Structure–property relationships of nanocomposites based on polylactide and MgAl layered double hydroxides

The influence of distinct carbon based nanofillers: expanded graphite (EG), conducting carbon black (CB), thermally reduced graphene oxide (TRGO) and multi-walled carbon nanotubes (CNT) on the thermal, dielectric, electrical and rheological properties of polybutylene terephthalate (PBT) was examined. The glass transition temperature (T g ) of PBT nanocomposites is independent of the filler type and content. The carbon particles act as nucleation agents and significantly affect the melting temperature (T m ), the crystallization temperature (T c ) and the degree of crystallinity of PBT composites. PBT composites with EG show insulating behaviour over the tested concentration range of 0.5 to 2 wt.-% and hardly changed rheological behaviour. CB, CNT and TRGO induce electrical conductivity to their particular PBT composites by forming a conducting particle network within the polymer matrix. CNT reached the percolation threshold at the lowest concentration (<0.5 wt.-%), followed by TRGO (<1 wt.-%) and CB (<2 wt.-%). With the formation of a particle network, the flow behaviour of composites with CB, CNT and TRGO is affected, i.e., a flow limit occurs and the melt viscosity increases. The degree of influence of the carbon nanofillers on the rheological properties of PBT composites follows the same order as for electrical conductivity. Electrical and rheological results suggest an influence attributed to the particle dispersion, which is proposed to follow the order of EG<< CB< TRGO

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“…The degree of crystallinity was calculated from melting enthalpies by the following equation [34,35]:…”

Section: Methodsmentioning

confidence: 99%

Carbon-based nanofillers/Poly(butylene terephthalate): thermal, dielectric, electrical and rheological properties

et al. 2015

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“…The positive charge of the layers is balanced by intercalated hydrated anions [25]. Unmodified HT, as well as commercial or ad hoc modified HT, have been extensively used as filler for PLA based nanocomposites [26][27][28][29][30][31]. Nevertheless, to the best of our knowledge no work investigated how the reprocessing affects the properties of PLA/HT nanocomposites.…”

Section: Introductionmentioning

confidence: 99%

Structure-properties relationships in melt reprocessed PLA/hydrotalcites nanocomposites

Scaffaro¹,

Sutera²,

Mistretta³

et al. 2017

Express Polym. Lett.

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Abstract. In this work the effect of multiple reprocessing was studied on molecular structure, morphology and properties of poly(lactic acid)/hydrotalcites (PLA/HT) nanocomposites compared to neat PLA. In addition, the influence of two different kinds of HT -organically modified (OM-HT) and unmodified (U-HT) -was evaluated. Thermo-mechanical degradation was induced by means of five subsequent extrusion cycles. The performance of the recycled materials was investigated by mechanical and rheological tests, differential scanning calorimetry (DSC), intrinsic viscosity measurements and SEM observation. The results indicated that the best morphology was achieved in the systems incorporating OM-HT. On increasing the extrusion reprocessing cycles, the properties showed behavior due to two opposite effects: i) chain scission due to thermo-mechanical degradation and ii) filler dispersion effect resulting from multiple processing. In particular, at low reprocessing cycles, both tensile and rheological properties seem to be mainly affected by HT dispersion, especially when OM-HT was added. After five reprocessing cycles, on the contrary, chain scission, i.e. thermo-mechanical degradation, dominated. As regards the effect of the presence of organic modifier in HT, the results indicated that this variable apparently did not affect the macroscopic performance of the nanocomposites, especially at high reprocessing cycles.

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“…9 Layered double hydroxide (LDH)s can offer good flame retardancy and smoke suppression not only because of their unique chemical composition similar to aluminium hydroxide/magnesium hydroxide (ATH/MH), but also because of their flake-like morphological structure like montmorillonite (MMT). [10][11][12][13] Furthermore, some modified LDHs with intercalated flameretardant anions such as NO 2 3 and PO 32 4 enhance its flame retardancy. 14,15 Sulfamic acid (SA) and its derivatives have been documented for their flame retardancy in polymers, 16,17 and the synergistic flame retardancy of SA/MMT in PA6 has been reported by Lewin.…”

Section: Introductionmentioning

confidence: 99%

Flame retardancy and thermal and mechanical performance of intercalated, layered double hydroxide composites of polyamide 11, aluminum phosphinate, and sulfamic acid

Zhang

Tang

Jiang

et al. 2016

J of Applied Polymer Sci

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Sulfamic acid-intercalated MgAl-layered double hydroxide (SA-LDH) was prepared and added with aluminum phosphinate (AlPi) into polyamide 11 (PA11). The results showed that AlPi/SA-LDH made a positive contribution to both flame retardancy and thermostability, and the effect was demonstrated with the limiting oxygen index (LOI), vertical burning tests (UL-94), cone calorimetry (CONE), and thermogravimetric analysis (TGA). The char morphologies were observed by SEM, and its chemical composition was investigated by Fourier transform infrared spectroscopy (FTIR). The decomposition mechanism was examined by TGA-FTIR. The results showed that the LOI of PA11 was only 23.0 and cannot pass any UL-94 rating. The addition of 20% AlPi increased the LOI to 31.5 and passed the UL-94 V-1 rating, and AlPi/SA-LDH 15%/5% increased the LOI to 32.4 and also passed the UL-94 V-1 rating. The CONE results revealed that 20% of either AlPi or AlPi/SA-LDH brought about a 30% decrease in the peak heat release rate (pHRR). The contribution of SA-LDH to flame behavior was especially reflected in the postponement of pHRR. SEM showed that the char morphologies became denser after SA-LDH incorporation. The improvement in thermal stability of the AlPi/SA-LDH combination was documented by TGA in both N 2 and air atmospheres. The mechanical performance deterioration caused by AlPi was partly improved by SA-LDH. The storage modulus (E 0 ) below the T g of AlPi/SA-LDH 15%/5% was about 300 MPa higher than with 20% AlPi. This was attributed to a compatibility improvement. The interaction forces among PA11, AlPi, and SA-LDH were probed by X-ray photoelectron spectrometry.

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Structure–property relationships of nanocomposites based on polylactide and MgAl layered double hydroxides

Cited by 63 publications

References 76 publications

Carbon-based nanofillers/Poly(butylene terephthalate): thermal, dielectric, electrical and rheological properties

Carbon-based nanofillers/Poly(butylene terephthalate): thermal, dielectric, electrical and rheological properties

Structure-properties relationships in melt reprocessed PLA/hydrotalcites nanocomposites

Flame retardancy and thermal and mechanical performance of intercalated, layered double hydroxide composites of polyamide 11, aluminum phosphinate, and sulfamic acid

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