Crystal Structure of Nylon 6/Inorganic Layered Silicate Nanocomposite Film.

Fujimoto, Koji; Yasukawa, Masaki; KATAHIRA, Shinichiro; Yasue, Kenji

doi:10.1295/koron.57.433

Cited by 12 publications

(6 citation statements)

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“…Therefore, no specific feature emerges by the addition of fillers. This is in contrast to polyamide nanocomposites in which a new crystalline peak appears (7) (8) . Likewise, no features appear by the filler addition both in FT-IR and DSC spectra as shown in Figs.…”

Section: Instrumental Analysesmentioning

confidence: 59%

Filler-content Dependence of Dielectric Properties of Low-Density Polyethylene/MgO Nanocomposites

et al. 2006

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Recently, polymer nanocomposites (NCs) are gaining new attraction as insulating materials, since their superior dielectric properties are being recognized. In the present paper, basic dielectric properties of NCs of low-density polyethylene (LDPE) and magnesium oxide (MgO) nano-fillers with various filler contents are examined. The samples tested were LDPE/MgO NC sheets with a thickness of about 100 µm, which contain 1, 5, and 10 phr (parts per hundred parts of resin by weight) MgO particles with average and max diameters of 50 and 200 nm, respectively. As a reference, LDPE without MgO particles was also used. Instrumental analyses were carried out by ultraviolet-visible absorption spectroscopy (UVA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) spectroscopy, and Fourier-transform infrared absorption (FT-IR) spectroscopy. Permittivity was measured at temperatures from 20 to 100 °C for frequencies from 30 to 10 5 Hz. Conduction current was measured under dc electric field of 25 kV/mm. Space charge distribution was measured at room temperature by the pulsed electroacoustic method. Optical transparency first increases by the addition of MgO fillers up to 1 to 5 phr, and then it decreases. Thermal properties and morphology are insensitive to the filler addition, as far as those analyzable by XRD, FT-IR, and DSC are concerned.

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Section: Instrumental Analysesmentioning

confidence: 59%

Filler-content Dependence of Dielectric Properties of Low-Density Polyethylene/MgO Nanocomposites

et al. 2006

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“…It is well-recognized that the presence of clay promotes the formation of the γ-phase of nylon-6. Studies indicate , that the chain axes of the γ-crystallites are parallel to the clay surfaces in thinner films. Also, either the zigzag plane of the molecule or the H-bonding sheet plane is parallel to the clay surfaces .…”

Section: Discussionmentioning

confidence: 99%

“…Also, either the zigzag plane of the molecule or the H-bonding sheet plane is parallel to the clay surfaces . The crystal growth direction is not specified; however, the model proposed by Fujimoto et al indicates growth normal to the clay surface. The generality of the foregoing studies is questioned in the study of a 3-mm-thick, injection-molded bar (mold temperature 60 °C) of an IsP NnC.…”

Section: Discussionmentioning

confidence: 99%

Solid-State NMR Investigation of Paramagnetic Nylon-6 Clay Nanocomposites. 1. Crystallinity, Morphology, and the Direct Influence of Fe³⁺ on Nuclear Spins

2001

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Several exfoliated nylon-6/clay nanocomposites (NnC's) were investigated and compared with pure nylon-6 using solid-state NMR, both proton and 13C. NnC's had nominally 5 mass % clay and were generated both by blending and by in situ polymerization (IsP). Most of the studied NnC's contained layered, naturally occurring montmorillonite clays having nonstoichiometric amounts of nonexchangeable Mg2+ and Fe3+ ions that substitute into octahedral Al3+ sites along the midplane of the 1-nm-thick clay layers. The Fe3+ ions impart a useful paramagnetism to the clay. Each Mg2+ ion leaves an embedded negative charge that must be neutralized with some cation at the surface of the clay. All clays were initially treated with a cationic so-called organic modifier (OM), often a substituted ammonium ion, which increases the clay layer spacing, attaching ionically to the surface of the clay layers. Clay is found to promote growth of the γ-crystalline phase of nylon-6 for both blended and IsP NnC's; α-crystallites are characteristic of the pure nylon-6. Stability of the γ-phase to annealing at 214 °C was investigated. Conversion of γ- to α-crystallinity during annealing was minimal, except for an injection-molded IsP NnC, which had been exposed to a temperature of 295 °C during molding. This high processing temperature produced an irreversible change. An attempt was made to understand, at least qualitatively, the nature of the spectral density of magnetic fluctuations associated with the paramagnetic Fe3+ sites in the clay. For this purpose, we looked directly at the influence of Fe3+ on the 13C and proton observables in organically modified clays (OMC). We agree with other investigators that the spectral density of paramagnetic fluctuations at the surface of the clay is determined mainly by spin-exchange interactions between Fe3+ sites; thus, the spectral density can be altered by changing the Fe3+ concentration. Moreover, we find that the spectral density is very wide, having strong contributions all the way from mid-kHz fluctuations to MHz fluctuations near the proton Larmor frequencies. Significant variations in the α/γ ratio were also observed in the injection-molded disk, which reflect either a processing-induced heterogeneity in clay dispersion or a significant variation in cooling history from region to region. Proton spin diffusion and multiple-pulse methods were utilized to compare morphologies for a diamagnetic NnC and nylon-6 with the same thermal histories. Long spacing, crystallinity, and the mobility of the noncrystalline nylon-6 segments are very similar for NnC's and nylon-6.

