Polyvinyl acetate glass transition temperature

In particular, blends of PVDF with a series of different polymers (polymethylmethacrylate [100-102], polyethylmethacrylate [101], polyvinyl acetate [101]), for suitable compositions, if quenched from the melt and then annealed above the glass transition temperature, yield the piezoelectric [3 form, rather than the normally obtained a form. The change in the location of the glass transition temperature due to the blending, which would produce changes in the nucleation rates, has been suggested as responsible for this behavior. A second factor which was identified as controlling this behavior is the increase of local /rans-planar conformations in the mixed amorphous phase, due to specific interactions between the polymers [102]. 

Glassy polymers with much higher glass transition temperatures and more rigid polymer chains than rubbery polymers have been extensively used as the continuous polymer matrices in the zeolite/polymer mixed-matrix membranes. Typical glassy polymers in the mixed-matrix membranes include cellulose acetate, polysul-fone, polyethersulfone, polyimides, polyetherimides, polyvinyl alcohol, Nafion , poly(4-methyl-2-pentyne), etc. 

Epoxy resins may be blended with certain vinyl polymers to improve the impact strength and peel strength of the adhesive. Polyvinyl acetals, such as polyvinyl butyral and polyvinyl formal, and polyvinyl esters are compatible with DGEBA epoxy resins when added at concentrations of 10 to 20% by weight. The addition improves the resulting impact resistance and peel strength of the cured adhesive. However, temperature and chemical resistance are sacrificed by the addition of the low-glass-transition-temperature vinyl resins. 

R. A. Stratton and J. D. Ferry Dynamic mechanical properties of polyvinyl acetate in shear in the glass transition temperature range. J. Phys. Chem. 67, 152—161 (1963). 

Polyvinyl alcohol (PVA) is a water-soluble polymer with a glass transition temperature, T, of 80 °C. Although its name implies a homopolymer stmcture, the structure of commercial PVA is a copolymer of vinyl alcohol and vinyl acetate as seen in Fig. 4.2. PVA is made by the incomplete hydrolysis of polyvinyl acetate... 

Early fundamental studies of gas transport in polymers were almost entirely confined to hydrocarbon materials above their glass transition temperatures. The essentially nonpolar structures of the elastomers led to a number of reasonably successful attempts to correlate gas transport parameters with various physical characteristics of the gases and the polymers. These have been summarized and discussed in a number of papers In addition to studies with hydrocarbon elastomers a few studies of other amorphous polymers above their glass transition temperatures have dealt with polyvinyl acetate silicones and fluorocarbon polymers Recent studies have also dealt with poly(methyl aciylate) poly-(vinyl methyl ether) and poly(vinyl methyl ketone) With these more... 

The silicone content of the polyvinyl acetate-silicone copolymers can be varied by up to 50% or more. The glass transition temperature Tg is usually in the range between 10 and 35 °C. Typical molecular weights are between 10 000 and approximately 80 000 g/mol. 

Glass transition temperature a glass transition temperature of 42.5°C has been reported for polyvinyl acetate phthalate the glass transition temperature was shown to fall with the addition of increasing amounts of the plasticizer diethyl phthalate. ... 

Polyvinyl acetate is a glassy, amorphous polymer with Glass transition temperature about 28 °C. The effect of increasing the proportion of ethylene is to reduce the strong forces between the chains, which, in the homopolymer, are associated with a high concentration of polar acetate groups. Consequently, the glass transition temperature falls and is as low as 25 °C for a VA content of 65%. The properties at room... 

Journal of Polymer Science Polymer Physics Edition 39, No.14, 15th July 2001, p.1659-64 EFFECT OF RESIDUAL WATER AND FREE VOLUME ON THE GLASS-TRANSITION TEMPERATURE AND HEAT CAPACITY IN POLYSTYRENE/POLYVINYL ACETATE-CO-BUTYL ACRYLATE STRUCTURED LATEX FILMS... 

EVA (ethylene vinyl acetate) is a copolymer which is available in various compositions of ethylene and vinyl acetate. At a content of 50 vinyl acetate or more the crystallinity has been vanished completely. Give qualitatively the nitrogen permeability at room temperature for a copolymer with 10%, 50% and 90% vinyl acetate respectively and indicate the character of the polymer in terms of rubbery and glassy, crystalline and amorphous (The glass transition temperatures of the pure polymers polyethylene and polyvinyl acetate are given in table II - 5). 

The glass transition temperatures of polyvinyl acetate emulsions may be lowered further by adding a plasticizer such as dibutyl phthal-ate (Fig. 10). Plasticizer addition will, in turn, increase water resistance (Fig. 11). 

When added to an emulsion, plasticizers will also lower the glass transition temperature (Tg) of the polyvinyl acetate film, making it softer and more flexible (Fig. 15). Finally, plasticizers will increase the tackiness of the film, reduce its heat-sealing temperature, and improve its water resistance (Fig. 16). ... 

Polyvinyl acetals of any glass transition temperature between roughly 20 C to 120 C can be obtained by formulating with mixed aide-... 

For most applications the glass transition is far more practically manipulated with plasticizers. From Fitzhugh s data the mechanical glass transition temperature lowers on average 1.3 C per part dibutylphthalate (DBF) added to one hundred parts polymer. The glass transition temperature for DBF plasticized polyvinyl acetals, can be estimated from the fraction of plasticizer P and the mechanical resin glass transition temperature Tq, using... 

Below the glass transition temperature the polyvinyl acetals of aldehydes with fewer carbons than butyral exhibit moduli above the 2 x 10 dynes/cm associated with fully amorphous polymers. The butyral and higher aldehydic carbon acetals are probably less oriented and exhibit moduli in line with fully amorphous polymers. The embrittlement temperature is precipitously lower for acetals with four or more carbons in the original aldehyde. 

Typical values for the glass transition temperature of acrylic and polyvinyl acetate sealants are in the range of — 15°C to —20°C. The glass transitions of neoprene and fluoro-polymer sealants range from —22°C to —32°C. Polysulfide and polyurethane sealants exhibit glass transitions at approximately —40°C. Silicone sealants have the best low-temperature performance with glass transitions of approximately —65°C. 

As already mentioned, ethylene vinyl acetate copolymers can be synthesized in every ratio of the comonomers. The resulting polymers exhibit the complete scale of properties from thermoplastic material to elastomers. Polyethylene is a well-known thermoplastic with a very low glass transition temperature at about — 120°C and very high crystallinity of 40%-60%. Polyvinyl acetate is also a thermoplastic, but with a glass transition temperature of 28°C and completely amorphous stmcture. 

Here the values are nearly constant up to an amount of 50 wt% vinyl acetate. Then the glass transition temperature increases steadily. By extrapolation of the last data to the value of polyvinyl acetate, the measured value is found. 

Similar efforts have been made in other application areas. In gas separation, the addition of Ti02 nanoparticles to polyvinyl acetate improved the thermal stability of the resulting membranes, which was demonstrated by an inaease in the glass transition temperature (Ahmad and Hagg 2013). In this case, it was found that the addition of Ti02 up to 10 wt% improved both the permeability and selectivity of the membranes for gas separation, including H2, CO2,02, and N2. Similar observations were made on the effect of silica nanoparticles on the permeability of CO2 and CH4 for two types of nanocomposite membranes based on polyester urethane and polyether urethane (Hassanajili et al. 2013). Khan et al. (2013) studied mixed matrix membranes composed... 

Research on the physical aging of glassy polymers began with the discovery by Kovacs [1] that the volume of the polyvinyl acetate (PVAC) system slowly decreased (densified) with time, when rapidly quenched from above its glass transition temperature ). This research area... 

---