a linear combination of Gauss Lorentz profiles: 2 and 2( x − xoi ) (1 − f i ) Fi ( x ) = f i H i exp− ln 2 + w (x − x [ + 1 2 i 2 2( x − xoi ) (1 − f i )H i Fi ( x ) = f i Hwhere: i exp − ln 2 + 2 (1) wi 1 + [2( x − xoi ) / wi ] (1) where: where: x – scattering angle 2θ, Hi – peak height, wi – width at half height, xoi x – scattering angle 2θ, Hi – peak height, fi – shape factor, fiwequals 0 for profile 1 forpoGauss profile at Lorentz half height, xoi and – peak i – width sition, f – shape factor, f equals 0 for x – scattering angle 2θ, Hi – peak height, wi – width at half height, xoi – peak position i i Lorentz profile and 1 for Gauss profile. fi – shape factor, fi equals 0 for Lorentz profile andof1 the for crystalline Gauss profile. The starting values peak positions were calculated The starting values of the crystalline peak unit cell dimensions. In contrast to other similar investigations, th positions were calculated using the polyThe starting values of the crystalline peak positions were calculated using the polyethylene recorded and analysed in aunit broad θ range: 4°–60° covering not on ethylene cell 2dimensions. In contrast to other similar investigations, the WAXS unit cell dimensions. In contrast to other similar investigations, the WAXS patterns were phas (110) peaks but all the peaks characteristic of the crystalline patterns were recorded and analysed in a recorded and analysed in a broad range: 4°–60° covering not was only approximated the highest (200) and angles.2θThe amorphous broad 2θ scattering range: 4°–60° covering not onlyby two br (110) peaks but all the peaks characteristic crystalline phase, located at from higher Figure 2. WAXS pattern of the EO6 sample resolved into crystalline peaks and amorphous the highest (200) and (110) peaks but all the2θintermaximum, locatedof atthe lower diffraction angles, results scattering, assuming a two-phase structure. the peaks characteristic of the crystalangles. The amorphous scattering was by two broad maxima. The first the second oneapproximated observed at higher angles results from intra-molecular line phase, located at higher 2θ angles. maximum, located at lower diffraction angles, The results frommaxima the scattering inter-molecular scattering and amorphous was approxicase of polyethylenes, the are located at 2θ ≈ 19–20° mated by two broad maxima. The first the second one observed at higher anglescurve results intra-molecular scattering is [9,shown 10]. Ininthe diffraction of from LPE resolved into components Fig. 1. maximum, located at lower diffraction case of polyethylenes, the maxima are located at 2 θ ≈ 19–20° and 2 θ ≈ 39–40°. The angles, results from the inter-molecular scattering andinthe second one observed diffraction curve of LPE resolved into components is shown Fig. 1. at higher angles results from intra-molecular scattering [9, 10]. In the case of polyethylenes, the maxima are located at 2θ ≈ 19–20° and 2θ ≈ 39–40°. The diffraction curve of LPE resolved into comFigure 3. Width at ponents is shown in Figure 1. half height of the first amorphous maximum during cooling for LPE and two chosen copolymers EO2 and EO7 [4]. The dotted lines indicate the melting temperatures. 58 In the first trials, the diffraction curves were resolved into components assuming an ideal two-phase structure of the investigated polymers. In the 2θ range, 10°–30°, the experimental curve was approximated by two FIBRES & TEXTILES in Eastern Europe January / December / B 2008, Vol. 16, No. 6 (71) peaks representing (200) and (110) crystalline reflections and a broad peak representing the first amorphous maximum. However, for all the samples, the quality of fit was poor. An example is given in Figure 2, which is related to the sample EO6. The differential plot shows considerable differences between the experimental and theoretical curves in the 2θ range corresponding to the considered peaks. These problems with fitting are consistent with the results of our previous studies [4], which have indicated a composed structure of the amorphous scattering in the WAXS patterns of LPE and ethylene1-octene copolymers. It was shown that the position, the width at half height and the shape of the first amorphous maximum change with the temperature of a polymer and the most sudden