Surface structure of polyethylene crystals as revealed by surface decoration. I. Preliminary survey

Bassett, G. A.; Blundell, D.J.; Keller, A.

doi:10.1080/00222346708212744

Cited by 65 publications

(19 citation statements)

References 14 publications

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“…For all the freeenergy in the backward rate constants ('I' =0 in eqs (14)) the distribution also becomes infinitely broad, while for all the energy in the forward or equally divided between forward and backward rate constants the distribution remains finite, and the approach to the infinite length is logarithmic, as was found also by Fran k and Tosi, although at twice the undercooling.…”

Section: Discussionsupporting

confidence: 51%

See 1 more Smart Citation

Kinetics of crystallization in multicomponent systems. II. Chain-folded polymer crystals

Lauritzen¹,

Passaglia²

1967

J. RES. NATL. BUR. STAN. SECT. A.

118

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Using polyethylene as an example, the kinetics of growth of chain-fold ed polymer crystals is treated using a theory for the kinetics of growth of chains in multicomponent systems. The kinetic chain is co nsidered to be a chain-folded strip growing on the lateral face of a chain-folded lamella, and the various components are the possible lengths I) the polymer chain may form on folding at the end of the growing strip. Thus, the number of components is in principle infinite, but it is sufficient to take a number of the order of 20-50 for the calculations. By an iteration procedure, the calculations are carried out so that the average thickness of the strip is the same as that of the chain-folded lamella on which it grows. This necessitates modification of the rate constants that would be used without this requirement. The rate of growth, average thickness and its standard deviation, and the pair distribution are calculated as a function of undercooling and other relevant parameters of the system. The results for the rate of growth and thickness are similar to those of simpler theories, provided that the co nstant end-surface free-energy of those theories is replaced by a temperature dependent "effective" surface free-energy. The standard-deviati on of the thickness is larger than commonly believed, values of 8 to 14 A being typical. Consequently, the crystals as grown may have quite rough fold surfaces, although the equilibriu m roughness will be less.

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Section: Discussionsupporting

confidence: 51%

“…' /Ji , ai) and f3i) were calculated from eqs (14). From these, the values of Ai defined by eq (3) were calculated by the iteration procedure outlined in 1 and LDP until co vergence to one part in 10 7 was obtained.…”

Section: Methods Of Calculationmentioning

confidence: 99%

Kinetics of crystallization in multicomponent systems. II. Chain-folded polymer crystals

Lauritzen¹,

Passaglia²

1967

J. RES. NATL. BUR. STAN. SECT. A.

118

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“…Their size evidently is exaggerated by decoration before and during replication (2). Decoration undoubtedly plays a significant role here but we believe the primary process to be plastic deformation.…”

Section: Nature Of the Globular Impmentioning

confidence: 99%

Analysis of the structure of intramembrane particles of the mammalian urinary bladder.

