The Raman shift and crystallite modulus were measured under the application of tensile force for a giant single crystal and a series of uniaxially oriented semicrystalline samples of poly(trans-1,4-diethyl muconate) (polyEMU). The apparent Raman shift factor alpha(app) or a vibrational frequency shift per 1 GPa tensile stress was higher for the semicrystalline samples with lower crystallinity or lower bulk modulus. The apparent crystallite modulus E-c(app) or Young's modulus along the chain axis in the crystalline region was not constant but varied remarkably between the giant single crystal and semicrystalline samples. A systematic change in a alpha(app) and E-c(app) among the polyEMU samples with different preparation history could be interpreted quantitatively on the basis of a mechanical series parallel model consisting of crystalline and amorphous phases. The origin of different E-c(app) and alpha(app) was speculated to be a stress concentration on the taut-tie chain contained as a parallel crystalline component in the mechanical model. (C) 2003 Wiley Periodicals, Inc.