changes occur during melting or crystallization. In a solid state, the value of the angular position 2θ of the amorphous maximum as well as its width at half height are considerably higher than the values expected from the extrapolation of the respective data for molten polymer (Figure 3 [4]). Figure 4. WAXS pattern of the EO6 sample resolved into components. One additional peak represents a partially ordered phase. The abruptly changing width and the sudden change in the shape of the amorphous maximum, as well as the shift in its position, suggest that the amorphous phase contains two contributions and the total amorphous scattering is composed of two parts. One part is related to a typical liquid-like amorphous phase and the other one to better-ordered and denser regions. The changes observed during cooling and heating can be interpreted as being caused by the originating and disappearing of those partially ordered regions. Based on these results, we assumed a 3-phase structure of the investigated polymers and tried to account for the third phase in the deconvolution of the diffractogram. At the beginning, we employed a 4-peak approximation in the 2θ range 12°–30°: 2 crystalline reflections (110) and (200), the amorphous maximum and the fourth peak were related to the intermediate phase. Such an approach is equivalent to the assumption of a quasi-hexagonal structure of the third phase. Unfortunately, the quality of fitting did not increase satisfactorily – the differential plot still showed clearly visible errors in the fitting of the curves. A plot obtained for the sample EO6 is given in Figure 4. For this reason, we adopted the ideas of Baker and Windle[11] in our further analysis. Investigating sev- Figure 5. WAXS pattern of the EO6 sample resolved into components. Two additional peaks represent a partially ordered phase. eral polyethylenes with a broad range of branching, Baker noticed that the unit cell parameters refined from the fitting of the theoretical curve just to the (110) and (200) reflections were clearly larger than those refined from the higher angle reflections. The extent of the discrepancy was higher, the more branched the polyethylenes were. Baker has found that such an effect is caused by a clear asymmetry of the peaks (110) and (200). He indicated the excess scattering on the left, low-angle side of these peaks. Baker proposed that the excess scattering is produced by a third, partially ordered component of the polymer structure. FIBRES & TEXTILES in Eastern Europe January / December / B 2008, Vol. 16, No. 6 (71) Based on the difference plot between the theoretical and experimental curves, he showed that the scattering produced by the third component contains two peaks, which are broader, clearly smaller and shifted towards lower angles with respect to the “true” crystalline (110) and (200) reflections. Because of a lower degree of order, the contribution of the third phase to the weaker, higher angle crystalline reflections is negligible [11]. Adopting the suggestions of Baker, we decomposed the WAXS patterns, introducing two additional peaks related to the partially ordered component. This time, the quality 59 a) b) Figure 6. WAXS pattern of the EO7 and LPE sample resolved into components. The peaks related to the transition phase are denoted as “(110)” and “(200)”; a) LPE sample, b) E07 sample. of fit was much better. The result of decomposition for the sample EO6 is shown in Figure 5 (see page 59). In Figures 6.a and 6.b, similar plots but in a narrower angular range are shown for the samples LPE and EO7. Two additional peaks related to the transition phase are denoted by quotation marks: “(110)” and “(200)”. It is seen that their shift with respect to the crystalline reflections (110) and (200) is much higher for the samples with high 1-octene content than for LPE. This means that the higher the degree of branching of a copolymer, the more loosely packed are the molecular chains in the transition regions. The calculated positions of the “(110)” and “(200)” Figure 7. Angular positions of the “(110)” and “(200)” peaks versus the number of CH3/1000, calculated for all the investigated samples. 