Polymer-insert

Use of an expandable polymer insert that expands during the paint setting. 

The sustained release of artificial tears has been achieved by a hydroxypropylcel-lulose polymer insert [77], However, the best known application of diffusional therapy in the eye, Ocusert-Pilo, as shown in Figure 7, is a relatively simple structure with two rate-controlling membranes surrounding the drug reservoir containing... 

Figure 16.24 shows the schematic representation of dispersed clay particles in a polymer matrix. Conventionally dispersed clay has aggregated layers in face-to-face form. Intercalated clay composites have one or more layers of polymer inserted into the clay host gallery. Exfoliated polymer/clay nanocomposites have low clay content (lower than intercalated clay composites which have clay content -50%). It was found that 1 wt% exfoliated clay such as hectorite, montmorillonite, or fluorohectorite increases the tensile modulus of epoxy resin by 50-65%. ... 

This, then, is the key to how the pluronics stabilize liposomes and cell membranes. At low pressure, when the membrane would normally pull apart, pluronics insert and inaease the surface pressure. At high surface pressure, the polymer is ejected from the membrane onto the surface. Thus, a mechanism for membrane hole sealing can be envisaged. Under normal conditions, the pluronics are squeezed out of the membrane. If a hole is formed in the membrane, however, the polymer inserts into the membrane defect, keeping the membrane intact. 

M. Doyle, T.F Fuller, and Newman, Modeling of galvanostatic charge and discharge of thelith-ium/polymer/insertion cell, Journal of the Electrochemical Society, vol. 140, no. 6, pp. 1526-1533, 1993. 

The QCM has recently been introduced to monitor the mass associated with the ion insertion process in conducting polymers. Most of the polymers insert and release anions upon redox cycling, and the QCM has been used to determine whether this is the only process which occurs. A typical experimental arrangement for such studies is shown in Figure 2.6. 

A thin film was made by scraping off the outer surface of the polymer insert and dissolving it in decalin solvent to create a thin (30 Dm thick) film. The IR spectrum recorded on the thin film showed the polymer to be a polypropylene copolymer with ethylene, but it also showed an anomalous peak at 1735.7 em (Fig. 10.29). This is the charaeteristic position of the earbonyl group (C=0) produced by premature oxidation of the polymer ... 

Fig. 4. DSC curves of inserts prepared with poly(vinyl alcohol) PVA-C. Key a) polymer film b) pilocarpine nitrate c) polymer insert containing pilocarpine nitrate d) pilocarpine PAA-salt e,f) polymer insert containing pilocarpine PAA-salt heating and cooling, respectively.

Mass Transfer from Tri-layer Packages (Recycled Polymer Inserted Between Two Virgin Layers) in Liquid Food... 

Polymer Insertion Reactions. It was of interest to us to increase the siloxane content of the synthesized polymers and thus change their properties. Since polymer 3-CI2 contains an -Si-O-Si- linkage, it should be possible to insert cyclic siloxanes into the polymer backbone via the common ring-opening processes used to make polymeric silicones (Scheme 4) (28,29). This method would be an alternative to using long-chain siloxanes in the original polymer synthesis (Scheme 2, x 2). 

Keywords Ophthalmology Polymers Inserts Hydrogels Microparticles Nanoparticles Drug delivery... 

Gas solubiUties can also be determined by molecular dynamics simulations, using the Widom test particle insertion method to calculate the excess chemical potential fiex. or free energy of the penetrant molecules. The solubility can be obtained using Henry s law. If E is the interaction energy of a virtual penetrant molecule with the polymer inserted at random within the sample (the molecule is invisible to the polymer) then... 

Doyle, M., Fuller, T.F., and Newman, J. (1993) Modeling of galvanostatic charge and discharge of the lithium polymer insertion cell. J. Electrochem. Soc., 140, 1526-1533. 

Another method of pilocarpine release is the use of a thin laminate of hydrophile polymers inserted in the conjunctiva cul-de-sac. This pilocarpine Ocusert system releases pilocarpine at a constant pre-determined rate. The sustained-release system, providing such advantages as maximum duration of pressure control, less round-the-clock pressure variation, use of smaller drug concentrations with decrease of ocular and systemic side effects, also has some disadvantages one problem is the burst phenomenon, in which there is a large initial release of pilocarpine after insertion, resulting in severe miosis and ciliary body spasm. Up to the present several cases of loss of device and 8 -formation, comeal erosion, subconjunctival bleeding and displacement to the pupil have been reported. 

Contrary to what many people think, PLSNs are not a recent discovery. One of the earliest systematic studies of the interaction between a clay mineral and a macromolecule dates backs to 1949, when Bower described the absorption of DNA by montmorillonite. Even in the absence of X-ray diffraction (XRD) evidence, this finding implied insertion of the macromolecule in the lamellar structure of the silicate. In the case of synthetic polymers, Uskov found in 1960 that the softening point of polymethylmethacrylate derived by polymerisation of methylmethacrylate was raised by montmorillonite modified with octadecyl-ammonium, while in the following year Blumstein obtained a polymer inserted in the structure of a montmorillonite by polymerising a previously inserted vinyl monomer. In 1965 Blumstein first reported the improved thermal stability of a PMMA/clay nanocomposite. He showed that PMMA inserted between the lamellae of montmorillonite clay resisted thermal degradation under conditions that would otherwise completely degrade pure PMMA." ... 

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