Fillers In Composite Materials Research Articles

Development of CaCO3 novel morphology through crystal lattice modification assisted by sulfate incorporation and vibration

CaCO3 has long been used as a filler to increase many properties of the material. The filler commonly consists of inexpensive materials that replace some volume of the more expensive materials, which can reduce the cost of the final product. CaCO3 morphology that can be used as filler depends on the filler's function, such as filler for paper, paint, rubber, or composite. A filler for composite materials is needed to increase interfacing interactions between the particulate fillers and the matrix. So, the particulate in a broader shape will be the best choice to function for such filler. In this research, in an attempt to increase the interfacing interaction, CaCO3 morphology was modified in such a way through crystal lattice modification assisted by sulfate incorporation and vibration. SEM analysis was implemented, and showed that the research successfully produced novel morphology in branchy-like polymorphs. FTIR analysis also proved that the crystal lattice has been modified. The morphology in branchy-like polymorph is supposed to increase interfacing interaction between CaCO3 as the filler and the matrix. The methods are also supposed to be implemented as the research is scaled up to commercial scale.

Serendipitous relationship between discrete distribution models representing random orientations of fillers in composite materials and the golden ratio

The purpose of this study is to establish simple discrete distribution models capable of expressing the two and three-dimensional random orientation states of fillers in composite materials. Initially, a new method is proposed to divide the elastic constants into isotropic and anisotropic parts. Employing this method, for the composite material containing ellipsoidal fillers with various orientations in the material, the macroscopic elastic constants and thermal expansion coefficients of the material are derived based on the Mori–Tanaka method. Subsequently, the analysis of the macroscopic properties is performed for fillers oriented two and three-dimensional discrete distributions. As a result, it is found that when both angular pitches of the azimuth angle and the rotational angle of the fillers in a plane are at most 72°, the macroscopic elastic constants and the thermal expansion coefficients of the material exhibit in-plane isotropy, leading to the realization of a two-dimensional random state. Furthermore, if the angular distribution of the zenith angle and azimuth angle corresponds to the vertices of the regular dodecahedron and icosahedron, and the angular pitch of the rotational angle of the fillers is at most 72°, the macroscopic properties of the material become isotropic, resulting in a three-dimensional random state. Notably, the angle of 72° and the orientation angles of the vertices of the regular dodecahedron and icosahedron are associated with the golden ratio. Therefore, this analysis suggests a serendipitous relationship between the golden ratio and the angular pitch that simplifies the random orientation distribution of fillers.

INFLUENCE OF GRAPHITED DUST ON THE ABRASION PROCESSES OF COMPOSITE MATERIAL BASED ON POLYTETRAFLUOROETHYLENE

Purpose. Study of the influence of graphitized dust on abrasive wear of polytetrafluoroethylene-based composites. Research methods. Experimental studies were performed using modern methods of physical and mechanical tests, which ensures the reliability of the results. A laboratory mixer with a rotating electromagnetic field and a hydraulic table press TU 10003 TORIN were used for the production of samples. Weighing of samples for experiments was carried out on a VLR-200 scale, abrasion assessment was carried out on a HECKERT machine. The friction surfaces were studied using a BIOLAM-M microscope. Results. The conducted studies showed that the index of abrasive wear of the composite with a polytetrafluoroethylene matrix decreases from 2.974 mm3/m to 2.539 mm3/m with a content of 10 % of graphitized dust. This helps to increase the service life of parts, which will reduce the frequency of their replacement, as well as reduce production costs. Given that graphitized dust is a waste of metallurgical production, its secondary use as a filler for composite materials allows to partially solve the environmental problem of disposal of production waste. Scientific novelty. Today, the production of products from composite materials is one of the promising directions of production, because the combination of a polymer matrix with various fillers makes it possible to obtain more economically profitable materials, forming the necessary physical properties. The possibility of using production waste as a filler allows solving the current problem of recycling and disposal of environmentally harmful substances. Therefore, the conducted research opens up new ways to solve a complex of environmental and economic problems. Practical value. The obtained results are important in the further process of manufacturing composite materials. The ability to increase the resistance of the material to abrasive abrasion allows the production of parts that work in friction conditions.

