Hypersonic velocity in binary polymer mixtures: Poly(dimethylsiloxane)ndash;poly(ethylmethylsiloxane)

摘要

The first Brillouin experiment on the blend poly(dimethylsiloxane)ndash;poly(ethylmethylsiloxane) with critical concentration Jgr;PDMS=0.53 and an upper critical solution temperatureTc=58thinsp;deg;C is reported. The theoretical calculation of the sound velocitycLin compressible binary mixture is based on the random phase approximation for a ternary incompressible system. According to this new result, the speedcL, in the absence of dispersion effects, depends mainly on free volume and segmentndash;segment interaction potential and remains finite as the blend approachesTc. The main experimental features are in agreement with the theoretical predictions.