Viscoelasticity and birefringence of poly(2‐vinylnaphthalene)

Complex Young’s modulus, E*(ω), and complex strain‐optical coefficient, O*(ω), of Poly (2‐vinylnaphthalene) (P2VN) were studied in the glass‐to‐rubber transition zone at frequencies ranging from 1 to 130 Hz at various temperatures between 145 and 200 °C. In comparing the master curves of E*(ω) and O*(ω), we apply the modified stress‐optical rule to deliberate the glass transition modulus attributable to different relaxation mechanisms. The characteristics of master curves are also compared with those of polystyrene (PS), poly (a‐methylstyrene) (PMS), and polycarbonate (PC) in view of their chemical structures. The stress‐optical coefficient, CR, determined in the rubbery zone, is −8.3×10−9 Pa1, which is 1.6 times larger than that of PS. The large negative value may be due to the large optical anisotropy of naphthyl side group. In the glassy zone, the relative rate of decrease of E‘(ω) with ω is lower compared with the other polymers. This behavior is believed to be attributed to β relaxation of large naph...