X-ray diffraction in polymer science

1 1)Identification ofsemicrystalline polymers and Recognition ofcrystalline phases (polymorphism) of polymers 2)Polymers are never 100% crystalline. XRD is a primary technique to determine the degree of crystallinityin polymers. 3) Microstructure: Crystallite size in polymers is usually on the nano-scale in the thickness direction. The size of crystallites can be determined using variants of the Scherrer equation. 4) Orientation: Polymers, due to their long chain structure, are highly susceptible to orientation. XRD is a primary tool for the determination of crystalline orientation through the Hermansorientation diffraction in polymer science5 10 15 20 25 30 35 402002 = I2 (deg)PEpolyethylene1102 = 1) Identification of semicrystalline polymersPositions and Intensities of the peaks are used for identifying the =2 The diffraction of unoriented samples in transmission by using a flat filmis characterized by concentric circles called Debye Scherrer Rings Unoriented PE200(2 = )110(2 = )

2 The diffraction of unorientedsamples in reflectionUnoriented PEX ray diffraction of semicrystalline and amorphous polymer510 15 20 25 30 35 40400310210220211( )300( )I2 (deg)110( )s-PSsyndiotattic polystyrene 510 15 20 25 30 35 40I2 (deg)s-PSsyndiotactic polystyrene amorphous510152025303540__030220_421_322 _421420040410002040_111_111_101_04103102 0200510600410400210310210210010010132131 030220200210211220300110 Intensity DCE 2 (deg)_410_321301302230121401231331_11210 2210020_121111_301_321211230121212_32230 2411411210020111s-PSPosition and Relative intensities are the fingerprint of crystalline phases of polymer1) Identification of crystalline phases of polymersab 0510152025303540T = 280 CmaxT = 290 CmaxT = 300 CmaxT = 310 CmaxT = 320 Cmaxt = 5 minmax + edcbaIntensity2 (deg)s-PSIdentification of crystalline phases of polymers also if they are present in I + IIForma I + IIForma III2 (deg)Forma I(110)I(300)I(211)I(220)I(200)II(220)II( 311)IIi-PBX ray diffraction of semicrystalline polymer and inorganic compound 510 15 20 25 30 35 40400310210220211( )300( )I2 (deg)110( )s-PSsyndiotattic polystyrene inorganic compound polymer 5101520253035404550556065707580I2 (deg) ( )2 ( )What about this spectra?

3 PolimeroCarica inorganicaDiffrazione dei raggi X del campione prima TGAD iffrazione dei raggi X del campione dopo TGA amorphous / crystalline ( polymer , inorganic/organic compound) crystalline phasesThe peak positions, intensities, widths and shapesprovide important information about the structure of the material degree of crystallinity : xcamorphousecrystallinecrystallinIIIxc+= 2)XRDa primary technique to determine the degree of crystallinityin determination of the degree of crystallinity implies use of a two-phase model, the sample is composed of crystals and amorphous and no regions of semi-crystalline organization. amorphousecrystallin III+=5101520253035I2 The diffraction profile is divided in 2 parts: peaks are related to diffraction of crystallites, broad alone is related to scattering of amorphous phase.

4 AmcrcrKAAAxc+=Kis a constant related to the different scattering factors of crystalline and amorphous phases. For relative measures K= 1. PEIa= diffracted intensity of amorphous phaseIb= diffracted intensityof backgroundIc= diffracted intensity of crystalline phase IcIaIbThe assumption is that the areas are proportional to the scattering intensities of crystalline and amorphous phases2) XRD: determination of degree of crystallinityin (deg) 510152025302 (deg)IntensityThe half-width of peaks is related to crystallite to broadening can be due to lattice distortion, structural disorder as well as instrumental large correspond to smaller crystallites3) Microstructure.

5 Crystallite size in polymersHalf-width narrow correspond to bigger crystallitesB= 2 = 2 2 2 12 (deg) = B bb= broadening instrumental = broadening due to crystallites dimensionsB= half-width of peaksIntensityImaxImax/22 22 1B2 Crystallite size in polymers:cos =KLhklScherrer s EquationLhkl= crystallite dimensions (in ) along the direction perpendicular to the crystallographic plane hkl. = half-width of peak related to the crystallographic plane hkl(rad).K= constant (usually K= ) = diffraction angle of the hkl reflection. = wavelength used ( Cuk = .)bcan be measured by the half-width of a peak of crystalline compounds low molecular ) Microstructure: Crystallite size in polymers4)Orientation: Polymers, due to their long chain structure,are highly susceptible to orientationDraw directioncfiberX-rayFiberaxesX-ray diffraction of oriented polymer .

