Abstract :
We present an exactly soluble Rouse-like model of the linear polymer chain dynamics in which the effects of solvent molecule dynamics and ultrasonic absorption are treated. Calculations for the relaxation time spectra, total intrinsic viscosity [ηT(ω)], intrinsic viscosity [η(ω)], elastic modulus G(ω) and specific heat capacity C(ω) of the polymer are presented in the free-draining limit. The calculations were carried out according to the configuration interaction method currently used in quantum mechanics. The relaxation time spectrum corresponding to dynamics of low frequency modes shows a Rouse-like character, whereas the relaxation time spectrum associated with dynamics of moderate frequency modes is narrower. The behaviour of the intrinsic viscosity [η(ω)] and elastic modulus G(ω) are shown to be represented by the model within the low frequency range. In the moderate- and high-frequency regions, [η(ω)] drops to zero and [ηT(ω)] reaches a plateau value equal to the sum of both the single bead intrinsic viscosity [ηN] and the effective solvent intrinsic viscosity [ηeff]. Behaviour of the specific heat capacity C(ω) is shown to be represented by the model at acoustic frequency region. The model is shown to be Rouse-like and representative for the description of ultrasonic absorption studies.
