Polyvinyl alcohol molecular weight

Macroporous polyvinyl alcohol particles with a molecular weight cutoff of ca. 8 X 10 in gel-permeation chromatography have been prepared. The particles are produced by first dispersing an aqueous solution of polyvinyl alcohol in an organic solvent to make spheres of polyvinyl alcohol solution. Holding the dispersion in such a state that a gel will then form spontaneously will cause the gel to react with glutaraldehyde in the presence of an acidic catalyst (85). 

The adsorption of fully and partially hydrolyzed (88%) polyvinyl alcohol (PVA) on 190-1lOOnm monodisperse polystyrene latex particles was investigated. The effect of molecular weight was investigated for 190 nm-size particles using the serum replacement adsorption and desorption methods. The adsorption density at the adsorption-isotherm plateau followed the relationships for the fully hydrolyzed... 

Polyvinyl alcohol(PVA) was obtained from the Kurarey Co.,Ltd. Japan the molecular weight and the degree of hydrolysis were determined by the supplier as 88,000 and 80 %, respectively. The molecular weight and the molecular weight distribution data of the polymer samples are shown in Table 1. 

When vinyl flouride is polymerized, a certain percentage of the flourine atoms are found on adjacent carbon atoms. When polyvinyl alcohol made by hydrolyzing polyvinyl acetate was treated with periodic acid by Flory, he found that the molecular weight was greatly reduced, indicating that there were 1,2-glycol units in the chain. But most of the polymers were regular head-to-tail polymers. 

The plasticizer-range alcohols are largely used as feedstock for production of high molecular weight diesters of phthalic, adipic, azelaic, and sulftiric acids. All these are used primarily in plasticizers for polyvinyl chloride (PVC) and other plastics. The plastics industry also uses them as additives for heat stabilization, to control the viscosity of PVC plastisols, ultraviolet absorbers, flame retardants, and antioxidants. They are also found in synthetic, lubricants, agricultural chemicals, and defoamers. 

Exercise 29-17 Polyvinyl alcohol prepared by hydrolysis of polyethenyl ethanoate (polyvinyl acetate Table 29-1) does not react with measurable amounts of periodic acid or lead tetraethanoate (Sections 16-9A and 20-4A). However, periodic acid or lead tetraethanoate treatment of the polymer does decrease the number-average molecular weight, for a typical sample from 25,000 to 5000. Explain what these results mean in terms of the polymerstructures and the mechanism of the polymerization. 

PC PE PES PET PF PFA PI PMMA PP PPO PS PSO PTFE PTMT PU PVA PVAC PVC PVDC PVDF PVF TFE SAN SI TP TPX UF UHMWPE UPVC Polycarbonate Polyethylene Polyether sulfone Polyethylene terephthalate Phenol-formaldehyde Polyfluoro alkoxy Polyimide Polymethyl methacrylate Polypropylene Polyphenylene oxide Polystyrene Polysulfone Polytetrafluoroethylene Polytetramethylene terephthalate (thermoplastic polyester) Polyurethane Polyvinyl alcohol Polyvinyl acetate Polyvinyl chloride Polyvinyl idene chloride Polyvinylidene fluoride Polyvinyl fluoride Polytelrafluoroethylene Styrene-acrylonitrile Silicone Thermoplastic Elastomers Polymethylpentene Urea formaldehyde Ultrahigh-molecular-weight polyethylene Unplasticized polyvinyl chloride... 

Poly(vinyl acetate vinyl alcohol) - A water plasticized polyvinyl acetate with minor hydrolysis to form vinyl alcohol sites to a molecular weight of -50,000 g/ mole plasticized with mono/diethylene glycol dibenzoate. This material was dissolved in ethanol for application purposes. 

Fig. 9. Exclusion molecular weight of polyvinyl acetats crosslinked with 20% 1,4 butanediol divinyl ether iner compound i-amyl alcohol / i-octane, abscissa given in volume fraction of nonsolvent...

