Silicone polymers polymer molecular weight

Polymer-Fluid Equilibria and the Glass Transition Most polymer systems fall in the Class HI or Class V phase diagrams, and the same system can often change from one class into the other as the polymer s molecular weight changes. Most polymers are insoluble in CO9 below 100°C, yet CO9 can be quite sohible in the polymer. For example, the sorption of CO9 into silicone rubber is highly dependent upon temperature and pressure, since these properties have a large influence on the density and activity of CO9. 

Elemental analyses were performed by Galbraith Laboratories, Inc., of Knoxville, TN. The compositions of the HS-MOTSS copolymers were derived from the average of the values calculated from the reported halogen and silicon content. The molecular weight and dispersity of the polymers were measured in tetrahydrofuran by size... 

To qiMc Robert West. "Although the myth that silicon is not capable uf extensive cnienaiion Mill posisls. very large cyclic polysilancs have been synthesized as well as polvsibnc polymers with molecular weights in the hundreds of thousands." I nn-Appl. C/kw 1982. 4. [Pg.905]

The polymers have a viscosity range from 0.5 cP for hexamethyldisiloxane to several million centipoise for gums used in silicone rubber manufacture. Molecular weight-viscosity relationships have been described earlier [48]. Copolymers have also been described using modified synthetic approaches [50,51]. 

The decompressive release of supercritical carbon dioxide during spray application produces a new type of spray that can have superior atomization characteristics compared to conventional air-less and air-assisted application methods (41). Supercritical carbon dioxide has good solvent properties in a variety of polymers. Solubility of the polymer is influenced by polymer molecular weight, polydispersity, solubility parameter, functionality, and structure (42). Significantly increased solubility has been demonstrated by including fluorine, silicon, and bulky substituent groups in the polymer structure. 

Silicone Heat-Cured Rubber. Sihcone elastomers are made by vulcanising high molecular weight (>5 x 10 mol wt) linear polydimethylsiloxane polymer, often called gum. Fillers are used in these formulations to increase strength through reinforcement. Extending fillers and various additives, eg, antioxidants, adhesion promoters, and pigments, can be used to obtain certain properties (59,357,364). 

Silicone Resins. Sihcone resins are an unusual class of organosdoxane polymers. Unlike linear poly(siloxanes), the typical siUcone resin has a highly branched molecular stmcture. The most unique, and perhaps most usehil, characteristics of these materials are their solubiUty in organic solvents and apparent miscibility in other polymers, including siUcones. The incongmity between solubiUty and three-dimensional stmcture is caused by low molecular weight < 10, 000 g/mol) and broad polydispersivity of most sihcone resins. 

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