Sealing Capability

The distinction between an adhesive and a sealant is not well defined as adhesives are often required to act as sealants. In the same way, a sealant has to show some 

The silicone adhesive family often provides the desired properties for many applications where a seal is required. These products are suitable where there are severe movements between substrates caused by changes in temperature, pressure and vibration. However, aggressive chemicals such as jet fuel, strong acids or alkalis, organic chemicals, can cause swelling and debonding of silicone sealants and thus affect the permeability and integrity of the seal. 

The Health and Safety Executive (HSE) website (umnu.hse.gov.uk) [2] gives very thorough notes and guidance on all aspects of health and safety in the workplace. The suppliers of all adhesives and chemicals in the EC (and indeed in most countries) are required to provide an Material Safety Data Sheet (MSDS) for each product they sell. 

The MSDS (Section 15) will also include risk phrases (R) and Safty phrases (S) and many of these will also be included on the product packaging. 

However, in April 2009, the MSDS sheets were no longer covered by the Chemicals Hazard Information and Packaging for Supply (CHIP) Regulations and have been transferred to the European Registration, Evaluation, Authorisation and restriction 

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D. P. Wilkinson, J. Stumper, S. A. Campbell, M. T. David, and G. J. Lament. Electrochemical cell with fluid distribution layer having integral sealing capability. US Patent 5976726 (1999). 

Weight loss3 (leakage) 12 Sealing capability, proper rubber sealability... 

O-rings are commonly found on mechanical vacuum pumps, rotary valves, and O-ring joints. O-rings are used to separate environments. If an O-ring is attacked by the chemicals from one or both of these separated environments and fails, it will lose its protective sealing capabilities. Similarly, if an O-ring is left in a chemically destructive environment, it may become dysfunctional without ever having been used. 

Wilkinson D P etal., 1999, Electrochemical Cell with Fluid Distribution Layer Having Integral Sealing Capability. US Patent 5,976,726. 

The interfaclal-polymerization technology for the preparation of ultra-thin composite membranes with its self-sealing capability... 

Recently, scientific interest has been concentrated on interactions between amphiphilic block copolymers and lipid mono- and bilayers [196-200], Understanding the nature of such interactions will open a route towards multiple applications in fields as biophysics, biomedicine, and biotechnology. Particular areas of scientific interest are, for instance, elucidation of the mechanism of membrane-sealing capabilities of block copolymers penetrating into lipids [198,201] and how adsorption of amphiphilic block copolymers to liposomes enhances their stability [202,203], Furthermore, the interactions between polymers and biomembranes play a central role in the investigation of polymer-induced flip-flop within lipid membranes [200, 204, 205], and in the triggered generation of synthetic membrane channels and pores in lipid membranes [196],... 

Self-sealing capability. When lipid bilayers are disrupted, they immediately and spontaneously reseal (Figure 11.22) because a break in a lipid bilayer exposes the hydrophobic hydrocarbon chains to water. Because breaches in cell membranes can be lethal, this resealing property is critical. (In living cells, certain pro-... 

Seal Substitution of cheap compounding ingredients High volume swell and loss of sealing capability Accurately specify all major ingredients in rubber and plastic components... 

Solid fillers are added to some anaerobic adhesives and sealants for various purposes. Mica, talc, and other mineral fillers can help to provide an instant seal capability to anaerobic pipe sealants. The sensitivity of the anaerobic cure system to metal contamination requires that these fillers be chosen very carefully. 

Holding power may be insufficient, and a loss of parallelism and, therefore, sealing capability may result. 

Monolithic refractories have lower thermal expansion than most refractory bricks. Whatever small expansion does occur can usually be absorbed by the supports. Therefore, unlike refractory bricks, monolithic refractory walls do not require clearances for thermal expansion. Clearances required for brick construction may allow passage for furnace gas leaks out or air into a furnace. The superior sealing capability and reduced expansion of monolithic refractories make them suitable for higher furnace... 

Nunamaker E A (2006), Alginate as a novel material for duraplasty Investigation of the material properties, in vivo stability, and sealing capabilities . Doctoral dissertation. University of Michigan. 

High pressure sealing capability Poor fatigue life... 

Additionally, the classification of a product that has both adhesion and sealing capabilities is obscure. For this reason, the classification does not have a well-defined demarcation line. In some respects, the physical properties of urethane adhesives differ from those of urethane sealants. In line with that, this section presents the main types of polyurethane sealants and adhesives, their characteristics, advantages and disadvantages according to the form in which they are found, i.e. 100% solids, solventbome, waterborne, and the cure characteristics whether one or two-component material. 

Bleed and temperature optimized septa (BTO , Chromatography Research Supplies, Inc., Louisville, KY, USA) are well suited for trace GC and GC-MS applications which require low bleed and extended sealing capabilities for high injection numbers. As an additional benefit, many septa provide a pre-drilled needle guide for increased septum lifetime, which makes them ideal for the use with liquid autosamplers as well as with SPME. BTO septa are specified for use with up to 400 °C inlet temperature, are preconditioned and require very little additional conditioning before use. It is recommended to change septa at the end of a day, so the septa can condition overnight to ensure the lowest bleed for the next day analyses. 

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