Electron Irradiation Effects in Polyoxymethylene Crystals Grown Inside Trioxane Crystals

1971 ◽  
Vol 29 ◽  
pp. 78-79
Author(s):  
J. P. Colson ◽  
D. H. Reneker
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Detailed Examination ◽  
The Other ◽  
Electron Micrograph ◽  
Irradiation Effects ◽  
Threefold Axis ◽  
Typical Sample ◽  
Polymer Crystals ◽  
Chain Axis

Polyoxymethylene (POM) crystals grow inside trioxane crystals which have been irradiated and heated to a temperature slightly below their melting point. Figure 1 shows a low magnification electron micrograph of a group of such POM crystals. Detailed examination at higher magnification showed that three distinct types of POM crystals grew in a typical sample. The three types of POM crystals were distinguished by the direction that the polymer chain axis in each crystal made with respect to the threefold axis of the trioxane crystal. These polyoxymethylene crystals were described previously.At low magnifications the three types of polymer crystals appeared as slender rods. One type had a hexagonal cross section and the other two types had rectangular cross sections, that is, they were ribbonlike.

Dynamic low-dose electron diffraction and imaging of phase transitions in polymers

1993 ◽  
Vol 51 ◽  
pp. 890-891
Author(s):  
David C. Martin ◽  
Jun Liao
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Electron Diffraction ◽  
Low Dose ◽  
Dark Field ◽  
Continuous Change ◽  
Selected Area Electron Diffraction ◽  
Resolution Electron ◽  
Chain Axis ◽  
High Resolution Electron Micrographs

By careful control of the electron beam it is possible to simultaneously induce and observe the phase transformation from monomer to polymer in certain solid-state polymcrizable diacetylenes. The continuous change in the crystal structure from DCHD diacetylene monomer (a=1.76 nm, b=1.36 nm, c=0.455 nm, γ=94 degrees, P2l/c) to polymer (a=1.74 nm, b=1.29 nm, c=0.49 nm, γ=108 degrees, P2l/c) occurs at a characteristic dose (10−4C/cm2) which is five orders of magnitude smaller than the critical end point dose (20 C/cm2). Previously we discussed the progress of this phase transition primarily as observed down the [001] zone (the chain axis direction). Here we report on the associated changes of the dark field (DF) images and selected area electron diffraction (SAED) patterns of the crystals as observed from the side (i.e., in the [hk0] zones).High resolution electron micrographs (HREM), DF images, and SAED patterns were obtained on a JEOL 4000 EX HREM operating at 400 kV.

An Exact Method to Determine the Chain Axis Orientation Distribution in High Performance Fibers from a Single Inter-Chain Reflection

1988 ◽  
Vol 134 ◽  
Author(s):  
Ravi F. Saraf ◽  
T.J. Watson
Keyword(s):  
High Performance ◽  
Orientation Distribution ◽  
Inversion Method ◽  
Computation Method ◽  
Axis Orientation ◽  
Complete Chain ◽  
Orientation Function ◽  
Two Samples ◽  
Chain Axis ◽  
Oriented Polyethylene

ABSTRACTAn exact pole inversion method is used to calculate the complete chain-axis orientation distribution from a single inter-chain reflection. A brief outline of the formulation and computation method is given. This method is demonstrated by comparing the measured chain-axis distribution from a (002) reflection of oriented polyethylene samples, to the calculated distribution from (110) and (200) reflections of the same sample. The error in the Hermans Orientation function is less than 0.5% for the two samples tested.

Characterization of molecular orientation under tensile deformation by near infrared spectroscopy

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Masami Mizushima ◽  
Takanobu Kawamura ◽  
Kenji Takahashi ◽  
Koh-hei Nitta
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Tensile Deformation ◽  
Crystal Form ◽  
Orientation Function ◽  
Chain Axis ◽  
Stretching Vibration ◽  
Novel Method

AbstractWe present a novel method for characterizing orientation behavior of typical polyethylene (PE) materials such as HDPE, LLDPE, and LDPE. The chain orientation to the stretching direction was examined under uniaxial deformation by near infrared spectroscopy. Then we obtained directly the orientation function of PE chain axis (c-axis) from the CH stretching vibration of NIR spectra as a function of extension time or strain. We compared the present method with the conventional infrared IR method where the orientation function of PE c-axis (chain-axis) has been indirectly obtained from the b-and a-axis’s assuming the orthogonal crystal form by using the CH2 rocking vibrations in IR spectra

Ordered Structures of Poly(p-hydroxybenzoic acid). 1. Nonbonded Interactions in Layers of Phenyl Rings Orthogonal to the Chain Axis

1994 ◽  
Vol 27 (17) ◽  
pp. 4726-4732 ◽  
Author(s):  
Natalia V. Lukasheva ◽  
Alla Sariban ◽  
Thomas Mosell ◽  
Juergen Brickmann
Keyword(s):  
Hydroxybenzoic Acid ◽  
Ordered Structures ◽  
Nonbonded Interactions ◽  
Chain Axis ◽  
Phenyl Rings

scholarly journals Temperature dependence of the elastic modulus of crystalline regions of polyethylene in the direction perpendicular to the chain axis.

1986 ◽  
Vol 43 (12) ◽  
pp. 881-888 ◽  
Author(s):  
Katsuhiko NAKAMAE ◽  
Takashi NISHINO ◽  
Katsuhiko HATA ◽  
Tsunetaka MATSUMOTO
Keyword(s):  
Elastic Modulus ◽  
Temperature Dependence ◽  
Chain Axis

A Wide Line Nuclear Magnetic Resonance Study of Molecular Motion in n-Alkyl Ammonium Chlorides

1973 ◽  
Vol 51 (12) ◽  
pp. 1990-1994 ◽  
Author(s):  
J. Tsau ◽  
D. F. R. Gilson
Keyword(s):  
Fatty Acids ◽  
Molecular Motion ◽  
Nuclear Magnetic Resonance Study ◽  
Metal Salts ◽  
Alkali Metal Salts ◽  
Magnetic Resonance Study ◽  
Line Nuclear Magnetic Resonance ◽  
Chain Axis ◽  
Wide Line ◽  
Alkyl Ammonium

Wide line n.m.r. studies of n-alkyl ammonium chlorides, C3–C10, show two transitions. The first transition is due to reorientation about the chain axis, the second to a transition to a mesomorphic phase. This phase is probably similar to that observed for the alkali metal salts of fatty acids.

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