Filler Interaction Research Articles

NITROGEN-CONTAINING SILANE COUPLING AGENTS: SYNTHESIS AND STRUCTURE EFFECT ON TIRE PERFORMANCE OF SILICA/SSBR/BR COMPOSITES

ABSTRACT We report synthesis of nitrogen-containing silane coupling agents (N-SCAs) and their use in a 1:1 mixture by weight with bis(triethoxysilylpropyl)tetrasulfide preparation of silica/solution SBR (SSBR)/BR composites. These N-SCAs contain in their structures, inter alia, a tertiary amine center (N1, N2), a carbamate (N3), or a urea (N4) group. In addition, N1, N3, and N4 were equipped with allyl side arms to increase the hydrophobization effect of silica particle as well as to achieve a balance between the filler–filler and filler–matrix networks being formed. By contrast, N2 consists of glycidyl side arms that contribute to the filler–filler interaction even more. The silica/SSBR/BR blends and subsequent vulcanizates were prepared and then thoroughly investigated via dynamic mechanical analysis, rubber process analysis, and tensile testing. The composite based on N1 (V/N1) exhibited exceptionally great tensile strength, abrasion resistance, and winter traction, accompanied by soft hysteresis. Therefore, N1 has potential applications in preparation of winter tire tread materials.

The structural, mechanical, optical and dielectric properties of aminated PMMA-Ag-GO nanocomposite for coatings

The present study reports the synthesis and characteristics of an aminated PMMA-Ag-GO polymer nanocomposite (PNGAg) for coatings. The XRD diffractogram data indicated the presence of crystallinity in samples. The lattice strain of (002) planes and crystallite size were computed to estimate the number of graphene oxide (GO) layers. The homogenous dispersion of GO with silver (Ag) nanoparticles over the surface of the samples was verified by the SEM and EDAX tests. The thermal stability and interaction of fillers with aminated PMMA is confirmed by of TGA–DTA and FTIR analysis. Moreover, the substantial shift of FTIR bands supports the bonding of functional groups with Ag decorated GO and the stability of nanocomposite. The estimated mechanical properties like flexural strength and composite modulus (> 90 MPa) supported the applicability of PNGAg as coatings. The UV–Vis spectroscopy evidenced the characteristic absorption peaks of GO in line with range of UVC radiation in aminated PMMA. Along with high values of relative permittivity, the shift of loss tangent maxima to higher end with increase in GO concentration is attributed to greater number of interfaces. Owing to the functionalisation by naproxen along with dispersion of GO, contributed to MWS polarisation and hence strengthen the dielectric properties. As the concentration of GO rises from 0.1 mol% to 0.7 mol%, substantial shift of AC conductivity (i.e. 2.49 × 10−6 Scm−1 to 37.9 × 10−6 Scm−1) is observed. The high conductivity of PNGAg5 at 0.9 mol% GO suggests the presence of numerous layers, leading to increased interfacial polarization and a higher dielectric constant. In addition to that, the semi-circle in impedance plot and bulk resistance also supported the optimal dielectric properties of samples. As a whole, the results have shown that PNGAg nanocomposites are good coating materials for wide variety of devices.

Application of wet carbon black masterbatch in green mining radial tires

AbstractIn the context of environmental protection and energy consumption reduction, reducing the rolling resistance of mining machinery tires is one of the important methods to achieve the goal of green mining. This study probes the effects of wet mixing with a wet carbon black masterbatch on the rolling resistance and grounding performance of wide‐body vehicle tire treads by investigating the cross‐linking structure, rubber–filler (R–F) interaction force, and physicomechanical properties of the wet mixing rubber compounded with a wet carbon black masterbatch. The results indicate decreases in the maximum torque‐minimum torque difference, cross‐link density, and R–F interaction of the wet mixing rubber and increased filler–filler (F–F) interaction and carbon black dispersion. Meanwhile, the tensile elongation of the wet mixing rubber increases, its DIN abrasion property improves, and its Tanδ decreases at 60°C. A numerical method to estimate tire steady‐state rolling resistance is also developed. Finite element simulation analysis reveals that the steady‐state rolling resistance of the wet mixing rubber is reduced by 7.04% at 100% standard load, and its grounding performance is enhanced. By proposing a method to reduce the rolling resistance of tires, this study also provides a reference for the development of wide‐body vehicle tires.Highlights Explored the filler interaction of wet mixing rubber. Explained the low energy loss of wet mixing rubber. Proposed a new finite element method for calculating tire rolling resistance.

