skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Insights into the thermomechanical and interfacial behaviors of polymer‐clay nanocomposites via coarse‐grained molecular dynamics simulations
Title: Insights into the thermomechanical and interfacial behaviors of polymer‐clay nanocomposites via coarse‐grained molecular dynamics simulations
Abstract Polymer‐clay nanocomposites (PCNs) are commonly applied as multi‐functional structural materials with exceptional thermomechanical properties, while maintaining the characteristics of lightweight and optical clarity. In this study, building upon previously developed coarse‐grained (CG) models for nanoclay and poly (methyl methacrylate) (PMMA), we employ molecular dynamics (MD) simulations to systematically investigate the thermomechanical properties of PCNs when arranged in stacked configurations. Incorporating stacked clay nanofillers into a polymer matrix, we systematically conduct shear and tensile simulations to investigate the influences of variations in weight percentage, system temperature, and nanoclay size on the thermomechanical properties of PCNs at a fundamental level. The weight percentage of nanoclay in nanocomposites proves to have a significant influence on both the shear and Young's modulus (e.g., the addition of 10 Wt% nanoclay leads to an increase of 32.6% in the Young's modulus), with each exhibiting greater mechanical strength in the in‐plane direction compared to the out‐of‐plane direction, and the disparity between these two directions further widens with an increase in the weight percentage of nanoclay. Furthermore, the increase in the size of nanoclay contributes to an overall modulus enhancement in the composite while the growth reaches a saturation point after a certain threshold of about 10 nm. Our simulation results indicate that the overall dynamics of PMMA are suppressed due to the strong interactions between nanoclay and PMMA, where the confinement effect on local segmental dynamics of PMMA decays from the nanoclay‐polymer interface to the polymer matrix. Our findings provide valuable molecular‐level insights into microstructural and dynamical features of PCNs under deformation, emphasizing the pivotal role of clay‐polymer interface in influencing the thermomechanical properties of the composite materials. HighlightsCG modeling is performed to explore the thermomechanical behavior of PCN.Effects of nanoclay weight percentage and size on modulus are studied.Interface leads to nanoconfinement effect onTgand molecular stiffness.Correlations between molecular stiffness and modulus are identified.Simulations show spatial variation of dynamical heterogeneity.  more » « less
Award ID(s):
1750316 2331017
PAR ID:
10523467
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
Wiley
Date Published:
Journal Name:
Polymer Composites
Volume:
45
Issue:
9
ISSN:
0272-8397
Page Range / eLocation ID:
8508 to 8526
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; (, Polymer Composites)
    Abstract This study presented the use of SrTiO3/Y2O3nanoparticles for the reinforcement of dental poly(methyl methacrylate) (PMMA) to enhance its mechanical properties important for everyday use of denture base materials. The average crystallite size of prepared nanoparticles was 19.9 nm. The influence of 0.5, 1.0, and 1.5 wt% SrTiO3/Y2O3loading on absorbed impact energy, microhardness and tensile properties was investigated. Scanning electron microscopy of the composite fracture surface revealed multiple toughening mechanisms, with agglomerates directly included in the crack pinning, indicating improvement in mechanical performance. Dynamic mechanical analysis proved that agglomerates improved the elastic behavior of PMMA and confirmed the absence of a residual monomer. After the incorporation of SrTiO3/Y2O3, the mechanical properties of composites showed a high increase compared to neat PMMA. The optimal concentration of nanoparticles was 1 wt%, for which the microhardness, modulus of elasticity, and absorbed impact energy were higher by 218.4%, 65.8% and 135.6%, respectively. With such a high increase, this research showed that SrTiO3/Y2O3represents an efficient filler which use does not have to be limited to dental materials. HighlightsSrTiO3/Y2O3hybrid nanoparticles were prepared.PMMA‐SrTiO3/Y2O3composite showed increase in impact resistance up to 135.4%.Elastic behavior of PMMA was improved.With 1 wt% of SrTiO3/Y2O3, microhardness increased by 218.4%. 
    more » « less
  2. ; ; ; ; (, Polymer Composites)
    Abstract Considering their simplicity, processibility, and tunable rheological properties, polymer composite‐type precursors hold exceptional promise in the processing of polymers, ceramics, metals, and their composites. This large variety of precursors used in many different applications cover a large compositional space with dramatically varying rheological properties. Understanding how precursor composition influences their rheological properties is a key need towards streamlining the design and implementation of these precursors. With regard to this design advancement, this study elucidates the composition‐rheology relationships of graphene‐poly(ethylene) oxide (PEO) composite inks as a sample polymer composite‐type precursor. To this end, shear and extensional rheology of numerous compositions were studied across a wide compositional space, which varied graphene concentration, total solid concentration, and binder molecular weight. These studies showed that composition greatly affected various rheological parameters, such as the overall presence of yielding behavior. Specifically, this study illustrated the influence of (i) binder structure, (ii) total solid loading, and (iii) binder‐filler interactions on ink rheology. Extensional rheology was studied to examine how relaxation behaviors were dependent on composition and explicate how relaxation behaviors coincide with responses to shear forces. In tandem, our results illuminate significant composition‐rheology relationships in polymer composite‐type precursors. HighlightsRheology of polyethylene oxide‐graphene composite precursors were studied.Shear and extensional rheology, and their correlations were investigated.Composition‐binder molecular weight‐yielding relationships were elucidated.Extensional relaxation regimes were identified with respect to composition.Results can be used to determine compositional ranges for different processes. 