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“…Along with crystallization rate, disruption of crystal lamella organization also arises from the extreme H:\root108\submission\ma049768ksi20040410_084634.doc 04/10/04 4 number density of layered silicate layers which leads to excessive nucleation density as well as physically barriers to spherulitic growth 25 . Avrami indices obtained from isothermal DSC of nylon 6 -synthetic layered silicate nanocomposite indicated that the spherulites in the nanocomposites were crystallized in a two-dimensional fashion 33 . Other studies reported formation of axialites rather than spherulites 25 .…”

Section: Nylon 6 Nanocompositesmentioning

confidence: 99%

“…Low volume percent (1-5vol%) addition of layered silicate impact polymer crystallite development, having been observed in the vast majority of investigations on semicrystalline polymer PLSNs, including polypropylene -maleic anhydride polypropylene 1,2 , poly(L-lysine) 3 , PET 4,5 , sulfo-PET 4 syndiotactic-polysytene 6,7 , polyethylene-vinylacetate 8 , poly(ethylene oxide) 9 , poly (vinyl alcohol) 10 and polyamides (6,6 11 ; 10,10 12 ; 12,12 13 ). Nylon 6 nanocomposites [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] have been the most extensively studied semicrystalline nanocomposite to date, greatly facilitated by the substantial investigations available on the unfilled polymer [34][35][36][37][38][39] .…”

Section: Introductionmentioning

confidence: 99%

Isothermal Crystallization of Nylon-6/Montmorillonite Nanocomposites

2004

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The isothermal crystallization of in-situ-polymerized and melt-processed nylon-6/montmorillonite nanocomposites was studied by simultaneous small- and wide-angle X-ray scattering using synchrotron radiation. The isothermal crystallization rates, in the nucleation-controlled regime, for the nanocomposites are significantly faster than that for the pristine nylon-6 and suggest that the layered silicates act as nucleating centers. Within the experimental resolution, the initial crystal phase formed between 185 and 205 °C in the presence of the layered silicate is the metastable γ-phase, whereas the α-phase develops in the pristine nylon-6 at comparable temperatures. Additionally, the strong silicate−polymer interactions present in the in-situ-polymerized nanocomposites alter the crystallization process, creating a much weaker temperature dependence for the crystallization kinetics. Finally, the presence of well-dispersed layered silicates significantly disrupts the development of lamellar structure but does not alter the overall amounts of crystallinity.

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Crystal Structure of Nylon 6/Inorganic Layered Silicate Nanocomposite Film.

Cited by 12 publications

References 0 publications

Filler-content Dependence of Dielectric Properties of Low-Density Polyethylene/MgO Nanocomposites

Filler-content Dependence of Dielectric Properties of Low-Density Polyethylene/MgO Nanocomposites

Solid-State NMR Investigation of Paramagnetic Nylon-6 Clay Nanocomposites. 1. Crystallinity, Morphology, and the Direct Influence of Fe³⁺ on Nuclear Spins

Isothermal Crystallization of Nylon-6/Montmorillonite Nanocomposites

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Crystal Structure of Nylon 6/Inorganic Layered Silicate Nanocomposite Film.

Cited by 12 publications

References 0 publications

Filler-content Dependence of Dielectric Properties of Low-Density Polyethylene/MgO Nanocomposites

Filler-content Dependence of Dielectric Properties of Low-Density Polyethylene/MgO Nanocomposites

Solid-State NMR Investigation of Paramagnetic Nylon-6 Clay Nanocomposites. 1. Crystallinity, Morphology, and the Direct Influence of Fe3+ on Nuclear Spins

Isothermal Crystallization of Nylon-6/Montmorillonite Nanocomposites

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Solid-State NMR Investigation of Paramagnetic Nylon-6 Clay Nanocomposites. 1. Crystallinity, Morphology, and the Direct Influence of Fe³⁺ on Nuclear Spins