Polydime thylsiloxanes

Precipitated and pyrogenic silicas are widely employed in antifoams used in industry. To be effective, the silica surface must be rendered hydrophobic by reaction with an agent such as polydime thylsiloxane. The hydrophobic particles are dispersed in a carrier fluid such as mineral or silicone... 

Chain Extension and Curing. An equivalent weight of TMP (in a 50% solution as above), 0.1 wt % stannous octoate (T-9), a 1 wt % flow agent composed of a 1 1 mixture of cellulose acetate butyrate, and a polydime thylsiloxane-polyoxyalkylene copolymer (L-522) were added to the prepolymer solutions. Films were cast and cured at 150°C for 4 hr. At this temperature, deblocking occurs followed by chain extension and cross-linking. 

The newest data show that in polydime thylsiloxanes, the molecular chains possess a helical structure with three to six silicon atoms in the helix [16, 17]. Under the action of high temperatures, such a structure creates favorable conditions for the closing of rings with chain cleavage. This is also confirmed by the experimental observations. Polydimethyl-siloxane decomposes into low-molecular cyclic polymers upon heating under vacuum at high temperatures, without appreciable cleavage of the Si—C bonds ... 

Name(s) PTFE-modified PE polymer (1), polyether-modified polydime-thylsiloxane (2), HD polyethylene wax (3), polyolefin coated with PTFE (4), polyethylene wax modified with PTTE (5), PTFE (6), polyether siloxane copolymers (7)... 

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