    more » « less
  3. ; ; ; (, Polymer Composites)
    Abstract Polymer composites with salts or conductive fillers are promising for various solid‐state energy storage applications, where processability is often determined by their rheological properties. This study investigates the effect of lithium salts and conductive fillers on the rheological behavior of polylactic acid (PLA)‐based composites. We specifically examine how these additives influence complex viscosity and the interactions between the salt, fillers, and polymer. Our findings reveal that adding salt to the polymer reduces its viscosity, whereas adding conductive fillers imparts a shear‐thinning property, which is advantageous for thermal processing methods like thermal drawing, injection molding, or 3D printing. The combination of salt and conductive fillers results in multifunctional electrode‐electrolyte composites with enhanced shear‐thinning behavior and improved storage modulus. Characterizations through x‐ray diffraction, electrical measurements, and transmission electron microscopy link the electrical properties and morphology with rheological behavior. The formation of a robust filler network in these composites ensures stable viscoelastic behavior across a range of temperatures and frequencies, indicating their suitability for efficient manufacturing of polymer‐based solid‐state electrode‐electrolyte composites via thermal processing. HighlightsShear‐thinning behavior enhanced by conductive fillers.Viscosity increased with CB and CNT fillers, forming robust networks.Salt reduced viscosity but filler networks dominated flow behavior.Filler combinations led to stable viscoelastic properties across temperatures.Polymer electrolyte–electrode composites improved processability and storage modulus. 
    more » « less
  4. ; (, Polymer Composites)
    Abstract Despite the growing interest in flexible electronics and wearable sensors, research in piezoresistive polymer nanocomposites has stagnated in consideration of the polymer matrices, particularly in additive manufacturing (AM) applications. This research focuses on using a low‐molecular isoprene rubber (IR) as a matrix filled with carbonaceous nanoparticles conductive carbon black (CCB) and carbon nanotubes (CNT) to create piezoresistive sensors printed via direct ink writing (DIW). Using IR as a matrix not only provides an avenue for an alternate sensor matrix, but also offers a distinct advantage for retrofit sensor applications to other diene rubber substrates due to both the feedstock and substrate possessing the same vulcanization mechanism. Thereby, the rheological, mechanical, and piezoresistive properties of the IR nanocomposites are fully investigated, with emphasis on non‐ambient conditions (temperature and durability). In this work it is shown that while CCB exhibits a lower gauge factor (between 1.5 and 8) across all strain rates, strain ranges, and temperatures when compared to CNT compounds (gauge factors between 1.5 and 260), CCB compounds possess better linearity, less temperature deviation, and overall better performance under cyclic loading conditions. This is followed by demonstrations for real‐world applications, including the direct‐to‐product printing of a CCB strain gauge on a chloroprene rubber substrate. HighlightsAM via DIW of piezoresistive isoprene sensors filled with conductive CB and multi‐wall carbon nanotubes.Printed samples capable of achieving tensile strength >3.5 MPa.CB sensors showed less sensitivity, but better durability and repeatability compared to carbon nanotube filled sensors.Piezoresistive isoprene strain gauge printed on chloroprene substrate with direct adhesion. 
    more » « less
  5. ; ; ; ; (, Polymer Composites)
    Abstract Carbon‐based nanoparticles are widely regarded as promising nanofillers in nanocomposites to pursue advanced properties. To date, there has been a lack of systematic investigation into the structural variations of nanofillers and their influences on dispersion characteristics, as well as the resulting mechanical properties of nanocomposites. In this study, nanodiamond (ND), carbon nanotube (CNT), and graphene (GNP) were selected as the representative zero‐, one‐, and two‐dimensional nanofillers, respectively. A novel functionalization technique utilizing carboxymethyl cellulose (CMC) was employed to disperse nanofillers. The various characterization techniques and experimental results revealed that CMC functionalization was effective in reducing the agglomeration and improving the distribution uniformity of all three nanofillers. Among the three nanofillers, zero‐dimensional ND exhibited the most homogeneous dispersion quality in epoxy nanocomposites. The strongest abrasion resistance was found in ND‐reinforced epoxy nanocomposites, while CNT‐reinforced epoxy nanocomposites exhibited the best tensile properties. HighlightsNanodiamond with a spherical structure had better dispersion characteristics.Cylindrical carbon nanotube and planar graphene tended to agglomerate.Nanodiamond reinforced nanocomposites had better abrasion resistance.Carbon nanotube reinforced nanocomposites had better tensile properties.Carboxymethyl cellulose functionalization was valid for all three nanofillers. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Text Encoded Conversion
  • XML
  • Save / Share this Record
  • Send to Email