PVA foams

Polyvinyl alcohol (PVA) foams can have plastic memory capabilities similar to those of polyurethanes (Tadavarthy et al., 1975). Currently PVA is mostly used as a foam in... 

The fully and super hydrolyzed PVA grades are preferred by the paper industry for their superior strength, greater adhesion to cellulose, better water resistance, and better foaming characteristics. However, the intermediate and partially hydrolyzed grades provide better surface filming characteristics on many paper and paperboard substrates. 

After filtration, a deep washing of the resultant catalyst with hot water, until negative chloride test, was made for each preparation. For avoiding foam formation, PVA was used in a low quantity (PVA/Au = 0.05) as suggested by the preliminary tests. 

Fig. 7.24. Kinetics of destruction of foamed emulsion from 1% NaDoS containing 0.5% PVA...

Fig. 7.24 depicts the results from the kinetics of destruction of a foamed emulsion produced from 1% NaDoS solution and 0.05% PVA, its drainage and separation of the emulsion from it. The determined period of half-life of the foamed emulsion the time of drainage of one half of the volume of the aqueous solution (tl) and the time for separation of... 

Madders. Phenolic polymers are known to have high rigidity, and this property extends to phenolic foams, which are highly friable. In order to reduce friabUity and permit some flexibUity and toughness, various kinds of modifiers are sometimes used. Reactive modifiers are used in the course of resol-resin preparation, and they become integral parts of the polymer structure. Examples include PVA (polyvinyl alcohol), PVA-PVC (polyvinyl alcohol-polyvinyl chloride-copolymer), resorcinol, o-cresol, furfuryl alcohol, and other various types of polyols. 

Waste Disposal. All processes must include some form of washing step to remove impurities from the bottles. If the adhesive, poly(vinylacetate), PVA, is to be separated through dissolution or hydrolysis to poly(vinyl alcohol), the waste stream will contain PVA and/or dissolved polyvinyl alcohol in addition to the other contaminants which must be removed. Paper fibers are another major source of impurities. For a lOMM Ib/yr plant about 75,(XX) Ib/yr PVA will be removed via the effluent. Environmental regulations probably require that this problem be addressed, especially since polyvinyl alcohol is an excellent foaming agent. 

Note A = acrylic CA = cellulose acetate CAB = cellulose acetate butyrate CN = cellulose nitrate E = epoxy EC = ethyl cellulose N = nitrile P = phenolic PC = polycarbonate PA = polyamide PE = polyethylene PET = polyester, thermoset PP = polypropylene PS = polystyrene PVA = polyvinyl acetate PVC = polyvinyl chloride UFF = urethane flexible foam UFR = urethane rigid foam. 

The ultimate breaking stresses were compared in the process of compression of foam concretes modified with copper/carbon nanocomposites obtained in different nanoreactors of polyvinyl alcohol [21, 22]. The sizes of nanoreactors change depending on the crystallinity and correlation of acetate and hydroxyl groups in PVA which results in the change of sizes and activity of nanocomposites obtained in nanoreactors. It is observed that the sizes of nanoeomposites obtained in nanoreactors of PVA matrixes 16/1 (ros) (NC2), PVA 16/1 (imp) (NCI), PVA 98/10 (NC3), correlate as NC3 > NC2 > NCI. The smaller the nanoparticle size the greater its activity, and the less amount of NS is required for self-organization effect. 

PPY-PVA and PPY-PEG composites were fabricated by vapor polymerization of pyrrole onto EeCls-loaded hydrogel matrices [87]. FeCl3-loaded PVA and PEG matrices were freeze-dried to form microstructures. The resulting composites have fine foam-like lattice structure with low weight density. The tensile strength and conductivity of 20 wt% PPy-PVA were 2.0 0.2 MPa and 0.1 S cm , respectively. 

Butylene carbonate Dibutoxyethoxyethyl phthalate Ethylene carbonate N-(2-Hydroxypropyl) benzenesulfonamide plasticizer, PU foam Pentaerythrityl trioleate Tris (2,3-dichloropropyl) phosphate plasticizer, PU resins Triethylene glycol plasticizer, PU sealants Polypropylene glycol dibenzoate plasticizer, PU-based sealants Benzyl phthalate plasticizer, pulp/paper Oleyl alcohol Propylene glycol laurate plasticizer, PVA emulsion paints s-Dioctyl phthalate plasticizer, PVAc Butyl oleate Butyl ricinoleate Dibutoxyethoxyethyl adipate Dibutoxyethoxyethyl glutarate Dibutyl adipate... 

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