Simple Mechanical Blending Research Articles

Enhanced EMI shielding effectiveness of green Eucommia ulmoides gum composites through heterogeneous and crystalline structures

In order to mitigate the increasing severity of electromagnetic interference (EMI), it is imperative to develop advanced rubber composites. Despite recent advancements in structural design and filler hybridization for enhancing their EMI shielding performance, challenges persist in terms of suboptimal mechanical properties and intricate processing techniques. To overcome these limitations, bio-based Eucommia ulmoides gum (EUG) composites with segregated network structures were fabricated by simple mechanical blending, capitalizing on the characteristics of highly cross-linked rubbers with restricted molecular chains. Highly cross-linked EUG (HCE) effectively segregated the conductive fillers into the EUG phase, while the crystallization of EUG promoted the dispersion of fillers within the amorphous region of the EUG. Therefore, a highly efficient 3D conductive network was formed due to the segregated structure and crystallization, enabling the EUG/HCE/CNT composite to achieve an exceptional shielding effectiveness (SE) value of 83.0 dB with a high absorption loss ranging from 8.2 GHz to 12.4 GHz.

2‐Dimensional Magnesium Oxide/Polyaniline Nanocomposite Modified Glassy Carbon Electrode for Electrochemical Detection of Dopamine and 4‐Nitrophenol

AbstractIn this study, we have developed an electrochemical sensor based on a polyaniline (PANI) integrated magnesium oxide nanosheet (MgO‐NSs) modified glassy carbon electrode (GCE) for the rapid electrochemical detection of dopamine (DA) and 4‐nitrophenol (4‐NP). 2‐D MgO‐NSs were synthesized using a straightforward one‐step sugar‐blowing method, and PANI was synthesized by the oxidative polymerization of aniline. The nanocomposite (PANI‐MgO) was prepared by simple mechanical blending of MgO‐NSs with PANI. The as‐synthesized nanocomposites were characterized using several analytical techniques to determine their morphological and microstructural properties. The as‐synthesized PANI, MgO, and PANI‐MgO were further electrochemically characterized using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) techniques. The fabricated PANI‐MgO/GCE showed a considerable increase in the redox peak currents of DA and 4‐NP, suggesting that PANI‐MgO/GCE substantially enhances the electrocatalytic oxidation of DA and the reduction of 4‐NP. The analytical performance of PANI‐MgO/GCE for the detection of DA and 4‐NP was investigated using Differential Pulse Voltammetry (DPV). The developed sensor was successfully applied for the detection of DA and 4‐NP in real samples with good recovery results.

A novel strategy to functionalize styrene butadiene rubber toward enhanced interfacial interaction with silica

AbstractIncorporation of nanofillers (such as silica) into elastomer matrix is the most common strategy to prepare high‐performance rubber products. However, the poor dispersion of nanofillers in non‐affinity rubber materials and the weak interfacial interaction significantly limit the processing and mechanical properties. To reduce the polarity difference and enhance the interfacial interaction between silica and styrene butadiene rubber (SBR), we prepared a hydroxyethyl acrylate‐grafted SBR (SBR‐g‐HEA) through the redox initiator system, and subsequently fabricated SBR‐g‐HEA/silica nanocomposites by simple mechanical blending. The effects of reaction conditions on the grafting rate were studied in detail. ATR‐FTIR and 1H‐NMR collectively confirmed the successful grafting of HEA groups on SBR molecular chains, and the grafting fraction could be regulated from 0% to 2.5%. Scanning electron microscope (SEM) and rubber processing analyzer (RPA) showed that the incorporation of HEA could significantly improve the dispersion of silica nanoparticles in SBR matrix. Notably, the resulting SBR‐g‐HEA exhibited significantly enhanced attributes when compared to their unmodified counterparts, including superior mechanical properties, improved wear resistance, and reduced heat generation. The strategy proposed here provided insights toward the fabrication of non‐affinity rubber/filler nanocomposites for high‐performance rubber products and green tire.

