Polystyrene metal composites

The capacity of studied organopolymeric sorbents depends on metal nature (Pd (II) > Au (III) > Pt (IV)) as well as on the composition and stmcture of sorbent matrix (polyvinylpyridine macroporous > polystyrene macroporous > polystyrene fibrous). 

Another differential reaction is copolymerization. An equi-molar mixture of styrene and methyl methacrylate gives copolymers of different composition depending on the initiator. The radical chains started by benzoyl peroxide are 51 % polystyrene, the cationic chains from stannic chloride or boron trifluoride etherate are 100% polystyrene, and the anionic chains from sodium or potassium are more than 99 % polymethyl methacrylate.444 The radicals attack either monomer indiscriminately, the carbanions prefer methyl methacrylate and the carbonium ions prefer styrene. As can be seen from the data of Table XIV, the reactivity of a radical varies considerably with its structure, and it is worth considering whether this variability would be enough to make a radical derived from sodium or potassium give 99 % polymethyl methacrylate.446 If so, the alkali metal intitiated polymerization would not need to be a carbanionic chain reaction. However, the polymer initiated by triphenylmethyl sodium is also about 99% polymethyl methacrylate, whereas tert-butyl peroxide and >-chlorobenzoyl peroxide give 49 to 51 % styrene in the initial polymer.445... 

Although a majority of these composite thermistors are based upon carbon black as the conductive filler, it is difficult to control in terms of particle size, distribution, and morphology. One alternative is to use transition metal oxides such as TiO, VO2, and V2O3 as the filler. An advantage of using a ceramic material is that it is possible to easily control critical parameters such as particle size and shape. Typical polymer matrix materials include poly(methyl methacrylate) PMMA, epoxy, silicone elastomer, polyurethane, polycarbonate, and polystyrene. 

The peaks in particle incorporation often55 56,77,85,89 occur at the same current density as kinks in the polarization curve for metal deposition. For Au-Ai203 composite deposition77 the peaks and kinks also correlate with the preferred orientation of the Au crystallites. Similarly, for zinc-polystyrene composites54,76 the peak in polystyrene codeposition corresponds to a change in morphology of the zinc deposit. Polarization... 

Figure 1.2. Typical microhardness values of polymers compared with data for metals. LDPE, low-density polyethylene HDPE, high-density polyethylene PA, polyamides POM, polyoxymethylene CEPE, chain-extended polyethylene CF-composite, carbon-fibre composite PS, polystyrene PEN, poly(ethylene naphthalene-2,6-dicarboxylate. (From Balta Calleja Fakirov, 1997.)...

---