Poly PVOH films

The poly(vinyl alcohol) (PVOH) used in this study is Elvanol grade HV from DuPont chemicals. The material is derived from poly(vinyl acetate) (PVAc) by hydrolysis and is in powder form as received. The degree of hydrolysis for Elvanol HV is 99.8% (0.2% residual acetate groups). The molecular of the material used in this investigation is Mw =105,600 - 110,000. PVOH films were produced as described elsewhere 14). Samples were drawn in tension at a strain rate of 1.4 x 10 sec to a maximum draw ratio = 3.08 at 22 C. As-cast material has an equilibrium water content of 5.3 wt% at 22 C and 50% relative humidity (RH) giving a Tg value of 3rc. The HOPE is Hoechst unfractionated Hostalen GF 7660, Mw = 1.06x10 M = 1.01x10. Hydrostatic extrudon, with extrusion temperatures from 60-100 C and strain rates from 2.5 x 10 sec tol.4 x 10 sec" was us to vary draw ratio (die size was varied) with a maximum draw ratio Xm = 16. The maximum draw ratios were limited by fracture. 

Water-Soluble Films. Water-soluble films can be produced from such polymers as poly(vinyl alcohol) (PVOH), methylceUulose, poly(ethylene oxide), or starch (qv) (see Cellulose ethers Polyethers Vinyl polymers). Water-soluble films are used for packaging and dispensing portions of detergents, bleaches, and dyes. A principal market is disposable laundry bags for hospital use. Disposal packaging for herbicides and insecticides is an emerging use. 

Poly(vinyl alcohol) has also been shown to provide mechanically adaptive properties to composite films comprised of a PVOH electrospun mat and a PVAc or EO-EPI matrix. Films made from such composites exhibited controlled response to hydration that resulted in a two fold decrease of the storage modulus which, in the case of the PVAc composite, was fully reversible. Expanding on this concept and in a similar motif to the aforementioned CNC composites, Korley and coworkers have recently showcased the potential use of montmorillonite in mechanically adaptive composite materials. Montmorillonite is a layered silicate with high aspect ratio and surface area and is often used in polymer composites to mechanically reinforce the resulting material, while its dispersibility and tunable surface chemistiy make its use particularly attractive. In this case, the incorporation of montmorillonite in the PVOH fibrous filler resulted in enhanced moduli when the polymer matrix consisted of EO-EPI, as opposed to the limited enhancement observed in the case of a PVAc matrix. Nonetheless, both composites showed mechanically switching properties upon hydration, with the weight fraction of montmorillonite affecting the mechanical contrast as well as the response time. ... 

PVOH miscibility has been noted with poly(N, N-dimethyl acrylamide) [962] and partial miscibility noted with methyl cellulose [963]. With poly(N, N-dimethyl acrylamide), vinyl alcohol-vinyl acetate copolymers are miscible above 12 mole% vinyl alcohol. Fully hydrolyzed PVOH is not miscible with poly(2-ethyl oxazoline)(PEOx), but ethylene-vinyl alcohol copolymers (68 and 78 mole% vinyl alcohol) are miscible with PEOx [964]. Vinyl acetate-vinyl alcohol copolymers were shown to be miscible with PEOx over a wide range of copolymer compositions [965]. The immiscibility of fully hydrolyzed PVOH was attributed to the hydroxyl self-association dominating the competing hydroxyl-amide association. PVOH blends with sodium polystyrene sulfonate gave flexible, transparent films with good electrical conductivity [966]. Phase separation of PVOH/PEO [967] and PVOH/hydroxypropylmethyl cellulose blends [968] has been reported. PVOH/polyethyleneimine blends have been studied for membrane separations involving isomer separation [969]. PVOH/poly(ethyl oxazoline) blends have noted in a series of patent applications related to proton-conducting membranes [970]. 

Adhesives are often based on blends to optimize the key properties of interest, but as they are often designed for specific applications, the blend compositions are rarely disclosed. However, a large number of patents exist related to adhesive compositions. Blends of alky(meth)acrylates and poly(vinyl alkyl ethers) were described for self-adherent (Tg < 10 °C) adhesives or hot melt adhesives for labels, adhesive tapes or films [171]. Hot melt adhesives based on a blend of poly(vinyl alcohol) and copolymers of alkyl(meth)acrylates and other vinylic monomers were described for paper, wood and other cellulosic articles [172]. The PVOH based hot melt adhesives offer the advantage of repulpability for paper/cellulosic products requiring adhesives. A waterborne adhesive for coating friable surfaces (e.g., chalky weathered paint or masonry) was described as comprising a blend of separate emulsion polymers [173]. The examples noted blends of a MMA-nBA-MAA emulsion terpolymers with MMA-nBA emulsion copolymer with the copolymer having a particle size less than 120 nm. 

Boration causes aqueous solutions of PVOH to develop strong wet tack after cooking. Adhesives based on tackified (borated) poly(vinyl alcohol) work particularly well where they can be applied as a very thin film and then the sub-... 

Over the years poly vinyl alcohol (abbreviated PVOH or PVAl) proofed to be the most preferred protective colloid for that purpose. In a cementitious environment PVOH will be partly saponified and also absorbed of fine particles within a mortar, i.e. cement and fillers. This results in a film forming of the dispersed polymer and finally the polymer film is not redispersible any more. Since the polymer film (acting as a binder) is distributed throughout the cement matrix it improves dramatically the adhesion, abrasion resistance, flexural strength, flexibility, water impermeability/water repellency (hydrophobicity) and workability of a cementitious system. 

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