Good Filler Dispersion Research Articles

Nanocellulose functionalized with cinnamon essential oil: A potential application in active biodegradable packaging for strawberry

The COVID-19 pandemic has aggravated existing problems associated with the high consumption of plastic products and their incorrect disposal, resulting in serious social, economic, and environmental problems. The development of biodegradable packaging has been growing in recent years due to the demand for food safety and quality. This work aimed to prepare PBAT active films loaded with cellulose nanofibers (CNF) embedded with cinnamon essential oil (EO) by the wire extension method. The possible interactions between NC-EO-PBAT were investigated, and the results confirmed the EO presence that physically interacted with the PBAT matrix, altering the polymeric molecular conformations. All films showed high thermal stability, being adequate for application in the food industry. The films containing the modified-CNF showed a Fickian controlled diffusion, and the higher essential oil release was verified for lower filler contents. The modified-CNF decreased the water vapor permeability due to the oil hydrophobic oil and good filler dispersion, which impacted the film's performance as packaging for strawberries. The fruits packed in films with 0.5 wt% of modified-CNF have lower weight loss after 15 days of storage, better freshness preservation, and no fungal attack. The results indicated that the developed films improved the strawberries' qualities and have antimicrobial properties against Salmonella and Listeria monocytogenes, offering a potential alternative to synthetic materials as food packaging.

Spectral characterization of morphological structure of organomodified montmorillonite clay-based epoxy nanocomposite

Effect of organoclays on formation of intercalated/exfoliated structure in epoxy–clay nanocomposites at 2 wt% filler loading was carried by spectral analysis. Organoclays were dispersed in epoxy matrix by ultrasonication method. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) were carried to characterize function group, morphology of structure, surface and glass transition temperature of the nanocomposite, respectively. FTIR study reveals the presence of epoxy in the galleries of organoclays was confirmed and proves the existence of chemical bonds between the organoclays and the epoxy matrix. XRD analysis indicated that, the interlayer spacing between the clay platelets was increased significantly, thus, the polymer is able to intercalate between the clay layers. As a result, the fully exfoliated structure was found in the E + NC-III nanocomposite while the intercalated structure was obtained in the E + NC-I, E + NC-II, E + NC-IV and E + NC-V nanocomposites. The glass transition temperature measured by TGA was increased with the addition of organoclay in epoxy matrix but decreased for unmodified nanoclay and neat composite. SEM imaging showed good filler dispersion and distribution in E + NC-III nanocomposite, highlighting the very smooth surface due to absence of clay aggregates and no voids.

High density polyethylene composites containing alumina-toughened zirconia particles: Mechanical and tribological behavior

Alumina-toughened Zirconia (ATZ) was used as filler with the purpose to endow High Density Polyethylene (HDPE) with enhanced mechanical and wear properties, hence widening the application field of the polyolefin as biomaterial. Composites with ATZ percentages ranging between 2 and 12 wt% were produced by melt extrusion followed by compression molding. A good filler dispersion was obtained for all the materials, despite the presence of few voids and agglomerates observed at increasing ATZ loadings. The polymer crystallinity was enhanced by filler incorporation, particularly at high percentages. The combination of high crystallinity and, mainly, lack of voids and agglomerates, appeared responsible for the improvement of Young modulus and mechanical strength. The filler positively affected the wear resistance of the composites under lubricated conditions. Indeed, under dry condition, the filler debris formation, arising from the poor interaction with the polymer matrix, resulted in an increase of the wear volume. Conversely, in the presence of water and fetal bovine serum, the layer adsorbed at the surface promoted an easy removal of the filler debris, hence highlighting the positive effect of ATZ.

