Near-infrared (NIR) spectroscopy (1.0-2.5 Mm or 10 000-4000 cm-1) was successfully utilized to monitor monomer conversion during conventional, anionic solution polymerization. The conversion of the vinyl protons in the monomer to methylene protons in the polymer was easily monitored under conventional (10-20% solids) solution polymerization conditions. Despite the presence of the NIR probe, the "living" nature of the polymerizations was maintained in all cases. Both styrene and isoprene polymerization kinetics were investigated in nonpolar and polar solvents, and relative rate constants were compared to values previously reported in the literature. In addition to the need for an inert probe, high sampling frequencies were required since polymerization times ranged from 5 s in tetrahydrofuran to 20 min in cyclohexane. Copolymerization kinetics have also been studied in order to determine the feasibility of NIR as an on-line structural probe. In fact, preliminary data indicate that NIR is capable of detecting sequence distributions for tapered block copolymers, geometric isomer content, and reactivity ratios for free-radical copolymerization. Future studies will focus on the application of NIR to elucidate polymerization mechanisms and deleterious side reactions.
The effect of polymer structure on blend miscibility with poly(vinylphenol) (PVPh) has been studied for a variety of polyesters that contain aromatic moieties in their backbone. In general, polyesters derived from aliphatic diols showed evidence of interaction and miscibility with PVPh. However, immiscibility was observed if the aromatic content of the polyester was very high. Polyesters derived from aromaticcontaining diols generally showed little interaction and no miscibility with PVPh. Both solution-blending and melt-blending methods were utilized to prepare the blends. Good correlation between the thermal behavior and infrared results was observed. Miscibility of PVPh was observed with polyesters consisting of terephthalic acid and a mixture of ethylene glycol and 1,4-cyclohexanedimethanol moieties for copolymer compositions containing at least 20 mol % ethylene glycol. Miscibility was observed with polyethylene terephthalate), poly(butylene terephthalate), poly(2,2-dimethylpropylene terephthalate), polyethylene 2,6naphthalenedicarboxylate), and a copolymer of terephthalic and pentanedioic acids with 1,2-propanediol and glycerol as well as with several cyclic aliphatic copolyesters containing 1,4-cyclohexanedicarboxylic acid. Miscibility of PVPh was not observed with poly(l,4-cyclohexylene dimethylene terephthalate), Ardel D100, Eastman Kodar copolyester A150, several other polyesters with high aromatic content, and two liquid crystalline polyesters.
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