Optimal temperature histories for the batch thermal polymerization of styrene are determined using Pontryagin's maximum principle. The theoretical predictions are compared with experimental measurements of conversion and molecular weight distribution. The excellent agreement suggests policy improvements in batch radical chain growth polymerizations.

The multistep solidification process of various ternary blends has been correlated to the chain dynamics and crystallization kinetics of individual components. These blends include a noncrystallizable poly-(propylene glycol), an acrylate, poly(methyl methacrylate-co-n-butyl methacrylate), and crystallizable polyesters such as poly(hexamethylene adipate) or poly(hexamethylene sebacate). When the sample temperature is lowered from the molten state, the contribution of each component in the solidification process can be readily recognized. The viscosity increase takes place in two steps. The initial increase is due to reduced segmental mobility. The second is due to the increase in crystallinity. On the basis of the data obtained for binary blends, the contribution of the crystallizable component in the viscosity change can be deduced. Although only minor structural differences exist between two polyesters, their phase diagrams differ considerably. As expected, these differences in phase diagrams led to different crystallization kinetics of the polyesters and associated solidification process.

High-quality polarized Raman spectra have been obtained for various poly(vinylidene fluoride) (PVDF) structures, crystalline and amorphous. The results encouraged us to revisit the Raman band assignment, especially within the conformational sensitive region (400−1100 cm-1) and to use the new understanding to characterize the amorphous region of PVDF. Vibrational bands have been assigned on the basis of polarization characteristics observed and the potential energy distribution (PED) calculated. The simulated results agree well with the experimental polarized Raman study. On the basis of the calculated PED, combined with the simulation of different conformational sequences (tttt, tttg, tgtg‘ tggg, gggg), spectroscopic features (band intensity at 648 cm-1 and the frequency change of the 856 cm-1 band) were associated with the distribution of rotational isomeric states. Two rotational isomeric state (RIS) models were analyzed and compared in the simulation of the amorphous state. On the basis of the spectroscopic features of experimental and simulated Raman spectra, it was concluded that the model which predicts higher gauche population more accurately describes the amorphous state. This analysis provides an opportunity to describe the amorphous state in a quantitative manner.

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