60 peaks versus the number of CH3 groups per 1000 carbon atoms in the main chain are shown in Figure 7. Based on these angular positions and assuming a “quasiorthorhombic” structure of the transition component, the a and b unit cell parameters and the density of this phase were estimated. In this estimation, it was assumed that the height of the unit cell (c edge) is the same as in crystalline polyethylene. The obtained results are shown in Figure 8. The density of the transition phase continuously decreases. In the case of LPE, it is close to the density of the crystalline phase of PE at room temperature (25 °C): 0.999 g/cm3 [12]. For the sample with high 1-octene content, the density tends to the values typical of the amorphous phase: 0.851 g/cm3 [12]. As can be seen in Figure 8, the values obtained for the last two samples (EO7 and EO8) were estimated below this level. These errors are caused by the fact that the crystalline peaks in the WAXS patterns of these samples are broad and weak (see Figure 6.b). As a consequence, the deconvolution of these patterns into component peaks may cause an incorrect estimation of their angular positions. Nevertheless, the trend in the observed changes in the density of the transition phase is clear and understandable. Most probably, the transition phase is located on the border between the crystalline and amorphous phases. It is formed of stretched sectors of molecular chains emerging from the surfaces of crystallites and partially retaining the alignment and order typical of the crystalline phase. In the case of linear polyethylene, the degree of packing of the chains in the transition regions, and consequently its density, is not too much less than in the crystallites. However, in the samples with a high concentration of branches formed of the 1-octene comonomer, the chains Figure 8. Density and weight fraction of the third transition phase versus the number of CH3/1000. FIBRES & TEXTILES in Eastern Europe January / December / B 2008, Vol. 16, No. 6 (71) emerging from the crystallites lose their alignment and order at much smaller distances from the surfaces of the crystallites and consequently the density of the transition regions tends to the density of the amorphous phase. The mass fraction of the transition phase (TX) was calculated as the ratio of the total area of the “(110)” and “(200)” peaks to the total area of the WAXS pattern after the background subtraction. In the same way, the mass fractions of crystalline (CX) and amorphous (AX) phases were calculated. The results of the calculations are given in Table 2 (see page 62). As one can see, the mass fraction of the transition phase continuously decreases when the degree of branching increases. This result is fully consistent with that obtained in our first paper, resulting from the measurements of the angular position of the first amorphous maximum [4]. The mass fractions of all three phases were also determined using the method of Strobl and Hagedorn [5], which is based on the analysis of Raman spectra. In this method, the Raman spectra of the investigated samples are resolved into three components originating from the orthorhombic crystalline phase, a liquid-like amorphous phase and a third, partially ordered phase. According to Strobl and Hagedorn [5], the third phase is of a disordered, anisotropic structure, where the chains are stretched but have lost their lateral order. The mass fractions of these three phases are calculated directly from the integral intensities of characteristic bands. The total, integral intensity of the CH2 twisting vibrations range (1250-1350 cm-1) is independent of the degree of crystallinity and for this reason can be used as a standard with which the intensities of other bands can be compared [5]. This range contains a narrow band localized at 1295 cm-1 arising from the crystalline phase and a much broader band at 1303 cm-1 coming from the liquid-like amorphous phase. The narrow band at 1416 cm-1 is a part of the CH2 bending range, which is split into two component branches at 1416 cm-1 and 1440 cm-1 by the crystal field. For this reason, the band is related to the orthorhombic crystalline phase. The mass fractions of the crystalline (CR), liquid-like amorphous (AR) and transition (TR) phases contained in the investigated samples were calculated using the following formulas: a) 3.4 1295 3.2 