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Glass transition and film formation of VeoVa/vinyl acetate latices; role of water and co‐solvents
Author(s) -
Heymans Denis M. C.,
Daniel Mervyn F.
Publication year - 1995
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.1995.220060506
Subject(s) - vinyl acetate , materials science , glass transition , plasticizer , polymer , monomer , copolymer , chemical engineering , emulsion , differential scanning calorimetry , polymer chemistry , viscoelasticity , particle (ecology) , emulsion polymerization , aqueous solution , solvent , composite material , organic chemistry , chemistry , thermodynamics , oceanography , physics , geology , engineering
The physical forces causing deformation of latex particles during the film formation process have been witley studied. However, the forces resisting particle deformation are still poorly characterized. It is clear that the extent of particle deformation is dependent on the viscoelastic nature of the polymer. In an emulsion, the latex particles will normally contain water, surfactants and “free” monomers which lead to plasticization of the polymer. Although this effect has been recognized, so far it has been studied only on films that had been dried and then partially or completely swollen by water. In this work, plasticization of the emulsion polymers by water and co‐solvent has been quantified via differential scanning calorimetry investigation directly on the aqueous latex dispersions. More specifically, the plasticizing effect of water on VeoVa/vinyl acetate copolymer latices and its influence on minimum film‐forming temperature (MFFT) has been studied. A linear correlation has been found between T g and MFFT for the wet latices. This new direct method should help to improve our understanding of the forces resisting latex film formation. Additionally, the homogeneous distribution of the hydrophobic and hydrophilic monomers (VeoVa and vinyl acetate respectively) in the latex particles was verified via a 13 C‐NMR (nuclear magnetic resonance) study performed directly on the latices. This study confirmed that no significant core/shell type of morphology had influenced latex film formation.