Temperaturabh�ngigkeit der Realstruktur des kristallinen Anteils von LDPE

Abstract

Wide angle X-ray scattering experiments with LDPE at various temperatures from 20~ to 106~ have been exploited with respect to lattice parameters, degree of crystallinity, and dimensions of microparacrystals and their lattice defects. The density of the crystals decreases within the measured temperature range in steps from 0,998 9 103 kg m -3 to 0,952 . 103 kg m -3. Above 90~ we detected microparacrystals with a great extension in direction of the b-axis. At low temperatures additional microparacrystals exist, which are characterized by a prominent extension perpendicular to the 110-planes. The lattice defects discussed for the two kinds of microparacrystals show pronounced differences. The coherent scattering regions of the crystals in direction of the a-, b-, and c-axes are discussed within the framework of a structure model of the lamella, which leads to the conclusion that the molecular axis of the chain (c-axis) is inclined to the lamellae surface by 45 ~ Schliisselw6rter: Polyethylene, Wide angle X-ray scattering, Temperature dependence of 94~ -106~

Chain-structure-superstructure relations in eutectoid copolymers

“…This agrees fairly well with the ratio as deduced from the WAXS line-width analy- ~) according to [31] sis [6][7][8][9][10][11]. This agrees fairly well with the ratio as deduced from the WAXS line-width analy- ~) according to [31] sis [6][7][8][9][10][11].…”

“…Asbach and Wilke [6] deduced from the linewidths of WAX-interfaces of PE 1840 D the length of the principle axes Di of the shape ellipsoid at different temperatures. According to Fig.…”

“…According to Fig. Parameters used in the analysis of caloric melting curves [2][3][4][5][6]16,17] T m ature, save increasing values of (D 1/Di) at temperatures close to the maximum melting point. Parameters used in the analysis of caloric melting curves [2][3][4][5][6]16,17] T m ature, save increasing values of (D 1/Di) at temperatures close to the maximum melting point.…”

“…To prove the foregoing conclusions we derive the thickness number distribution of x-ray-coherent crystal blocks tP((y[hu])) with the aid of ~[hkl] taken to be equal with values as deduced from the shape ellipsoid [6].…”

“…Solid solutions are formed, the properties of which are in accordance with thermodynamics [1][2][3][4][5]. A small fraction of very thick crystals are laterally largely extended [6]. Moreover, the extension of crystal blocks is in all directions of the same order of magnitude [6][7][8][9].…”