Filled Polymer Composites Research Articles

Determination of Mechanical and Tribological Properties of Silicone-Based Composites Filled with Manganese Waste.

High-tonnage industrial processes generate high amount of waste. This is a growing problem in the whole world. Neutralizing such waste can be time consuming and costly. One of the possibilities of their reuse is to use them as fillers in polymer composites. Introduction of the filler in polymer matrix causes change in its mechanical and tribological properties. In the article, the effect of introducing fillers from post-production waste, and its effect on changing the physical properties of silicone-based composites filled with manganese (II) oxide and waste manganese residue was investigated. The composites were made by gravity casting. Composites with 2.5, 5, 7.5, and 10 wt% of the fillers were examined. The composite materials were subjected to tests such as: density, hardness, resilience, tensile test, abrasion resistance, and ball-on-disc. Microscopic images showed that, the particles of the fillers are uniformly distributed in silicone matrix with the formation of smaller agglomerates. Such agglomerates introduced a discontinuity in the structure of the polymer material, which caused a decrease in the tensile strength and elongation at break for all tested compositions in comparison with the mechanical properties of the silicone used as the matrix. However, it was found that all silicone-based composites filled with manganese (II) oxide and manganese residue showed a reduction in abrasive wear, compared to the reference sample.

Experimental study on tensile strength of copper microparticles filled polymer composites printed by fused deposition modelling process

PurposeThe purpose of this paper is to investigate the variables of the fused deposition modelling (FDM) process and improve their effect on the mechanical properties of acrylonitrile butadiene styrene (ABS) components reinforced with copper microparticles.Design/methodology/approachIn the experimental approach, after drying the ABS granule, it was mixed with copper microparticles (at concentrations of 5%, 8% and 10%) in a single screw extruder to fabricate pure ABS and composite filaments. Then, by making the components by the FDM process, the tensile strength of the parts was determined through tensile strength tests. Taguchi DOE method was used to design the experiments in which nozzle temperature, filling pattern and layer thickness were the design variables. The analysis of variance (ANOVA) and signal-to-noise analysis were conducted to determine the effectiveness of each FDM process parameter on the ultimate tensile strength of printed samples. Following that, the main effect analysis was used to optimize each process parameter for pure ABS and its composite at different copper contents.FindingsThe study allows the layer thickness and filling pattern had the highest effects on the ultimate tensile strength of the printed materials (pure and composite) in the FDM process. Moreover, the results show that the ultimate tensile strength of the ABS composite containing 5% copper was nearly 12.3% higher than the pure ABS part. According to validation tests, the maximum error of experiments was about 0.96%.Originality/valueIn this paper, the effect of copper microparticles (as filling agent) was investigated on the ultimate tensile strength of printed ABS material during the FDM process.

Decoupling of inter-particle polarization and intra-particle polarization in core-shell structured nanocomposites towards improved dielectric performance

Conductive-filler filled polymer composites have exhibited great potential due to the high dielectric constant that can be reached near the percolation threshold, yet the associated high dielectric loss prohibits wide use in practice. Recently, extensive efforts have been devoted to encapsulating conductive fillers with an insulating shell, with the aim to constrain the dielectric loss; but such efforts also significantly reduce dielectric constant. This dilemma raises the question of whether core-shell structured fillers are ultimately beneficial for the dielectric performance of composites, which is less explored. In this study, we investigate polymer nanocomposites containing a series of Al@Al2O3 nanofillers with different shell thicknesses. It shows that the high dielectric constant of percolative composites is contributed by a fast intra-particle polarization and a slow inter-particle polarization. Formation of an insulating shell enables the independent control of the two polarizations, which are otherwise coupled (increasing or decreasing together) in regular percolative composites. By promoting intra-particle polarization and suppressing inter-particle polarization, the core-shell structured nanocomposites can obtain a high dielectric constant and concurrently low dielectric loss, far surpassing the unmodified nanofiller composites. Moreover, the thermal conductivity and high field resistivity are also improved, resulting in a stable and low temperature during operation. This work offers a new paradigm for the design of percolative polymer composite with high dielectric constant and low dielectric loss as well as improved thermomechanical properties.

Epoxy Composites with High Thermal Conductivity by Constructing Three-Dimensional Carbon Fiber/Carbon/Nickel Networks Using an Electroplating Method.

