• To introduce the concept of a unit cell as the minimum structure necessary to replicate all of a perfect crystal through translational operations. • To describe the relationship between the morphology of polymer single crystals prepared by crystallization from dilute solution and bulk polymers prepared by crystallization from the melt.
Crystal structures of polyethylene showing views along the chain axis: (a) orthorhombic unit cell; (b) monoclinic unit cell. The orthorhombic crystal phase of polyethylene has, like most polymer crystals, pronounced anisotropic properties.
Crystalline structure of polyethylene. a Side-view of …
We systematically study polyethylene at various pressures and temperatures to figure out its physical and chemical stability and further on its degradability, by performing first-principle ...
The orthorhombic unit cell, identical with the crystal structure of straight-chain alkanes, is the most stable crystal structure. The unit cell with the space group notation Pnam-D 2h contains 4 CH 2 groups and the all-trans chains are parallel (Fig. 1a). The zigzag planes of the chains of the ortho-rhombic cell have different orientations (Fig ...
Electronic Structure of Polyethylene: Role of Chemical, Morphological ...
2017年7月21日 · In this comprehensive study, we reveal the role of chemical and morphological imperfections that inevitably exist within the technologically important prototypical and pervasive insulator,...
Morphology of Semicrystalline Polymers | SpringerLink
2019年12月21日 · The presence of molecular (point) defects in polymer crystals is typically indicated by an expansion of the unit cell. The unit cell parameters of branched polyethylene have been extensively studied and compared with those of linear polyethylene (Fig. 7.12).
Polyethylene unit cell. | Download Scientific Diagram
We study, via united atom molecular dynamics (MD) simulations, the crystallization of six polyethylene (PE) systems, each consisting of alternating layers of molten linear polymer of two...
Unit cell variations of polyethylene crystal with temperature and ...
1978年2月1日 · The unit cell dimensions for the drawn and the extended chain crystal samples of polyethylene (PE) have been measured at temperatures between 20° and 130°C under hydrostatic high pressures up to 4000 kg/cm 2, by the use of high pressure and high temperature X-ray diffraction apparatus.
03MAE324 - SOS35a - Princeton University
A unit cell of polyethylene showing the long, parallel macromolecules that pass through many such unit cells. The cell has an orthorhombic structure. The molecular sections shown may be different parts of the same molecule, or different macromolecules entering the crystalline region from adjacent amorphous sections.
The unit cell structures of crystalline polymers for (a) polyethylene ...
The atomic structures of the individual polymer chain in bulk crystalline polymers are shown in Fig. 1, and the unit cell for three types of crystalline polymers is shown in the top panel of...