Graphene-based phononic crystal lenses: Machine learning-assisted analysis and design

The advance of artificial intelligence and graphene-based composites brings new vitality into the conventional design of acoustic lenses which suffers from high computation cost and difficulties in achieving precise desired refractive indices. This paper presents an efficient and accurate design methodology for graphene-based gradient-index phononic crystal (GGPC) lenses by combing theoretical formulations and machine learning methods. The GGPC lenses consist of two-dimensional phononic crystals possessing square unit cells with graphene-based composite inclusions. The plane wave expansion method is exploited to obtain the dispersion relations of elastic waves in the structures and then establish the data sets of the effective refractive indices in structures with different volume fractions of graphene fillers in composite materials and filling fractions of inclusions. Based on the database established by the theoretical formulation, genetic programming, a superior machine learning algorithm, is introduced to generate explicit mathematical expressions to predict the effective refractive indices under different structural information. The design of GGPC lenses is conducted with the assistance of the machine learning prediction model, and it will be illustrated by several typical design examples. The proposed design method offers high efficiency, accuracy as well as the ability to achieve inverse design of GGPC lenses, thus significantly facilitating the development of novel phononic crystal lenses and acoustic energy focusing.

Physical, morphological, mechanical and thermal properties of polyester composites reinforced with orientation of purun fiber (Eleocharis dulcis) composition

Purun fiber (PF), which has been used as a raw material for handicrafts, can be used as a filler in composite materials. The purpose of this study is to determine the characteristics of polyester composites with the addition of PF filler at concentrations (5, 10, and 15 %) with arrangements, namely parallel, random, and woven. In this study, the method used was the press molding method with a size of 20 × 20 × 0.3 cm. The resulting composite was analyzed for functional groups, physical properties, morphological properties, mechanical properties, and thermal properties. The functional group results of PF treatment showed a sharp absorption at wave numbers 1724–2983 cm−1, indicating the presence of C=C vibrations in the aromatic ring. For all fiber arrangements, the addition of 10 % PF resulted in the best composite structure. The results of the highest composite physical properties include density, water absorption, and thickness swelling of 0.958 g/cm−3, 10.079 %, and 24.57 × 10−3, respectively. The results of the highest composite mechanical properties are tensile strength, tensile modulus, elongation, and flexural strength of 813.9519 MPa, 9345.737 MPa, 14.06 MPa, and 58.8399 MPa, respectively. While the results of the thermal properties that can be seen from the percent weight loss of the composite obtained the best results in random samples with a variation of 10 %, the effect of the PF filler ratio on composite heat flow obtained the best results, namely in samples parallel to 5 % with a temperature of 500.87 °C. It can be summarized that PF has the potential as a filler in the manufacture of composites.

Mechanical and tribological properties of epoxy composites reinforced with food-waste fillers

One of the assumptions of the zero-waste economy is to reduce the amount of industrial waste produced, process it, and recover it without burning or burying it. Citrus peels are among the food wastes that are difficult to recycle. Due to the long time of decomposition and the waxes and fats in their structure, the shells rarely end up in composters and, consequently, are not included in natural fertilisers. The assumptions fit into the research described in the article.The authors investigated the possibility of using ground peels of citrus fruits: grapefruit, key lime, lemon and orange as fillers in composite materials in which the role of the matrix was played by epoxy resin. Composite materials with 2.5, 5 and 10% filler content were prepared. The materials were tested using the tensile, hardness, and abrasive tests using the pin-on-disc method.The research was to answer whether adding citrus waste can change the physicochemical properties of composite materials based on epoxy resin and native resin. Particular attention was paid to the properties that are important from the point of view of engineering applications: mechanical properties and tribological properties.In the face of challenges related to the growing amount of waste from the food industry, joint materials engineering tries to answer whether this waste can be used in the production of composite materials. In several publications from recent years, it has been postulated that used food industry products can be used as fillers for composite materials, as they can, on the one hand, improve specific physicochemical properties of new materials and manage food waste.The tests proved that composite materials with grapefruit and key lime as a filler were characterized by the best tribological properties, mechanical properties, and hardness, which were unchanged or better than the epoxy resin used as a matrix.

