Copolymer latex comparison

Ihe effect of composition drift and the resulting particle stmeture was studied by Zosel et al. [194]. They used dynamic medianical testing to study the properties of latex films and tensile bars. In a comparison of the mamic mechanic propoties of films of solution-polymmzed copolymers of BA and acrylic acid (AA), of bloids of a PBA latex and PAA homopolymer, and of copolymer latexes, they noted a pronounced difleraice in the properties, with those of the emulsion copolymer intermediate to the other products. The structure of the films, as determined 1 TEM, cemfirmed the differmces. The structure of the films and the resulting properties of various mulsion copolymer systems could be traced back to mtXKMner reactivity and water solubility, but also to process mode and ccHiditions. 

A study [17] has been made of the effect of a dialyzed styrene-acrylate copolymer latex on the foam and the resistance to antifoam of three different surfactants—SDS, aerosol OT (sodium bis-diethylhexyl sulfosucdnate), and Triton X-100 (OP.EOjq)— all at a nominal concentration of 0.03 M. The polymer particles were dispersed in the surfactant solutions at a proportion of 25.5 wt.%. Adsorption of the surfactant onto the polymer particles significantly reduced the concentration of free surfactant in solution. A comparison was therefore made between the foam and resistance to antifoam behavior of the latex polymer-containing surfactant solution and a surfactant solution at the same depleted surfactant concentration, but containing no polymer. These depleted solutions were all submicellar—from about 80% to 99.9% of the surfactant (depending on the surfactant) was lost by adsorption onto the polymer-water surface. 

This paper presents the physical mechanism and the structure of a comprehensive dynamic Emulsion Polymerization Model (EPM). EPM combines the theory of coagulative nucleation of homogeneously nucleated precursors with detailed species material and energy balances to calculate the time evolution of the concentration, size, and colloidal characteristics of latex particles, the monomer conversions, the copolymer composition, and molecular weight in an emulsion system. The capabilities of EPM are demonstrated by comparisons of its predictions with experimental data from the literature covering styrene and styrene/methyl methacrylate polymerizations. EPM can successfully simulate continuous and batch reactors over a wide range of initiator and added surfactant concentrations. 

Elucidation of the morphology of the two stage latex particles, which had complete second stage monomer association, was carried out by a comparison with the corresponding copolymer and mechanical blend systems using electron microscopy and thermal analysis techniques. 

As previously mentioned, the properties of olefm-CO copolymers depend strongly on the nature of the olefin employed. The glass transition temperature of 1-olefin-CO copolymers decreases from room temperature to nearly -60 °C upon increasing the chain length of the 1-olefin from propylene to 1-dodecene [33]. By contrast to polar ethylene-CO copolymers, copolymers with higher l-olefins display a hydrophobic character. For 1-olefin copolymerization, catalysts with entirely alkyl-substituted diphosphine hgands R2P-(CH2) -PR2 (R=alkyl, by comparison to R=Ph in dppp) such as 3 are particularly well-suited [48]. Efhylene-l-olefin-CO terpolymers and 1-olefin-CO copolymers can be prepared in aqueous polymerizations [43, 47, 48]. In the aforementioned copolymerization reactions, the polyketone was reported to precipitate during the reaction as a sohd [45, 47, 48, 50]. However, in the presence of an emulsifier such as sodium dodecyl sulfate (SDS) and under otherwise suitable conditions, stable polymer latexes can be obtained. 

In the latter, the undecenoic acid termonomer, with a hydrophilic carboxylic acid moiety, can function as a copolymerizable stabilizer. By comparison to terpo-lymerization in non-aqueous polymerizations in methanol, the high local concentration of the liquid termonomer in droplets in the aqueous polymerization is beneficial for its incorporation. The 1-olefin copolymers exhibit glass transition temperaUires of Tg+10 to -55 °C, and thus can form films upon drying of a latex at room temperature. 

Mn 2 to 4). In olefin polymerization as well as CO copolymerization, a Umited conversion of liquid 1-olefin (co)monomers is yet to be overcome in many cases. As an example of properties that could find potential appUcation, polyolefins contain a negligible proportion of double bonds by comparison to styrene-butadiene copolymers, a hydrocarbon polymer currently prepared by free-radical emulsion polymerization on a large scale. This can result in a considerably higher stability towards UV-Ught and air of polymer films formed from polyolefin latexes. 

The effect of the Tg of the latex on the film-formation behaviour of a series of 2-ethylhexyl acrylate/methyl methacrylate emulsion copolymers was studied. Stage 1 of fihn formation was examined using a combination of DMA and conductivity measurements. Stages 2 and 3 were investigated using calorimehic compensation, DSC, dielectric spectroscopy and atomic force microscopy. Comparison of the results from the different methods employed led to a detailed model of the film-formation process in which the temp, used relative to the minimum film-formation temp, determined the effectiveness of the processes. The relative usefulness of the techniques used in their ability to characterise the various stages in the film-formation process was assessed for these copolymer systans. 23 refs. 

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