3.0 2.8 2.6 2.4 1439 2.2 1129 2.0 1.8 1061 1.6 1.4 1.2 1460 1416 1.0 0.8 0.6 1305 0.4 1368 0.2 1550 1500 1450 1400 1350 1300 1250 1169 1200 1150 1100 1050 cm-1 b) 2.1 2.0 1.9 1.8 1.7 1437 1.6 1295 1.5 1.4 1.3 1.2 1.1 1457 1.0 1061 0.9 0.8 1128 1305 0.7 0.6 1081 0.5 0.4 1416 0.3 1366 0.2 1169 0.1 1550 1500 1450 1400 1350 1300 1250 1200 1150 1100 1050 cm-1 c) 1.4 1.3 1.2 1.1 1.0 1451 1436 0.9 0.8 1305 0.7 0.6 0.5 1295 0.4 1060 0.3 1416 0.1 1550 1129 1367 0.2 1062 1500 1450 1400 1350 1300 1250 1200 1150 1100 1050 cm-1 Figure 9. Raman spectrum of the sample resolved into individual bands: a) EO1, b) EO5, c) EO8. FIBRES & TEXTILES in Eastern Europe January / December / B 2008, Vol. 16, No. 6 (71) 61 Table 2. Mass fractions of amorphous (A), crystalline (C) and transition (T) phases determined with WAXS and Raman methods. ing the third phase are introduced. The additional peaks are located close to the crystalline reflections (110) and (200), WAXS Raman Mole % of on the left sides of these reflections. As a Sample CH /1000 3 1-octene AX CX TX AR CR TR consequence, the third phase is treated as HDPE + + 32 53 15 31 65 4 a quasi-orthorhombic one. Based on the LPE 0 0 33 55 12 31 68 1 angular positions of these peaks, found from the decomposition of the WAXS EO1 0.8 3.9 43 48 9 43 48 9 patterns, the density of the third phase EO2 1.77 8.4 56 37 7 54 31 15 was estimated. The obtained results show EO3 4.34 19.2 66 31 3 66 14 20 that, when the number of side branches EO4 5.42 23.3 67 30 3 68 17 15 in a polyethylene chain increases, the EO5 5.5 23.6 69 28 3 70 13 17 density smoothly decreases from the valEO6 6.64 27.7 70 28 2 69 13 18 ues close to the density of the crystalline EO7 9.15 35.9 88 10 2 90 5 5 phase, in the case of linear polyethylene, EO8 11.27 42.1 92 8 91 2 7 to the values close to the density of the amorphous phase, for the copolymers I1303 I1303scopic methods differ considerably. On with high 1-octene content. The crystalI1416 I1416 (2) TR = 1 − (AR T +RC=R 1) − (AR + CR (2) ) AR = AR = CR = CR = 0.46 ⋅ I tw 0.46 ⋅ I tw I tw (2) I tw the other hand, the mass fractions of the linity and mass fraction of the transition I1303 phase - also decrease continuously with liquid–amorphous phase simi-1 are very -1 (2) =where TRand = 1I−integral (ARare + Cthe I1303 are the intensities intensities the bands of located thecorrelation bands at 1416 located cm atand 1416 1303 cmresults cm and 1303 cm where I1416 and I1416 R ) integralof 1303 increasing 1-octene content. lar. The between the I tw 1 1 obtained for this parameter is asshown and I1303 are integral in- vibrations , Itw is thewhere: integral , Itw isI1416 the intensity integral ofintensity the the whole of twisting the whole twisting region vibrations used region as a standard used and a standard and -1 tensities of the bandsoflocated at 1416 cmat and 1303 tensities the bands located 1416 cm-1 cm in Figure 10. It is evident that the “de- A comparison of the mass fractions of all 0.46 is a scaling 0.46 is coefficient a scaling obtained coefficient forobtained a completely for a completely crystalline polyethylene. crystalline polyethylene. andvibrations 1303 cm-1region , Itw is the integral intensity andgrees of amorphicity” determined with three phases determined with the WAXS hole twisting used as a standard TheofRaman The spectra Raman were spectra decomposed wereregion decomposed into individual into bands individual bands a methods least-squares using coina least-squares method and the Raman spectroscopic the WAXS and using Raman the whole twisting vibrations or a completely crystalline polyethylene. method shows that the total amounts of cide very well with each other. In other used as a standard and 0.46 is a scaling curve fittingcurve method fitting implemented method implemented in the computer in theprogram computer GRAMMS, program GRAMMS, universally universally used in used in coefficient obtained omposed into individual bands for usinga acompletely least-squareswords, the total mass fraction of the crystalline and transition phases estithe analysiscrystalline the of analysis infrared spectra. of infrared Thespectra. bands were The bands approximated were approximated by linear combination byordered a linear phases combination of theis mated of the with these