Graphene/MXene/Cellulose cellulosic paper-based flexible bifunctional sensors utilizing molecular bridge strategy with tunable piezoresistive effect for Temperature-Pressure sensing

Wearable technology is changing the way we interact with the digital world. Wearable systems can enable a smarter lifestyle when connected to other smart devices. This work reports a bifunctional sensor prepared from cellulosic paper as substrate for response to both temperature and pressure. The introduction of CMC-Na improves the dispersion of the binary hybrid conductive fillers in the deionized water. Meanwhile, relying on the intermolecular forces of both hydrogen bonding and cation-π interaction, the interfacial interactions of the binary hybrid conductive fillers are strengthened, which is anticipated to create a stable and homogenous conductive layer. And the concept of “effective conductive fillers distribution density” is introduced to explain and analyze the pressure sensing mechanism. The reported sensor has a pressure sensitivity of −1.6189 %/kPa, a sensing range of 370 kPa, and a response recovery time of 37.5 ms/37.5 ms. In addition to its response to mechanical force, the sensor has a detecting range of 23–58 °C, a response recovery time of 325 ms/1000 ms, and a temperature coefficient of resistance (TCR) of −1.77 %/°C. The potential applications of this sensor demonstrate the excellent gesture tracking characteristics, multi-point tactile sensing capability, and dual stimulus–response of the sensor.

Investigation of thermodynamically induced nanoparticle localization in Poly(vinylidene fluoride)/Poly(lactic acid) blends with surface-grafted carbon nanotubes

Physically anchoring multi-walled carbon nanotubes (MWCNT) onto the polymer blend interface has been extensively investigated, however, the tunable localization of polymer grafted MWCNT in immiscible polymer blends is seldom reported. Herein, poly(methyl methacrylate) (PMMA) grafted MWCNT (PMMA-g-MWCNT) were nondestructively prepared via the surface-initiated atom transfer radical polymerization. The compatibilization effects of PMMA-g-MWCNT on morphology and mechanical properties of blend composites are investigated. The results demonstrate that the fillers are distributed at the blend interface due to the high affinity between PMMA and PVDF. The interaction between PMMA and PLA changes the crystallinity of blends. Moreover, the surface modification of MWCNT enhances the interaction of filler and matrix, and the elongation at break is as high as 52 % for composites with 10 % PMMA-g-MWCNT. The fracture surface of specimen after tensile tests exhibits an obvious ductile transition with filler contents. This work systematically discussed the relationship between the PMMA-g-MWCNT distribution and the mechanical strength of composites, which provided a solid experimental foundation on the toughening mechanism of PMMA-g-MWCNT used as a compatibilizer for PVDF/PLA blends.

Impact of proximity of hard and soft segment on IR frequency of carbamate links correlating the mechanical properties of surface-functionalized fly ash–reinforced polyurethane composites

Abstract Polyurethane composites synthesized by interaction of fly ash filler with polyether polyol, cross-linking agent, and curing agent in a certain ratio. The study’s findings show that the mechanical properties of polyurethane composite are lowered by the hydroxyl moieties of surface-functionalized fly ash that are chemically or physically linked. The study also reveals that prior subjecting the samples of surface-functionalized fly ash–reinforced polyurethane composite material for destructive analysis by UTM for evaluating mechanical properties. The in-depth study of the IR spectroscopy data of the composites is done focusing onto the stretching frequency of carbonyl group of carbamate links the trend in mechanical behavior of the samples, the number of fly ash–carbamate links, and proximity of HS–SS (hard segment–soft segment) of fly ash–reinforced polyurethane composites can be foretold. By a detailed analysis of the patterns of carbonyl stretching frequencies of carbamate links, one can gain insight into the microphasic level of the separation and proximity of hard and soft segments in composites, which govern their mechanical properties. The relationships between carbamate carbonyl stretching frequencies and mechanical characteristics of composites have been found to be inversely correlated. In order to offset the excess hydroxyl group contribution due to OH-loaded fly ash, as indicated by the isocyanate (NCO) peak intensity (2,240–2,280 cm−1) in the composite’s infrared spectra, the studies were conducted at a higher index ratio (1.64).

