Silicone rubber table

It is important to note that the liquid silicone rubber (Table I) is sensitive to impurities and the cure of the liquid will be inhibited by a range of chemical contaminants. It is therefore necessary to ensure that all moulds and mixing implements are scrupulously clean. 

On this basis, a number of active sites have been developed for the production of RTV-1 type silicon rubbers (Table 5). The key for this curing behavior is that atmospheric moisture is sufficiently active to start and accelerate the crosslinking reactions. 

Some of the advantages and limitations of the following elastomers are given in the text ethylene acrylate. Table 8.4 acrylate. Table 8.5 Hypalon, Table 8.6 chlorinated polyethylene. Table 8.7 polyurethane. Table 8.8 silicone rubber. Table 8.9. 

Table 6. Properties of Different Classes of Silicone Rubbers ...

Table 9. Electrical Properties of Typical Silicone Rubber ...

Table 29.5 Physical properties of general purpose silicone rubbers (Values determined at 20°C after curing for 24 hours at 250 C) ...

The accuracy of constant k has been evaluated by comparing the experimental values of 0(t) with the values deduced from Eq. (28) for contact times greater than 30 minutes shown in Table 1. Good agreement between both series of values justifies the simple model of diffusion of TCP in silicone rubber. 

The authors of the above-discussed results consider the constant rate of heparin elution to be absolutely necessary for a successful functioning of the implant. Catheters made of these copolymers are much better, in respect of their thromboresistant properties, than the commercially available poly(tetrafluoroethylene) polyethylene, and plasticized polyvinyl chloride catheters (Table 8). The tested catheters were clotted in 9 cases of 81 (11 %), whereas usual silicone rubber catheters were clotted in 5 cases of 8 (63 %)70). 

A rather similar dependence was observed by Hoffman et al. 98) for heparin covalently immobilized on silicone rubber, which had been pre-modified by graft-copolymerization of hydroxyethyl methacrylate and N-vinylpyrrolidone (Table 11). 

There is further data confirming the results compiled in Table 12. Figure 5 shows the results of the studies on the interaction of heparinized silicone rubber with blood 4). The surface is seen to adhere the platelets up to its complete saturation, which then prevents further interaction. 

From the data in Table III. 1 it may be seen that cellophane and cellulose acetate have very large permeabilities to water also, the solubility of water in these materials is great, so they are clearly unsuited as moisture barriers. Of the elastomers listed, silicone rubber has the highest permeability to air. 

In the case of pervaporation of dissolved volatile organic compounds (VOCs) from water, the magnitude of the concentration polarization effect is a function of the enrichment factor. The selectivity of pervaporation membranes to different VOCs varies widely, so the intrinsic enrichment and the magnitude of concentration polarization effects depend strongly on the solute. Table 4.2 shows experimentally measured enrichment values for a series of dilute VOC solutions treated with silicone rubber membranes in spiral-wound modules [15], When these values are superimposed on the Wijmans plot as shown in Figure 4.12, the concentration polarization modulus varies from 1.0, that is, no concentration polarization, for isopropanol, to 0.1 for trichloroethane, which has an enrichment of 5700. 

Table 4.2 Enrichment factors measured for the pervaporation of VOCs from dilute solutions with silicone rubber spiral-wound modules...

Table 9.2 Typical silicone rubber membrane module pervaporation separation factors (VOC removal from water)...

Table 4.2 illustrates the various selectivity factors for some typical rubbery polymers, that is, silicone rubber, poly(dimethyl siloxane), and natural rubber, polyiso-prene, and a glassy polymer, polysulfone. Here, we consider the important 02/N2 pair and several pairs involving C02 that will be our focus later. In all the cases, the solubility selectivity is greater than unity and there is not a large difference between rubbery and glassy polymers. For most of these pairs, the diffusion selectivity is greater than unity, but there are some exceptions for C02/02 and C02/N2 that reflect... 

Table 4.3 shows the permselectivity characteristics of pure, semicrystalline PEO films [76]. The selectivity characteristics for 02/N2 are rather similar to those for silicone rubber and natural rubber shown in Table 4.2. However, the values of permselectivity for C02 relative to the various light gases shown are all much higher than Table 4.2 shows for the rubbery polymers listed there and even for polysulfone except for C02/CH4. Comparison of the data in Tables 4.2 and 4.3 makes it clear that this high permselectivity of PEO stems from its high solubility selectivity for C02 versus other gases this is augmented by modest values of diffusivity selectivity. Data in Table 4.4 for the C02/N2 pair illustrate that this effect can be translated into various block-copolymer structures when the PEO content is high enough to ensure it is the continuous phase. In fact, nearly all these materials have higher permselectivity and solubility selectivity for C02/N2 than does pure PEO (see Table 4.3) however, the diffusion selectivity for these copolymers is much closer to, or even less than, unity than seen for pure PEO. Furthermore, the copolymers all have much higher absolute permeability coefficients than does PEO.

Fig. 13f shows a silicone rubber float and through hole, made by molding so as to fit precisely into the hole [34]. This structure is suitable for the high pressure micropump. The size and characteristics are summarized in Table 2. 

Table 20. The main properties and applications of silicone rubber compounds and rubbers based on them...

The principle of these electrodes is a little different, and is normally based on the measurement of the pH of a solution of electrolyte placed between a membrane and a glass electrode, the membrane being porous to the species it is desired to determine (Table 13.3). The dissolved gas conditions the pH of the solution behind the membrane. Membranes can be microporous (for example PTFE) or homogeneous (for example silicone rubber). 

The property profile of silicone rubber thus obtained is now comparable to that of high consistency silicone rubber. This is shown in Table 1. 

TABLE 1. Comparison Of Typical Liquid Silicone Rubber With A Typical High Consistency Silicone Rubber... 

TABLE IV Comparison Of Energy Consumption For Coating Conductive Core With Liquid Silicone Rubber vs Silicone Rubber Dispersion... 

A short computer program was used to find the propagation constants from the impedance tube data using suggestions from (6-7). Data for a silicone rubber sample appears in the table below and a plot of the data is shown in Figure 5. 

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