Aspects Concerning the Fabrication of Magnetorheological Fluids Containing High Magnetization FeCo Nanoparticles

Recently, our collaborative work in the fabrication of a magnetorheological fluid (MRF) containing high magnetization FeCo nanoparticles (NPs, fabricated in our laboratories using the chemical reduction technique; MS = 212 Am2/kg) as magnetic fillers have resulted in a new MRF with superior performance up to 616.7 kA/m. The MRF had a yield stress value of 2729 Pa and good reversibility after a demagnetization process. This value competes with the best ones reported in the most recent literature. Nevertheless, the fabrication process of this type of fluid is not an easy task since there is a strong trend to the aggregation of the FeCo NPs due to the strong magnetic dipolar interaction among them. Thus, now we present the analysis of some aspects concerning the fabrication process of our FeCo NPs containing MRF, mainly the type of surfactant used to cover those NPs (oleic acid or aluminium stearate) and its concentration, and the procedure followed (mechanical and/or ultrasound stirring) to achieve a good dispersion of those magnetic fillers within the fluid.

Construction of micro-thermal conductive network of self-assembled CNTs hybrids with 1D–0D structure

In this context, carbon nanotubes (CNTs)/silver nanoparticles hybrids with special 1-dimensional–0-dimensional (1D–0D) structure were successfully fabricated via self-assemble of dopamine followed by reduction reactions of silver cations aiming to synthesize more efficient thermal conductive fillers for the formation of heat flow transfer network in PA6 matrix. FTIR, XRD, TG and TEM revealed the characteristics of functionalized CNTs. Meanwhile, the effect of CNTs hybrids with 1D–0D structure on the construction of heat flow network and thermal conductivity was also investigated. Experimental results showed that thermal conductivity of composites enhanced with increased filler content, the highest thermal conductivity of the PA6/CNTs hybrids composites reached 0.65 W m−1 K−1, which was 2.1 times that of pure PA6 and 32% higher than that of pristine CNTs-filled composites (0.55 W m−1 K−1) with same filler content (10 vol%), and this was ascribed to the better dispersion of fillers and enhanced interfacial interaction between fillers and matrix, as well as the special structure of CNTs hybrids that could abundance the heat transfer path. The crystallinities and dynamic thermal mechanical properties were also analyzed. The enhanced storage modulus (1940 MPa for pure PA6 to 3650 MPa for PA6/CNTs hybrids composites at 5 °C) and higher glass transition temperature along with the change of crystallization behavior of fabricated composites were in accordance with the thermal conductive behavior. The thermal conductive model and its mechanism were then proposed and further confirmed by scanning electron microscopy.

CNC dispersion in PLA and PBAT using two solvents: morphological and rheological properties

Cellulose nanocrystals (CNCs) were dispersed via solution casting in amorphous (A) and semi-crystalline (SC) poly (lactic acid) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT). The protocol, optimized following the Hansen solubility parameter theory, relies on binary mixtures of tetrahydrofuran and dimethyl sulfoxide for the polymers and CNCs, respectively. First highlighted through atomic force microscopy, good filler dispersion and distribution were confirmed by a decrease of the linear viscoelastic region and significant increases of the complex viscosity, storage modulus, and apparent yield stress of the nanocomposites with CNC content, specifically at low frequencies. CNC percolation thresholds of 1, 0.3, and 0.3 wt% were determined in A-PLA, SC-PLA, and PBAT, respectively. These are the lowest to be reported in the literature until now. While PLA retained solvent traces, leading to a significant plasticizing effect, solvent removal was complete in PBAT. It was attributed to the crystallization of PBAT at the drying temperature (70 °C).

Extrusion of highly filled flexible polymer sheet

AbstractHighly‐filled polymer systems include color masterbatches, feedstocks for powder injection molding, and rigid sheets with high levels of flame retardants, but they have not been explored for flexible sheet. This work investigated the (a) selecting a polymer matrix with enough melt strength and flexibility to form a stable sheet with high filler loading, (b) the maximum achievable filler loading for the sheet, and (c) optimizing the process of extruding a highly‐filled flexible polymer system. Extrusion grade low‐density polyethylene (LDPE) provided sufficient flexibility and permitted a maximum filler loading of 36 vol% (~78 wt%). Good dispersion of the nanoparticle filler, however, required two passes through multiple screw extruders and a small reduction in the viscosity of the LDPE. Sheet with thickness of 415 μm, surface roughness of <1 μm, and sufficient flexibility was extruded continuously at a rate of 10 m/min., but it required a more traditional coat hanger manifold to prevent filler hang up in the sheet die. The filler particles were distributed uniformly through the core and skin of the sheet, giving the sheet good mechanical properties.