Robertson¹,

Vergara²

1980

The Journal of Cell Biology

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The luminal and discoid vacuole membranes of the superficial cell layer of the transitional epithelium of the mammalian urinary bladder have been studied by thin-sectioning and freeze-fracture-etch (FFE) electron microscope methods. For the FFE studies membranes were deposited on a cationized glass surface, covered by a thin copper disc, and fractured under liquid N2. Specimens were etched at -100°C and replicated at -190°C. A model of the lattice membrane derived from thin sections was used to predict the heights of the fracture faces above the glass surface . A hexagonal pattern of globular intramembrane particles spaced 160 A apart was seen in the external fracture (EF) face plaques as previously described and regarded as the dominant structure. However, very extensive areas of another pattern, seen before in only limited areas, have been found in the EF faces . The pattern consists of a smooth hexagonal lattice with the same space constant as the globular one but a different structure . By image analysis it consists of overlapping domains bordered by shared but incomplete metal rims . Each domain has a central spot of metal encircled by a shadow . The surface of the smooth lattice is partly complementary to the corresponding protoplasmic fracture (PF) face which shows a similar hexagonal lattice with the same space constant . The height of the smooth EF lattice above the glass substrate is the same as the plane of the center of the lipid bilayer predicted by the model . The mean heights of the particles of the globular EF lattice are greater than the total thickness of the membrane as predicted by the model and confirmed by measurements . The globular EF lattice is not complementary and it is concluded that the globular particles do not exist in the native membrane but arise artifactually during the preparatory procedures .Porter and Bonneville (36) first noted the unusual features of the luminal membrane of the mammalian urinary bladder epithelial cell, and it subsequently has been the subject of numerous investigations by groups associated with Porter (11,12,33,37,47) and 29,42,56,57), by ourselves (30,38,53,54), and others (28) . It is now established that 70-75% of the surface area of the luminal membrane and the membranes of the related discoid vacuoles in the luminal epithelial cell display external plaques 0.2-0.5 ,um in diameter comprised of particles in hexagonal array with p6 plane group symmetry spaced -160 A center-to-center . In negatively membranes are more flexible and are often sharply folded, particularly in the discoid vacuoles . For this reason the interplaque membrane is frequently called the "hinge" membrane to distinguish it from the "plaque" or "lattice" membrane .In freeze-fracture-etch (FFE) preparations the 120 A surface particles have a counterpart in an array of globular particles in the external fracture (EF) faces (8, 42). The EF particles usually appear globular and have been said by Staehelin et al . (47) to rise 40 A above the EF face and to fit into corresponding p...

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“…the screw dislocation responsible for layer stacking and rumpling of surfaces) it is not difficult to imagine how difficult it is to fit two such layers, especially since the crystals are rapidly grown from evaporated solvent. The assumption of layer independence for a diffraction model is a logical consequence and has been corroborated by earlier experiment by B assett et al [67], in which paraffin crystal surfaces were decorated with gold. Quickly grown crystals always showed a greater surface decoration than slowly grown crystals, indicating a greater surface rough ness in the former case.…”

Section: Discussionmentioning

confidence: 51%

Transmission Electron Diffraction Intensities from Real Organic Crystals: Thin Plate Microcrystals of Paraffinic Compounds

Dorset

1978

Zeitschrift Für Naturforschung A

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Solvent-grown microcrystals of long polymethylene compounds packing in the 0 ± methylene subcell are found to have some of the defect structures seen for crystalline polyethylene. Crystals composed either of rectangular layers or of oblique layers both exhibit the growth around a screw dislocation characterized earlier by other workers. In addition, rectangular layer crystals o f orthorhombic n-hexatriacontane give evidence of mfralamellar edge dislocations. When rectangular layer crystals of cetyl palm itate are grown from hot ethanol, the same surface corrugations are found as seen earlier for polyethylene and orthorhombic paraffins. Oblique layer crystals have not demonstrated these latter two defect structures. All crystals show evidence o f appreciable bending.As was found to be true for rectangular layers of n-paraffins, bending has some influence on the electron diffraction intensities from an oblique layer. Another important factor is a perturbation due to defects along long chain axes which disrupts the ordered packing of polar regions, and causes incoherent scatter from these regions. In addition, observed screw dislocations give a nonuniform end plane, causing isolation of layers from one another. Diffraction models accounting for bending or isolation o f chain layers in an oblique layer both explain the observed near in variance of certain intensities which are due to the coherent scattering from the line grating formed by rows o f carbon atoms in the tilted chain aggregate. Forbidden reflections predicted by a bending model are less important than those anticipated by the multiple scattering from a laminated layer model. As these forbidden reflections are mostly identified for multilayer crystals and since crystal structure analysis indicates most of the long chain in a oblique monolayer to be diffracting coherently, the concentration of Reneker-type defects in the centers of chains is probably not great enough to isolate small chain length laminae within a monolayer.

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Surface structure of polyethylene crystals as revealed by surface decoration. I. Preliminary survey

Cited by 65 publications

References 14 publications

Kinetics of crystallization in multicomponent systems. II. Chain-folded polymer crystals

Kinetics of crystallization in multicomponent systems. II. Chain-folded polymer crystals

Analysis of the structure of intramembrane particles of the mammalian urinary bladder.

Transmission Electron Diffraction Intensities from Real Organic Crystals: Thin Plate Microcrystals of Paraffinic Compounds

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