Heat dissipation problem is the primary factor restricting the service life of an electronic component. The thermal conductivity of materials has become a bottleneck that hinders the development of the electronic information industry (such as light-emitting diodes, 5G mobile phones). Therefore, the research on improving the thermal conductivity of materials has a very important theoretical value and a practical application value. Whether the thermally conductive filler in polymer composites can form a highly thermal conductive pathway is a key issue at this stage. The carbon fiber/carbon felt (CF/C felt) prepared in the study has a three-dimensional continuous network structure. The nickel-coated carbon fiber/carbon felt (CF/C/Ni felt) was fabricated by an electroplating deposition method. Three-dimensional CF/C/Ni/epoxy composites were manufactured by vacuum-assisted liquid-phase impregnation. By forming connection points between the adjacent carbon fibers, the thermal conduction path inside the felt can be improved so as to improve the thermal conductivity of the CF/C/Ni/epoxy composite. The thermal conductivity of the CF/C/Ni/epoxy composite (in-plane K∥) is up to 2.13 W/(m K) with 14.0 wt % CF/C and 3.70 wt % Ni particles (60 min electroplating deposition). This paper provides a theoretical basis for the development of high thermal conductivity and high-performance composite materials urgently needed in industrial production and high-tech fields.

Dependence of the polycarbonate mechanical performances on boron nitride flakes morphology

A key requirement for the exploitation of two-dimensional (2D)-crystals in the field of composites relies on their large-scale production. In this respect, liquid phase exfoliation of layered-crystals is emerging as one of the most promising approaches for the scalable production of high-quality 2D-crystals. However, the dependence of the 2D crystal flakes morphology, i.e. thickness and lateral size, on the mechanical properties of the polymer composites is not fully understood yet. Herein, we tackle this issue by designing an environmentally friendly approach, based on the exfoliation of bulk hexagonal-boron nitride (h-BN), widely used as filler in polymer composites for its high intrinsic stiffness, i.e. approaching 1 TPa, in a water/surfactant solution with controlled thickness and lateral size by using cascade ultra-centrifugation. Our approach allows us to obtain two populations of flakes with aspect ratio, i.e. lateral size over thickness, equal to 250 and 350, respectively. The h-BN flakes with tuned aspect ratio are subsequently used as filler in a polycarbonate (PC) matrix by exploiting solution blending in 1,3-dioxolane, a solvent with Hansen’s solubility parameters matching the ones of h-BN, thus enhancing the dispersion of the filler inside the matrix, as evaluated by Raman mapping. We tested the composite mechanical properties finding that flakes with higher aspect ratio show superior reinforcements in terms of both ultimate tensile strength and Young’s modulus, compared with their lower aspect ratio counterparts. As example, at 0.1 wt% of loading, the difference in reinforcement in terms of Young’s Modulus is of 56 MPa, being the increment, compared to pristine PC, of ∼22% for composites produced with higher aspect ratio fillers, whereas it is instead of only ∼17% for lower aspect ratio fillers.

Thermomechanical Characterization of Rice Husk–Filled Carbon-Reinforced Hybrid Polymer Composites

Abstract Rice husk–filled polymer composites have important application in thermal insulation. But their low mechanical strength, such as tensile strength, flexural rigidity, shear strength, etc., makes their mechanical application limited. In this study, to increase the mechanical strength of rice husk–filled polymer composites, particulate carbon fiber is added by a hand lay-up process, and the result is called rice husk–filled carbon-reinforced hybrid polymer composites. In the first part of the study, the thermal conductivity of the composites at different percentages of rice husk with a fixed percentage of carbon (5 %) is analyzed by experimentation. It is observed that, up to 17 % of rice husk, the thermal insulating property increases and then decreases afterward. In the later part, the characterization of the mechanical properties of the developed composites at 17 % of rice husk with a fixed percentage of carbon (5 %) is done by conducting experiments, such as tensile tests, microhardness tests, and scanning electron microscopy analysis.

High-Density Bio-PE and Pozzolan Based Composites: Formulation and Prototype Design for Control of Low Water Flow.

An eco-friendly solution to produce new material for the material extrusion process is to use quarry waste as filler for biopolymer composites. A quarry waste that is still studied little as a filler for polymer composites is pozzolan. In this study, the optimization of the formulations and processing parameters of composites produced with pozzolan and bio-based polyethylene for 3D printing technology was performed. Furthermore, a precision irrigation system in the form of a drip watering cup was designed, printed, and characterized. The results showed that the presence of the pozzolan acted as a reinforcement for the composite material and improved the cohesion between the layers of the 3D printed objects. Furthermore, the optimization of the process conditions made it possible to print pieces of complex geometry and permeable parts for the control of the water flow rates with an order of magnitude in the range from mL/h to mL/day.

