An Unusual Crystallization Behavior in Polyamide 6/Montmorillonite Nanocomposites

Wu, Qiuju; Liu, Xiaohui; Berglund, Lars A.

doi:10.1002/1521-3927(20011101)22:17<1438::aid-marc1438>3.0.co;2-u

Cited by 93 publications

(69 citation statements)

References 11 publications

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“…The incorporation of 20 wt.% kenaf fiber alone resulted in a considerable decrease in percent crystallinity, and the lower percent crystallinity was partially explained by the restriction of polymer chains (Fornes and Paul 2003). A similar effect was reported in clay-Nylon 6 composites (Wu et al 2001;Fornes and Paul 2003).…”

Section: Resultssupporting

confidence: 82%

“…where ∆Hf is the heat of fusion of the PA 6 and PA 6-based NFCs, ∆Hf ̊ the heat of fusion for 100% crystalline PA 6 (∆H100=190 J/g), and ω is the mass fraction for PA 6 in the composites (Wu et al 2001). TGA measurements were performed using a Mettler Toledo analyzer (Columbus, OH, USA), and each 10 mg sample was scanned from room temperature to 600 °C at a heating rate of 10 °C/min under nitrogen flow (20 mL/min) to prevent sample oxidation.…”

Section: Methodsmentioning

confidence: 99%

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Thermal Analysis of Polyamide 6 Composites Filled by Natural Fiber Blend

Kiziltas¹,

Han²,

Kızıltaş³

et al. 2016

BioResources

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aThis study describes changes in the viscoelastic and thermal properties of composites made with various percentages (up to 20 wt.%) of a natural fiber blend (a mixture of flax, kenaf, and hemp fibers) and polyamide 6 (PA 6). According to the differential scanning calorimetry (DSC) analyses, the incorporation of natural fibers produced minor changes in the glass transition (Tg), melting (Tm), and crystallization temperature (Tc) of the PA 6 composites. Because of the reinforcing effect of natural fibers, the storage modulus (E') from dynamic mechanical thermal analysis (DMTA) increased as the natural fiber content increased. The E' values at room temperature and Tg were 3960 MPa and 1800 MPa, respectively, with the incorporation 20 wt.% fiber, which were 68% and 193% higher than the E' value of neat PA 6. As the natural fiber content increased, the thermal stability of the composites decreased, and thermogravimetric analysis (TGA) showed that the onset temperature of rapid thermal degradation decreased from around 440 (neat PA 6) to 420 °C (20 wt.% natural fiber blend). The addition of 20 wt.% single type fibers showed comparable DSC and TG results to the incorporation of 20 wt.% natural fiber blends.

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Section: Resultssupporting

confidence: 82%

Section: Methodsmentioning

confidence: 99%

Thermal Analysis of Polyamide 6 Composites Filled by Natural Fiber Blend

Kiziltas¹,

Han²,

Kızıltaş³

et al. 2016

BioResources

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“…It is interesting to observe that the new peaks on the exotherms of PA6/graphite composites appear at higher temperature with the increasing amount of graphite content. Similar appearance of exotherms with double peaks in PA6/MWNTs composites was reported before [42][43][44]. The appearance of higher crystallization temperature is related to the increase of graphite content.…”

Section: Dsc Measurementssupporting

confidence: 86%

Synergistically improved thermal conductivity of polyamide-6 with low melting temperature metal and graphite

Jia¹,

He²,

Yu³

et al. 2016

Express Polym. Lett.

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Abstract. Low melting temperature metal (LMTM)-tin (Sn) was introduced into polyamide-6 (PA6) and PA6/graphite composites respectively to improve the thermal conductivity of PA6 by melt processing (extruding and injection molding). After introducing Sn, the thermal conductivity of PA6/Sn was nearly constant because of the serious agglomeration of Sn. However, when 20 wt% (5.4 vol%) of Sn was added into PA6 containing 50 wt% (33.3 vol%) of graphite, the thermal conductivity of the composite was dramatically increased to 5.364 versus 1.852 W·(m·K) -1 for the PA6/graphite composite, which suggests that the incorporation of graphite and Sn have a significant synergistic effect on the thermal conductivity improvement of PA6. What is more, the electrical conductivity of the composite increased nearly 8 orders of magnitudes after introducing both graphite and Sn. Characterization of microstructure and energy dispersive spectrum analysis (EDS) indicates that the dispersion of Sn in PA6/graphite/Sn was much more uniform than that of PA6/Sn composite. According to Differential Scanning Calorimetry measurement and EDS, the uniform dispersion of Sn in PA6/graphite/Sn and the high thermal conductivity of PA6/graphite/Sn are speculated to be related with the electron transfer between graphite and Sn, which makes Sn distribute evenly around the graphite layers.

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“…For many polymers including polypropylene [18][19][20], polyoxymethylene [21], poly(ethylene terephthalate) [22], poly(butylene terephthalate) [23], poly(butene-1) [24], but in particular polyamides [25][26][27][28][29][30][31][32][33][34], it has been shown that addition of nanofillers often enhance crystallization and even support the formation of specific crystal polymorphs. In fewer cases, however, a retardation of the crystallization process has also been reported, likely due to an immobilization of polymer chain segments at the polymer/nanofiller interface [35,36].…”

Section: Introductionmentioning

confidence: 99%

Crystallization kinetics of polyamide 11 in the presence of sepiolite and montmorillonite nanofillers

2016

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The crystallization kinetics of polyamide 11 (PA 11) in presence of sepiolite and organomodified montmorillonite nanofillers has been studied in a wide range of temperatures and cooling rates by conventional differential scanning calorimetry (DSC) and fast scanning chip calorimetry (FSC). The presence of the nanofillers has a negligible effect on the crystallization temperature of PA 11 at low cooling rates. However, at rapid cooling conditions a distinct nucleating effect of the nanofillers is detected. The critical cooling rate to suppress crystallization increases from 600 K s -1 to about 1000 and 3000 K s -1 in nanocomposites containing sepiolite and montmorillonite, respectively. Regardless the cooling rate applied for solidification the melt, in the nanocomposites the crystallinity of PA 11 is 5 to 10 % higher than in neat PA 11, with the highest values obtained for the montmorillonite-containing system. The nucleating effect of the nanofillers onto the crystallization of the PA 11 is confirmed by analysis of the half-times of isothermal crystallization, and by analysis of the spherulitic superstructure. All measurements proved a saturation of the nucleation efficiency at a loading of the nanofiller of 2.5 m%.

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An Unusual Crystallization Behavior in Polyamide 6/Montmorillonite Nanocomposites

Cited by 93 publications

References 11 publications

Thermal Analysis of Polyamide 6 Composites Filled by Natural Fiber Blend

Thermal Analysis of Polyamide 6 Composites Filled by Natural Fiber Blend

Synergistically improved thermal conductivity of polyamide-6 with low melting temperature metal and graphite

Crystallization kinetics of polyamide 11 in the presence of sepiolite and montmorillonite nanofillers

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