Capillary Flow Properties of Fractionated Polychloroprene

Rheological properties of polypropylenes with different molecular weight distribution characteristics

“…The fact that γ˙ c ′ increases with temperature holds for any polymers and is common knowledge. The increase of γ˙ c ′ with increasing MFI or with decreasing molecular weight is also generally reported for PP19, 20 and other polymers 9, 17, 23, 29–34. As for the effect of molecular weight distribution, no study on PP is found.…”

“…As for the temperature dependence of τ c , that τ c scarcely changes or slightly increases with increasing temperature is reported for PP38–41 and most other polymers,11, 17, 38, 39, 42, 43 and is main stream, a reverse tendency being reported for PVC 15, 34, 44. As for the molecular weight dependence of τ c , a reduction of τ c with increasing molecular weight is reported for PP19, 29, 41, 45 and other polymers,9, 23, 29–33, 42, 44 some reports19, 20, 30 declaring τ c × M w = constant (3–4 × 10 10 Pa). Kamide et al25 report that τ c of PP is constant, independent of the molecular weight.…”

“…The die swell ratio at a constant shear rate is generally higher as the molecular weight is higher and the molecular weight distribution is broader. The former (effect of molecular weight) is reported for PP,25 PE,26, 27 HDPE,28 and polychloroprene 24, 29. The latter (effect of molecular weight distribution) is reported for PP in relation to general molecular weight distribution,19 for PE in relation to M w /M n ,27 for HDPE in relation to M w /M n ,28 and for polychloroprene in relation to M z /M w 24.…”

Rheological properties of metallocene isotactic polypropylenes

“…The increase of critical shear rate γ˙ c with increasing MFI or with decreasing molecular weight is also generally reported for PP6, 12, 13 and other polymers 11, 14–21. As for the effect of molecular weight distribution, Fujiyama et al6 found that γ˙ c increases with increasing M z / M w and is proportional to M z / M w 2 .…”

“…The die–swell ratio at a constant shear rate is generally higher as the molecular weight is higher and the molecular weight distribution is broader. The effect of molecular weight is reported for PP,5, 6 polyethylene (PE),7, 8 high‐density polyethylene (HDPE),9 and polychloroprene 10, 11. The effect of molecular weight distribution is reported for PP in relation to general molecular weight distribution12 and in relation to M w / M n and M z / M w ,6 for PE in relation to M w / M n ,8 for HDPE in relation to M w / M n ,9 and for polychloroprene in relation to M z / M w 10.…”