High resistivity‐temperature effect of resistivity for economical and facile conductive polymer composites with low percolation threshold via self‐constructed dual continuous structure

AbstractIn this work, electrically conductive polyethylene/polypropylene‐flake graphite composites with different ratios (HDPE/PP‐FG) were prepared by simple mechanical blending (Mec) and melt blending (Mel) technologies, combining with the grinding technique. According to the effect of preparation technique, dual continuous microstructures for Mec‐HDPE/PP‐FG composites were self constructed by controlling specific molding temperature. As a result, the percolation threshold of 1.33 wt% of Mec‐HDPE1/PP4‐FG was achieved, much lower than that of Mel‐HDPE1/PP4‐FG (7.02 wt%) and the maximum in conductivity was over 10−3 S/m at about FG content of 6 wt%. However, Mel‐HDPE1/PP4‐FG only showed the electrical conductivity of about 8.0 × 10−11 S/m when FG content was 6 wt%. Meanwhile, Mec‐HDPE/PP‐FG composites presented obvious positive temperature coefficient (PTC) effect of electrical resistivity, without negative temperature coefficient (NTC) effect and PTC intensity was up to 6.57 orders of magnitude, far higher than those of Mel‐HDPE/PP‐FG composites. In addition, the excellent repeatability in PTC behaviors for Mec‐HDPE/PP‐FG was achieved after several run cycles. Therefore, the study on economical and facile polymer materials with high performance PTC characteristics had the great significance in practical application.

Tunable Van der Waals interfacial interaction for ultrahigh-damping rubber bends

High-damping rubber materials are of crucial significance for realizing high-performance green tire due to their contributions in noise and vibration reduction, auto-braking, and service life. However, the polarity difference and mismatched surface energy significantly reduce the interfacial interaction and compatibility between non-polar tread rubber materials and polar polymers. Herein, we fabricated a multi-functionalization high vinyl polybutadiene rubber (MFHVBR)/ethylene-vinyl acetate rubber (EVM) blend by simple mechanical blending. The incorporation of polar functional groups could increase the surface energy of MFHVBR, which was beneficial for regulating the interfacial compatibility and van der Waals interaction between non-polar rubber matrix and polar polymer matrix. A quantitative correspondence between van der Waals interaction and damping properties was determined. The optimized MFHVBR/EVM blends showed ultrahigh damping properties with an effective damping temperature range of −12.4–62.6 °C, which totally covered the service temperature of tires. The effective damping temperature range width of 75 °C was among the highest value of reported high-damping rubber materials. Meanwhile, the vulcanization efficiencies and physical mechanical properties were obviously improved. Collectively, the developed strategy herein and the proposed surface energy-performance relationship suggest a feasible pathway toward low-cost and high-performance green tire tread rubber materials.

ZrO2 Nanoparticle Embedded Low Silver Lead Free Solder Alloy for Modern Electronic Devices

In this article, the authors present the synthesis of Sn–1.0Ag–0.5Cu (SAC105) alloy embedded with zirconium oxide nanoparticles using simple mechanical blending and casting route. The cast samples were characterized in terms of microstructural evolution, wetting, microhardness, and drop test reliability. The characterizations were performed by using a tabletop X-ray diffraction, field emission scanning electron microscope, and the compositions were identified by energy dispersive spectroscopy. The results showed that addition of ZrO2 nanoparticles significantly refines the grain size, Ag3Sn, and Cu6Sn5 intermetallic compounds thickness by 46, 14, and 26% respectively as compared to the single component SAC105 alloy. The results were also compared with those of standard Sn–3.0Ag–0.5Cu (SAC305) alloy. Although the spreading and microhardness of SAC105 is found to be slightly poor or comparable to SAC305 yet drop test reliability can be improved significantly after addition of ZrO2 nanoparticles appreciably. This kind of refinement results in a cheap alternative to SAC305 with comparable mechanical strength and high solder joint reliability.

Dense yttria-stabilized zirconia obtained by direct selective laser sintering

This work demonstrated the possibility to manufacture dense yttria-stabilized zirconia (YSZ) parts by direct laser beam sintering using a commercial 3D SYSTEMS machine. To achieve this, several requirements of the process itself had to be met. First, an efficient laser-matter interaction had to be achieved. Indeed, a major issue to overcome was the intrinsic nonabsorbance property of the YSZ powder at the Nd:YAG laser wavelength. This issue was solved by adding a small amount of graphite to the YSZ powder that resulted in a simple mechanical blending of the two compounds. The graphite adjunction allowed an increase in the absorbance value from 2% to approximately 60%. The chemical composition of the powder blend and the density and the particle size distribution of the starting material used in this work enabled adequate heat transfers due to the appropriate thermophysical properties. Finally, a set of machine parameters that allows to manufacture parts with a high relative density, good geometrical accuracy, and mechanical strength was experimentally determined. Ultimately, it was found that the direct SLS allows the reproducible manufacture of simple YSZ parts with a relative density of 96.5%.

