Should polymer nanocomposites be regarded as molecular composites?

Marom, G.; Wagner, H. Daniel

doi:10.1007/s10853-017-1113-7

Cited by 32 publications

(12 citation statements)

References 18 publications

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“…Thereby, asphaltenes act as reinforcing particles at the room temperature, and as plasticizers at elevated ones. Wherein, the mixture containing 10 wt% of asphaltenes can be considered as an example of a molecular nanocomposite, [ 77‐79 ] since the size of both asphaltene molecules and their nanoaggregates is of the order of a few nanometers and the asphaltenes are dissolved in the medium of block copolymer (ie, deagglomerated to a nanoscale level). At higher asphaltene content, the strength decreases to its initial value, probably due to the agglomeration of asphaltenes.…”

Section: Resultsmentioning

confidence: 99%

Asphaltenes as a tackifier for hot‐melt adhesives based on the styrene‐isoprene‐styrene block copolymer

Ignatenko

Kostyuk

Смирнова

et al. 2020

Polymer Engineering & Sci

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The use of heavy crude oil asphaltenes and resins (termed asphaltenes) as the components of hot‐melt adhesives based on the styrene‐isoprene triblock copolymer was considered. The rheological, thermophysical, strength, and adhesive characteristics of the mixtures containing from 10 to 40 wt% of asphaltenes were studied. The addition of 10 to 20 wt% of asphaltenes enhanced the strength and adhesive properties of the mixtures and only slightly changed their rheology. The higher concentrations of asphaltenes reduced the viscosity of the mixtures but did not lead to improved characteristics of the adhesives. The ambiguous effect of asphaltenes is probably due to their uneven distribution between the microphases of the block copolymer as well as their ability to act both plasticizers and reinforcing particles depending on temperature. A comparison of asphaltenes and conventional tackifiers based on hydrocarbon resins revealed their comparable effect on the properties of the block copolymer.

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Section: Resultsmentioning

confidence: 99%

Asphaltenes as a tackifier for hot‐melt adhesives based on the styrene‐isoprene‐styrene block copolymer

Ignatenko

Kostyuk

Смирнова

et al. 2020

Polymer Engineering & Sci

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“…An obvious way forward is to adapt the continuum mechanics theories developed for macroscopic composites, such as those reinforced by carbon or glass fibers, to composites at the nanoscale. Some researchers have taken an opposing viewpoint and have suggested that polymer nanocomposites are actually quasi-homogeneous molecular blends that should be regarded as molecular composites or self-reinforced compo-sites (12,13) and that the properties are controlled by interactions on the molecular scale between the nanoparticles and the polymer matrix.…”

Section: (A)mentioning

confidence: 99%

Composites with carbon nanotubes and graphene: An outlook

Kinloch

Suhr

Lou

et al. 2018

Science

732

388

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Composite materials with carbon nanotube and graphene additives have long been considered as exciting prospects among nanotechnology applications. However, after nearly two decades of work in the area, questions remain about the practical impact of nanotube and graphene composites. This uncertainty stems from factors that include poor load transfer, interfacial engineering, dispersion, and viscosity-related issues that lead to processing challenges in such nanocomposites. Moreover, there has been little effort to identify selection rules for the use of nanotubes or graphene in composite matrices for specific applications. This review is a critical look at the status of composites for developing high-strength, low-density, high-conductivity materials with nanotubes or graphene. An outlook of the different approaches that can lead to practically useful nanotube and graphene composites is presented, pointing out the challenges and opportunities that exist in the field.