two methods agree very polyethylene. ordered anda partially the computer program GRAMMS, universally used inestimated similarly with the two meth- well. However, the values obtained for Gauss and Lorentz Gauss and functions. LorentzThree functions. examples Threeofexamples Raman spectra of Raman for spectra the EO1,forEO5 the and EO1,EO8 EO5 and EO8 The Raman spectra were decomposed ands were approximated by a linear combination of theods; however, the individual fractions each individual phase do not coincide. samples areinto samples shown inareFig. shown 9 a)–c). in Fig. 9 a)–c). individual bands using a least- are different. Such discrepancies may The discrepancies may be caused by a xamples of Raman spectra for the EO1, EO5 and EO8 different be caused by the the transition fitting method implementThesquares resultscurve The of the results calculations of the calculations are given inare Table given 2. in The Table comparison 2. fact Thethat comparison shows that shows the that the “perception” of the transition ed in the computer program GRAMMS, phase is “seen” differently in these two phase in these methods and by problems mass fractions massoffractions the transition of the transition crystalline phases crystalline determined phasesMoreover, determined with the X-ray diffraction the X-ray with the isolation of the “crystalline” band methods. towith calculate thediffraction theand analysis ofand infras are given universally in Table 2. used The in comparison shows that the at 1416 cm-1 in the Raman spectra of the mass fraction of the crystalline phase in red spectra. The bands were approximatand Raman and spectroscopic Raman spectroscopic methods differ methods considerably. differ considerably. On the otherOnhand, the other the mass hand,fractions the mass fractions rystalline phases with the X-ray ed by determined a linear combination of the diffraction Gauss the Raman method, we have to isolate samples with high 1-octene content. of the liquid–amorphous of the liquid–amorphous phase are very phase similar. are very Thesimilar. correlation The correlation between -1thebetween results obtained the results obtained CH2 and Lorentz functions. Three examples fer considerably. On the other hand, the mass fractionsthe band 1416 cm from a broad -1 range (1430-1550 cm ) ofcomof spectra EO1, for this parameter forRaman this is parameter shownforinisthe Fig. shown 10.EO5 inIt Fig. isand evident 10. bending It is thatevident the “degrees that theof“degrees amorphicity” amorphicity” ry similar. The between results 9.a-c obtainedposed of 4 bands. In the case of samples EO8correlation samples are shown the in Figure determined determined with the WAXS with the andWAXS Raman and methods Raman coincide methods very coincide well with veryeach wellother. with each In other other. InReferences other (see pagethat 61).the “degrees of amorphicity”with medium and low crystallinity (see 10. It is evident 1. McFaddin D., Russel K., Wu G., Heydig words, the words, total mass the total fraction massof fraction the ordered of the andordered partially ordered partially ordered is estimated phasesmay is estimated Figureand 9), such aphases decomposition an methods The coincide very wellcalculations with each other. In otherresult in an underestimation of this band R.J. Polym. Sci. (1993), 31, 175. results of the are given similarly with similarly the two withmethods; the two however, methods; the however, individual the individual fractions are fractions different. are Such different. 2. Such Simanke A., Alamo R.G., Galland G., 2. Theordered comparison that and as a consequence of too low a mass he ordered in andTable partially phasesshows is estimated Mauler R.S. Macromolecules (2001), discrepancies discrepancies may be caused may by be the caused fact that by the the fact transition that the phase transition is “seen” phase differently is “seen” in differently these in these the mass fractions of the transition and fraction of the crystalline phase and, 34, 6959. owever, the individual fractions are different. Suchin turn, too high a mass fraction of the crystalline phases determined with fraction the two methods. twoMoreover, methods. to Moreover, calculate tothecalculate mass the mass of the fraction crystalline of the phase crystalline in thephase Raman in the Raman 3. Sajkiewicz P., Hashimoto T., Saijo K., phase (see Equation 2). -1 ct that the transition phase is “seen” differently in thesetransition X-ray diffraction and Raman spectroGradys A. Polymer (2004), 46, 513. -1 -1 -1 method, wemethod, have to we isolate havethe to band isolate 1416 the cm band 1416acm from broad from CHa2 bending broad CHrange (1430range cm –(1430 cm – S. Fibres&Text. (2005), 5, 30. 