Dynamic Birefringence of Vinyl Polymers

Abstract

The complex strain-optical ratio, O*(ω), and the complex Young's modulus, E*(ω), of four vinyl polymers, atactic polypropylene, 1,2-polybutadiene, poly(ethylethylene), and poly(4-vinylbiphenyl), were measured from the rubbery plateau to the glassy zone to investigate the origin of the birefringence and the chain orientation in the glassy zone. The data, including those for polystyrene and poly(vinyl naphthalene), were analyzed through a modified stress-optical rule: The rule states that O*(ω) and E*(ω) are described as a sum of two component functions (denoted by R and G) and that a proportional rule similar to the ordinary stress-optical rule holds well for each of the R and G components with different stress-optical coefficients. The R and G components have been interpreted to be respectively related to the orientation of the main chain axis toward the stretch direction and tilting of the structural units by a rotational orientation about the main chain axis. According to this interpretation, the stress-optical coefficients for the R and G components are predicted to decrease and increase, respectively, with increasing size of the side chain. The present study shows the validity of this prediction. In addition, it is suggested that the degree of the rotational orientation responsible for the G component becomes larger with increasing size of the side chain.

Atomistic Monte Carlo simulation of steady-state uniaxial elongational flow of long-chain polyethylene melts: dependence of the melt degree of orientation on stress, molecular length and elongational strain rate

“…very favorably with the experimentally measured value for high-molecular weight, linear, high-density PE melts, which is reported [8][9][10][11][12] to be around 2.20 6 10 -9 Pa -1 .…”

“…9 by the dashed line) is about 2.35 6 10 -9 Pa -1 . [8][9][10][11][12] The deviation of our simulation estimate of the stress optical law coefficient at infinite chain length from the experimental value can be explained in terms of the molecular model we use, which tends to overestimate the conformational stiffness of chains. As reported in ref., [16] the molecular model described in Section 2 predicts a value for the characteristic ratio of PE as " X e v equal to C v = 9.03.…”

Dynamically cured polypropylene/Novolac blends compatibilized with maleic anhydride‐g‐polypropylene

“…During these processes, the polymer should be heated above its T g , drawn under shearing stress in the injection or extrusion flow, and then cooled below the T g to form a certain shape. By conducting the drawing above the T g , the polymer chains are oriented and specific orientational birefringence is induced; this property is then frozen below the T g and remains in the material, thereby affecting its optical properties 25. Thus, in addition to high transparency and moderate refractive index, low birefringence is also required in polymeric materials for optical applications.…”

Molecular Cooperativity in Large Deformation and Subsequent Structural Relaxation for Epoxy Glass

“…[13][14][15][16][17][18][19][20][21][22] The MSOR is considered to be a powerful tool also for epoxy glass to study its plastic deformation mechanism.…”