ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

Hits per page

hits 1 - 2 | 2 hits

Sorting

Electronic Resource

Electron-microscopic investigation of the morphology of a melt-crystallized polyaryletherketone (1985)

Lovinger, Andrew J. ; Davis, D. D.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 58 (1985), S. 2843-2853

add to mindlist on the mindlist

Details

ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: We have studied the structure and morphology of the useful high-temperature/high-strength polymer polyaryletherketone (PEEK) by transmission electron microscopy and three-dimensional electron diffraction after finding suitable solvents (α-chloronaphthalene and benzophenone) that allowed casting of the required ultrathin polymer films. When crystallized from the melt, PEEK grows in the form of spherulites consisting of narrow lamellae and having the b axis of the unit cell radial. Additionally, at high temperatures in these ultrathin films, the spherulites attain an extraordinary cylindrical symmetry as a result of growth of their lamellae on edge, with the c crystallographic direction parallel to the film plane and the a direction corresponding to the cylinder axis. Reasons for this mode of growth are attributed to the highly anisometric molecular cross section normal to the chain direction, which favors crystal nucleation on the substrate with the bc plane. At lower temperatures during crystallization from the melt, a more random lamellar disposition is seen in these thin-film spherulites, although lamellae on edge still predominate. Crystallization by heating from the quenched glassy phase yields random lamellar aggregates and small spherulites. The glassy phase in ultrathin PEEK shows no consistent morphological features down to a level of resolution of 1.0 nm. Scanning electron microscopic examination of the free surfaces of bulk samples crystallized under controlled conditions both from the melt and from the glass, show that our findings from ultrathin films (with the exception of the quasicylindrical spherulitic substructure) also apply to these thicker specimens.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.335856

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

A kinetics study of the reaction of Cl with NO2This work was supported by a NASA contract. The results were presented at the 13th Informal Conference on Photochemistry, Clear Water Beach, Florida, January 4-7, 1978. (1988)

Ravishankara, A. R. ; Smith, G. J. ; Davis, D. D.

New York, NY : Wiley-Blackwell

International Journal of Chemical Kinetics 20 (1988), S. 811-814

add to mindlist on the mindlist

Details

ISSN: 0538-8066

Keywords: Chemistry ; Physical Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The third order rate coefficients for the addition reaction of Cl with NO2, Cl + NO2 + M → ClNO2 (ClONO) + M; k1, were measured to be k1(He) = (7.5 ± 1.1) × 10-31 cm6 molecule-2 s-1 and k1(N2) = (16.6 ± 3.0) × 10-31 cm6 molecule-2 s-1 at 298 K using the flash photolysis-resonance fluorescence method. The pressure range of the study was 15 to 500 torr He and 19 to 200 torr N2. The temperature dependence of the third order rate coefficients were also measured between 240 and 350 K. The 298 K results are compared with those from previous low pressure studies.

Additional Material: 1 Tab.