6 Fiber patternequatorl=0 (hk0)First layer l=1 (hk1)Second layerl=2 (hk2)i-PP fiber))/(( 1-Rytansencl=c= periodicity along the chain axes = wavelength used (CuK = )llll= layerx, y= distance of reflections from the center along equatorial and meridian linesR= chamber radius meridianyx = RytancosRxcoscos1- 23602 Distance from layers correspond to caxesX-ray diffraction of fibers annealed at different TTrans-planar conformationc= Helical conformationc= = 50 % = 100 % = 500 % = 200 %Oriented sPPfiber stretched at different =100(Lf-Li)/LiLf = final lengthLi = initial lengthFirst layer l=1 (hk1)equator l=0 (hk0)Azimutal scan:measuring the intensity at 2 constant, by varying the angle.

7 If = 0 for meridian reflection (00l)<cos2 00l> = 1 e fc=1 The fiber is perfected oriented: fc= 1 Orientation with respect to draw directionparameterparallelrandomperpendi cular<cos2 >f111/300-1/2 The degree of orientation can be determined from the intensity distribution of the corresponding diffraction on the Debye ring by using theHermans Orientation Function()13212 = cosfZ = draw axesabc a,Z b,Z c,Z 2 ( ) >= < = d)I(d 2/02/02222sencossenIcoscoscoshklhklhklIf the radiation is perpendicular to the fiber axesAverage cosine squared value of angleTypes of ORIENTATIONGEOMETRY(Heffelfinger& Burton)1 PREFERRED ORIENTATIONC rystallographic elementsReference elements1 Random---2 AxialCrystallographic Axes parallel to reference axescdraw axes3 PlanarCrystallographic Axes on a reference plane cfilm plane4 Planar-axialCrystallographic plane Parallel to a reference axes(100)draw axes5 UniplanarCrystallographic plane Parallel to a a reference plane (100)film plane6 Uniplanar-axialCrystallographic Axes parallel to reference axesand a Crystallographic plane Parallel to a a reference planec(100)draw axesfilm planeC.

8 J. Heffelfinger, R. L. Burton J. Polym. Sci. 47, 289 (1960). Types of Orientation in polymers510152025303540 DCE clathrate 240101150 DCBAE170111060130040110020030210 Intensity040 Figure 22 (deg)111020020010010040410030020600211 410400220300200110 230_510152025303540 DCE clathrate '' ''13104124015010100217011106014013012004 0110020 ABCDE411_321_230_030410002 Figure 1040_041031020 200510600410400210310 2102100100101321310302202002102112203001 10 Intensity2 (deg)121401231331020210020111_111302111_ 111_411322_321_420040410__Uniplanar orientation: spsfilmendedgethrough Through direction Edge direction End direction MD TD Types of Orientation in polymers010 Uniplanar orientation.

9 (010)Rizzo, Lamberti, Albunia, Ruiz de Ballesteros, Guerra , 35, 5854 Albunia, Rizzo, Guerra Chem. , 21,3370010 Film surfaceAlong the chain projections of packing of forms of s-PS showing (010) planes parallel to the film surface(010) planes correspond to rows of parallel helices with minimum interchain distances ( ) and maximuminterplanar distances( )s-PSco-crystalsChatani, Y.; Shimane, Y.; Inagaki, T.; Ijitsu, T.; Yukinari, T.; Shikuma, H. polymer , 1993, 34, 1620. De Rosa, C.; Rizzo, P.; Ruiz de Ballesteros, O.; Petraccone, V.; Guerra G. polymer , 1999, 40, nmRLa/2acbLLRRU nique feature of s-PS:three uniplanar orientationsacbLLRRS olution casting; Spin-coatingSolvent induced crystallization on amorphous filmTHF, CHCl3 Rizzo, Lamberti, Albunia, Ruiz, GuerraMacromolecules2002, 35, 5854p-xylene, dichloroethaneRizzo, Costabile, GuerraMacromolecules2004, 37, 3071Bp > 140 CRizzo, Spatola, Del Mauro, GuerraMacromolecules2005, 38, 10089Bp < 110 CRizzo, Della Guardia, GuerraMacromolecules2004, 37, 8043 Film thicknessa//c//a c//a//c Albunia, Rizzo, Tarallo, Petraccone, Guerra Macromolecules 2008,41, 8632biaxial M RIEEEEsPS Films: Orientation Upon Biaxial Balanced DrawingPaola Rizzo*, Alexandra R.

10 Albunia Macromolecular Chemistry and Physics 2011, 212,1419-26caa//c//010 Film surfacea// c// planescorrespond to rows of parallel helices with minimum interchaindistances ( ) and maximum interplanar distances ( )a//c//Planes(sPS)syndiotactic polystyrene(PET)polyethylene terephthalatebiaxial M RIEEEEBin, Y.; Oishi,K.; Yoshida, K.; Nakashima T.; Matsuo, M.; J. polymer , 2004,36,394-402(a= b= c= = =118 =112 ) triclinic lattice(100)uniplanar orientationUniplanar orientationUniplanar orientationA crystalline planepreferentiallyparallel to the film planePrimary slip-plane:-containing the chain axis- and having the highest densityPaola Rizzo, Vincenzo Venditto, Gaetano Guerra, Antonio Vecchione Macromolecular Symposia2002, 185, 53-63.