Ethylene-co-vinyl acetate

Release of tetracycUne hydrochloride from PCL fibers was evaluated as a means of controlled administration to periodontal pockets (69). Only small amounts of the drug were released rapidly in vitro or in vivo, and poly(ethylene-co-vinyl acetate) gave superior results. Because Fickian diffusion of an ionic hydrochloride salt in a UpophiUc polymer is unlikely, and because PCL and EVA have essentially identical Fickian permeabilities, we attribute this result to leaching of the charged salt by a mechanism similar to release of proteins from EVA (73). Poly-e-caprolactone pellets have been found unsuitable for the release of methylene blue, another ionic species (74,75). In this case, blending PCL with polyvinyl alcohol (75% hydrolyzed) increased the release rate. 

Poly(propylene-co-1 -hexene) Poly(ethylene-co-vinyl acetate) Styrene-ethylene-butylene-styrene - - oil Styrene-butadiene-styrene -I- oil Nitrile rubber Nitrile rubber -I- diluent ... 

Elvax Poly(ethylene-co-vinyl acetate) DuPont... 

Polypyrrole/poly(ethylene-co-vinyl acetate) conducting composites with improved mechanical properties were prepared by a similar method [167], In addition, polyaniline/polystyrene [168] and polyaniline/poly(alkyl methacrylate) [169] composites have been synthesised. A solution of persulphate in aqueous HC1 was added to an o/w HIPE of polymer and aniline in an organic solvent, dispersed in aqueous SDS solution, causing aniline polymerisation. Films were processed by hot- or cold-pressing. 

The Cypher sirolimus-eluting stent from Cordis uses a blend of poly(ethylene-co-vinyl acetate) (PEVA) and poly(n-butyl methacrylate) (PBMA) as the polymeric matrix for sirolimus release. Both PEVA and PBMA have individually been used as implants in humans and demonstrated excellent biocompatibility. The blend of PEVA and PBMA is physically mixed with sirolimus in a weight ratio of 2 1. In vivo studies have shown that the majority of the drug is released in a sustained fashion in 30 days with complete drug release in 90 days as... 

The solubility data in Table I may be used to test the log P correlations in poly(ethylene-co-vinyl acetate) and polyether-urethanes. The correlations in Equations 19 and 20 are derived by combining this data with the reported (20) water solubilities and octanol-water partition coefficients of the steroids (22-24). 

Figure 10. Correlation of log P of the solvent pairs, poly(e-caprolactonc-co-e-caprolactam)-water, poly(ethylene-co-vinyl acetate), polydimethylsiloxane-water, and octanol-water. Unpublished results.

Table IV. Calculated and Experimental Solubilities (mg/ml) of Progesterone and Naltrexone in Water, Poly(e-capro-lactone) and Poly(ethylene-co-vinyl acetate)...

B. Rimez, H. Rahier, G. Van Assche, T. Arttoos, M. Biesemans, and B. Van Mele, The thermal degradation of poly(vinyl acetate) and poly(ethylene-co-vinyl acetate), Part I Experimental study of the degradation mechanism, Polym. Degrad. Stab., 93, 800-810 (2008). 

The nanodispersed nanoadditives usually show enhanced fire performance and CCA has been the most powerful tool in analyzing the flammability of the PNs. In most cases, the PNs, as seen in Figure 11.20, show a significantly reduced peak HRR in the CCA curve. More examples of this are seen in PA-6/clay nanocomposite, which shows a 63% reduction in the peak HRR at 5% loading (Figure 11.2898 in which the heat release rate as a function of time for pure PA-6 and its clay nanocomposites is shown) and in poly(ethylene-co-vinyl acetate) (EVA)/clay nanocomposite,99 which shows a reduction of the peak HRR at about 50% at 5% organoclay loading. 

Internal plasticizers are synthesized by copolymerization of suitable monomers. Polymeric non-extractable plasticizers, mostly copolymers having substantially lower glass transition temperatures due to the presence of plasticizing ( soft ) segments such as poly(ethylene-co-vinyl acetate) with approximately 45 % vinylacetate content, ethylene-vinyl acetate-carbon monooxide terpolymer, or chlorinated PE, are available for rather special applications in medicinal articles (Meier, 1990). In this case, the performance of the internally plasticized polymers is the principal advantage. However, copolymerization may account for worse mechanical properties. A combination with external plasticizers may provide an optimal balance of properties. For example, food contact products made from poly(vinylidene chloride) should have at most a citrate or sebacate ester based plasticizers content of 5 % and at most 10 % polymeric plasticizers. 

Flow-induced miscibility was also found for blends of poly(ethylene-co-vinyl acetate) and solution chlorinated polyethylene undergoing simple shear flow at... 

As a silicone mbber membrane is not permeable to hydrophilic or high molecular weight compounds, concerted efforts were made to develop other biocompatible polymers for use in implantable devices. Such polymers include poly(ethylene-co-vinyl acetate), poly (ethylene), poly(propylene), poly(hydroxymethyl methacrylate), poly(lactide-co-glycolide), poly (anhydrides) and poly(ortho esters). The characteristics and applications of each important polymer family will be discussed later in this chapter. 

Poly(ethylene-co-vinyl acetate) (EVA copolymer) is also widely used as a non-degradable polymeric implant. These copolymers have the advantages of ... 

The implant consists of a tablet-shaped ganciclovir reservoir. The drag is initially completely coated with poly(vinyl alcohol) (PVA) and then coated with a discontinuous film of hydrophobic, dense poly (ethylene-co-vinyl acetate) (EVA). Both polymers are nonerodible and hydrophobic (the PVA used in the implant is cross-linked and/or high molecular weight, to ensure it does not dissolve when exposed to water). The entire assembly is coated again with PVA to which a suture tab made of PVA is attached (Figure 4.5). 

Besides poly(dimethylsiloxane), other elastomeric polymers have been employed in the manufacturing of vaginal rings, such as poly(dimethylsiloxane/vinylmethylsi-loxane), styrene-butadiene-styrene block copolymer, and poly(ethylene-co-vinyl acetate) [123-125], In fact, poly(ethylene-co-vinyl acetate) (commonly referred as EVA) appeared in the mid 1990s as an alternative to poly(dimethylsiloxane), when the manufacturer of this last material stopped supplying it for human use, demonstrating it to be very suitable for the production of controlled-release systems. 

Lipson and Guillet (1982) provide Henry s Law constants for the chloroform -poly(ethylene-co-vinyl acetate) [P(E VAC)1 system at 338.15 K. 

P(DMS S) P(E P) P(E VAC) PEA PEAD poly(dimethylsiloxane-co-styrene) poly(ethylene-co-propylene) poly(ethylene-co-vinyl acetate) polylethyl acrylate) polylethylene adipate)... 

Pratt, A. Dodrill, A. Controlled antibody release from a matrix of poly(ethylene-co-vinyl acetate) fractionated with... 

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