Poly , impregnation

Organic titanates can be used to cross-link sUicones on leather (49). Tetrabutyltitanate and tetrakis( P-aminoethoxy)titanium cross-link sUicones, eg, poly(dimethyl sUoxane), to iacrease both water repeUency and durabUity. For example, good repeUency results from the impregnation of leather with a solution of 10 wt % tetrabutyltitanate ia butyl acetate, foUowed by impregnation with a 9 1 mixture of sUicones and tetrabutyltitanate (50). 

Poly(vinyl chloride) is commercially available in the form of aqueous colloidal dispersions (latices). They are the uncoagulated products of emulsion polymerisation process and are used to coat or impregnate textiles and paper. The individual particles are somewhat less than 1 p,m in diameter. The latex may be coagulated by concentrated acids, polyvalent cations and by dehydration with water-miscible liquids. 

A number of higher poly(vinyl ether)s, in particular the ethyl and butyl polymers, have found use as adhesives. When antioxidants are incorporated, pressure-sensitive adhesive tapes from poly(vinyl ethyl ether) are said to have twice the shelf life of similar tapes from natural rubber. Copolymers of vinyl isobutyl ether with methyl acrylate and ethyl acrylate (Acronal series) and with vinyl chloride have been commercially marketed. The first two products have been used as adhesives and impregnating agents for textile, paper and leather whilst the latter (Vinoflex MP 400) has found use in surface coatings. 

Cured phenolics are universally brittle in nature. This is true of both resoles and novolacs and does not depend much on the source of methylene used to promote cure. Consequently, the fillers used in molded articles are highly important to the design of the manufactured product. With resoles, the fiber or filler are usually the primary component of the final composite, with the resole acting as a binder or impregnating agent. With novolacs the resin may be the major component in the molded part. Poly-silanes and other organic polymers are also added in some applications to promote impact resistance and toughness [192]. 

Polyaddition reactions based on isocyanate-terminated poly(ethylene glycol)s and subsequent block copolymerization with styrene monomer were utilized for the impregnation of wood [54]. Hazer [55] prepared block copolymers containing poly(ethylene adipate) and po-ly(peroxy carbamate) by an addition of the respective isocyanate-terminated prepolymers to polyazoesters. By both bulk and solution polymerization and subsequent thermal polymerization in the presence of a vinyl monomer, multiblock copolymers could be formed. 

In the meantime another development had decisively altered the outset situation plastics had been discovered and synthesized, among them also some acid-stable ones such as phenol-formaldehyde resin or poly(vinyl chloride) (PVC). These opened up new possibilities cellulose papers could be impregnated with phenol-formaldehyde resin solution and thus rendered sufficiently acid-stable, and sintered sheets from PVC powder were developed. Independent separators producers were founded, combining knowledge of the chemical industry with experience of the battery industry and thus accelerating the development process. 

Up to now, a variety of non-zeolite/polymer mixed-matrix membranes have been developed comprising either nonporous or porous non-zeolitic materials as the dispersed phase in the continuous polymer phase. For example, non-porous and porous silica nanoparticles, alumina, activated carbon, poly(ethylene glycol) impregnated activated carbon, carbon molecular sieves, Ti02 nanoparticles, layered materials, metal-organic frameworks and mesoporous molecular sieves have been studied as the dispersed non-zeolitic materials in the mixed-matrix membranes in the literature [23-35]. This chapter does not focus on these non-zeoUte/polymer mixed-matrix membranes. Instead we describe recent progress in molecular sieve/ polymer mixed-matrix membranes, as much of the research conducted to date on mixed-matrix membranes has focused on the combination of a dispersed zeolite phase with an easily processed continuous polymer matrix. The molecular sieve/ polymer mixed-matrix membranes covered in this chapter include zeolite/polymer and non-zeolitic molecular sieve/polymer mixed-matrix membranes, such as alu-minophosphate molecular sieve (AlPO)/polymer and silicoaluminophosphate molecular sieve (SAPO)/polymer mixed-matrix membranes. 

The cationic polymerization of vinyl isobutyl ether at —40°C produces stereoregular polymers (structure 5.21). The carbocations of vinyl alkyl ethers are stabilized by the delocalization of p valence electrons in the oxygen atom, and thus these monomers are readily polymerized by cationic initiators. Poly(vinyl isobutyl ether) has a low Tg because of the steric hindrance offered by the isobutyl group. It is used as an adhesive and an impregnating resin. 

A similar result was seen in the performance of a sample of hydrophilic poly-urethane-grafted reticulated foam without carbon. (Figure 4.15). Figure 4.16 shows the analysis of the effect of the carbon-impregnated foam. It is clear from these data that the carbon-impregnated foam showed significant improvement in effectiveness. In all the extractions cited below, the CoFoam contained about 1.7 g carbon. 

The membrane at the bottom of the electrode in Figure 15-20 is made from poly(vinyl chloride) impregnated with ion exchanger. One particular Ca2+ liquid ion exchanger consists of the neutral hydrophobic ligand (L) and a salt of the hydrophobic anion (Na R ) dissolved in a hydrophobic liquid ... 

Instead of monomers, polymers in solution can be grafted on Nylon structures. Aqueous solution of poly(acrylic add) is used for impregnation of polyamide fabrics which is subsequently dried during 1 to 5hrs at 80-150° C after which cure is carried out for 15 to 60 min at 150-218° C (99). A copolymer of styrene-maleic anhydride is said to be grafted on polycaprolactam by heating at 230° C at a pressure of 25 kg/cm2 (100). 

Preparation of polv-alumazane. Poly-alumazane (denoted as Al-N) was prepared according to literature data8 with some minor alterations. 20 g aluminum trichloride (AlCl-j) (Merck, PA) was dissolved in 500 ml nitromethane (Merck) in a 1 1 three-necked flask and 20 g silica (C 560, 200-500 /im, Uetikon, Switzerland, dried in vacuum at 120 °C) was added. After impregnation of the silica with AlClj the silica was treated with gaseous ammonia, followed by heating in nitrogen gas to 500 °C. The poly-alumazane was further prepared according to literature. 

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