PVA is further modified to obtain polyvinylacetatephthalate (PVAcP), which is used in enteric coatings. PVAcP is prepared from the reaction of partially hydrolyzed polyvinyl alcohol, sodium acetate and phthalic anhydride. It consists of 55 to 62% of phthalyl groups. The PVA used is a low molecular weight grade with 87 to 89 mole% hydrolyzed. Since only vinyl alcohol portions of the partially hydrolyzed PVA are phthalated, the acetyl content remains constant before and after the reaction. 

For Saffil alumina fiber, aluminum oxychloride [Al2(OH)jCI] is mixed with a medium molecular weight polymer such as 2wt% polyvinyl alcohol. The aqueous phase contains an oxide sol and an organic polymer. The sol is extruded as filaments into a coagulating (or precipitating) bath in which the extruded shape gels. The gelled fiber is then dried and calcined to produce the final oxide fiber. This solution is slowly evaporated in a rotary evaporator imtil a viscosity... 

Effect of Acetyl Content of Polyvinyl Alcohol. Fig. 3 shows the effect of a low concentration (0.10% w/v) of Gohsenol samples which have similar molecular weights but varying acetyl contents on the rate of polymerisation of vinyl acetate solutions. Increase of acetyl content decreases the rate of polymerisation. However this effect cannot account for the difference between the samples shown in Fig. 2 because these differ by only 0.1% in acetyl content. On the other hand any effect of acetyl content in the Vlnol series was small rates of 5.8, 5.9, and 5.4 %/min were observed using Vlnol 325, 425, and 523 which have similar molecular weights and acetyl contents of 1.8, 4.0, and 12 mole % respectively. 

Effect of Molecular Weight of Polyvinyl Alcohol. The table shows the rates observed with a standard concentration (0.36% w/v) of grades of similar acetyl content (12-13 mole %) for the polymerisation of 2% vinyl acetate solutions. The 4% solution viscosities are either the means of the range specified for the grade or, for the Gohsenol series, actual batch values. 

The effects of commercial grades of polyvinyl alcohol obtained from several manufacturers on the rate of polymerisation of vinyl acetate aqueous solutions and emulsions initiated by potassium persulphate at 60°C have been investigated. Increasing concentrations of polyvinyl alcohol in the same range tend to reduce the rate of polymerisation of the solutions but Increase the rate of polymerisation of emulsions. Considerable differences were noted between the effects of nominally simileir grades from different sources. Attempts to correlate the effect on the rate of polymerisation of vinyl acetate solutions with the acetyl content and molecular weight of the polyvinyl alcohol appear to have been confounded by an uncontrolled variable. A subsequent publication from the U.S.S.R. indicates that this may be the concentration of a by-product formed during the hydrolysis of the polyvinyl acetate. Other factors which may account for the effects are also discussed. 

A)H Dextran and alginic acid Hydroxyethyl cellulose and hydroxypropyl cellulose Polyvinyl alcohol, polyhydroxyethyl methacrylate, and low-molecular-weight polyethylene oxide... 

Polyvinyl acetate phthalate is a reaction product of phthalic anhydride, sodium acetate, and a partially hydrolyzed polyvinyl alcohol. The polyvinyl alcohol is a low molecular weight grade, and 87-89 mole percent is hydrolyzed. Therefore, the polyvinyl acetate phthalate polymer is a partial esterification of a partially hydrolyzed polyvinyl acetate. 

Polyvinyl alcohol is a water-soluble synthetic polymer represented by the formula (C2H40) . The value of n for commercially available materials lies between 500 and 5000, equivalent to a molecular weight range of approximately 20 000-200 000, see Table I. 

For most applications, 0.1% of F-68, F-88 and various PEGs and PVAs should be sufficient for mechanical protection. Higher concentrations of pluronics (up to 0.2%) may be necessary in some cases, but this has not been well documented. Among the large variety of PEGs available, those of molecular weights between 1400 and 15 000 have been found successful for mechanical protection. Polyvinyl alcohol of only one molecular weight (10 000) has been examined, and has been found to have excellent protective properties. 

Lemol [Borden], TM for a series of polyvinyl alcohols in partially and fully hydrolyzed form at various molecular weights. Supplied as nondusting, white granules with d 1.2-1.3. 

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