Portal de Periódicos da CAPES

Redispersible latex polymer

1963; Wiley; Volume: 7; Issue: 6 Linguagem: Inglês

10.1002/app.1963.070070623

1097-4628

L. F. Guziak, William N. Maclay,

Advanced Polymer Synthesis and Characterization

Abstract Latices containing 55 parts of styrene, (45 − X ) parts of 2‐ethylhexyl acrylate, and X parts of methacrylic acid, where X > 15, have been shown to yield discontinuous crazed films upon drying. These clear transparent polymer granules upon immersion in water containing a base are peptized to form a reconstituted latex containing spherical particles of the same size as the original latex particles. Inclusion of small amounts of a filming aid in the original or reconstituted latex permits the deposition of continuous polymer films which are rendered water‐resistant by baking. The property of redispersibility in water of transparent flakes of polymer is attributed to limited particle coalescence in the polymer grit. The incorporation of relatively high levels of carboxyl groups in the polymer is essential to the redispersion of the polymer by dilute solutions of base. Ionization of the carboxyl groups on the particle surfaces upon addition of a base gives rise to the sudden development of repulsive Coulombic forces which cause particle separation, after which surface forces are sufficient to restore the semiplastic particles to their original spherical shape. Inability to redisperse the film a second time may be due to polymer plasticization or to the migration of carboxyl groups to the particle interior as a result of coalescence forces.