Reinforcement Filler Research Articles

Lignin–Poly(vinyl alcohol) Compound from Acetalization Synthesis as a Reinforcing Filler for High-Performance Gel-Spun Fibers

Lignin–Poly(vinyl alcohol) Compound from Acetalization Synthesis as a Reinforcing Filler for High-Performance Gel-Spun Fibers

Production of a Wood–Plastic Composite with Wastes from Disposable Masks and Corrugated Cardboard: A Sustainable Post-Pandemic Approach

The increasing demand for disposable textile products, personal care items, and electronic commerce has led to a substantial rise in waste generation, particularly from nonwoven fabric masks (wNWFs) and corrugated cardboard (wCC). This study assessed the feasibility of utilizing these waste materials, which were produced in significant amounts during the COVID-19 pandemic, as both a matrix and reinforcement filler in wood–plastic composites (WPCs). The WPC was fabricated using either two extrusion cycles or thermokinetic homogenization, with both processes being followed by hot pressing. The formulations consisted of virgin polypropylene (vPP), wNWF, and wCC in proportions of 45, 45, and 10 wt %, respectively. The results demonstrated that the composites produced via two extrusion cycles exhibited a tensile strength that was 85% higher and three-point flexural strength three times greater than those produced through thermokinetic homogenization. These findings contribute to advancements in scientific and technological knowledge and offer an efficient solution for managing these types of waste, which continue to be generated post-pandemic.

Smart and Sustainable 3D-Printed Nanocellulose-Based Sensors for Food Freshness Monitoring.

Annually, about one-third of the food produced around the world is wasted due to spoilage. Food contamination and spoilage, along with the use and disposal of nondegradable packaging materials, impact human health and have huge economic and sustainability implications. Achieving sustainability within the food system requires innovative solutions to reduce the environmental footprint. Herein, we describe the formulation, scalable manufacturing, and characterization of three-dimensional (3D)-printed sensors prepared from a mixture of edible biopolymer hydrogels, 8% alginate, and 10% gelatin and nanocellulose (CNC) as a reinforcement filler. We demonstrate that incorporating CNC improves the overall mechanical performance of the printed film and enables the stabilization of pH-responsive dyes for monitoring the release of total volatile basic nitrogen (TVB-N), an indicator of food freshness. Mechanical performance enhancement includes increases of 43% in load-depth indentation, 28.2% in hardness, and 17.4% in elastic modulus. This enhancement facilitates its use as a smart label technology, enabling the visual assessment of spoilage when placed inside packaging over a period of 3 days at room temperature. The 3D-printed film exhibits excellent durability, flexibility, shape memory, and robustness, along with pH responsiveness, showing distinctive color changes over the pH range of 2 to 13. These performances are demonstrated in packaged meat and fish, enabling monitoring over several days and illustrating potential as a real-time freshness indicator. The material formulations developed in this work are biodegradable, eco-friendly, and inexpensive, making them suitable candidates for smart and sustainable food packaging.

Utilizing Coconut Biochar as a Bio‐reinforcing Agent in Natural Rubber Composites

AbstractThis research investigates the pyrolysis of biochar from different parts of residual aromatic young coconut waste, namely coconut fruit, coconut bunch, and coconut leaf, to be used as fillers in natural rubber (NR). Scanning electron microscopy coupled with energy dispersive X‐ray spectroscopy reveals that biochar has a flake‐like structure with a high carbon content (67%–77%). The biochar is mixed with NR using a two‐roll mill at filler contents of 0, 10, 20, 30, and 40 phr (part per hundred of rubber). Adding coconut fruit biochar at 40 phr increases the Shore A hardness to 59.62, a remarkable 47% improvement compared with unfilled NR. The maximum tensile strength occurs at 20 phr, while the highest tensile modulus (4.53 MPa) and tear strength (17,344 N m−1) are observed at 40 phr. Moreover, the swelling index of composites in toluene decreases slightly as biochar content increases, and the crosslink density is higher for NR filled with coconut fruit biochar than for other biochar types. Based on these results, coconut fruit biochar is identified as the most effective reinforcement filler for NR among the biochar types studied. Consequently, it can be used as a bio‐reinforcing agent in NR composites, contributing to sustainability and eco‐friendliness.