Rational design of semi-interpenetrating network based on hyperbranched polyglycerol grafted MXene/polyurethane–epoxy for compressed hydrogen storage

Hydrogen (H2) energy has emerged as a promising alternative in the automotive sector to replace fossil fuel; however, its storage with volumetric efficiency remains a challenge. The latest type IV storage vessel featuring a polymeric liner with composite overwrap incurs hydrogen saturation, which eventually causes failure. To prevent the H2 dissolution in the liner, we have developed a barrier coating comprised of polyurethane/epoxy semi-interpenetrating network (S-IPN) combined with hyperbranched polyglycerol grafted MXene (h-MXene). The hyperbranched structure facilitated the dispersion of MXene in the coating solution by enhancing the exfoliation and improved the polymer filler interaction by forming covalent and H-bonding through end-terminal hydroxyl groups. Leveraging the dense network of S-IPN combined with the dispersed layer structured h-MXene significantly increased the tortuosity of the spray-coated barrier film applied to the nylon 6 liner. The coating exhibited a 90 % reduction in the H2 gas permeability at only 2 wt% h-MXene concentration, which further improved to above 98 % at 10 wt% loading. Additionally, the h-MXene considerably improved the adhesion with the liner even in a highly stretched condition, signifying the durability of the coating under cyclic pressurization and depressurization of the storage vessel.

Influence of silane-modified palm oil as a green processing oil in silica-reinforced SBR/BR compounds for tire tread applications

This study focuses on the usage of silane-modified palm oil (Si-m-PO) to replace petroleum-based processing oils, i.e., distillate aromatic extract (DAE) and treated distillate aromatic extract (TDAE), in silica-reinforced styrene butadiene rubber/butadiene rubber (SBR/BR) compounds for green tire tread products. The preparation of a novel processing oil based on Si-m-PO was successful on the laboratory scale, as verified by nuclear magnetic resonance, where the grafting efficiency of silane in oil molecules was 58%. Among the different types of processing oils, the presence of Si-m-PO in the compounds resulted in lower filler-filler interactions than the ones with TDAE and unmodified PO but higher than DAE. The Si-m-PO showed an effective reduction in filler–filler interaction compared to unmodified PO, possibly because the Si-m-PO could cover silica surfaces via silane linkage, leading to hydrophobicity of silica surfaces. Overall, the compounds containing Si-m-PO represented higher mechanical properties than the other oils. Furthermore, the Si-m-PO provided the same level concerning rolling resistance and enhanced wet traction, when compared to unmodified PO. Therefore, Si-m-PO can be applied as a biobased processing oil in tire tread applications.

Influence of the number of end-chain amine-functionalized arms of star-shaped functionalized SBR

Star-shaped SBRs with alkoxy silyl groups in the center of the molecule and amine groups at the polymer chain ends were prepared. The number of arms were varied, and its influence on the silica/silane-filled compound properties was investigated. The polymer–filler interactions and the filler–filler interactions were evaluated from the viscoelastic properties. The flocculation, tensile properties and tanδ at 60 °C, an indicator of rolling resistance, were investigated as well. The polymer–filler interactions were increased in the SBR with a higher number of arms due to the higher amount of amine groups in these SBRs. The Payne effect was slightly increased with a higher number of arms. This indicates a deteriorated micro-dispersion of the silica caused by too many interactions generated by the higher amount of amine groups in SBR. These high interactions due to the amine groups lead to higher tensile moduli. The combination of the higher polymer–filler interactions and the higher Payne effect in SBR with a high number of arms results in the same tanδ compared to the SBR with a low number of arms.

