Silicone-Rubber-Based Compositions

An hydrophilic/hydrophobic SIN composition suitable for soft contact lenses was disclosed by Falcella et Hydroxy ethyl methacrylate or 

Clark disclosed an adhesive composition based on three PDMS linear polymer derivatives. Polymer I had —OH groups, attached to silica atoms, polymer II had —CH=CH2, and polymer III had —H groups. After application, the Si—H groups reacted with the Si—CH=CH2 to form network I. On further heating, polymer I self-crosslinks to make a type of SIN. Thus, good bonding and tack can be combined at the intermediate stage. 

---

P dzich, Z., Bukanska, A., Bielihski, D. M., Anyszka, R., Dul, J., Parys, G. (2012). Micro structure evolution of silicone rubber-based composites during ceramization at different conditions. Int J Adv Mater Manuf Charact, 1,29-35. 

Ceramizable (ceramifiable) silicone rubber-based composites are fire resistant materials developed especially for cable covers application. In case of fire, electrical installations are endangered of short circuit effect which can deactivate lots of important devices, like fire sprinklers, elevators, fire alarms or lamps indicating route to emergency exits. Ceramizable composites are able to sustain functioning of electric circuit on fire and high temperature up to 120 min by producing ceramic, porous layer protecting copper wire inside a cable. 

This study has shown that the best composition of fillers promoting ceramization of silicone rubber-based composites consists of boron oxide (fluxing agent) and mica (refractory filler). Good mechanical properties and processability, in combination with very good mechanical properties and nanoporous structure after ceramization give to this composite large industrial implementation capacity. 

Processing requirements for thermoset composites, with specific examples of silicones, were recently reported.514 Composites based on the low molecular weight polysiloxanes for medical applications have been reviewed (in Russian).515 Silicone rubber/hydrogel composites have been evaluated for medical applications.516... 

DuckovaK et al. (1993) Silicone rubber-hydrogel composites as polymeric biomaterials. Part 5. Transdermal therapeutic systems based on hydrogel-filled silicone rubber. Eur J Pharm Biopharm 39(5) 208—211... 

BORON OXIDE AS A FLUXING AGENT FOR SILICONE RUBBER-BASED CERAMIZABLE COMPOSITES... 

Boron oxide particles were incorporated to silicone rubber-based mixes containing fumed silica (reinforcing filler) and reference mineral fillers - aluminum hydroxide, wollastonite, calcined kaolin, mica (phlogipite) and surface modified montmorillonite with dimethyl-dihydrogenatedtal-low quaternary ammonium salt. Acidic character of boron oxide, which can disturb the peroxide curing process, was compensated by addition of magnesium oxide. The influence of boron oxide particles on properties of composites was determined and mechanism of their ceramization process studied. 

Similarly, the coammonolysis of a mixture of dimethyldichlorosilane and vinyltrichlorosilane can yield polyvinylmethyldimethylsiloxane varnish, which has a relatively high adhesion to metals, glass and rubber based on silicone elastomers this varnish is also used in glue compositions. The coammonolysis of a mixture of dimethyldichlorosilane and phenyltrichlorosilane produces polydimethylphenylsilazane varnish. 

Hron, R, and Slechtova, J. 1999. Shape memory of composites based on silicone rubber and polyacrylamide hydrogel. Die Angewandte Makromolekulare Chemie 268 29-35. 

Chemicals derived from silica used in molding as a release agent and general lubricant. A silicon-based thermoset plastic material. Polyorganosiloxanes of different composition (e.g., polydimethylsiloxane, silicone rubber), structures (linear or network), and molecular weight, used as high-temperature oil, resin, or elastomer. 

Ceramizable silicone-based materials are dispersion t5q)e of composites, in which mineral particles (refractory fillers and, in some compositions, fluxing agent particles) are dispersed in continuous phase of silicone rubber [1-18]. Mechanism of protecting ceramic shield creation on the border between fire and material includes ... 

Figure 6.31 shows some experimental data for the pervaporation of water/ethanol mixtures by a silicone rubber membrane preferentially permeable to ethanol. The experiment was conducted at 23 C for downstream pressures of 667, 1200, and 2100 Pa (5,9, and 16 mmHg). As reported by Hoover and Hwang [250] and Tanigaki et al. [245], the silicone membrane showed preferential permeation to ethanol. Evidently, the downstream pressure has little effect on both permeate composition and permeation rate, supporting the calculated results shown in Figure 6.30. When the experimental data arc closely examined, however, the relative permeation rate decreases slightly with an increase in the downstream pressure. The calculated values in Figure 6.30 show exactly the same tendency, justifying the transport model on which the calculation is based. It has to be noted, however, that the saturation vapor pressure of water and ethanol at 60 C are 1.99 x l(f and 4.69 x lO Pa (149.4 and 351.9 mmHg), respectively. When the downstream pressure approaches the saturation vapor pressure, the assumption on which the theoretical calculation is based (i.e., (he vapor permeation prevails across the membrane cross-.section) becomes invalid, since liquid penetrates more deeply into the pore.

---