Polyvinyl acetate solubility parameter

These products are produced by the reaction of partially hydrolyzed PVAc with aldehydes. The acetal rings on these random amorphous polymer chains restrict flexibility and increase the heat deflection temperature to a value higher than that of PVAc. The heat deflection temperature of polyvinyl formal is about 90 C and is dependent on the specific composition of this complex polymer. Because of the presence of residual hydroxyl groups, commercial polyvinyl formal has a water absorption of about 1%. Polyvinyl formal has a Tg of 10S . It has a solubility parameter of about 10 H and is soluble in solvents with similar solubility parameters, such as acetone. 

Intractable polymers, such as polyvinyl chloride (PVC), may be flexibilized, to some extent, by the formation of copolymers, such as the copolymers of vinyl chloride and vinyl acetate or octyl acrylate, or by the addition of nonvolatile low-molecular-weight compounds (plasticizers) having solubility parameters similar to those of the polymer. Thus PVC is plasticized by the addition of dioctyl phthalate. The flexibility of these products is proportional to the amount of plasticizer added. Copolymers, such as the vinyl chloride-vinyl acetate copolymer, require less plasticizer to obtain the same degree of flexibility. 

This puts this polymer remote from the usual range of silicone rubbers, which have solubility parameters of about 15 (mJ m 3)l/2, and close to polycarbonates, which have a value of 19.4 (mJnT3)172, and nitrile rubbers and polyvinyl acetates, which are similar. 

On the other hand polyvinyl acetate is very soluble in methanol even though the difference between the solubility parameters is 9.8. 

In addition to polymer content additives, and temperature, the nature of the solvent can have a marked influence on the transport properties of the resulting membrane. Eirich et al9 discovered that regardless of the nature of the polymer, the highest porosity membranes were made from casting solutions utilizing solvents with high solubility parameters. Eirich investigated cellulose acetate, polystyrene, polyvinyl chloride, polyvinylidene difluoride, polycarbonate, polymethyl methacrylate, polyacrylonitrile, and polyacrylonitrile/polyvinyl... 

Calculate the solubility parameters and 6h of polyvinyl alcohol and polyvinyl acetal polymers. The structures of the repeat units of the polymers are... 

Both polymers are outside the range of the solubility parameters that enable the manufacture of satisfactory desalination mcmhran< < When 20% of polyvinyl alcohol is mixed with 80% of polyvinyl acetal. 

Blends of NBR with Polyvinyl Acetate PVAC) and its Copolymers Stollfuss investigated blends of NBR with polyvinyl acetate (PVAC) and its copolymers. The object was to obtain better low-temperature flexibility, compression set behaviour, and ageing resistance than that possible with NBR/PVC blends. Although the solubility parameters are similar in the two cases and the formation of a homogeneous phase was expected, only two-phase systems were found, except in the case of a vinyl acetate/maleic acid ester copolymer. All the mechanical properties, and also the resistance to ozone, were inferior to those of the NBR/PVC blends. Only the resistance to ageing was improved. 

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