Intrinsic viscosity-molecular weight relations for hydrolytic polycaprolactam

In situ Polymerization Approach to Graphene-Reinforced Nylon-6 Composites

“…The intrinsic viscosity (η in ) of free PA6 was obtained from the viscosity measurements in 85% and R = 0.82). 42 Table 1 shows that the molecular weights of free PA6 samples decreased with increasing the feed fraction of GO, from 20636 for neat PA6 to 3103 g/mol for NG-10 composite. Figure 4b gives the relationship between the measured M η and the theoretic molecular weight (M th ) calculated from eq 1 with the feed percentage of GO, showing the similar decreasing tendency with increasing the feed content of GO.…”

“…To speculate the length of grafted PA6 chains on graphene sheets, we investigated the molecular weight of free PA6 collected from the supernate of NG composites solution after centrifuging. The intrinsic viscosity (η in ) of free PA6 was obtained from the viscosity measurements in 85% formic acid solution in a Ubbelohde viscometer, and the viscosity-average molecular weight ( M η ) was calculated from Mark−Houwink equation, η in = K [M η ] α (where K = 2.26 × 10 −4 and α = 0.82) . Table shows that the molecular weights of free PA6 samples decreased with increasing the feed fraction of GO, from 20636 for neat PA6 to 3103 g/mol for NG-10 composite.…”

“… a Intrinsic viscosity of free nylon-6 of NG composites, which was measured at 25 °C in 85% formic acid solution by a Ubbelohde viscometer. b The molecular weight of free PA6 thereof was calculated from Mark−Houwink equation, where K = 2.26 × 10 −4 and α = 0.82 c The residual weight percentage at 550 °C in the corresponding TGA curve. d The melting temperature measured by DSC. …”

“… b The molecular weight of free PA6 thereof was calculated from Mark−Houwink equation, where K = 2.26 × 10 −4 and α = 0.82 …”

Simulation of hydrolytic polymerization of .epsilon.-caprolactam in various reactors. A review on recent advances in reaction engineering of polymerization

“…Now, a fully automatic apparatus may also be available. The solvents used for the viscometry are concentrated sulfuric acid (11,51,71,94,99), mcresol (32,46,59,89,114), formic acid (25,51,63,98), tetrafluoropropanol-H20-LiCl (114), tricresol (97), trifluoroethanol (63), phenol-tetrachloroethane (84), ethanol-LiCl3 or LiN03 (13), and antimony trichloride (2) (concentrated sulfuric acid and formic acid are recommended in JIS relation can be expressed by the Kuhn-Mark-Houwink-Sakurada equation. In table XIV are listed the constants of the equation together with the solvents and temperatures used for the observations.…”