Polystyrene, latex

The condensation method begins with molecular units, and the particles are built-up by a process of nucleation typical example is the preparation of polymer lattices, in which case the monomer (e.g., styrene or methylmethacrylate) is emulsified in water using an anionic or nonionic surfactant (e.g., sodium dodecyl sulphate or alcohol ethoxylate). A polymeric surfactant is also added to ensure the long-term colloid stabiHty of the resulting latex. An initiator such as potassium persulphate is then added and, when the temperature of the system has increased, initiation occurs that results in formation of the latex [polystyrene or poly(methylmethacrylate)]. 

Fig. 7.27 Observed banding patterns as the gravity changes from 0 to 1.8 g [312]. Two suspensions of latex polystyrene are shown ...

Synonyms Atactic polystyrene Benzene, ethenyl-, homopolymer Ethenylbenzene homopolymer Polystyrene latex Polystyrene resin Polystyrol PS Styrene polymer Styrene, polymerized Vinylbenzene polymer... 

Slyrene-ethylene/butylene-styrene block copolymer Poly (styrene-co-allyl alcohol). See Styrene/allyl alcohol copolymer Poly (styrene-co-butadiene). See Styrene/butadiene polymer Poly (styrene-co-maleic anhydride). See Styrene/MA copolymer Polystyrene latex Polystyrene resin. See Polystyrene Polystyrene, sulfonated. See Sodium polystyrene sulfonate... 

The adhesive tapes used for the slip experiments were prepared by sparingly coating their sur ces with small (.5pm) fluorescent latex (polystyrene) particles. After these adhesive tapes were placed on the test substrates, they were peeled at a 40 peel... 

In the reported particle collision experiments with negatively charged latex, polystyrene, and silica spheres, most of the step features in the recorded chronoamperograms showed a cmrent decrease due to the blocking of redox mediator diffusion by adsorbed particles. However, a small number of steps showed a current increase, suggesting removal of a particle from the surface. However, in... 

Fig. XI-7. Volume fraction profile of 280,000-molecular-weight poly(ethylene oxide) adsorbed onto deuterated polystyrene latex at a surface density of 1.21 mg/m and suspended in D2O, from Ref. 70.

An important step in tire progress of colloid science was tire development of monodisperse polymer latex suspensions in tire 1950s. These are prepared by emulsion polymerization, which is nowadays also carried out industrially on a large scale for many different polymers. Perhaps tire best-studied colloidal model system is tliat of polystyrene (PS) latex [9]. This is prepared with a hydrophilic group (such as sulphate) at tire end of each molecule. In water tliis produces well defined spheres witli a number of end groups at tire surface, which (partly) ionize to... 

Fig. 4. Load vs compression for plastic foams (149). A, polystyrene, 32 kg/m (2 lbs/fT) B, polyethylene, 32 kg/m C, latex mbber foam. To convert...

In recent years, synthetic polymeric pigments have been promoted as fillers for paper. Pigments that ate based on polystyrene [9003-53-6] latexes and on highly cross-linked urea—formaldehyde resins have been evaluated for this appHcation. These synthetic pigments are less dense than mineral fillers and could be used to produce lightweight grades of paper, but their use has been limited in the United States. 

Styrene [100-42-5] (phenylethene, viaylben2ene, phenylethylene, styrol, cinnamene), CgH5CH=CH2, is the simplest and by far the most important member of a series of aromatic monomers. Also known commercially as styrene monomer (SM), styrene is produced in large quantities for polymerization. It is a versatile monomer extensively used for the manufacture of plastics, including crystalline polystyrene, mbber-modifted impact polystyrene, expandable polystyrene, acrylonitrile—butadiene—styrene copolymer (ABS), styrene—acrylonitrile resins (SAN), styrene—butadiene latex, styrene—butadiene mbber (qv) (SBR), and unsaturated polyester resins (see Acrylonithile polya rs Styrene plastics). 

Commercial styrene is used almost entirely for the manufacture of polymers. Polystyrene accounts for 64% of the worldwide demand for styrene. The rest is for manufacture of copolymers ABS, 9% SB latex, 7% UPR, 5% SBR, 4% others, 11%. 

Fig. 8. The stabiUty and instabiUty regions of a polystyrene latex with added aluminum salt at different pH values (17).

Polystyrene and closely related thermoplasties such as the ABS polymers may be proeessed by sueh techniques as injection moulding, extrusion and blow moulding. Of less importance is the processing in latex and solution form and the... 

The relationship between the increase in contact radius due to plastic deformation and the corresponding increase in the force required to detach submicrometer polystyrene latex particles from a silicon substrate was determined by Krishnan et al. [108]. In that study, Krishnan measured the increase in the contact area of the partieles over a period of time (Fig. 7a) and the corresponding decrease in the percentage of particles that could be removed using a force that was sufficient to remove virtually all the particles initially (Fig. 7b). 

Paine et al. [99] tried different stabilizers [i.e., hydroxy propylcellulose, poly(N-vinylpyrollidone), and poly(acrylic acid)] in the dispersion polymerization of styrene initiated with AIBN in the ethanol medium. The direct observation of the stained thin sections of the particles by transmission electron microscopy showed the existence of stabilizer layer in 10-20 nm thickness on the surface of the polystyrene particles. When the polystyrene latexes were dissolved in dioxane and precipitated with methanol, new latex particles with a similar surface stabilizer morphology were obtained. These results supported the grafting mechanism of stabilization during dispersion polymerization of styrene in polar solvents. 

Sheu and coworkers [111] produced polysty-rene-polydivinylbenzene latex interpenetrating polymer networks by the seeded emulsion polymerization of styrene-divinylbenzene in the crosslinked uniform polystyrene particles. In this study, a series of uniform polystyrene latexes with different sizes between 0.6 and 8.1... 

Figure 19 The scanning electron micrographs of the polystyrene seed latex and the copolymer latices carrying carboxyl, hydroxyl and amine functional groups, (a) PS/PAA, (b) PS HEMA, (c) PS/PDMAEM. The original SEM photographs were taken with 10,000 x magnification and reduced at a proper ratio to place the figure. (From Ref. 93. Reproduced with the permission of John Wiley Sons, Inc.)...

A very similar effect of the surface concentration on the conformation of adsorbed macromolecules was observed by Cohen Stuart et al. [25] who studied the diffusion of the polystyrene latex particles in aqueous solutions of PEO by photon-correlation spectroscopy. The thickness of the hydrodynamic layer 8 (nm) calculated from the loss of the particle diffusivity was low at low coverage but showed a steep increase as the adsorbed amount exceeded a certain threshold. Concretely, 8 increased from 40 to 170 nm when the surface concentration of PEO rose from 1.0 to 1.5 mg/m2. This character of the dependence is consistent with the calculations made by the authors [25] according to the theory developed by Scheutjens and Fleer [10,12] which predicts a similar variation of the hydrodynamic layer thickness of adsorbed polymer with coverage. The dominant contribution to this thickness comes from long tails which extend far into the solution. 

Garda-Salinas M. J., Romero-Cano M. S., de las Nieves F. J.. Zeta potential study of a polystyrene latex with variable surface charge influence on the electroviscous coefficient. Progr Colloid Polym Sci (2000) 115 112-116. 

Rubio-Hernandez F.J., Gomez-Merino A.I., Ruiz-Reina E., Carnero-Ruiz C. The primary electroviscous effect of polystyrene latexes. Colloids and Surfaces A Physicochemical and Engineering Aspects 140 (1998) 295-298. 

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