A Novel Super-Toughness and Self-Healing Solid Polymer Electrolyte for Solid Sodium Metal Batteries.

Solid sodium metal batteries (SSMBs) offer an alternative promising power source for electrochemical energy storage due to their high energy density and high safety. However, the inherent sodium dendrite growth and poor mechanical properties of electrolytes seriously limit their application. Herein, a network structure composed of polyethylene oxide-based composite polymer electrolyte (CPE) is designed with liquid metal nanoparticles (LM) for SSMBs, in which LM can move in the solid electrolyte with the electric field driven. This effect can facilitate the inactivated sodium return to the metal sodium anode, and alloy with dendrites at the same time, which is beneficial for inhibiting the growth of dendrites. The symmetric cell with the CPE containing LM achieves good cyclic stability of more than 1800 and 800h at 0.1 and 0.2mAcm-2, respectively. The energy density of the pouch battery can reach 230Whkg-1. In sum, LM presents great potential to be employed as a performance reinforcement filler for CPEs, which paves the way for achieving high-performance SSMBs.

A novel printing strategy to fabricate polyetheretherketone (PEEK)-based composites via hollow filaments filled with multiple reinforcements

ABSTRACT Polyetheretherketone (PEEK)-based composites fabricated by material extrusion (ME) have attracted broad research attention; however, the complex pre-made composite filament process makes them inflexible. In this work, a novel composite printing strategy was proposed by filling composite powder into hollow filaments to construct composite filaments for printing. This strategy eliminated the screw extrusion composite filament process and fabricated composite parts directly using composite powders. Hydroxyapatite-reinforced polyetheretherketone (HA-PEEK) and carbon fibre-reinforced polyetheretherketone (CF-PEEK) composite specimens were fabricated based on the proposed printing method, and their chemical, physical, and mechanical properties were investigated. To improve the mechanical performance of the specimens, annealing was conducted. It was found that the printed composite specimens had excellent mechanical properties. The highest flexural strengths of the 10% HA-PEEK-R and 5% CF-PEEK-R specimens were detected as 352.9 and 399.4 MPa, respectively. The compression strengths of the 10% HA-PEEK-R and 20% CF-PEEK-R specimens peaked, representing 123.0 and 137.2 MPa, respectively. Furthermore, adding different functional reinforcement fillers or various filler contents to different segments of hollow filaments, sandwich structures and gradient structures were successfully fabricated.

Environmentally Benign High‐Performance Composites‐Based Hybrid Microcrystalline Cellulose/Graphene Oxide

ABSTRACTA novel silane functionalization prepared by a solution mixing approach of epoxy composites filled with eco‐friendly reinforcement filler, that is, graphene oxide (GO) and microcrystalline cellulose (MCC). The developed composites were subjected to comprehensive analysis using various characterization techniques, encompassing mechanical testing, water absorption analysis, thermal stability assessment, and scanning electron microscopy (SEM). The tensile strength and Young's Modulus of the epoxy composite filled with 1.0 wt.% of GO (EGO1.0) demonstrated the highest value viz. 29.83 MPa and 1991.71 MPa, respectively, when compared to neat epoxy composite (E0). Meanwhile, the thermal gravimetry analysis (TGA) studies, particularly char yield, highlight improvements in the thermal stability of the EGO2.5 composite, that is, 23.39% representing a 33.73% increment compared to the E0 composite. The synergistic effect of hybrid filler, achieved by a combination of micro and nanoparticle fillers within an epoxy matrix, was investigated as a virtuous alternative to the conventional epoxy nanocomposites. A uniform dispersion of GO on the MCC surface leads to significant improvements in the mechanical properties and thermal stability of the epoxy‐reinforced composite. The maximum tensile strength, Young's Modulus, and break strain of 39.77 MPa, 2591.27 MPa, and 2.90%, respectively, were observed for the modified EGO1.0MCC1.5 composite. The synergistic effect of hybrid eco‐friendly reinforcement fillers (GO/MCC) and a strong interfacial adhesion between the matrix and filler reduces the formation of defects, thereby resulting in good stress transfer from matrix to fillers.