Construction of silver-epoxy adhesive with suppressed silver migration rate based on thiol-silver interaction

The silver migration limits the application of silver based conductive adhesives in wet environment. The existing methods for inhibiting silver migration in epoxy conductive silver adhesives involve one or more issues such as cost, complexity, and inhibition of conductivity. Moreover, there is currently a lack of strategies that can suppress the silver migration effect while ensuring good dispersion of silver fillers in the matrix and constructing a good filler matrix interface. Herein, a facile method was reported suppressing the silver migration in silver-epoxy conductive adhesive. Tetrafunctional thiopentaerythritol tetramercaptoacetate (PERTMA) was introduced into 1,4-cyclohexanedimethanol diglycidyl ether (CHDMGE) epoxy resin as the curing agent. This method utilized the strong interaction between silver and thiols, including coordination and covalent bonding, to achieve good compatibility between filler and matrix. By tightly combining silver with the resin system, the content of free silver atoms was reduced, capturing and inhibiting the hydrolysis of silver atoms and their migration with current, and the conductivity of the conductive silver adhesive was not greatly degraded due to the silver-thiol interaction. At the same time, the introducing of PERTMA was able to reduce the surface hydrophilicity of epoxy resin, which also helped suppressing the silver migration effect under humid circumstances. The interaction between silver and thiol was characterized, and the influence of silver content on the curing behavior, material mechanical performance, conductivity, resistivity on silver migration and flexibility was explored. The CHDMGE/PERTMA/Ag conductive adhesive based on strong thiol-silver interaction had excellent resistance to silver migration, which occurred after 3500s, which was 10.67 times longer than the control group. In addition, the silver filler enhanced the tensile strength of the matrix resin by this thiol-silver interaction. This study will provide new ideas for the design and development of silver migration resistant conductive adhesives based on matrix filler interaction.

New role of ionic liquid as accelerator activator in rubber compounds and its influence on curing and mechanical properties

AbstractThis study focuses on the effect of ionic liquids (ILs) on the cure characteristics and filler dispersion of natural rubber (NR) and styrene‐butadiene rubber (SBR) gum and filled compounds. The complexation of ionic liquid with zinc oxide (ZnO) increases the activity of ZnO and the cure rate together with improved filler dispersion. This has also increased the rubber filler interaction. Imidazolium and chloride based ionic liquids with different cationic groups were compared and characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, and differential scanning calorimetry to understand the thermal and chemical behavior of the compounds. Interestingly, it was found that the ionic liquid can act as an activator and is able to accelerate the vulcanization rate with improved rubber filler interaction. The complexes formed by IL‐Zn were shown to be much more reactive than Zn‐stearic acid complexes. The dispersion of carbon black in the NR and SBR compounds was studied by using Field Emission Scanning Electron Microscope and Transmission Electron Microscope and the results demonstrate that ILs could significantly improve the filler dispersion. Thus, this study has revealed the multifunctional role of ionic liquids in rubber compounds.Highlights This article describes the dual role of the ionic liquid (IL) in rubber compounds. It can act both as an accelerator‐activator as well as an efficient dispersing aid. The complexation of IL with zinc oxide (ZnO) plays a crucial role in enhancing the activity of ZnO. As a result, the physico‐mechanical properties of both natural rubber and styrene‐butadiene rubber based compounds are significantly improved.

SiO2@Al2O3 binary filler: A chance for enhancing the heat transport in rubber composites for tire applications