Graphene/polyaniline nanocomposites: effect of in-situ polymerization and solvent blending methods with dodecylbenzene sulfonic acid surfactant

Polyaniline (PANI) has fascinated considerable interest from industrial and academic researchers due to their great potential in many electronic applications. The present study aims to enhance the electrical and thermal properties of the graphene/PANI nanocomposites using different fabrication methods and modifications in the nanocomposites formulation. Comparison on the properties of graphene/PANI nanocomposites produced by in-situ polymerization and solvent blending methods and also the effects of dodecylbenzene sulfonic acid (DBSA) surfactant are investigated. Electrical conductivity, thermal conductivity, thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy were used to characterize the sample. Results showed that graphene/PANI nanocomposites produced by the in-situ polymerization method have better electrical conductivity, thermal conductivity and thermal stability if compared to that of the solvent blending method. The in-situ polymerization method exhibits a smaller diameter size of PANI fiber and good dispersion of graphene filler. Furthermore, the addition of DBSA surfactant in the graphene/PANI nanocomposites developed homogeneity and uniform dispersion of the graphene filler within the PANI matrix. In conclusion, graphene/PANI with surfactant nanocomposites produced by the in-situ polymerization method showed higher electrical and thermal conductivity by 10% and 6%, respectively, if compared to the in-situ polymerization without surfactant. Thermal stability also showed improvement with the addition of surfactant.

Design and fabrication of conductive composite films with high elasticity and strength using hybrid polymer matrix

ABSTRACT Flexible conductive polymer composites with good mechanical property play an important role in the modern electronic industry. In this study, aromatic poly(amide-imide) (PAI) and thermoplastic polyurethane (TPU), functionalized multi-wall carbon nanotube (FMWCNT) and reduced graphene oxide (RGO), were, respectively, used as polymer matrix and conductive filler to fabricate conductive polymer composites. Combing the advantages of PAI (high strength) and TPU (good elasticity), PAI-TPU/FMWCNT-RGO polymer composites exhibited a high tensile strength of 58.8 MPa and good elongation at break of 255%. On the other hand, the hybrid conductive filler of FMWCNT-RGO possessed a 3D structure, which is beneficial for improving conductive property, and thus a relative high conductivity of 35.9 S m−1 was achieved. The enhanced mechanical and conductive properties are mainly ascribed from the good compatibility between the polymer matrix and conductive fillers, which promotes the good dispersion of conductive filler into the polymer matrixes.

Synthesis and Characterization of Water-Based Epoxy-Acrylate/Graphene Oxide Decorated with Fe3O4 Nanoparticles Coatings and Its Enhanced Anticorrosion Properties

ABSTRACT In this article, water-based epoxy–acrylate (EP/AC) emulsion coatings and its nanocomposites with Fe3O4 nanoparticles, graphene oxide nanosheets and graphene oxide which was decorated with Fe3O4 nanoparticles were synthesized. This was executed by means of a pre-emulsion seeded semi-batch emulsion polymerization handle with a blend of conventional anionic surfactant (Polyalkylene glycol ether sulfate, ammonium salt-EXOSEL 20 S) and typical nonionic type emulsifier (Octylphenol polyoxyethylene ether OP-10) for emulsion polymerization (schematic 1). Prepared nanoparticles were investigated with different analyzing methods like FT-IR, XRD, SEM-EDAX and TGA. The impact of the distinctive nanostructures in an (EP/AC) resin, on coated steel panels with the features of corrosion conservation, was investigated by the test of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Morphology of surface and thermal behavior of nanocomposite tests were executed using surface filtering electron microscopy (FE-SEM) and thermal gravimetric analysis (TGA). Different analyses resulted from nanostructures and nanocomposites approved very good dispersion of fillers in nanocomposite beads. Besides, they indicate the effective role of nanoparticles especially graphene oxide which was decorated with Fe3O4 nanoparticles in corrosion resistance of water-based EP/AC coatings and other properties of coated instances.