Particles reinforcement via friction stir processing (FSP): A Review

Abstract Friction stir processing (FSP) is a variant of friction stir welding (FSW) follows the same principle of operation as that of FSW; however, its purpose is very much different. FSP can be employed for the reinforcement of particulate filler in materials to form surface composites. FSP carries a tool of cylindrical shape with shoulder and pin. Being mounted with the spindle of the machine, it can rotate with high speed as well as exert vertical force and hence plunges the pin in to the materials. Heat originated due to friction softens the material beneath shoulder and as tool passed through ahead the material is processed and consolidated. During processing, materials experience severe deformation and mixing. Also, the temperature of the materials goes high significantly due to the synergetic effect of friction and plastic deformation. Due to the material mixing and thermo-mechanical nature, the process opens the door for the possible incorporation of second phase particles in the processed region. In this review, firstly processing/reinforcement approaches will be discussed which will be followed by effect of process parameters. After that, microstructure evolution and related mechanical properties will be discussed in detail. The synergism among process parameters, microstructure and mechanical properties will also be discussed.

Use of graphene (go and rGO) as a reinforcement filler to increase the beta phase in fluorinated copolymer nanocomposites

The present study aims to evaluate the influence of different types of graphene, graphene oxide (GO, synthesized by the Hummers method) and reduced graphene oxide (rGO, obtained by thermal reduction of GO) on the piezoelectric properties of composites based on PVDF copolymer. Hydrogen-fluorine interaction is expected to occur between GO or rGO and the fluorinated copolymer, increasing the β-conformation content in the polymer. The samples were prepared in the molten state at two concentrations of each charge inside a twin-screw extruder with interpenetrating screws. The characterizations of the nanocomposites were made according to their thermal and electrical properties. The effect of graphene incorporation into the P(VDF-TrFE) matrix was observed from thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results obtained indicated that the incorporation of graphene contributed to the increase in the β phase content of P(VDF-TrFE), which is indicative of the increase in its piezoelectricity.

Mechanochemical Methacrylation of Lignin for Biobased Reinforcing Filler in Rubber Compounds

Mechanochemical Methacrylation of Lignin for Biobased Reinforcing Filler in Rubber Compounds

Effects of spherical fillers reinforcement on the efficacy of thermal conductivity in epoxy and polyester matrices: Experimental validation and prediction using finite element method

AbstractThe creation of a theoretical heat conduction model for polymers embedded with spherical inclusions is described in this study. It also contains the experimental confirmation of the suggested correlation for utilizing the model to estimate the effective thermal conductivity (K) of such composites. According to ASTM‐E‐1530, composites are made with varying amounts of aluminium oxide and pine wood dust reinforced in polyester resin. The effective thermal conductivities (Keff) of the composites are then determined using the Unitherm TM model 2022. Ansys 19.R2 software is used to evaluate the effective thermal conductivity of these composites with a uniform filler distribution, while Digimat‐FE software is used determine the thermal conductivity values of such particle filled polymer composites with a random filler distribution. After comparison and validation with experimental data, these values are shown to be fairly good agreement with the theoretical values from the suggested correlation. The investigation is further expanded to determine the thermal conductivities for epoxy composites using wood apple shell dust and coir dust particle. Also epoxy and polyester composites reinforced with SiO2 and TiO2 have been investigated in the similar manner. The main thrust of this report to validate the numerical results of composites by varying numerous polymers. The thermal conductivity all the composites grow monotonically with increase in filler content. The thermal conductivity of silicon dioxide, titanium oxide, and aluminium oxide filled epoxy composites is measured as 1.5, 7, and 35 W/m‐K respectively.Highlights In this study spherical fillers are successfully used as a potential filler material in polyester composites The thermal conductivity predicted by proposed mathematical model of polyester is validated with measured value and found better agreement. The Ansys 19.R2 and digimat software are used to predict the thermal conductivity values of these composites. The mathematical model is further used to predict thermal conductivity of epoxy composites to check the accuracy of the model.

Biomedical Composites of Polycaprolactone/Hydroxyapatite for Bioplotting: Comprehensive Interpretation of the Reinforcement Course.

