Synergistic effects of filler size on thermal annealing-induced percolation in polylactic acid (PLA)/graphite nanoplatelet (GNP) nanocomposites

Gao, Yuqing; Picot, Olivier T.; Zhang, Han; Bilotti, Emiliano; Peijs, Ton

doi:10.1080/20550324.2017.1333780

Cited by 15 publications

(10 citation statements)

References 54 publications

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“…Authors found, that the addition of clay, wood flour, cellulose and basalt fibers, combined with annealing lead to higher crystallinity and enhanced Young modulus, impact strength, flexural modulus and stiffness, but their flexural strength decreased [17][18][19]. Systematic effects on electrical conductivity of carbon nanotube filled polymers were observed as a function of annealing temperature and time, and this relationship was related to reorientation of nanotubes due to enhanced polymer mobility [20][21][22][23]. Moreover, electrical conductivity of hybrid nanocomposites incorporating small and large GNP fillers was found greatly improved by pre-melt annealing at elevated temperatures [23].…”

Section: Introductionmentioning

confidence: 99%

Exploring thermal annealing and graphene-carbon nanotube additives to enhance crystallinity, thermal, electrical and tensile properties of aged poly(lactic) acid-based filament for 3D printing

Kotsilkova

Petrova-Doycheva

Menseidov

et al. 2019

Composites Science and Technology

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The shelf life performance of polylactic acid (PLA) filaments for 3D printing is limited by aging mechanisms in terms of durability. In this work, the aged PLA and composite filaments filled with 12 wt% of graphene nanoplatelets (GNP), multiwall carbon nanotubes (MWCNT), and their hybrid mixture (1:1) were studied, after 24 months storage in a laboratory environment. Solid annealing at 80°C for 4 h and pre-melt annealing at 120°C for 3 h were applied in order to improve the performances of the aged filaments. It was found that the graphenecarbon nanotube fillers enhance the crystallinity, thermal stability, electrical conductivity and tensile Young's modulus, along with reduced tensile strength, elongation and toughness, compared to the neat PLA. The annealing was found efficient to substantially improve mechanical, thermal and electrical properties of the aged PLA-based composite filaments however, the annealing temperature have to be tuned according to the type of carbon nanofiller and the target properties.

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Section: Introductionmentioning

confidence: 99%

Exploring thermal annealing and graphene-carbon nanotube additives to enhance crystallinity, thermal, electrical and tensile properties of aged poly(lactic) acid-based filament for 3D printing

Kotsilkova

Petrova-Doycheva

Menseidov

et al. 2019

Composites Science and Technology

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“…A comparative crystallization study on PLA composites filled with CNTs and GNPs found that both nanofillers act as heterogeneous nucleation agents, however, the induction ability of CNTs is stronger than that of GNPs, due to the multiple orientations of PLA lamellae on the large two-dimensional flat surface of GNPs, which suppressed the crystal growth [11]. The carbon filler loading may affect the melting behavior and properties of PLA significantly, producing higher crystallinity and enhanced Young modulus, impact strength, flexural modulus, and stiffness [12]. Moreover, systematic effects on the electrical conductivity of carbon nanotube filled polymers were observed as a function of annealing temperature and time, and this phenomenon was related to the reorientation of nanotubes due to enhanced polymer mobility, that was named "dynamic percolation", as opposed to traditional statistical percolation [13].…”

Section: Introductionmentioning

confidence: 99%

Effects of Filament Extrusion, 3D Printing and Hot-Pressing on Electrical and Tensile Properties of Poly(Lactic) Acid Composites Filled with Carbon Nanotubes and Graphene

et al. 2019

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In this study, the effects of three processing stages: filament extrusion, 3D printing (FDM), and hot-pressing are investigated on electrical conductivity and tensile mechanical properties of poly(lactic) acid (PLA) composites filled with 6 wt.% of multiwall carbon nanotubes(MWCNTs), graphene nanoplatelets (GNPs), and combined fillers. The filaments show several decades’ higher electrical conductivity and 50–150% higher values of tensile characteristics, compared to the 3D printed and the hot-pressed samples due to the preferential orientation of nanoparticles during filament extrusion. Similar tensile properties and slightly higher electrical conductivity are found for the hot-pressed compared to the 3D printed samples, due to the reduction of interparticle distances, and consequently, the reduced tunneling resistances in the percolated network by hot pressing. Three structural types are observed in nanocomposite filaments depending on the distribution and interactions of fillers, such as segregated network, homogeneous network, and aggregated structure. The type of structural organization of MWCNTs, GNPs, and combined fillers in the matrix polymer is found determinant for the electrical and tensile properties. The crystallinity of the 3D printed samples is higher compared to the filament and hot-pressed samples, but this structural feature has a slight effect on the electrical and tensile properties. The results help in understanding the influence of processing on the properties of the final products based on PLA composites.

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“…Nanofillers are known to act as nucleating agents in polymer matrices, altering polymer crystallinity in the nanocomposite system and resulting in altered properties . Since PLA is a semicrystalline polymer, its mechanical properties will strongly depend on crystallinity and any observed increase in mechanical properties may therefore not be solely the result of mechanical reinforcement by the nanofillers.…”

Section: Resultsmentioning

confidence: 99%

Multilayer coextrusion of graphene polymer nanocomposites with enhanced structural organization and properties

Gao

Picot

et al. 2017

J of Applied Polymer Sci

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A potential advantage of platelet-like nanofillers as nanocomposite reinforcements is the possibility of achieving twodimensional (2D) stiffening through planar orientation of the platelets. Forced assembly by multilayer coextrusion, which enables the in-plane orientation of platelet-like fillers in alternating layers, was used in this work to produce poly(lactic acid) (PLA)/graphene multilayer films. These films exhibited a multilayer structure made of alternating layers of neat PLA and PLA containing graphite nanoplatelets (GNPs). Electron microscopy revealed information on the orientation of the individual GNPs. X-ray diffraction results indicated that the thickness of the individual GNPs was reduced during the multilayer coextrusion process. A significant reinforcement of 120% at an overall GNP loading of 1 wt % in PLA was achieved. This high effective reinforcement was attributed to the high degree of planar alignment, improved dispersion and exfoliation and increased aspect ratio of the GNPs in the composite layers after multilayer coextrusion. Improved water vapor barrier properties were also achieved as a result of the highly organized 2D nanofillers in the multilayer films. These industrial scalable multilayer nanocomposite films open up possibilities for lightweight and strong packaging materials for food and industrial applications.

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Synergistic effects of filler size on thermal annealing-induced percolation in polylactic acid (PLA)/graphite nanoplatelet (GNP) nanocomposites

Cited by 15 publications

References 54 publications

Exploring thermal annealing and graphene-carbon nanotube additives to enhance crystallinity, thermal, electrical and tensile properties of aged poly(lactic) acid-based filament for 3D printing

Exploring thermal annealing and graphene-carbon nanotube additives to enhance crystallinity, thermal, electrical and tensile properties of aged poly(lactic) acid-based filament for 3D printing

Effects of Filament Extrusion, 3D Printing and Hot-Pressing on Electrical and Tensile Properties of Poly(Lactic) Acid Composites Filled with Carbon Nanotubes and Graphene

Multilayer coextrusion of graphene polymer nanocomposites with enhanced structural organization and properties

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