The influence of Fe3O4@GNP hybrids on enhancing the EMI shielding effectiveness of epoxy composites in the X-band

In this work, the electromagnetic interference (EMI) shielding effectiveness in the X band frequency range of 8–12.4 GHz of epoxy nanocomposites containing Fe3O4 nanoparticles decorated graphene nanoplatelets (i.e., Fe3O4@GNP hybrids) is investigated. The hybrid nanostructures were synthesized in situ by a simple co-precipitation technique and were incorporated into the epoxy matrix by melt blending following a solvent-less approach. Scanning electron microscopy performed on the hybrid nanostructures revealed a good distribution of Fe3O4 nanoparticles on the GNP sheets in the hybrid. A series of epoxy nanocomposites containing varying content of Fe3O4@GNP, GNP and/or Fe3O4 nanoparticles were synthesized and compared for their EMI shielding effectiveness. The SEM of the composite cross-section reveals good filler dispersion in the composites. Overall the nanocomposites containing Fe3O4@GNP hybrids exhibited enhanced EMI shielding performance when compared to samples containing equivalent loading of only GNP and/or Fe3O4. The 1 mm thick composite sample containing 1:3 (wt/wt) Fe3O4: GNP hybrid attenuated 89 % of incident wave power and exhibited an EMI shielding effectiveness value of 9.6 dB in the X-band.

Mechanical behaviour of additively manufactured bioactive glass/high density polyethylene composites

Bioactive glass (BAG) is a well-known biomaterial that can form a strong bond with hard and soft tissues and can also aid in bone regeneration. In this study, BAG is added to a polymer to induce bioactivity and to realize fused filament fabrication (FFF) based printing of polymer composites for potential orthopaedic implant applications. BAG (5, 10, and 20 wt%) is melt compounded with high density polyethylene (HDPE) and subsequently extruded into feedstock filament for FFF-printing. Tensile tests on developed filaments reveal that they are stiff enough to resist forces exerted during the printing process. Micrography of printed HDPE/BAG reveals perfect diffusion of raster interface indicating proper selection of printing parameters. Micrography of freeze fractured prints shows the homogeneous distribution and good dispersion of filler across the matrix. The tensile, flexural, and compressive modulus of FFF-printed HDPE/BAG parts increases with filler addition. BAG addition to the HDPE matrix enhances flexural and compressive strength. The tensile and flexural behaviour of FFF-prints is comparable to injection molded counterparts. Property maps exhibit the merits of present study over the existing literature pertaining to desired bone properties and polymer composites used in biomedical applications. It is envisioned that the development of HDPE/BAG composites for FFF-printing can lead to possible orthopaedic implants and scaffolds to mimic the bone properties in customised anatomical sites or injuries.

Stabilization of the cellular structure of polypropylene foams and secondary nucleation mechanism in the presence of graphene nanoplatelets

Graphene nanoplatelets (GNPs) consisting of few-layered graphene (FLG) with surface area of about 400 g/cm2 were prepared from expanded graphite (EG) using a shear-induced thermomechanical exfoliation process. Melt compounded composites of EG with polypropylene (PP) exhibited good filler dispersion with no visible aggregation, whereas PP-GNP composites contained finely-dispersed nanometer-scale FLG. Foams were prepared through a batch foaming process using nitrogen as the physical blowing agent, at temperatures ranging from 140 to 180 °C. The presence of EG particles and finely-dispersed GNPs promoted heterogenous nucleation, resulting in cell densities of the order of 107 cells/cm3, and a fine micro-cellular structure with an average cell diameter in the range of 20 μm–60 μm. It was further noted that the foams exhibited secondary nucleation effects stemming from the presence of very finely dispersed platelets, resulting in a secondary population of smaller cells in the range of 1 μm–10 μm. The compressive modulus of the composite foams containing 9 wt% GNPs increased five-fold compared to the neat PP foams.