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“…The iPP/0.5%-VGCF nanocomposite in itself exhibited higher values than the neat iPP, showing the best dispersion of fully exfoliated single nanofibers with no aggregates. These well dispersed individual nanofibers of high aspect ratio could increase the energy by the classical debonding/fiber breakage/pull-out mechanism of fiber reinforced composites [10,20]. Conversely, the iPP/0.5%-GNP nanocomposite contained GNP aggregates of micro dimension, which contributed to the improvement of the fracture energy by the classical mechanism of crack-front pinning at adjacent particles and bowing away from them to increase the crack front surface area [21].…”

Section: Discussionmentioning

confidence: 99%

“…This finding reflects mainly the tensile strength and Young's modulus, where nanosystems suffer from aggregation, which impairs load transfer. This state may be different for the fracture toughness, which increases through mechanisms other than load transfer, e.g., crack front bowing and pull out [10,11]. Based on these findings, we examined the effect of geometry and chemical structure of the nanofillers on the fracture energy, and possible hybrid effects of hybrid systems comprised of isotactic polypropylene with different nanofillers.…”

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confidence: 99%

The Effects of Geometry and Chemical Composition of Nanoparticles on The Fracture Toughness of iPP Nanocomposites

Stern

Marom

2020

J. Compos. Sci.

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This research deals with possible hybrid effects in the fracture energy of hybrid nanocomposites while taking a critical approach toward the currently-prevailing engineering practice of applying classical composite micromechanics to nanocomposites. For this purpose, different nanoparticles were embedded in an isotactic polypropylene matrix. The particles had different geometries (fibrous and platelets) and different chemical structures (organic vapor grown carbon nanofibers (VGCF); graphene nanoplatelets (GNP); and inorganic nanoclays, SiO 2 nanofibers, and ZrO 2 nanofibers). Almost all the composite systems presented improvements in the fracture energy, whereas the iPP/VGCF/GNP presented a positive hybrid effect. The main conclusion was that each nanocomposite system should be analyzed individually according to the constituent properties; the quality of the dispersion; and, primarily, by the type of interaction between the particles and the matrix.(CNCs) and organically modified montmorillonite (OMMT). The total filler composition was 4%, with a ratio of 1:1 among the fillers. This led to the highest tensile strength and Young's modulus [5].Another property that can present a hybrid effect is toughness, as was demonstrated in our previous work; here, the PVB (polyvinyl butyral) that contained both surface-treated CNT and nanoclay introduced an improvement of 181% versus neat PVB [6]. El Miri et al. produced a system of PVA with cellulose nanocrystals (CNC) and graphene oxide nanosheets (GON). The sample that contained 5% filler in the ratio of 1:2 CNC:GON presented an improvement of 159% in toughness, 124% in tensile test, and 320% in Young's modulus [7]. Valentini et al. studied ethylene-propylene-diene terpolymer rubber (EPDM) with carbon black (CB) and graphite nanoplatelets (GNPs). The presence of both fillers enhanced the Young's modulus, maximum strength, damping, and thermal conductivity [8]. Saharudin et al. analyzed a composition of halloysite nanotubes (HNTs) and CNT embedded in epoxy. The hybrid set demonstrated the highest percentage of improvement: 45% for tensile strength, 49% for Young's modulus, 46% for flexural strength, 17% for flexural modulus, and 125% for fracture toughness [9].Despite these significant improvements achieved by nanofillers, we found that the nanocomposite systems failed to reach their theoretical values of mechanical properties as predicted by the models of micromechanics. This finding reflects mainly the tensile strength and Young's modulus, where nanosystems suffer from aggregation, which impairs load transfer. This state may be different for the fracture toughness, which increases through mechanisms other than load transfer, e.g., crack front bowing and pull out [10,11]. Based on these findings, we examined the effect of geometry and chemical structure of the nanofillers on the fracture energy, and possible hybrid effects of hybrid systems comprised of isotactic polypropylene with different nanofillers. We divided the fillers into two groups: The first group comprised par...

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Should polymer nanocomposites be regarded as molecular composites?

Cited by 32 publications

References 18 publications

Asphaltenes as a tackifier for hot‐melt adhesives based on the styrene‐isoprene‐styrene block copolymer

Asphaltenes as a tackifier for hot‐melt adhesives based on the styrene‐isoprene‐styrene block copolymer

Composites with carbon nanotubes and graphene: An outlook

The Effects of Geometry and Chemical Composition of Nanoparticles on The Fracture Toughness of iPP Nanocomposites

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