Toughness Reinforcement in Carbon Nanotube-Filled High Impact Polypropylene Copolymer with β-Nucleating Agent

In this work, carbon nanotubes (CNTs) were introduced into an impact polypropylene copolymer (IPC) with β-nucleating agent to prepare IPC composites just by means of a simple mechanical blending method without any special treatment of the CNTs. The resultant IPC composites demonstrated an impressively improved impact property (97.78% increment of toughness compared to pure IPC). It was found that CNT aggregates were dispersed in the polypropylene homopolymer (hPP) matrix rather than the interface between the dispersed phase and hPP host. At the presence of CNTs, the size of the ethylene–propylene random copolymer elastomer particles in the IPC nanocomposites was decreased as evidenced by scanning electronic microscopy, and moreover, the mobility of molecular chains in the amorphous phase of the hPP matrix and crystalline lamellae was enhanced as confirmed by dynamic mechanical analysis and small-angle X-ray scattering measurement. The selective distribution of CNTs, the decreased size of elastomer particl...

Tailoring dielectric properties of polymer composites by controlling alignment of carbon nanotubes

We prepared hydrogenated butadiene-acrylonitrile (HNBR) elastomer composites with random orientations of carbon nanotubes (CNTs) and aligned CNTs, denoted by random composites and aligned composites, respectively, by means of a simple mechanical blending method. The CNTs were dispersed uniformly in the HNBR matrix in both types of composites. Interestingly, at CNT contents of 1–2.5 vol%, the dielectric loss (tan δ) of the aligned composites increases slightly, and the dielectric constant (e′) of aligned composites increases largely with the increasing content of CNTs, whereas both the tan δ and the e′ of the random composites increase largely with the increasing content of CNTs. As a result, a high e′ (5000 at 1000 Hz) and a low tan δ (0.42 at 1000 Hz) were obtained in the aligned composite with a CNT content of 2.5 vol%, whereas a high e′ and a high tan δ were obtained in the random composites. The relationship between the microstructure and dielectric properties was qualitatively analyzed by means of the percolation theory and intercluster polarization model. The mechanism for the achievement of high e′ and low tan δ for dielectric composites was discussed. This study provides a guide to design microstructure that yields composites with improved dielectric properties.

Preparation and Study on the Electric Properties of PI-Al<sub>2</sub>O<sub>3</sub> /PI-TiO<sub>2</sub>/PI-Al<sub>2</sub>O<sub>3 </sub>Three Layers Nanocomposite Films

Polyimide-Al2O3 nanocomposite films were prepared via simple mechanical blending of Polyimide and surface modified Al2O3, and Polyimide-TiO2 nanocomposite films were prepared by the polymerization process of adding tetrabutyl orthotitanate (TBOT) and the coupling agent isocyanatopropyltriethoxysilane (ICTOS) in polyimide. The three layers nanocomposite films were characterized by scanning electron microscope (SEM). The homogeneous dispersion is observed by the SEM when the concentration of Al2O3 is low. The electrical properties of the nanocomposite films were investigated as a function of the concentration of the Al2O3 nanoparticles. The results show that the dielectric constant and the dielectric loss (tan δ) of these films increased with the increase of the content of silica particles.

Preparation and Characterization of Surface-Engineered Coarse Microcrystalline Cellulose Through Dry Coating with Silica Nanoparticles

A popular grade of microcrystalline cellulose (MCC) exhibits excellent tabletability, but marginal flowability for high-speed tableting operations. Accordingly, an enhancement in flowability, while preserving its tabletability, will make it a more useful excipient in pharmaceutical tablet formulations, especially for the direct compression process. In this work, we show that surface coating by silica nanoparticles, using either a dry comilling process or simple mechanical blending, is a valid strategy for achieving the goal. The effects of milling intensity, either the number of comilling cycles or blending time, and silica loading level have been evaluated. Results show that surface deposition of 0.1% silica nanoparticles substantially improves the flowability of this grade of MCC while preserving a significant portion of its tabletability. Higher silica loading leads to better flowability, but at the cost of reduced tabletability. However, even up to 2.0% silica deposition, its tabletability remains superior.

A novel method for the synthesis of YAG:Ce phosphor

YAG:Ce phosphor was synthesized by a novel simple method, wherein the admixture of three raw materials (Y 2O 3, α-Al 2O 3 and CeO 2) were first acidified by diluted nitric acid to prepare a precursor, followed by a high temperature heating treatment of the obtained precursor under reductive atmosphere. Through XRD measurement and SEM observation, it was found that Y 2O 3, one of the raw material, was firstly dissolved into the diluted nitric acid, and then recrystallized on the surface of both α-Al 2O 3 and CeO 2 to form a novel nano-flaky hierarchical architectures with the crystalline structure of yttrium nitrate hydroxide hydrates, which makes all the precursor more homogeneous than the admixture of the raw materials from simple mechanical blending method. In the following heating process, the obtained homogeneous admixtures with hierarchical architectures could easily transform into uniform YAG:Ce phosphor. The resulted YAG:Ce phosphor exhibited higher emission intensity than the sample synthesized from mechanical mixing raw materials.

