Glass transitions of styrene/α‐methylstyrene statistical copolymers and of their blends with PPO® resin

摘要

AbstractThe glass transition temperatures (Tg) and specific heat increments (ΔCp) atTgof S/AMS statistical copolymers having weight fractions AMS of 0.00, 0.09, 0.17, 0.26, 0.36, and 0.44 are (by DSC) 380.0 (0.280), 384.2 (0.275), 388.8 (0.284), 391.5 (0.275), 398.3 (0.272), and 405.9 (0.27) °K (J·g−·deg−), respectively. TheTg(ΔCp) for the PPO resin are 492.2 (0.221). The glass transitions of P(S/AMS) (1) + PPO resin (2) blends havingw2= 0.25, 0.50, and 0.75 were also measured. Examination of the copolymer and blendTgvs. composition data indicates that a relation recently proposed by Couchman gives a somewhat better approximation than the simple Fox relation. However, the nonadjustablek= ΔCp2/ΔCp1 constant in the Couchman relation must be replaced by a smaller empiricalkto give a true match of calculated to