Cross-linking of polystyrene by high-energy radiation. II. Molecular weight changes in the Pregel region

1968 ◽  
Vol 72 (12) ◽  
pp. 4229-4235 ◽  
Author(s):  
Louis M. Alberino ◽  
William W. Graessley
Keyword(s):  
Molecular Weight ◽  
High Energy ◽  
Cross Linking ◽  
Weight Changes ◽  
High Energy Radiation ◽  
Energy Radiation

Changes in silicone polymeric fluids due to high-energy radiation

1955 ◽  
Vol 230 (1180) ◽  
pp. 120-135 ◽  
Keyword(s):  
Molecular Weight ◽  
Radiation Dose ◽  
High Energy ◽  
Cross Linking ◽  
Polymeric Fluids ◽  
High Energy Radiation ◽  
Energy Radiation ◽  
Hydrocarbon Polymers ◽  
Amorphous Structures ◽  
The Relationship

When subjected to high-energy radiation, polydimethyl siloxanes can be cross-linked to form insoluble amorphous structures which are transparent and have marked rubber-liko properties. Data are given on the relation between molecular weight and bulk viscosity, which is often used to characterize these polymers. The relationship between cross-linking density and radiation dose is deduced from the changes in both solubility and fusibility, and is confirmed by elastic measurements. Unit pile radiation is found to produce cross-linking in about 2*2 % of the monomer units. Details are given of the change in solubility and swelling with radiation dose and of the mechanism of cross-linking. The energy per cross-link is about 32 eV, and is independent of molecular weight. A brief comparison is made with cross-linking in hydrocarbon polymers.

Molecular-weight changes in the degradation of long-chain polymers

1954 ◽  
Vol 224 (1156) ◽  
pp. 120-128 ◽  
Keyword(s):  
Molecular Weight ◽  
Main Chain ◽  
High Energy ◽  
Initial Distribution ◽  
Weight Changes ◽  
Chain Polymer ◽  
High Energy Radiation ◽  
Molecular Weights ◽  
Random Fracture ◽  
Long Chain

The changes in molecular weight of a long-chain polymer (initially of arbitrary molecular-weight distribution) are studied when the main chain is subjected to random fracture, such as occurs when certain polymers are exposed to high-energy radiation. For several distributions studied, all trace of the initial distribution curve is lost after an average of some 3 to 8 main-chain fractures per molecule. For lower degrees of degradation the shape of the curve of weight average against degradation can provide information as to the initial weight average, z average, z + 1 average molecular weights. The initial number-average can be obtained by a method of extrapolation.

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