Latex blend films

Figure 14.12 Three AFM images of P(BA-co-MMA) latex blend films. These film samples contain 40 vol% of a latex with 7" = 48 °C, and 60 vol% of a latex with...

Spiro JG, Parinha IPS, Winnik MA (2003) Thermodynamics and morphology of latex blend films. Macromolecules 36(20) 7791-7802. doi 10.1021/ma021579j... 

During the past few years, use of latex blends has gained more and more attention. Several implicit or explicit aims in blending large and small latex particles underlie the development of latex blend films. Many studies " focus on blends of large and small particles, blends of film-forming and non-filmforming (i.e., hard and soft) particles, and blends with various sizes and hardness... 

This is truly reflected in the morphology of the uncured clay preexfoliated rubber nanocomposite films (NLu NA) prepared by the latex blending method (Fig. 7a). Curing the NR/NA nanocomposites in situ prevulcanization (No>NA) does not alter the arrangements of dispersed clay layers greatly, as seen from the... 

Material. Optically clear films (about 5 mils thick) of three SA (saturated acrylic) plastics (3) that contained 25, 33, and 50% of an acrylic graft rubber (referred to as SA-1, SA-2, and SA-3) were compression molded. The acrylic graft rubber latices were latex blended with a resin latex composed primarily of methyl methacrylate, and the blend was coagulated. The compositions of these three polymers are as follows SA-1, 79/17/4 wt %—methyl methacrylate/butyl acrylate/styrene SA-2, 72/23/5 wt %—methyl methacrylate/butyl acrylate/styrene SA-3, 59/34/7 wt %—methyl methacrylate/butyl acrylate/styrene. All three graft rubbers contained low levels of a crosslinking comonomer (less than 1.0 wt %). 

Pre-crosslinked Latex Blends. In these materials the individual latexes are crosslinked during synthesis, then blended, and a film is formed. Because of limited deformation and/or interdiffusion capabilities, such films tend to be weak, and only used for special purposes [Zosel and Lay, 1993 Lesko and Sperry, 1997], However, light crosslinking, as occurs in SBR latexes, may be tolerated. Pre-crosslinked latex blends materials are actually not IPNs, because the definition requires that at least one of the polymers be polymerized and/or crosslinked in the immediate presence of the other. An application of pre-crosslinked suspension-polymerized blends, in anionic and cationic form, is as ion-exchange resins. In suspensions, the particles are larger, usually of the order of 10-200 pm. 

It was observed that intermediate compositions dried slower than the unblended constituents. The mechanical properties of latex blends comprising low and high particles, the film formation ability, and the comparison of results to classical theory of polymer blends containing hard particles have been reported by Lepizzera et al. [1997], This is one of the few studies in the literature that has attempted to correlate emulsion blend properties with empirical/theoretical relationships previously available in the open literature. 

Latex lENs. Latex interpenetrating elastomer networks, latex lENs, are latex blends that have been cross-linked after film formation. They are named after the early works of Frisch and co-workers, who called these materials interpenetrating elastomer networks (Frisch et al. 1969b). Many latex blends, as used in coatings especially, are cross-linked as finally used in service. 

Journal of Applied Polymer Science 86, No.ll, 9th Dec.2002, p.2788-801 MECHANICAL PROPERTIES OF FILMS PREPARED FROM MODEL HIGH-GLASS-TRANSrriON-TEMPERATURE/LOW-GLASS TRANSITION-TEMPERATURE LATEX BLENDS Jiansheng Tang Daniels E S Dimonie V ... 

No.6,23rd March 1999, p. 1715-21 LATEX BLENDS OF FLUORINATED AND FLUORINE-FREE ACRYLATES EMULSION POLYMERIZATION AND TAPPING MODE ATOMIC FORCE MICROSCOPY OF FILM FORMATION... 

Poly(styrene-co-butadiene) rubber and poly(acrylonitrile-co-butadiene) rubber latex mixture films were evaluated as precursors of polymer electrolytes. A 50 50 blend was the optimum for mechanical strength and ionic conductivity. A simple equivalent mechanical model for the relationship between the mechanical strength and the structure was developed, which gave good agreement with experimental results, including materials with co-continuous phase morphologies. 26 refs. 

Keddie JL, Meredith P, Jones RAL, Donald AM. Film formation of acrylic latices with varying concentrations of non-film-forming latex particles. Langmuir 1996 12 3793-3801. Winnik MA, Feng J. Latex blends an approach to zero VOC coatings. J Coat Tech 1996 68 39-50. 

Figure 9.5 TEM picture taken from the film cast of the PUR/NR (1/1) latex blend containing 10 phr LS.

Atomic force microscopy has also been used to investigate the morphology of natural rubber blended films. The natural rubber and poly(methyl methacrylate) particles in the latex films can be easily distinguished and are clearly... 

ACS, Polymeric Materials Science Engineering Fall Meeting 1999. Volume 81. Conference proceedings. New Orleans, La., 22nd-26th Aug. 1999, p. 173-4 FILM FORMATION IN POLYMER LATEX BLENDS MICROSPECTROSCOPIC 3D STUDIES Zhao Y Urban M W North Dakota State University (ACS,Div.of Polymeric Materials Science Engng.)... 

The Metravib Micromecanalyser is an inverted torsional pendulum, but unlike the torsional pendulums described eadier, it can be operated as a forced-vibration instmment. It is fully computerized and automatically determines G, and tan 5 as a function of temperature at low frequencies (10 1 Hz). Stress relaxation and creep measurements are also possible. The temperature range is —170 to 400°C. The Micromecanalyser probably has been used more for the characterization of glasses and metals than for polymers, but has proved useful for determining glassy-state relaxations and microstmctures of polymer blends (285) and latex films (286). 

Blends. Latex film properties are commonly modified through the blending of latexes, eg, a "soft" polymer is made slightly harder by blending with a "hard" latex. 

The carboxylated latexes are formulated to use a reduced amount of a less reactive 2inc complex. Special resin blends provide an optimum balance of film tack and strength, and are coUoidaHy compatible with the carboxylated latexes (158). Epon resins may also be used as an acid acceptor in place of 2inc oxide (160). 

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