Determination of the weight-average molecular weight of polyamide-6 on the basis of melt viscosity

Kembłowski, Z.; Torzecki, J.

doi:10.1007/bf01332371

Cited by 9 publications

(11 citation statements)

References 27 publications

(18 reference statements)

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“…The polymer melt viscosity extremely depends on the molecular weight. There is a well-known empirical power law between the zero-shear rate viscosity η 0 and weight average molecular weight M w [ 51 , 52 , 53 ]. η 0 = KM w α …”

Section: Resultsmentioning

confidence: 99%

Resin Transfer Moldable Fluorinated Phenylethynyl-Terminated Imide Oligomers with High Tg: Structure–Melt Stability Relationship

Hong

Yuan

et al. 2021

Polymers

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Phenylethynyl-terminated aromatic polyimides meet requirements of resin transfer molding (RTM) and exhibits high glass transition temperature (Tg) were prepared. Moreover, the relationship between the polyimide backbones structure and their melting stability was investigated. The phenylethynyl-terminated polyimides were based on 4,4’-(hexafluorosiopropylidene)-diphthalic anhydride (6FDA) and different diamines of 3,4’-oxydianiline (3,4’-ODA), m-phenylenediamine (m-PDA) and 2,2’-bis(trifluoromethyl)benzidine (TFDB) were prepared. These oligoimides exhibit excellent melting flowability with wide processing temperature window and low minimum melt viscosities (< 1 Pa·s). Two of the oligoimides display good melting stability at 280–290 °C, which meet the requirements of resin transfer molding (RTM) process. After thermally cured, all resins show high glass transition temperatures (Tgs, 363–391 °C) and good tensile strength (51–66 MPa). The cure kinetics studied by the differential scanning calorimetry (DSC), 13C nuclear magnetic resonance (13C NMR) characterization and density functional theory (DFT) definitely confirmed that the electron-withdrawing ability of oligoimide backbone can tremendously affect the curing reactivity of terminated phenylethynyl groups. The replacement of 3,4’-ODA units by m-PDA or TFDB units increase the electron-withdrawing ability of the backbone, which increase the curing rate of terminated phenylethynyl groups at processing temperatures, hence results in the worse melting stability.

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Section: Resultsmentioning

confidence: 99%

Resin Transfer Moldable Fluorinated Phenylethynyl-Terminated Imide Oligomers with High Tg: Structure–Melt Stability Relationship

Hong

Yuan

et al. 2021

Polymers

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“…Furthermore, considering the analogy in chemical structure of PA6 and PCL, one should expect similar dependence of the melt viscosity on molecular weight and temperature. In the range of weight‐average molecular weight M w = 20–40 kDa, PA6 and PCL have about the same viscosity just above their respective melting point, that is, T f ° ≈ 260°C for PA6 in the α crystal form [ 153,154 ] as compared to T f ° ≈ 65°C for PCL. [ 155,156 ] However, considering the strong temperature‐dependence of polymer viscosity, one can estimate PCL viscosity to be about one hundred times lower than that of PA6 at the same temperature T = 260°C, for the same molecular weight.…”

Section: Influence Of H‐bonds On Chain Mobility and Thermodynamic Promentioning

confidence: 99%

Overview and critical survey of polyamide6 structural habits: Misconceptions and controversies

Séguéla

2020

Journal of Polymer Science

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Various aspects of the structural habits and associated thermodynamic properties of polyamide6 are critically examined with regard to controversies that appeared in literature mainly due to misconceptions or erroneous/ambiguous interpretations of experimental findings. The structural habits under concern are the crystallization capabilities and chain topology, hydrogen bonds and sheet-like structure, crystalline polymorphism together with thermodynamic stability. Thermo-mechanical properties are also discussed for the sake of complementary argumentation. Comparisons are made with polycaprolactone, that is, the polyester homolog of polyamide6 regarding chain structure, in order to evaluate the actual role of the H-bonds on the structural habits. Additional comparisons with polyethylene and polypropylene are also made at several occasions for the sake of supporting argumentation on the structural behavior of polyamide6. A temperature-time-transformation diagram of polyamide6 is finally proposed from the gathering of plentiful literature data.

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“…The rheological properties of entangled polymer melts depend strongly on the polymer molecular weight, because molecular relaxation times increase rapidly with increasing molecular weight. It has been proposed20 that where $M_{{\rm w}} $ is the weight‐average molecular weight of the polymer (kg/kgmol) and $\eta _{0} $ is the zero‐shear‐rate viscosity of the polymer. If a relationship develops between two molecular weights $M_{{\rm w}_{1} } $ and $M_{{\rm w}_{2} } $ of a material with different zero‐shear‐rate viscosities, then the following equation applies: where $\eta _{0_{1} } $ and $\eta _{0_{2} } $ are the corresponding viscosity values.…”

Section: Resultsmentioning

confidence: 99%

Melt‐compounded nanocomposites of titanium dioxide atomic‐layer‐deposition‐coated polyamide and polystyrene powders

Nevalainen

Isomäki

Honkanen

et al. 2011

Polymers for Advanced Techs

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Polyamide and polystyrene particles were coated with titanium dioxide films by atomic layer deposition (ALD) and then melt-compounded to form polymer nanocomposites. The rheological properties of the ALD-created nanocomposite materials were characterized with a melt flow indexer, a melt flow spiral mould, and a rotational rheometer. The results suggest that the melt flow properties of polyamide nanocomposites were markedly better than those of pure polyamide and polystyrene nanocomposites. Such behavior was shown to originate in an uncontrollable decrease in the polyamide molecular weight, likely affected by a high thin-film impurity content, as shown in gel permeation chromatography (GPC) and scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer. Transmission electron microscope image showed that a thin film grew on both studied polymer particles, and that subsequent melt-compounding was successful, producing well dispersed ribbon-like titanium dioxide with the titanium dioxide filler content ranging from 0.06 to 1.12 wt%. Even though we used nanofillers with a high aspect ratio, they had only a minor effect on the tensile and flexural properties of the polystyrene nanocomposites. The mechanical behavior of polyamide nanocomposites was more complex because of the molecular weight degradation. Our approach here to form polymeric nanocomposites is one way to tailor ceramic nanofillers and form homogenous polymer nanocomposites with minimal work-related risks in handling powder form nanofillers. However, further research is needed to gauge the commercial potential of ALD-created nanocomposite materials.

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Determination of the weight-average molecular weight of polyamide-6 on the basis of melt viscosity

Cited by 9 publications

References 27 publications

Resin Transfer Moldable Fluorinated Phenylethynyl-Terminated Imide Oligomers with High Tg: Structure–Melt Stability Relationship

Resin Transfer Moldable Fluorinated Phenylethynyl-Terminated Imide Oligomers with High Tg: Structure–Melt Stability Relationship

Overview and critical survey of polyamide6 structural habits: Misconceptions and controversies

Melt‐compounded nanocomposites of titanium dioxide atomic‐layer‐deposition‐coated polyamide and polystyrene powders

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