AbstractThe present study reports on the development of a new binary filler system for rubber composites, SiO2@Al2O3, where Al2O3 sheets are grown onto SiO2 nanoparticles aggregates by a sustainable water‐based soft‐chemistry approach. The aim is to synergistically integrate the intrinsic thermal conductivity properties of Al2O3 with the peculiar reinforcement ability of SiO2 in an easy one‐pot solution, which has been exploited to prepare polybutadiene (PB) model composites by a simple solvent casting technique. More in detail, the binary filler was used as‐prepared or suitably surface functionalized with 3‐(Trimethoxysilyl)propylmethacrylate (TMSPM). The filler compatibilization and interplay with the polymeric matrix have been inspected by solid state NMR in conjunction with scanning electron microscopy. These investigations highlighted that the presence of alumina in the binary filler does not undermine the capability of silica in generating polymer chains stiffening and indicated a significant effect of the silanization in providing better filler networking and interaction with the PB host ensuring, in principle, an enhanced thermal transport. Accordingly, thermal conductivity measurements revealed that SiO2@Al2O3 introduction in PB induces a remarkable upgrade of the heat transfer, which becomes much more relevant upon surface modification with TMSPM. These results appear encouraging, paving the possibility of applying SiO2@Al2O3 model system to more complex case studies, where both improved thermal conductivity and enhanced reinforcement are required, such as tires tread formulations.Highlights A new SiO2@Al2O3 binary filler system was proposed following a soft‐chemistry approach. The binary filler was functionalized to enhance its compatibilization. Fillers were dispersed in polybutadiene by a simple solvent casting technique. Thermal conductivity measurements revealed a remarkable upgrade of the heat transfer ability.

Analytical Investigation of Microcrystalline Wood Charcoal Reinforced Polyester Composites Using ED-XRF, FTIR and SEM-EDS Techniques

Various weight fractions (ranging from 0 to 30 wt percent, at 5 wt percent intervals) of microcrystalline wood charcoal powder (75µm) were used to generate polyester-based particle reinforced composites. The developed wood charcoal (WC) particles reinforced polyester matrix composites were successfully characterized quantitatively, qualitatively, and functionally using an energy dispersive x-ray spectrophotometer (EDXRF), scanning electron microscope (SEM) enhanced with ancillary EDS for elemental identification capability and Fourier transform infrared spectrometer (FTIR). High peaks of Fe2O3 (3456cps/mA), CaO (4369cps/mA), CuO (2017cps/mA), ZnO (1646cps/mA) and Iron, calcium, copper, zinc were discovered in wood charcoal by EDXRF. The characteristics of reinforced polymer composites were found to be improved by these elements and oxides. The key elements revealed by EDXRF analysis were also validated by EDS elemental mapping. Due to the uniform distribution of the filler particles, SEM images showed that composites with microcrystalline wood charcoal reinforcement had strong interfacial adhesion and interlocking. According to FTIR functional analysis, interactions between the polyester matrix molecules and the microcrystalline wood charcoal fillers resulted in very slight alterations in the frequency bands of functional groups that are typically present in unsaturated polyester resin.

Investigation of the effect of silica particles and silane coupling agent on silica-filled tire tread compounds

Enhancing attributes such as abrasion resistance, wet grip, and rolling resistance significantly impacts the overall performance optimization in tire tread applications. These attributes are predominantly influenced by the dispersity of silica filler within tire tread compounds. Therefore, it becomes imperative to enhance silica dispersion by thoroughly investigating the impact of each constituent in the tire tread compound. This study aims to elucidate the effects of silica particle size and silane coupling agents on tire tread compound properties. The results demonstrate that larger specific surface area silica particles alongside 3-mercaptopropyltrimethoxysilane coupling agents effectively reduce filler–filler interactions and enhance silica dispersion within the tire tread compound. Consequently, these improvements contribute to the overall enhancement of tire tread compound performance. These findings offer valuable insights into advancing the reinforced performance of tire tread compounds through the synergistic utilization of each constituent.

Feasibility of using recycled waste travertine stone powder (RWTSP) as a substitute for mineral filler in microsurfacing surface treatment

