Silicone resins and rubber

A patent (FR 2474891 see CA 96 124298c) assigned to B.A. Ashby, GE Company, claims a platinum-siloxane complex which catalyzes hydrosilation of vinylsiloxanes or SiOH groups in the preparation of silicone resins and rubbers. 

Silicones pure silicon, fumed silica, silanes, silicone resins and rubbers Materials advanced ceramics, boron compounds, surface treatments and silicon carbide. 

Silicone resins and rubbers ctre cross-linked polymers with branched polymer chains containing M (monofunctional), D (difunctional), T (trifunctional), and Q (tetrafunctional) units. Slightly branched polymers made from D, T, and Q structures have lower bulk viscosity and intrinsic viscosity than linear polymers of the same average molecular weight. 

Methyl chloride is used in the production of tetramethyllead antiknock compounds for gasoline and methyl silicone resins and polymers, and as a catalyst carrier in low-temperature polymerization (e g., butyl rubber), a refrigerant, a fluid for thermometric and thermostatic equipment, a methylating agent in organic synthesis, an extractant and low-temperature solvent, a herbicide, a topical antiseptic, and a slowing agent (lARC, 1986 Lewis, 1993). 

The linear silicone fluids consists of D units. Silicone elastomers and rubbers are composed of D units bearing as side-chain or end-chain cross-linkable functional groups (vinyl, silanol). Highly branched silicone resins combine T units and D units and in other cases Q and M units. In this way a very great variety of products with a broad application range is obtained. 

Presently thousands of different industrial products have been developed. They include fluids, resins, and rubbers of different formulations which are used in various industries and in our daily life. It is not the object of this article to enter into the detail of various aspects of synthesis, production, grades, properties, applications of all silicone derivatives because many of them are not directly linked to cationic synthesis processes. Most of the information may be found in excellent fundamental books and reviews covering silicones. 

Silicones are the subject of many reviews (1 8). Commercial products include fluids, filled fluids and gums, greases, resins and rubber (1,2). Various forms of silicones and examples of applications are listed in Table 1. 

What is the formula of l simple silicone What is the difference in structure of silicone oil, silicone resin, and silicone rubber ... 

A small amount of curing agent is required for the preparation of cross-linked or vulcanised silicone resins and silicone rubber. This has the desired effect either during the polymerisation or later, during the baking or vulcanisation steps. 

Depending on their properties and applications, silicones can be classified as oils, resins and rubbers. 

There are three main forms of silicones, namely liquids, solids (resins) and rubbers. The resins are the most important from the food contact point of view. A major application is in the bakery industry where the resin is used to coat bread baking tins. 

Of technical importance are radically crosslinking reactions on finished articles of polyolefins by means of electron beams in order to increase, for example, the thermostability. The technical importance of networks consisting of polydienes and other rubbers, polyurethanes, formaldehyde resins, alkyd resins, and silicones has already been explained in Sects. 1.3.3.3,4.1 and 4.2. 

RESINS (Synthetic). A manufactured high polymer resulting from a chemical reaction between two (or more) substances, usually with heat or a catalyst. This definition includes synthetic rubbers and silicones (elastomers), but excludes modified, water soluble polymers (often called resins). Distinction should be made between a synthetic resin and a plastic the formei is the polymer itself, whereas the latter is the polymer plus such additives as niters, colorant, plasticizers etc. See also Elastomers and Plasticizers. 

Dibutyltin and dioctyltin diacetate, dilaurate, and di-(2-ethylhexanoate) are used as catalysts for the curing of room-temperature-vulcanized (RTV) silicone elastomers to produce flexible silicone rubbers used as sealing compounds, insulators, and in a wide variety of other applications. Dioiganotin carboxylates also catalyze the curing of thermosetting silicone resins, which are widely used in paper-release coatings. 

Chorvath I et al. (2002) Thermoplastic elastomer compositions containing silicone rubber and nylon resins and the dynamically vulcanizing method. US Patent... 

Several organic sealants such as epoxy resins, butyl rubber or silicones prove to be more or less permeable and the tiny amount of solvent in the cell is rapidly lost. Suitable organic sealing materials for this technology turn out to be thermoplastic materials, like polyethylene/carboxylate copolymers. So far, Surlyn 1702 ionomer from Dupont has been the main substance used to optimize cell performance and build module prototypes. However, the softening point of Surlyn is rather low (65° C) and at elevated temperatures (> 70°C), serious solvent loss is observed because the bond between Surlyn and TCO-coated glass is substantially weakened [7]. 

---