Robust materials in medical applications are sought after and researched, especially for 3D printing in bone tissue engineering. Poly[ε-caprolactone] (PCL) is a commonly used polymer for scaffolding and other medical uses. Its strength is a drawback compared to other polymers. Herein, PCL was mixed with hydroxyapatite (HAp). Composites were developed at various concentrations (0.0-8.0 wt. %, 2.0 step), aiming to enhance the strength of PCL with a biocompatible additive in bioplotting. Initially, pellets were derived from the shredding of filaments extruded after mixing PCL and HAp at predetermined quantities for each composite. Specimens were then manufactured by bioplotting 3D printing. The samples were tested for their thermal and rheological properties and were also mechanically, morphologically, and chemically examined. The mechanical properties included tensile and flexural investigations, while morphological and chemical examinations were carried out employing scanning electron microscopy and energy dispersive spectroscopy, respectively. The structure of the manufactured specimens was analyzed using micro-computed tomography with regard to both their dimensional deviations and voids. PCL/HAp 6.0 wt. % was the composite that showed the most enhanced mechanical (14.6% strength improvement) and structural properties, proving the efficiency of HAp as a reinforcement filler in medical applications.

Effect of borosilicate residue as flame retardant and reinforcement filler in polypropylene/natural fiber composites

AbstractThis study evaluated the influence of adding borosilicate residue (BS) as a flame retardant in polypropylene (PP) and natural fiber composites. The natural fibers used in this study come from the residue of the carpet industry, which is composed of PP and jute fibers (JT), while the PP used as the polymer matrix is postindustrial recycled material. The composites were produced by corotational twin‐screw extrusion and injection molding to obtain the test specimens. A coating process was carried out to add the water‐soluble fraction of BS to the surface of the compositions that did not receive it through incorporation during processing. To characterize the composites, flammability tests, thermogravimetric analysis (TGA), tensile strength test, and morphological analysis by scanning electron microscope (SEM) were performed. The addition of only 2 wt% BS content induces an increase in thermal stability of 32 and 109°C for composites with and without natural fibers, respectively. The addiction of 20 wt% BS elevates the elastic modulus up to 27% of the composites with and without natural fibers. The BS characterization indicates that it could be applied as a flame retardant when applied as coating methods using the water‐soluble fraction of BS, reducing the burning rate up to 92%. Flammability results are similar for formulations with and without natural fibers, indicating that the natural fibers did not influence the proposed flame retardant. The findings suggest that BS coating is a potential solution to improve the properties of natural fiber‐reinforced polymer composites while also promoting waste recycling. This approach produces composites with improved flammability, thermal stability, and mechanical properties, making them suitable for various end applications.

Vat photopolymerization of silica reinforced styrene-butadiene rubber elastomeric nanocomposites

Compared to their unfilled counterparts, elastomeric nanocomposites offer tailorable combinations of properties, including improved mechanical properties, increased durability, and enhanced thermal and electrical conductivity. However, the high viscosity caused by the presence of both the high molecular weight elastomer and the inclusion of fillers complicates additive manufacturing (AM) of elastomeric nanocomposites. This is especially challenging in vat photopolymerization (VP) AM, which requires resins that possess low viscosity (< 10 Pa·s) and exhibit sufficient storage modulus (∼ 104 Pa) when photocured. To address this process limitation, the authors have previously demonstrated decoupling the relationship between viscosity and molecular weight via VP of a photocurable composite latex resin. In this approach, a photocurable matrix is photocured as a scaffold around the latex particles, which provides sufficient modulus for the printed "green" part. Following a dehydration post-processing step, the latex particles coalesce to provide the final elastomeric mechanical properties without compromising feature resolution.In this work, the authors explore the effects of the addition of silica nanoparticles (10, 15, and 20 wt.%) on (i) the printability of photocurable styrene-butadiene rubber (SBR) latex resin and (ii) the mechanical properties of the resultant printed composites. The printable photocurable silica-SBR colloidal resin is realized by balancing the viscosity of the resin, the modulus of the cured green body, the silica nanoparticles content for reinforcement, and the high SBR content for elastomeric behavior. Specifically, the photocurable colloidal resin's viscosity is controlled by formulation design, while high silica nanoparticle content in the final part is achieved through evaporation of unreactive diluent. Characterization of the printed SBR nanocomposites with 20 wt.% silica reinforcement elucidated significant enhancements in the tensile strength (53 % increase), Young's modulus (671 % increase), and Shore A hardness (108 % increase) compared to printed SBR without filler reinforcement. To the authors' knowledge, this is the first report of 3D printing rubber nanocomposite using VP.