Preparation of high-performance natural rubber/carbon black/molybdenum disulfide composite by using the premixture of epoxidized natural rubber and cysteine-modified molybdenum disulfide

Molybdenum disulfide (MoS2) is a potential additive for rubber enhancement. However, its poor dispersion and weak interaction with matrix limit its further application. To improve the dispersion of MoS2 in natural rubber (NR) and enhance the interaction of MoS2 with matrix, single-layered MoS2 nanosheets are prepared and further modified by cysteine. The modified MoS2 nanosheets and epoxidized natural rubber (ENR) are premixed and then added into a NR/carbon black compound to obtain a NR/carbon black/ENR-modified MoS2 nanosheets composite. The reaction between modified MoS2 nanosheets and ENR is proved by FT-IR spectra. The modified MoS2 nanosheets can improve the dispersion of carbon black in NR, and ENR can significantly improve the dispersion of modified MoS2 nanosheets in the composite. The addition of ENR-modified MoS2 nanosheets premixture can improve the abrasion resistance, increase the crosslink density and control the dynamic mechanical properties of NR. These improved properties can be attributed to the good filler dispersion and enhanced filler–matrix interaction in NR matrix.

Novel nondestructive investigations of rubber products by terahertz spectroscopy & electrical measurement

Vulcanisation is a chemical process that is used to reinforce rubber, and the process makes it suitable for use in a number of products and industries. Both good mixing conditions and filler dispersion are essential to keep high-quality of rubber products; however, they are quite difficult to be evaluated by conventional techniques. Prof Yasuyuki Hirakawa is based at the Department of Electrical and Electronic Engineering, National Institute of Technology (KOSEN), Kurume College. He is working to further evaluate ways to enhance rubber's productivity and performance. This is being done using terahertz (THz) radiation and electrical current, which can evaluate and inspect materials in a non-destructive way.

Ionic Liquid as Dispersing Agent of LDH-Carbon Nanotubes into a Biodegradable Vinyl Alcohol Polymer.

A Zn/Al layered double hydroxides (LDHs) hosting carbon nanotubes (80% of CNTs) was synthesized and dispersed into a commercial biodegradable highly amorphous vinyl alcohol polymer at different loading (i.e., 1; 3; 5; 10 wt %). In order to improve the degree of dispersion of the filler into the polymer matrix, an ionic liquid (IL) based on 1-hexadecyl-3-methylimidazolium dimethyl-5-sodiosulfoisophthalate was added to the composites’ mixtures. Structural characterization of filler and polymeric composites was carried out. The analysis of thermal, mechanical and electrical properties of the composites, resulted improved compared to the unfilled material, allowed to hypothesize a good dispersion of the LDH-CNTs lamellar filler into the polymer matrix-assisted by the ionic liquid. This was demonstrated comparing electrical conductivity of composite at 5% of LDH-CNTs in the presence and in the absence of IL. The experimental results showed that the electrical conductivity of the sample with IL is four orders of magnitude higher than the one without IL. Furthermore, the percolation threshold of the whole system resulted very low—0.26% of LDH-CNTs loading, which is 0.21% of CNTs.

Highly enhanced electrical and mechanical properties of methyl methacrylate modified natural rubber filled with multiwalled carbon nanotubes

Developing conductive networks in a polymer matrix with a low percolation threshold and excellent mechanical properties is desired for soft electronics applications. In this work, natural rubber (NR) functionalized with poly(methyl methacrylate) (PMMA) was prepared for strong interfacial interactions with multiwalled carbon nanotubes (MWCNT), resulting in excellent performance of the natural rubber nanocomposites. The MWCNT and methyl methacrylate functional groups gave good filler dispersion, conductivity and tensile properties. The filler network in the matrix was studied with microscopy and from its non-linear viscoelasticity. The Maier-Göritze approach revealed that MWCNT network formation was favored in the NR functionalized with PMMA, with reduced electrical and mechanical percolation thresholds. The obvious improvement in physical performance of MWCNT/methyl methacrylate functionalized natural rubber nanocomposites was caused by interfacial interactions and reduced filler agglomeration in the NR matrix. The modification of NR with poly(methyl methacrylate) and MWCNT filler was demonstrated as an effective pathway to enhance the mechanical and electrical properties of natural rubber nanocomposites.