МІНЕРАЛЬНІ НАПОВНЮВАЧІ, МОДИФІКОВАНІ ПОГОНАМИ З ДЕЗОДОРАЦІЙНИХ КОЛОН ОЛІЄ-ЖИРОВИХ ВИРОБНИЦТВ

The aim of the work was to investigate for the first time the possibility of modification of disperse mineral fillers (chalk and magnesium hydroxide) deodorizing shoulder straps containing fatty acids obtained by refining sunflower oil for create filled polymer composites. In the study of composites based on PVC found an increase in their tensile strength, strength reaches almost 50 % increases. Accordingly, the relative elongation of these polymer composites increases. Shown to increase toughness with increasing content of modifier, with a greater increase in toughness for chalk than magnesium hydroxide for polyester resin composites. The maximum increase of toughness is more than 50 %. Thermomechanical studies have shown that the heat resistance of composites mainly increases with modified fillers.

PH triggered hydrogen bonding for preparing mechanically strong, electromagnetic interference shielding and thermally conductive waterborne polymer/graphene@polydopamine composites

Flexible and highly filled conductive polymer composites with strong mechanical properties are highly desirable as electromagnetic interference (EMI) shielding and thermally conductive materials for human protection and wearable devices. Herein, a tough interface has been built up by the combination of polydopamine modification and pH triggered hydrogen bonding to prepare flexible and mechanically robust waterborne polyacrylate/graphene@polydopamine composites. Graphene was modified with polydopamine via an in-situ polymerization method. By adjusting the initial pH value in the film formation process, the transition from electrostatic repulsion to hydrogen bonding between graphene@polydopamine and polyacrylate was engineered for improving the mechanical properties. At optimal pH value, the maximum tensile strength of the composite is enhanced by 137% compared with that of neat polymer matrix. Moreover, the composite with filler loading of 20 wt% exhibits an EMI shielding effectiveness of 58 dB at 0.6 mm thickness and thermal conductivity of 1.68 W/m·K, respectively. The practical application of the composite film and composite coated leather also demonstrates their outstanding flexibility, EMI shielding, and heat dissipation performance, indicating their excellent potential as EMI shielding and thermally conductive materials in wide areas such as wearable devices, telecommunication systems, and human protection.

Insight into the Surface Properties of Wood Fiber-Polymer Composites.

The surface properties of wood fiber (WF) filled polymer composites depend on the filler loading and are closely related to the distribution and orientation in the polymer matrix. In this study, wood fibers (WF) were incorporated into thermoplastic composites based on non-recycled polypropylene (PP) and recycled (R-PP) composites by melt compounding and injection moulding. ATR-FTIR (attenuated total reflection Fourier transform infrared spectroscopy) measurements clearly showed the propagation of WF functional groups at the surface layer of WF-PP/WF-R-PP composites preferentially with WF loading up to 30%. Optical microscopy and nanoindentation method confirmed the alignment of thinner skin layer of WF-PP/WF-R-PP composites with increasing WF addition. The thickness of the skin layer was mainly influenced by the WF loading. The effect of the addition of WF on modulus and hardness, at least at 30 and 40 wt.%, varies for PP and R-PP matrix. On the other hand, surface zeta potential measurements show increased hydrophilicity with increasing amounts of WF. Moreover, WF in PP/R-PP matrix is also responsible for the antioxidant properties of these composites as measured by DPPH (2,2′-diphenyl-1-picrylhydrazyl) assay.

A REVIEW: RELATION ON NATURAL FIBER LOADING TO THE TENSILE PROPERTIES OF TPU COMPOSITES

The natural fiber is considered recyclable and may have some potential for some application. Nowadays, this type of fiber has to gain popularity as a filler in polymer composites. Besides, it is readily available and environmentally friendly. It is also inexpensive because they are non-toxic and biodegradable waste. This paper presents the various natural fiber from fruit skin, fruit peel, agricultural residue, waste, and others as fillers in thermoplastic polyurethane (TPU). The author also reflects the key issue related to the effect of filler loading on the tensile properties of TPU composites. In general, the tensile strength of the natural fiber-filled polymer composites increases with fiber loading. The tensile properties are mainly influenced by the interfacial adhesion between the polymer and the fibers. Other than that, each type of fiber also plays a vital role in its properties and polymer adhesion. This review only focuses on the latest studies in the range of seven years from 2013 to 2019 [1].
 Keywords: Thermoplastic polyurethane, natural fiber, fiber loading, tensile properties, composites

