Polyisoprene sedimentation

Sedimentation coefficients, diffusion coefficients, and frictional ratios for polyisoprene in solution ... 

Field flow techniques have been reviewed in a number of articles [148-150]. Sedimentation field flow fractionation has found use in the separation of PVC [151, 152], polystyrene [151-153], poly(methyl methacrylate) [153, 154], poly (vinyl toluene) [155] and poly(glycidyl methacrylate) latexes [156] to produce particle-size distributions and particle densities. It has also been applied in polymer-aggregation studies [157], pigment [157] quality control and in the separation of silica particles [158] and its performance has been compared with that of ultracentrifugation [159]. Thermal field flow fractionation has been used successfully in the characterisation of ultra-high-molecular-weight polystyrenes [160, 161], poly(methyl methacrylate), polyisoprene, polysulphane, polycarbonate, nitrocellulose, polybutadiene and polyolefins [162]. In the difficult area of water-soluble polymers, poly(ethylene glycol), poly(ethylene oxide), poly(vinyl pyrrolidone) and poly(styrene sulphonate) have been analysed [163, 164]. In addition, compositional separations have been achieved for polystyrene-poly(methyl methacrylate) mixes [165] and comparisons between TFFF and SEC have been made [166]. 

Tong, et al.(21) and Ye, et al.(22,23) report sedimentation of 4.0 nm surfactant-coated calcium carbonate particles through monodisperse hydrogenated polyiso-prenes in decane. Unmodified hydrogenated polyisoprene is nonabsorbing to the coated carbonate spheres. Addition of an end-terminal amino group yields an... 

Figure 2.12 Sedimentation coefficients of 4.0 nm radius coated calcium carbonate microspheres through solutions of nonadsorbing hydrogenated polyisoprene, molecular weights (O) 17.5, ( ) 26, ( ) 33, and (0) 88 kDa, based on experiments of Tong, et a/. (21).

Figure 2.13 Sedimentation coefficient of 4.0 nm radius coated CaC03 microspheres in (i) solutions of adsorbing 25 kDa amine-terminal hydrogenated polyisoprene ( ), and (ii) solutions of nonadsorbing unmodified polyisoprene ( , dashed line), based on experiments of Ye, et al. 22). The two solid lines, which are very nearly indistinguishable on the scale of the figure, show stretched-exponential fits to s(c) and to the reported viscosity of these solutions(22).

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