A Novel Polystyrene Nanocomposite with Fully Phenyl POSSs Functionalized

AbstractTwo novel polyhedral oligomeric silsesquioxanes/polystyrene (POSS/PS) nanocomposites are synthesized by in situ polymerization of styrene, in the presence of 5% w/w of POSS in which two identical silicon cages Ar7(SiO1.5)8 (with Ar═Phenyl) are linked to different rigid molecular bridges. The obtained nanocomposites are characterized by 1H‐NMR spectroscopy, thermogravimetric analysis, and by scanning electron microscopy (SEM). The resistance to the thermal degradation is evaluated by measuring the temperature at 5% mass loss (T5%), whose values for the prepared nanocomposites are largely higher than those found for PS, in the same experimental conditions. SEM analysis showed a good dispersion of the molecular filler within the matrix, thus providing a justification for the increasing in PS/POSSs thermal stability.

Influence of Hybrid Cellulose/Bentonite Fillers on Structure, Ambient, and Low Temperature Tensile Properties of Thermoplastic Starch Composites

Thermoplastic starch (TPS) composites incorporating bentonite/cellulose (Bent/Cellulose) hybrid fillers in different ratios were prepared by film casting. Ultra‐sonication was done to promote good dispersion of filler in the host TPS and enhance the filler‐matrix interactions. Ultra‐sonicated fillers resulted in superior improvement in the tensile properties when the samples preconditioned at both ambient and 2°C. Upon preconditioning at 2°C, the TPS composite containing the ultra‐sonicated hybrid bent/cellulose in 80:20 ratio displayed the greatest tensile properties achievement among all the tested materials. These could be due to the effect of low temperature interactions between the starch, plasticizers, and the hybrid fillers. Differential scanning calorimetry analysis proved the changes in the crystallinity and dynamic characteristic of the TPS molecular chains which benefit in enhancing the biopolymer elongation at break and toughness, even when stored at refrigerated condition. In summary, the TPS/bent/cellulose composite has potential to be further developed for refrigerated food packaging application. POLYM. ENG. SCI., 60:810–822, 2020. © 2020 Society of Plastics Engineers

Tuning of Nano-Based Materials for Embedding Into Low-Permeability Polyimides for a Featured Gas Separation

Several concepts of membranes have emerged, aiming at the enhancement of separation performance, as well as some other physicochemical properties, of the existing membrane materials. One of these concepts is the well-known mixed matrix membranes (MMMs), which combine the features of inorganic (e.g., zeolites, metal–organic frameworks, graphene, and carbon-based materials) and polymeric (e.g., polyimides, polymers of intrinsic microporosity, polysulfone, and cellulose acetate) materials. To date, it is likely that such a concept has been widely explored and developed toward low-permeability polyimides for gas separation, such as oxydianiline (ODA), tetracarboxylic dianhydride–diaminophenylindane (BTDA-DAPI), m-phenylenediamine (m-PDA), and hydroxybenzoic acid (HBA). When dealing with the gas separation performance of polyimide-based MMMs, these membranes tend to display some deficiency according to the poor polyimide–filler compatibility, which has promoted the tuning of chemical properties of those filling materials. This approach has indeed enhanced the polymer–filler interfaces, providing synergic MMMs with superior gas separation performance. Herein, the goal of this review paper is to give a critical overview of the current insights in fabricating MMMs based on chemically modified filling nanomaterials and low-permeability polyimides for selective gas separation. Special interest has been paid to the chemical modification protocols of the fillers (including good filler dispersion) and thus the relevant experimental results provoked by such approaches. Moreover, some principles, as well as the main drawbacks, occurring during the MMM preparation are also given.