Effect of hygrothermal aging on the friction behavior and wear mechanism of the multi-filler reinforced epoxy composites for coated steel

Polymer-based composites for steel structure coating are an effective strategy to improve tribological properties and service durability under hygrothermal aging conditions. In the present paper, epoxy resin was improved by mechanical reinforcement and frictional lubrication fillers, and a kind of multi-filler reinforced epoxy composite (MFREC) was successfully prepared. Water uptake behavior, mechanical and thermal property evolution, friction behavior and wear mechanism as well as micro-topography analysis of MFREC under hygrothermal aging were conducted and discussed in detail. The research results showed that the water uptake curve of MFREC after distilled water and 5 wt% NaCl water solution immersions confirmed the two-stage diffusion model, where the quasi-equilibrium water uptakes were 4.23% and 3.67%, respectively. Additionally, the fundamental reason for the degradation of the mechanical and thermal properties of MFREC was the hydrolysis of the resin and the de-bonding of the fillers/matrix interface. The interface shear strength of MFREC adhesive and steel gradually decreased with the hygrothermal aging, but did not lose the bonding property, because the uniformly dispersed multi-fillers can fill the internal defects of the matrix and prolong the crack propagation path to block the effect. Before hygrothermal aging, MFREC had excellent friction and wear resistance compared to resin matrix, especially under water lubrication conditions. The anti-wear rate of MFREC increased by up to 59.6% compared to the room temperature dry test environment due to the coupling effects of the water lubrication and anti-friction characteristics of modified fillers. Hygrothermal aging had little effect (＜12%) on the friction coefficient of MFREC, but the anti-wear properties decreased significantly, especially the Ws increased by 255.1% under the 60 °C immersion condition. Because the degradation of thermal/mechanical properties was not enough to resist the high shear stress of the steel ball, leading to severe fatigue wear.

Preparation and mechanical characterization of natural polymer composite material obtained from fox tail palm seeds

This experimental investigation reveals the preparation of natural composite material from foxtail palm tree seeds. The fruits from the foxtail palm tree are used for the extraction of oil, and the by-product of the extraction process is freely dumped. This study attempts to utilize the waste by-product of foxtail palm tree fruit as a valuable natural composite material. The fabrication was done using the hand lay-up method for the proposed reinforcement (4% and 8%) of filler materials. The obtained composite materials are subjected to significant mechanical characterization of tensile behaviour, flexural property, and hardness. In addition, the morphological study was also carried out by the scanning electron microscope (SEM). The results show that, as the reinforcement percentages of filler material increase, the mechanical properties are improved. This may be due to the uniform dispersion of natural fibres in the polymer. The tensile strength was improved by 22.43% and 29.08% for 4% and 8% filler reinforcement. Similarly, the stiffness property was improved by 9.32% for 4% reinforcement and 18.68% for 8% reinforcement when compared with neat composite. The SEM images reveal the failure analysis, bonding strength and fibre pull-out in the composites. Finally, the foxtail fruit fibre shows promise as a reinforcing agent in composite materials, improving their mechanical properties and making them suitable for various applications requiring strength, stiffness, and resistance to deformation.

Preparing novel polylactic acid based bone scaffold composites with enhanced calcium phosphate deposition behavior and bioactivity via simple one‐step melt extrusion

AbstractPolylactic acid (PLA) is regarded as the most representative biomedical polymer materials. However, some problems, that is, its big brittleness, high hydrophobicity, and poor bioactivity, limit its application. Here, using poly(butylene adipate‐co‐terephthalate) (PBAT) as toughening agent, and incorporating ethylene diamine tetra(methylene phosphonic acid) (EDTMPA) for the first time with nano‐hydroxyapatite (nHA) as reinforcement filler, series of PLA/PBAT/nHA/EDTMPA as novel bone scaffold composites are successfully prepared via simple one‐step melt extrusion. The chemical composition, microstructures, thermodynamic properties, mechanical properties, hydrophilicity, and bioactivities of PLA/PBAT/nHA/EDTMPA were characterized. The test results show that these developed PLA‐based composites from safe biosources are greatly potential raw materials for bone scaffold because the existence of EDTMPA can chelate with calcium ions to promote calcium phosphate (CaP) deposition on the surface of bone scaffold composites. Especially, when the content of EDTMPA is 6 wt%, the comprehensive performance of the bone scaffold composite is the best. The research results indicate that these developed PLA‐based materials are greatly potential raw materials for bone scaffold composites.

