Lattice model of equilibrium polymerization.IV.Influence of activation,chemical initiation,chain scission and fusion,and chain stiffness on polymerization and phase separation

摘要

The influence of thermal activation,chemical initiation,chain fragmentation,and chain stiffness on basic thermodynamics properties of equilibrium polymerization solutions is systematically investigated using a flory-Huggins type lattice model.The properties treated include the average chain length L,extent of polymerization PHI,Helmholtz free energy F,configurational entropy S,specific heat C_V,polymerization transition temperataure T_p,osmotic pressure,II,and the second and third virial coefficients,A_2 and A_3.The dependece of the critial temperature T_c and critical composition phi_c (volume fraction of associating species)on te enthalpy triangle openh_p and entropy triangle opens_p of polymerization and on the strength epsilon_FH of the FH effective monomber-solvent van der Waals interactin (chi=epsilon_FH/T)is also analyzed as an illustration of the strong coujping between phase separatin and polymerization.For a given plymerization model,both T_C and phi_c,normalized by their values in the absence of polymerization,are functins of the dimensionaless "sticking energy"h_epsilon ident to(|triangle openh_p|/R)/(2epsilon_FH) (where R is the gas constant) and triangle opens_p.