2 bending 4. Rabiej the mass -1 fraction of the crystalline phase in the Raman 5. Strobl R.G., Hagedorn W. J.Polym. Sci. 1550 cm cm-1) of ) 1550 composed composed 4 bands. of In 4the bands. case In of the samples case of with samples medium with andmedium low crystallinity and low crystallinity -1 Polym. Phys. Ed. (1978), 42, 1181. 416 cm from110a broad CH2 bending range (1430 cm-1– Conclusions (see Fig. 9),(see such Fig. a decomposition 9), such a decomposition may result may in anresult underestimation in an underestimation of this band ofand thisas band a and6.asRabiej a M., Rabiej S. “Analiza rent100 The existence of a third, transition phase A =1.027*A 2.18 R=0.9976 the case of samples with medium and low crystallinity genowskich krzywych dyfrakcyjnych 90 is intermediate in and, the order consequenceconsequence of too low aofmass too low fraction a mass of the fraction crystalline of that the phase crystalline and, in phase turn, toodegree in high turn, aofmass too high a mass polimerów za pomocą programu kommay result in an80 underestimation of this band and as abetween the crystalline and amorphous puterowego WAXFIT”, Publishing House 70 fraction of the fraction transition of thephase transition (see equation phase (see (2)). equation (2)). ATH, Bielsko-Biała 2006. 60 on of the crystalline phase and, in turn, too high a massphases has already been proved in several papers dedicated to the structure of 7. Rabiej M. Polimery (2002), 47, 423. 50 uation (2)). 8. Rabiej M. Fibres&Text. (2003), 5, 83. 40 polyethylenes. In this work, we tried to Conclusions Conclusions 9. Monar K., Habenschuss A. J. Polym. 30 determine how to account for the third Sci. Polym. Phys. Ed. (1999), 37, 3401. 20 component in the analysis of the WAXS 10. Bartczak Z., Gałęski A., Argon A.S., CoConclusions 20 30 40 50 60 70 80 90 100 diffraction curves of of polyethylenes. It between The existence Theofexistence a third, transition of a Athird, phase transition that isphase intermediate that is intermediate in the degree in the order degree between of order hen R.E. Polymer (1996), 37, 2113. ,% was shown that the best fit of the theo- 11. Baker A.M.E, Windle A.H., Polymer, 42, the crystalline the and crystalline amorphous and amorphous phases has already phases has been already provedbeen in several proved papers inexperimental several dedicated papersdata todedicated(2001), to retical curves to the 667. hase that is Figure intermediate in the degree of order between 10. Comparison of the mass fractions was obtained when the suggestions of 12. Swan P.R. J. Polym. Sci. (1960), 42, 525. the structure the of structure polyethylenes. of polyethylenes. In this work, In we this tried work, to determine we tried to how determine to account how for to account the third for the third of the amorphous phase determined with has alreadythe been proved in several WAXS method (AX) andpapers with thededicated Raman toBaker [11] were adopted. In this apcomponentspectroscopic component in the analysis inmethod the of analysis the diffraction WAXS curves diffraction polyethylenes. curves of polyethylenes. It wasrepresentshown It was shown (A WAXS ). of the Received 23.05.2008 Reviewed 21.11.2008 proach,oftwo additional peaks work, we tried to determine how toR account for the third that the best that fit the of the besttheoretical fit of the theoretical curves to the curves experimental to the experimental data was obtained data waswhen obtained the when the AXS diffraction FIBRES & TEXTILES in Eastern Europe January / December / B 2008, Vol. 16, No. 6 (71) 62 curves of polyethylenes. It was shown suggestionssuggestions of Baker [11] of Baker were adopted. [11] were In adopted. this approach, In thistwo approach, additional twopeaks additional representing peaks representing rves to the experimental data was obtained when the R AX, % X R