Marine waste as a resource: Developing bio-epoxy composites for a sustainable future

Biowastes from discarded fishscales and seashells are rich sources of natural polymers, such as collagen, keratin, and calcium carbonate, that can be used to produce eco-friendly and biodegradable polymer composites. Therefore, utilizing the biowastes for manufacturing polymer composite can offer significant economic, environmental, and social benefits. This experimental study explores the use of Biopoxy matrix (SR33) and fish scale and seashell powders derived from biowastes as filler reinforcements while the composites were manufactured through open mold stir casting technique. Thereafter, the fillers were extracted and processed from raw waste sources, and were characterized using XRD and FTIR analyses. Mechanical and physical properties, including density, water absorption, fracture morphology, flexural, tensile, impact strength, and hardness, were also evaluated to assess the composite's performance. Additionally, thermal properties were investigated through DSC and TGA analyses. Interestingly, the results revealed that green composites with fish scale fillers at 2.5 wt% and seashell fillers at 7.5 wt% exhibited superior performance captured through enhanced mechanical and thermal properties versus control composite samples, suggesting their efficacy in reinforcing the biopoxy matrix. The study underscores the potential of utilizing biowaste-derived fillers for sustainable and eco-friendly composite materials. The combination of biopoxy with these specific filler concentrations presents a promising avenue for developing green composites with favorable mechanical and thermal characteristics, contributing to the ongoing efforts for sustainable material development.

Research Progress of Natural Rubber Wet Mixing Technology.

The performance of natural rubber (NR), a naturally occurring and sustainable material, can be greatly enhanced by adding different fillers to the NR matrix. The homogeneous dispersion of fillers in the NR matrix is a key factor in their ability to reinforce. As a novel method, wet mixing technology may effectively provide good filler dispersion in the NR matrix while overcoming the drawbacks of conventional dry mixing. This study examines the literature on wet mixing fillers, such as graphene, carbon nanotubes, silica, carbon black, and others, to prepare natural rubber composites. It also focuses on the wet preparation techniques and key characteristics of these fillers. Furthermore, the mechanism of filler reinforcement is also examined. To give guidance for the future development of wet mixing technology, this study also highlights the shortcomings of the current system and the urgent need to address them.

Exploring thermal and in-situ mechanical properties of flexible 2D tungsten disulfide foam-polymer composite for thermal management

In the realm of thermal management applications, there is a growing need for flexible materials that can efficiently dissipate heat. Polymer composites incorporating two-dimensional (2D) materials offer promising solutions due to their superior thermal and mechanical properties. Tungsten disulfide (WS2) is an excellent filler candidate for polymer composites due to its superior thermal conductivity, mechanical strength, and electrical properties. Unlike graphene, WS2 has a tunable bandgap, exhibits higher thermal resistance in inert atmospheres, is an effective lubricant over a wide temperature range of −190°C to over 800°C, and offers superior gamma radiation shielding. However, high-density 2D material polymer composite fabrication faces challenges due to the agglomeration tendency and sedimentation of heavy nanomaterials within the polymer matrix. This poor dispersion stability negatively impacts the performance and reliability of the composite. We developed a flexible WS2 foam-polydimethylsiloxane (PDMS) composite via freeze drying and vacuum-assisted infiltration, which not only overcomes fabrication challenges but also enables unique filler reinforcement foam designs. The thermal conductivity of WS2-PDMS foam was 1.57 times higher than that of neat PDMS. These thermal properties were modeled using the Lewis-Nielsen model. In-situ tensile tests were conducted to understand the mechanical reinforcing behavior and failure mechanisms of WS2 foam, which were further studied using the Gibson and Ashby model. The addition of WS2 into PDMS resulted in an elastic modulus 1.56 times higher than that of neat PDMS. The composite's mechanical properties were analyzed using the Halpin-Tsai model. These findings highlight the potential of WS2-PDMS composites for flexible thermal management applications.