LOW-TEMPERATURE MOTIONS IN, AND MECHANICAL-PROPERTIES OF, GLASSY PLASTICIZED POLYMERS

Ambient moduli and yield stresses of single-phase glassy plasticized thermoplastics reflect several characteristics of the diluent (D) and the resin in addition to T(g) reduction. Dynamic mechanical spectroscopy from -150-degrees-C to the blend T(g) shows broad new losses (I) starting at the NEAT D T(g), low-T losses (II) from internal motion in the diluent, and retardations (III) of resin secondary relaxations (if any) (i.e., anti-plasticization). NMR shows that micro-Brownian rotation of D molecules causes I. However I dies out with Ds of higher T(g) (e.g., 0-degrees). II arises from Ds with flexible rings. III occurs in BPA polycarbonate but not in polyphenylene oxide/polystyrene: this blend has little low-T loss, thus eliminating III as a possibility and making changes caused by D addition easier to understand. Finally, excess low-T(g) D existing as a second phase produces a very sharp loss peak (IV) at the D T(g). The I-IV contrast indicates that I arises from dissolved isolated D molecules.