Cross-linked polyvinyl

A weak cation-exchange resin is obtained by reaction of glyoxylic acid and a cross-linked polyvinyl alcohol. The polyvinyl alcohol is cross-linked with glutaraldehyde in the presence of hydrochloric acid. The cation-exchange resin has an exchange capacity of 3 meq/g or greater and a swelling volume of 10 ml/g or smaller (37-38). 

R. Audebert, J. Janca, P. Maroy, and H. Hendriks. Chemically cross-linked polyvinyl alcohol (PVA), process for synthesizing same and its applications as a fluid loss control agent in oil fluids. Patent GB 2278359,1994. 

A Du Pont patent (2) describes a colorless, viscous polyacetal from the divinyl ether of 1, 5-pentanediol and subsequent acetalization. This product can be used for cross-linking polyvinyl alcohol films. 

Wngard, Jr., L. B., T. R. Tritton, and K. A. Egler. 1985. Cell surface effect of adriamycin and carminomycin immobilized on cross-linked polyvinyl alcohdDancer Res45 3529-3536. 

Disintegrants and superdisintegrants Starch, sodium starch glycollate, cross-linked polyvinyl pyrrolidone... 

General purpose cross-linking polyvinyl acatate emulsion. Durable to laundering. 

Wu M, Bao B, Yoshii F, Makuuchi K. Irradiation of cross-linked polyvinyl alcohol blended hydrogel for wound dressing. / Radio-anal Nuclear Chem 2001 250(2) 391—395. 

Water can be removed from methanol by a membrane of polyvinyl alcohol cross-linked with polyacrylic acid, with a separation factor of 465.204 A polymeric hydrazone of 2,6-pyridinedialdehyde has been used to dehydrate azeotropes of water with n- and /-propyl alcohol, s- and tort butyl alcohol, and tetrahydrofuran.205 The Clostridium acetobutylicum which is used to produce 1-butanol, is inhibited by it. Pervaporation through a poly(dimethyl-siloxane) membrane filled with cyclodextrins, zeolites, or oleyl alcohol kept the concentration in the broth lower than 1% and removed the inhibition.206 Acetic acid can be dehydrated with separation factors of 807 for poly(4-methyl-l-pentene) grafted with 4-vinylpyridine,207 150 for polyvinyl alcohol cross-linked with glutaraldehyde,208 more than 1300 for a doped polyaniline film (4.1 g/m2h),209 125 for a nylon-polyacrylic acid membrane (5400 g/m2h), and 72 for a polysulfone.210 Pyridine can be dehydrated with a membrane of a copolymer of acrylonitrile and 4-styrenesulfonic acid to give more than 99% pyridine.211 A hydrophobic silicone rubber membrane removes acetone selectively from water. A hydrophilic cross-linked polyvinyl alcohol membrane removes water selectively from acetone. Both are more selective than distillation.212... 

The use of polymeric blend composites for corrosion protection of AA 2024-T3 has been reported, including composites formed by incorporating water-soluble conducting polymers (either polymethox-yaniline sulfonic acid or poly(4-(3-pyrrole) )butane sulfonate) into various binders (a cross-linked polyvinyl alcohol, a waterborne epoxy, a modified water-dispersible polyester, and a UV-curable urethane acrylate binder) [149]. The preparation of epoxy and polyaniline composite coatings has been described, using either nanodispersed EB particles [91] or EB that was first dissolved in selected amine hardeners before adding the epoxy resin [98]. Even with very low EB loadings, these workers reported enhanced corrosion protection for steel. 

Two different catalysts for hydrogen peroxide decomposition, the enzyme peroxidase (isolated from the horseradish root, HRP), and polymer-supported catalyst (acid form of poly-4-vinylpyri-dine functionalized by ferric sulfate, apFe) [99,100], are examined with an aim to compare their activity. The active center in the peroxidases is the ferric ion in protoporphyrin IX. Besides the complex made of ferric ion and protoporphyrin IX, that is ferricprotoporphyrin IX, also known as ferric heme or hemin, peroxidase possesses a long chain of proteins [101,102]. On the other hand, the macroporous acid form of polyvinyl pyridine functionalized by ferricsulfate is obtained from cross-linked polyvinyl pyridine in macroporous bead form [103]. Pyridine enables it to form coordination complexes or quaternary salts with different metal ions such as iron (111) [104]. An active center on the polymeric matrix functionalized by iron, as metallic catalyst immobilized on polymer by pyridine, has similar microenvironment conditions as active center in an enzyme [105]. 

A CO2/N2 selectivity of around 1,800 for cross-linked polyvinyl alcohol polymeric membranes containing amine functionality in the form of 2-aminoisobutyric acid-potassium salt (mobile amine carrier) and poly (allylamine) (fixed carrier), at 110 °C was reported by Zou et al. [13], The main differences between this study and that reported by Zou et al. [13] are as follows (1) they used two types of amine carriers while suggesting that the mobile carriers connibuted more to the CO2 flux than the fixed carriers as opposed to APTS-modified membranes where the carriers were fixed [attached to the pore walls], (2) in their study, water was used both on the feed and permeate side, enhancing the reaction rate of CO2 with... 

Cross-linked polyvinyl alcohol (PVA) nano-cables were formed in the presence of Cu ions by a one-step hydrothermal approach at 200°C [111]. Synthesis of metal-free snbmicro meter graphitic carbon plates from glucose with controllable thickness has been reported and H2SO4 used for the enhancement of carbonization [34]. Furthermore, a low amount of glncose and a high amount of... 

An interesting and separate application proposed for borate is as a component of a cement fluid loss additive. Cements require a minimum amount of water for proper hydration and setting and if water from the cement filters into the formation, the setting process can be compromised. Cements therefore contain fluid loss additives. A dried, preformed borate cross-linked polyvinyl alcohol (PVA)-sorbitol complex has been proposed for use as a fluid cement fluid loss additive [100]. This may have wider application in other oil well fluids. 

If the constant p is known, equation 6 or 7 permits the calculation of Me, the average molecular weight of a strand between cross-links, from swelling measurements. Such calculations have been made by Flory (1946) for butyl rubber and Doty and Zable (1946) for lightly cross-linked polyvinyl chloride. 

B.C. Thanoo, M.C. Suimy, A. Jayakrishnan, Controlled release of oral drugs from cross-linked polyvinyl alcohol microspheres, /Pharm Pharmacol, 45 16-20,1993. 

---