Performance evaluation of cellulose nanofiber reinforced polymer composites

In recent years, cellulose nanofiber (CNF) has become an avidly researched material in cutting edge research fields involving prominent researchers, both in academia and industry. This has become an exciting time reaching beyond just scientific curiosity as CNF is beginning to enter various marketplaces. CNF shows unique and potentially useful features, which includes abundance, high specific surface area, renewability, high strength, eco-friendliness and high crystallinity. It is an excellent material for polymer reinforcement. Many studies have been conducted to understand the effects of CNF as a filler in polymer composites. Interestingly, most CNF polymer composites have shown a better mechanical performance compared to the neat base polymer. Thus, this enhances the application of CNF into reinforced polymer composites in several industries such as automotive, packaging, medical implant, electronics, building material and paper. Therefore, in this review, the performances of CNF polymer composites are carefully evaluated. Beyond that, several factors influencing the performance of these composites are discussed.

Highly Thermally Conductive 3D Printed Graphene Filled Polymer Composites for Scalable Thermal Management Applications.

Efficient thermal transportation in a preferred direction is highly favorable for thermal management issues. The combination of 3D printing and two-dimensional (2D) materials such as graphene, BN, and so on enables infinite possibilities for hierarchically aligned structure programming. In this work, we report the formation of the asymmetrically aligned structure of graphene filled thermoplastic polyurethane (TPU) composites during 3D printing process. The as-printed vertically aligned structure demonstrates a through-plane thermal conductivity (TC) up to 12 W m-1 K-1 at 45 wt % graphene content, which is ∼8 times of that of a horizontally printed structure and surpasses many of the traditional particle reinforced polymer composites. The superior TC is mainly attributed to the anisotropic structure design that benefited from the preferable degree of orientation of graphene and the multiscale dense structure realized by finely controlling the printing parameters. Finite element method (FEM) confirms the essential impact of anisotropic TC design for highly thermal conductive composites. This study provides an effective way to develop 3D printed graphene-based polymer composites for scalable thermal-related applications such as battery thermal management, electric packaging, and so on.

충전재 하중이 폴리비닐알코올 및 에그쉘분말 바이오복합체의 특성에 미치는 영향

Biocomposite films made up of polyvinyl alcohol (PVA) and eggshell powder (ESP) were prepared by solution casting method. The physical propertiess, mechanical properties and biodegradability of biocomposites were studied based on various ESP loading (0 to 40 wt%). From raw material characterization, ESP was found to have similar composition to the calcium carbonate, which is widely used as filler in polymer composites. It was found that the tensile properties decreased with increasing ESP loading, attributed from poor interfacial adhesion and ESP agglomeration as proven by field emission scanning electron microscope (FE-SEM) micrographs. Water absorption and water vapour transmission were enhanced with addition of ESP. The biocomposite shows higher biodegradability in both soil burial and natural weathering with increasing ESP loading.

Eco‐friendly polymer composites: A review of suitable methods for waste management

AbstractThe amount of residues generated by agriculture, industrial, or urban activities continuously increases and, consequently, demands several methods for their correct management. The incorrect disposal can cause, in specific cases, environmental contamination by heavy metals or leaching as well as promote the spread of diseases as insect proliferation. Commonly, landfilling, incinerating, composting, or energy/fuel generation can control the disposal or reuse of residues. Among the methods for the reuse of wastes, the incorporation of residues as fillers in polymer composites has emerged as a distinct field. Some composites can potentially mitigate leaching compounds or improve mechanical, thermal, and acoustic properties. However, these improvements are a challenge to promote the use of waste fillers. Thus, this study aims to provide a state of view regarding a variety of wastes used as fillers in polymer composites and different methods to reach mechanical reinforcement as well as improve thermal conductivity and acoustic attenuation for future researches.

Studies of Resistance of PP/Natural Filler Polymer Composites to Decomposition Caused by Fungi.

