Polyurethanes migration from

Low bonding agent film weight Migration from polyurethane Contamination of bonding agent-coated parts Use heavier or multiple adhesive coats Substitute more compatible ingredients Check unbonded specimens for oil or dust Avoid overspray or excessive use of mold release... 

Table 16.5 Aromatic amine migration from polyurethane adhesives (Lawson 1994)...

There are many similar problems related to plasticizer compatibility. Plasticizer migrated from robber into polyurethane when crosslink density of polyurethane was lower. It had a sufficiently penetrable structure by molecules having sizes of penetrating... 

Solvent cementing is usually used for polyvinyl chloride (PVC). Because plasticizer migration from vinyls to the adhesive bond line can cause problems, adhesives selected must be tested for their compatibility with the plasticizer. Nitrile rubber adhesives are particularly good in this respect, although polyurethanes and neoprenes are also useful. 3M Company s Scotch-Grip 2262 adhesive (synthetic resin in solvent) is claimed to be exceptionally resistant to plasticizer migration in vinyls. 

From these and other experiments a construction was developed that included a core of nonionic hydrophilic polyurethane. The core served as a reservoir for ionized salt. A layer of anionic gel was placed on one side of the core a layer of cationic gel was placed on the opposite site. A current passed through the gel caused the cation to migrate into the anionic gel and led the gel system to contract. When the current flow was reversed, the ions returned to the reservoir. 

These materials have an obvious application to fusiform aneurysms, which are difficult to treat using coils or liquid embolics due to migration into the parent vessel. Shape memory polymers can potentially remove this limitation since the device is pre-formed to the aneurysm topography. Metcalf et al (2003) investigated a porous polyurethane shape memory polymer as an embolic device for fusiform aneurysms in an animal model. In this study, thick neointimal formation was found over aneurysm necks after a 12-week period. The porous nature of this material may have encouraged cell infiltration and neointimal growth to seal off the aneurysm from the rest of the vasculature (Metcalfe et al,... 

Polyurethane-based plasticizers can be obtained as a product of hydrolysis of poly-methane scrap as described elsewhere for material from printing rollers.These plasticizers were used to modify acrylonitrile-butadiene rubber.In still another development, diurethane was used in polyurethane elastomers. " Addition of diurethane improved potlife, and mechanical properties. The plasticizer performed better than DOP and it was substantially less migrating than DOP. " ... 

The sensitivity of FTIR spectroscopy to microscopic defects is greatly increased compared to a macroscopic measurement - if the defective area is examined. As opposed to single element, wide beam spectroscopy where the spectrum from the entire sample is obtained, the polymer does not overshadow the contaminant if a spectrum from a microscopic area of the sample is obtained. The contaminant can be later identified from a library of known compounds, providing clues to process control and helping to maintain quality control. This approach has been used to identify gel inclusions in poly(ethylene) [28, 29], contaminant on the surface of a semi-conductor device [30], acrylic fiber on a microcircuit die (Fig. 4) [31], contaminants in poly(vinyl chloride) (PVC) [32] and a mold release agent on the surface of a polyurethane [ 33 ]. An additive (erucamide) in linear low density polyethylene (LLDPE) that was found to migrate to the surface [34] thereby changing the surface properties could be readily identified. Various contaminants, whether in a... 

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