Short range order of amorphous polymers derived by WAXS

Abstract

Radial difference distribution functions were calculated for PC and a-PS in a temperature range from 293 K to 455 K using wide angle X-ray scattering. Corrections of experimental scattering curves were examined. An assignment for some distances to intra-and intermolecular correlations was made. Next neighbour distances obtained from RDDFs are in good agreement with theoretically computed distances. ZusammenfassungRadiale Dichtedifferenzfunktionen ffir PC and a-PS werden im Temperaturbereich zwischen 393 K und 563 K aus R6ntgenweitwinkel-Messungen berechnet. Die erforderlichen Korrekturen der experimentellen Intensit~itsverteilung werden sorgf{iltig iiberpriift. Fiir einige Abst~inde kann eine erste Zuordnung ihres inter-und intramolekularen Ursprungs gegeben werden. Die Abstandswerte fiir die n~ichsten Nachbarn aus der RDDF stimmen mit den theoretisch berechneten Werten sehr gut iiberein.

Molecular anisotropy effects in carbonK-edge scattering: Depolarized diffuse scattering and optical anisotropy

“…The / spectra were measured with = 30° using a silicon CCD subtending 0.062 sr at 2 = 100°, yielding a scattering vector q with magnitude q = 2.2 +/-0.07 nm -1 at 285 eV and oriented 20° off the surface normal. This q is well below the "polymerization" and "amorphous" peaks at 7 and 15 nm -1 measured with hard x-rays [23,[27][28][29], consistent with our observation of weak, flat intensity across the CCD, whose integrated signal is thus reported.…”

“…While clearly an oversimplification, assume each monomer is identical with ring axis strictly parallel to the backbone axis (Fig. 1), and with uniaxial scattering tensor = � While the q-dependence of / is usually of interest in x-ray scattering from polymers [27][28][29], the same spatial arrangement of scattering centers contributes to its hν dependence at fixed q, which thus is sensitive to the ensemble-average, 2-point density and orientation distribution of PS monomers. The polarized and depolarized elastic scattering contributions to / are related to spatial fluctuations in density and anisotropic orientation, respectively [1,2].…”

“…It is a disordered (amorphous) polymer containing 2 functional groups; highly anisotropic, rigid phenyl rings attached to the flexible polyethylene-like chain backbone as shown for a single monomer in Figure 1. The visible optical properties of aPS are well documented [19][20][21][22], as is its hard x-ray scattering in small-angle [23][24][25][26], wide-angle [23,[27][28][29], and surface sensitive [30][31][32] regimes. Spatially averaged anisotropy in C K-edge XAS has also been reported [12,13].…”

Structure and anisotropy in polycarbonate. I. Short range order of amorphous polycarbonate revealed by WAXS

“…The measured intensity consists of background scattering, multiple scattering, and coherent and incoherent scattering [7]. The measured intensity has to be corrected and normalized to electron units.…”

“…The normalization and correction procedure for isotropic samples in reflection geometry is described in [3,7]. The normalization and correction procedure for the oriented samples are quite analogous to the isotropic case, but before performing normaliza-don the isotropic mean value of the background corrected measured intensity I'meas(20, ~0) has to be computed.…”