Polydimethylsiloxane melting point

Figure 7. Semilogarithmic relationship between the mole fraction solubility ( ) of testosterone (o), progesterone ( ), and estradiol (A) derivatives in polydimethylsiloxane and the reciprocal of the melting point (T 1). (Reproduced from Ref. 21. Copyright 1976 American Chemical Society.)...

Materials. Both paraffin and fluorocarbon wax surfaces were studied. The paraffin was a household wax distributed by Esso, Inc. Two fluorocarbon waxes, telomers of tetrafluoroethylene (TFE), were used. One, a methanol telomer,had a crystalline melting point of 278°C. and an approximate molecular weight of 2000 [5] the other, a telomer of polydimethylsiloxane (Dow Corning DC 200 silicone oil), had a crystalline melting point of 275°C. [13]. 

The hybrid homosilphenylenepolysiloxane presents a better thermal stability than polydimethylsiloxane (PDMS). It is sohd (melting point = 148 °C instead of - 40 °C for PDMS). 

Comparison of viscosity and first normal stress coefficient 1/ = Ni/y by cone and plate (solid points) and birefringence (open points) for a polydimethylsiloxane melt. 

Noncross-linked linear polydimethylsiloxane (PDMS) is a comparatively rapidly crystallizing polymer, and its glass transition temperature and melting point are significantly below room temperature (Tg = 150°K, = 235 K). 

Silicones, mainly polydimethylsiloxane, are excellent mold-release agents. Their chains contain numerous polar groups that adhere strongly to the metal surface, and their methyl groups, pointing away from the surface, facilitate the flow of the melt plastic material. Silicones function thus as a permanent separation layer. Their heat stability is relatively high (around 300°C) and no carbon film is formed when they decompose. However, their presence creates some problems when impression or metallization is to be done afterward on the surface of products. 

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