The chain length dependency of molar association constant K_a of polymer in solution was investigated theoretically. K_a is proportional to the effective hydrodynamic volume V_ eff of polymer chain in solution. V_ eff is the product of a shape factor and hydrodynamic volume. On the basis of these results, the observed enhancement of Huggins coefficient for short chain and branched polymer could be satisfactorily interpreted.
Thermal evolution behavior of solution cast film of Poly(2,6 dimethyl 1,4 phenylene oxide)(PPO)/polystyrene(PS) blend was investigated by conventional and modulated differential scanning calorimetry. It was found that the original PPO/PS blend film is actually composed by a crystalline PPO phase and a non crystalline compatible PPO PS phase. The phase segregated structure state(A) will evolve to non crystalline homogenous structure(B) by subsequent thermal treatment. The effect of annealing temperature on the evolution process was discussed.
The concentration-dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of the self-association concept of polymer chain in solution. The molar selfassociation constant (Ka) is directly proportional to the effective hydrodynamic volume of the polymer chain in solution. In the sense of self-association or cluster formation of polymer chain in solution, there is no difference between branched and linear polymers.
The measured reduced viscosity\|concentration ( η \-\{sp\}/ c\|c ) curves of miscible PPO/PS、 immiscible PMMA/PS mixtures with different composition in toluene all deviate from linear and reveal downward turn in extremely dilute concentration region. Moreover, in the extremely dilute concentration region, the η \-\{sp\}/ c\|c curve of immiscible PVC/PS mixture solution shows upward turn in THF, while shows downward turn in DCE. These experimental facts indicate that such viscosity anomaly is not dependent of miscibility, but resulted from wall effects. Regarding the polymer mixture as a single solute, the interference of wall effects on viscosity measurement could be eliminated quantitatively with a proposed theoretical formula. After corrected, the true viscosity data of mixture shows normal linear η\-\{s p\}/ c\|c curve in the dilute and extremely dilute concentration region.