Enhancement of the photocatalytic reactivity of TiO2 nano-particles by a simple mechanical blending with hydrophobic mordenite (MOR) zeolite

The photocatalytic oxidation of gaseous acetaldehyde with O2 on commercial TiO2 nano-particles could be successfully enhanced by a simple mechanical blending with a high-silica mordenite (MOR) zeolite, the surface of which showed high hydrophobic properties. When the TiO2 nano-particles of ca. 5–20wt% were mixed with the MOR zeolite powders in an agate mortar for only 5min, the blended TiO2/MOR samples showed higher photocatalytic reactivity as compared to the pure TiO2 nano-particles. Since the high-silica zeolite powders are highly transparent in UV light regions, the incident UV light is effectively irradiated onto the whole part of the TiO2 nano-particles without any loss of light intensity. Furthermore, the siliceous MOR zeolite powders effectively adsorb the gaseous acetaldehyde molecules and supply them onto the surfaces of the blended TiO2 nano-particles, resulting in an enhancement of the photocatalytic reactivity.

Polymer-layered silicate nanocomposites. 1. A study of poly(ethylene oxide)/Na +-montmorillonite nanocomposites as polyelectrolytes and polyethylene-block-poly(ethylene glycol) copolymer/Na +-montmorillonite nanocomposites as fillers for reinforcement of polyethylene

Poly(ethylene oxide) PEO/Na +-montmorillonite and polyethylene–poly(ethylene glycol) (PE–PEG) diblock copolymer/Na +-montmorillonite nanocomposites have been prepared by melt intercalation method. The effect of thermal treatment on the amount of PEO and PE–PEG diblock copolymer intercalated into layers of Na +-montmorillonite and on ionic conductivity of PEO/Na +-MMT nanocomposites have been evaluated. It was found that PEO can be intercalated into the layers of Na +-MMT by simple mechanical blending and part of PE in PE–PEG diblock copolymers was also intercalated into the layers of Na +-MMT. The intercalated amount increases with thermal treatment time, which improves the ionic conductivity of the PEO/Na +-MMT nanocomposites. PE–PEG diblock copolymer/Na +-MMT hybrids can be considered as a new kind of fillers for the reinforcement of polyethylene. By only adding a small amount (1–15% by weight) of these fillers, tensile strength of polyethylene was improved significantly. This research provides valuable information for the development of new kinds of fillers for polymer reinforcement, and polyelectrolytes.

Fullerite additions as a phonon scattering mechanism in p-type Si-20 at.% Ge

In a series of experiments to evaluate the possibility of reducing the lattice thermal conductivity in silicon-germanium alloys through the formation of an inert, intragranular nanophase, a number of p-type Si-20 at.% Ge alloys, nominally doped with 0.5 at.% boron, were prepared with varying amounts of fullerite, a mixture of 90% C 60 + 10% C 70. The fullerite, in the form of a fine black powder with a particle size of 0.7 nm, was shown by X-ray diffraction (XRD) to be nearly amorphous. The alloys were synthesized by mechanical alloying (MA) and the fullerite was added during various stages of preparation. Following consolidation by hot pressing, the compacts were found to be fully dense and homogeneous. Slices of each compact were characterized by the Hall effect at room temperature and also by electrical resistivity, the Seebeck coefficient, and thermal diffusivity measurements to 1000 °C. Addition of 0.2–0.8 wt.% fullerite by a simple mechanical blending operation resulted in an overall decrease in the carrier concentration of up to 35% in alloys hot pressed at 1200 °C, compared with 3.0 × 10 20 cm −3 for baseline alloys without fullerite additions. Higher hot-pressing temperatures resulted in both an increase in the carrier concentration and carrier mobility. A reduction in thermal conductivity of up to 22% compared with standard p-type alloys was observed in samples containing 0.8 wt.% additions. In this study, a maximum integrated average figure of merit, Z, between 300 and 1000 °C of 0.65 × 10 −3 °C −1 was obtained, corresponding to 0.4 wt.% addition of fullerite, which is 30–35% higher than that of ‘standard’ p-type Si-Ge alloys doped with 0.25 at.% boron prepared by conventional methods. Larger amounts of fullerite caused a decrease in Z. Observation of selected samples by transmission electron microscopy (TEM) revealed that the fullerite reacted with silicon to form nanophase SiC inclusions.