Melting temperature of mixed microstructure polybutadiene

Rheological Study of Chain Dynamics in Dilute Binary Polymer Mixtures

“…For most samples, experiments were carried out at temperatures higher than -40 °C to avoid crystallization of the low molecular weight PBD. 27 The spectrometer is equipped with a 200-2000 g‚cm dual range, force rebalance transducer, and oscillatory shear measurements were carried out using a 25 mm diameter parallel plate flow cell. Gap settings of 0.5-1.0 mm were used.…”

The melt viscosity-molecular weight relationship for linear polymers

“…Viscosity data are available over a range of temperatures for the low molecular weight samples, and according to the superposition principle27 Vo (T) = cixbfq0(T0) (21) Since bx depends so weakly on temperature, its variation can be safely ignored to obtain the frequency shift factors simply from the viscosity ratios: = Vo (T) / »7 ( To) (22) Values of aT so obtained from the data in Table V (T0 = 25 °C) are also accurately described by WLF equations but with and C2 that vary systematically with molecular weight. The values in Table X were determined from capillary flow data alone (Table V) because temperature accuracy and control was better for those " Melt viscosity corrected to constant monomeric friction coefficient as described in Appendix B.…”

Detailed Atomistic Molecular Dynamics Simulation of cis-1,4-Poly(butadiene)

“…[18][19][20][21][22][23] Measurements have been performed with both polydisperse and monodisperse 18 1,4-PB samples and with different microstructures 19,21 in an effort to understand the effect of the relative cis/trans content on polymer viscoelasticity. Roovers 22 measured the viscoelastic properties of linear, high-molecular-weight polybutadienes at different temperatures and documented the validity of the scaling laws characterizing the dependence of η 0 on M. He concluded that, for molecular weights well above M c , η 0 ≈ M 3.4 , in agreement with the predictions of the modified reptation theory that incorporates contour length fluctuations.…”

“…From the point of view of experimental investigations (and restricting our literature survey to PB, on which the present simulation study will focus), attention has been paid to the development of techniques for the measurement of rheological properties, such as the plateau modulus, G N 0 , and the zero shear rate viscosity, η 0 , and for the estimation of the critical molecular weights, M e and M c , marking the passage from the Rouse to the entangled regime. [18][19][20][21][22][23] Measurements have been performed with both polydisperse and monodisperse 18 1,4-PB samples and with different microstructures 19,21 in an effort to understand the effect of the relative cis/trans content on polymer viscoelasticity. Roovers 22 measured the viscoelastic properties of linear, high-molecular-weight polybutadienes at different temperatures and documented the validity of the scaling laws characterizing the dependence of η 0 on M. He concluded that, for molecular weights well above M c , η 0 ≈ M 3.4 , in agreement with the predictions of the modified reptation theory that incorporates contour length fluctuations.…”