The article discusses the grain morphology of the natural filler from hazelnut and walnut shell flour. It was observed that the geometry of both meals is similar to each other and resembles uneven balls in shape. The heterogeneity and well-developed outer surface of the flour grains allow for filling the voids with the polymer matrix. The analysis of the surface of the SEM images allowed to observe the presence of natural filler flour grains in the entire volume of the produced polymer composites, uneven distribution and small agglomerates, as well as the presence of voids, distributed in the matrix and in the matrix/filler interface. As a result of the visual evaluation of the activity of microorganisms (mycelium) on the surface of the produced polymer composite materials PP/hazelnut and walnut shell flour with a different % share, different fraction, it was found that the best fungistatic effect was shown by the samples marked with the symbol hazelnut at the fraction 315–443 µm. The least fungistatic material was found to be the samples with walnut shell meal filler at the fraction 315–443 µm (F2 and F4), on which the microorganisms achieved significant growth (more than 50% of the test area). The highest value of contact angle was obtained for samples with hazelnut filler fraction 315–443 (C2 and C4), which also confirms its best fungistatic effect.

Controllable regulation of the segregated conductive networks targeted enhanced thermal conduction performance of polymer bonded explosives

Constructing continuous segregated conductive networks with highly thermally conductive fillers in polymer composites has been proved to be an effective way to increase the filler-filler contact and reduce the interfacial thermal resistance, which is quite helpful for the enhancement of the thermal conductivity. In this study, we have further optimized the thermal conduction performance of the composites through morphological control of the structure of segregated conductive networks. Our results reveal that the network continuity and density are the two main factors which will influence the thermal conductivity of the final polymer composites. Finally, the highest thermal conductivities of 1.221 and 1.421 W M-1 K−1 were achieved for the polymer composites at low filler content of 0.865 and 1.73 vol%, respectively, which are 74.9% and 103.6% higher than that of the corresponding pure polymer composites. Moreover, the mechanical properties of the composites were also preserved to some degree.

Modified Nanoclays/Straw Fillers as Functional Additives of Natural Rubber Biocomposites

Increasingly, raw materials of natural origin are used as fillers in polymer composites. Such biocomposites have satisfactory properties. To ensure above-average functional properties, modifications of biofillers with other materials are also used. The presented research work aimed to produce and characterize elastomeric materials with a straw-based filler and four different types of montmorillonite. The main research goal was to obtain improved functional parameters of vulcanizates based on natural rubber. A series of composites filled with straw and certain types of modified and unmodified nano-clays in various ratios and amounts were prepared. Then, they were subjected to a series of tests to assess the impact of the hybrids used on the final product. It has been shown that the addition of optimal amounts of biofillers can, inter alia, increase the tensile strength of the composite, improve damping properties, extend the burning time of the material and affect the course of vulcanization or cross-linking density.

Micro-scale Aluminium Filled Polymer Composites with Improved Mechanical and Thermal Properties via Hot-pressing

Polymer based thermal interface materials are widely utilized in aeronautical and aerospace equipment, and can significantly contribute to the cooling of devices, which depends on their high thermal conductivities. In this work, a poly(vinylidene fluoride) (PVDF) based composite with micro-scale aluminium particles is fabricated. The aluminium particles were successfully imbedded into the PVDF matrix, and the composite possesses dense structure caused by the hot-pressing process. Benefiting from that, the value of thermal conductivity improves to 1.82 W/(mK), which is 767% higher than that on pristine PVDF. Meanwhile, compared with pristine polymer, the mechanical performances, including tensile strength and modulus, are also significantly improved by 99% and 517%, respectively. The phenomenon can be attributed to the dense inner structure and effective heat transfer pathways of aluminium particles. This simple and effective strategy provides an available method to fabricate the thermoplastic polymeric composite with superior thermal and mechanical properties, used for the high-performance aeronautical and aerospace equipment.

Synthesis and Properties of Polymerization-Filled Composites Based on Polypropylene and Single-Wall Carbon Nanotubes

Composites based on polypropylene and single-wall carbon oxygen-containing nanotubes with a specific surface area of 360 and 500 m2/g are synthesized in the medium of liquid propylene using the catalytic system rac-Me2Si(2-Me-4-PhInd)2ZrCl2/МАО. Optimum polymerization conditions ensuring a fairly high rate of the process are determined, and the composites with the filler content in the range from 0.3 to 13.0 wt % are obtained. It is shown that the presence of functional groups enhances the filler agglomeration tendency during composite formation. Effects of the type of carbon nanofiller on the thermal stability, thermo-oxidative resistance, and thermal and electrophysical characteristics of the composites are studied. It is found that the filler inhibits the processes of oxidation and destruction of polypropylene crystallites.