Thermoreversible gelation in polymer systems—I: The sol-gel transition in dilute poly(vinyl chloride) gels

摘要: Abstract The gel to sol transition temperature (Tm) has been obtained at several concentrations between 25 g l−1 and 140 for six different samples of poly(vinyl chloride) in dioxan 63 92 a particular sample solvents. For the solutions, Ferry Eldridge relationships In M W =Const + ΔH m RT , C= Const approximate data give junction point energies (ΔHm) about 35 kJ mol−1. Two “regular” polymers, made low temperatures, higher values Tm as would be expected networks linked by “fringed micelle” crystallites; ΔHm only 27 mol−1 these two polymers suggest other complications such microsyneresis. Changes with solvent type are related Flory-Huggins interaction parameter χ molar value V form Flory depressed melting expression: 1 T − c ° = R(1−χ) ν 438 K T°c, ultimate pure chloride), 73 J cm−3 ΔHv, enthalpy per unit volume given this expression attributed minuteness crystallites that have melt sol-gel temperature.