Each year, a significant amount of construction waste (CW) is produced globally, creating a major environmental challenge for its proper disposal. Utilizing recyclable CW in pavements not only helps address environmental issues but also conserves non-renewable materials. This study aims to investigate and assess the effectiveness of substituting recycled waste travertine stone powder (RWTSP) as a mineral filler (MF) in the microsurfacing surface treatment mixing plan. Initially, the physical and chemical properties of the materials used in asphalt were evaluated. The performance of the microsurfacing treatment was then examined through tests including wet cohesion, wet track abrasion, loaded wheel-displacement, and loaded wheel-sand adhesion, conducted using five different combinations (RWTSP0 +MF100, RWTSP25 +MF75, RWTSP50 +MF50, RWTSP75 +MF25, and RWTSP100 +MF0) in accordance with ISSA A143 guidelines. Additionally, FESEM-EDS, XRF, and FTIR tests were performed to assess particle shape, analyze material surface, identify constituents, determine structure, and examine organic compounds, chemical bonds, functional groups, and molecular structure. The results indicated that mixes containing RWTSP filler improved the performance of microsurfacing. This is attributed to RWTSP filler's high percentage of CaO and SiO2, as well as its more uneven and rough surfaces compared to mineral filler. For instance, in an 8% bitumen mix, the blend containing 100% RWTSP increased cohesion at 30 and 60 min by 30.8% and 30.7% respectively, improved abrasion resistance by 50%, and reduced mixture bleeding by 10.3%. Moreover, this mix enhanced resistance against vertical and lateral displacements by 32.1% and 34.4% respectively. Finally, ANOVA analysis revealed that RWTSP filler, bitumen, and material interaction were key factors influencing the performance of microsurfacing.

Improved Lewis Acidity Using Ionic Liquid-Grafted Bimetallic Zr/Ti Uio-66 Fillers for Composite Solid Electrolytes

In recent years, solid-state lithium batteries have gained significant attention due to their high energy density and stability. However, challenges such as low ionic conductivity, non-homogeneous Li ion flux, and low interfacial compatibility of solid electrolytes still remain. Composite solid electrolytes (CSEs) have emerged as a potential solution to these issues, by combining an inorganic filler with a polymer matrix. To develop high-performance CSEs, extensive research has been conducted on inorganic active fillers with an abundance of Lewis acidic sites. The acidic sites of the filler can induce Lewis acid-base interactions, which can decrease the crystallinity of fillers by weakening the attraction between polymer segments and increasing chain mobility. Additionally, they increase the degree of dissociation of lithium salt, resulting in an increase in ionic conductivity. In terms of the concentration gradient of Li-ions, the free anion of lithium salt can be trapped by an acidic filler, thereby reducing the mobility and concentration of the anion. Finally, the acidic filler prevents the oxidation of ether oxygen groups in PEO, thus, improves its electrochemical stability. Furthermore, for increasing the ionic conductivity, inorganic filler should be an active filler capable of serving as Li-ion sources to the interfacial region between polymeric matrix and inorganic fillers, thereby facilitating Li-ion transport. Consequently, Li-ions can hop along the surface of active fillers. Therefore, in order to achieve high-performance CSEs with a polymer matrix, inorganic active fillers with an abundance of acidic sites have emerged as one of the most effective strategies for designing high performance fillers with good compatibility with the matrix. To address this technological need, in this work, we present a novel CSE based on a polyethylene oxide (PEO) matrix with a bimetallic (Zr/Ti) UiO-66-ionic liquid grafted filler (BUIL) that simultaneously modified the metal and ligand sites of UiO-66 MOF particles. The bimetallic structure of BUIL was prepared by replacing the metal sites of UiO-66 with Ti metal ions using the metal exchange method, resulting in the formation of more structural defects and an increase in the number of Lewis acid sites of filler. In addition, the pre-synthesized ionic liquids containing a -OH functional group (IL-OH), N-hydroxyhexyl-N’-methyl imidazolium bis(trifluoromethylsulfonyl)imide, were grafted when synthesizing UiO-66 with a ligand containing a -Br functional group. The BUIL filler functions as a high Lewis acid filler owing to its bimetallic structure and grafted ionic liquid. Also, to utilize BUIL as an active filler, lithium bis(trifluoromethanesulfonyl)imide/1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (IL, LiTFSI/EMIM-TFSI) was loaded into BUIL (IL@BUIL). In order to confirm the effect of Lewis acid filler interaction on PEO polymer matrix and lithium salt, various spectroscopic characterization methods were employed. As a result, CSEs containing IL@BUIL filler and PEO matrix exhibited markedly improved ionic conductivity, lithium-ion transference number, electrochemical stability, and long-cycle stability of Li metal electrode. After optimization, the ionic conductivity of CSEs at 30°C was enhanced to 0.458 mS cm-1, the lithium-ion transference number was raised to 0.668, and the electrochemical stability window was widened to 4.5 V. In addition, during a continuous plating/stripping test, the lithium metal symmetric cell of CSEs stably cycled for 500 h at a current density of 0.2 mA cm-2. Finally, LiFePO4/IL@BUIL/Li cell shows a capacity of 148 mA h g-1 at 1C.The present strategy of simultaneously modifying the metal and the ligand sites of MOF to improve the properties of CSEs can be used as a general platform for the design of a MOF filler in CSEs system, as well as a guideline for the next generation CSEs.

