Light Scattering Properties of Linear Polymers with Nearest and Next to Nearest Neighbour Interactions

1980 ◽  
Vol 27 (9) ◽  
pp. 1379-1389 ◽  
Author(s):  
I.A. Hadjiagapiou ◽  
G.J. Papadopoulos
Keyword(s):  
Light Scattering ◽  
Linear Polymers ◽  
Nearest Neighbour

Structure of Polybutadienes

1967 ◽  
Vol 40 (5) ◽  
pp. 1529-1543 ◽  
Author(s):  
W. S. Bahary ◽  
D. I. Sapper
Keyword(s):  
Light Scattering ◽  
Molecular Size ◽  
Structural Features ◽  
Melting Point Depression ◽  
Linear Polymers ◽  
Long Chain Branching ◽  
Molecular Weights ◽  
Catalyst Systems ◽  
Molecular Size Distribution

Abstract Polybutadienes made with six different catalyst systems were examined: (1) butyllithium, (2) “nickel-based”, (3) alfin, (4) “titanium-based”, (5) “cobalt-based”, and (6) free radical emulsion. The microstructure and macrostructure of the polybutadienes have been determined and are compared to the results published in the literature. These polybutadienes may be considered to be random terpolymers of cis, trans, and vinyl addition of butadiene. The glass transition temperature is specified by the vinyl content. The crystalline melting points of the high trans and also the high cis polybutadienes obey to a high measure Flory's equation for melting point depression of a random terpolymer. The molecular weights of the polybutadienes have been determined by light scattering and osmometry and the degree of long chain branching has been determined by the branching index, 〈g′〉. The macro-structural features of the linear polymers are confirmed by fractionation. However, the polydispersities calculated from fractionation data do not agree with those determined from light scattering and osmometry for the branched samples. The discrepancy is attributed to the method of characterization of the fractions. A distinction is made between molecular weight distribution and molecular size distribution.

The structure of amorphous and polycrystalline materials using energy-filtered RDF analysis

1992 ◽  
Vol 50 (2) ◽  
pp. 1190-1191
Author(s):  
David Cockayne ◽  
David McKenzie
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Density Function ◽  
Electron Diffraction Pattern ◽  
Polycrystalline Materials ◽  
Nearest Neighbour ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Reduced Density ◽  
System F

The technique of Electron Reduced Density Function (RDF) analysis has ben developed into a rapid analytical tool for the analysis of small volumes of amorphous or polycrystalline materials. The energy filtered electron diffraction pattern is collected to high scattering angles (currendy to s = 2 sinθ/λ = 6.5 Å-1) by scanning the selected area electron diffraction pattern across the entrance aperture to a GATAN parallel energy loss spectrometer. The diffraction pattern is then converted to a reduced density function, G(r), using mathematical procedures equivalent to those used in X-ray and neutron diffraction studies.Nearest neighbour distances accurate to 0.01 Å are obtained routinely, and bond distortions of molecules can be determined from the ratio of first to second nearest neighbour distances. The accuracy of coordination number determinations from polycrystalline monatomic materials (eg Pt) is high (5%). In amorphous systems (eg carbon, silicon) it is reasonable (10%), but in multi-element systems there are a number of problems to be overcome; to reduce the diffraction pattern to G(r), the approximation must be made that for all elements i,j in the system, fj(s) = Kji fi,(s) where Kji is independent of s.

Collision induced hyper-Rayleigh light scattering in CCl4

1996 ◽  
Vol 88 (3) ◽  
pp. 683-691 ◽  
Author(s):  
P. KAATZ ◽  
D.P. SHELTON
Keyword(s):  
Light Scattering ◽  
Rayleigh Light Scattering ◽  
Rayleigh Light
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