Investigation of the influence of nano-sized particles on the entanglement distribution of a generic polymer nanocomposite using molecular dynamics

The addition of nano-sized filler particles to polymers leads to significant improvements in their mechanical properties. These can be traced back to the matrix–filler interactions of the interphase, which can be analyzed using molecular dynamic simulations. Usually, research in this context studies the general number of entanglements or the radius of gyration. However, this publication presents a novel approach by investigating the radial distribution of entanglements in an effort to characterize the interphase. To this end, we employ a coarse-grained model for a generic polymer composite and study multiple systems with varying particle radius and matrix–filler adhesion. Furthermore, the highly customizable and computationally efficient nanocomposite system developed during this research serves as a foundation for the further characterization of polymer nanocomposites and their interphases.

3D Printing of Sustainable Coal Polymer Composites: Study of Processing, Mechanical Performance, and Atomistic Matrix–Filler Interaction

3D Printing of Sustainable Coal Polymer Composites: Study of Processing, Mechanical Performance, and Atomistic Matrix–Filler Interaction

Electromagnetic interference shielding composites and the foams with gradient structure obtained by selective distribution of MWCNTs into hard domains of thermoplastic polyurethane

In this paper, multilayer thermoplastic polyurethane (TPU)/multiwalled carbon nanotubes (MWCNTs) electromagnetic interference shielding composite foams with gradient structure was prepared. The gradient distribution of effective concentration of filler and cell size were realized by selective distribution of MWCNTs into hard domains of TPU, which improved interlayer interface polarization of electromagnetic waves and impedance matching between the material and the air. The average electromagnetic interference shielding efficiency (EMI SE) of TPU/MWCNTs composites with gradient structure is 1.2 times larger than that of homogeneous composites. After foaming, the average EMI SE of the gradient foams was higher than that of the homogeneous foams, with maximum average EMI SE of 35.4 dB. This work is the first time to correlate the interaction of fillers with the soft domains and hard domains of TPU and EMI shielding performance, providing a feasible method for designing lightweight composites with low filler and better EMI shielding performance.

Correlating microstructure-property relationships in carbon fiber-expanded graphite hybrid composites for synergistic improvements in thermal and mechanical properties

Thermally conductive and structurally reinforcing polymer composites are in high demand for applications such as electric vehicles, rapid prototyping, and thermal interface materials. Including a single geometry (platelet or rod) filler is a common strategy to improve the performance of polymers. However, the thermal and mechanical properties follow an inverse dependence and often require high filler loadings that compromise the overall properties. Hybridization of filler geometries has effectively improved the thermal conductive network while retaining mechanical performance. The focus of this work is to understand the effect of microstructure and interactions of hybrid fillers in high strength thermally conductive composites. For this study, expanded graphite, and carbon fibers (CFs) were used as the hybrid filler system to improve the thermal conductivity and mechanical properties of polyamide-based thermoplastic composites. The detailed microstructural study revealed that at a lower normalized weight ratio of CFs, the fibers bridge the expanded graphite particles to create a filler-filler network which leads to synergistic effect on both the tensile strength (by 29%) and thermal conductivity (by 290%) compared to a single-filler expanded graphite-based system. Above a critical mass fraction of CF, the planar graphitic orientation led to a loss in thermal conductivity which is attributed to reduced exfoliation and packing density of fillers.