Quantitively evaluation of fillers' alignment for targeted manufacturing of functional composite materials

AbstractFiller‐reinforced composite materials are widely used in numerous domains such as energy, optoelectronics, chemistry, and so forth, owing to their versatile microstructures, excellent properties, and low fabrication cost. By finely regulating the distribution and orientation of fillers in the base material, composite materials with fantastic thermal, chemical, and mechanical properties have been demonstrated, which are also known as “metamaterials”. For the anisotropic fillers, the orientation of fillers is crucial for designing and predicting the properties of composite materials. However, accurate and efficient evaluation of fillers' orientation remains a challenge, which severely hinders the microstructural design and topological optimization of composite materials. To solve this problem, a bidirectional pixel‐traversal method which combines with microscopic image processing was developed to evaluate the orientation of fillers in composite materials. Specifically, a vertical orientation maximization algorithm was designed to evaluate the oriented degree and oriented direction of the whole fillers, and a crossing traversal algorithm was designed to evaluate the oriented angle of individual filler. Further, this method was applied to the evaluation of microscopic images from different researches. The evaluated results show a high accuracy (average error is less than 2%) and wide applicability in the evaluation of different types of fillers. This method reveals the underlying relationship between microscopic filler orientation and macroscopic composites properties, which paves a new way for the direct optimization and processing of composite materials.

Using of microsilica for improvement of physical and mechanical properties of epoxide-based composite material

Utilization of industrial waste and secondary raw materials, in particular, in the production of metallic silicon and silicon-containing alloys, which include silica vapors (microsilica), is the main task of implementing environmental policy and solves the problem of their storage and negative impact on the environment, in order to reuse them in polymer composites. The use of microsilica as a filler in composite materials based on epoxy resins contributes to a positive effect on the basic properties of the resin, and also makes it possible to use the composite material as coatings and parts in the repair of machinery and equipment. The aim of the work was to establish the positive effect of microsilica as a filler in composite materials based on ED-20 epoxy resin on improving the physical and mechanical properties of composite materials. Within the framework of this work, studies were conducted to test composite materials based on ED-20 epoxy resin, differing in different filler content of 2, 5, 10, 15 wt. % on impact strength, tensile strength and modulus of elasticity, adhesion and impact strength of the coating. The analysis of the obtained results showed a positive effect of microsilica as a filler in composite materials based on ED-20 epoxy resin on the physical and mechanical properties of the composite material. The optimal filler content was determined, which is 2 % of the mass of the ED-20 epoxy resin, while an increase in adhesion, toughness of the composite material by 45 %, tensile strength and modulus of elasticity by 21 % and 5 %, respectively, and the strength of the coating on impact by 32 %, compared with the addition of microsilica in ED-20, which shows the prospects of using microsilica as a filler in composite materials

Formation of the structure and properties of highly filled polymer composite materials with a deformable disperse filler

The paper discusses the main patterns of structure formation and the production of highly filled polymer composite materials based on a deformable particulate filler from rice straw (agricultural waste) and a dispersion of polyvinyl acetate (PVA) in water. t has been established that when using a deformable filler of rice straw powder, it is possible to obtain under high pressure (up to ~230 MPa) pressing DFPCM with the highly-filled type of structure and the content of dispersed filler up to ~90% by volume. Such PCM has a sufficiently high level of physical and mechanical characteristics - compressive strength ~104 MPa and elastic modulus ~ 3.0 GPa, which opens up opportunities for its wide application and production of products for various purposes from "green chemistry" materials.

Innovative application of aluminum silicate microsphere (cenosphere) as an effective filler in composite materials

Aluminosilicate microspheres as industrial waste of thermal power plants as a result of the combustion of thermal coal are widely used in various industries due to the uniqueness of their physical and chemical properties. The paper considers the use of aluminosilicate microspheres in the technologies of creating composite materials based on butadiene-styrene and nitrile rubbers with increased properties of the obtained materials for abrasive wear. Changes in the typical characteristics of the obtained rubber composite materials due to the addition of aluminosilicate hollow microspheres in the amount of 1 to 8 mass percent to the rubber matrix were studied. The deformation-strength characteristics of the latest composites and the effect of aluminosilicate microspheres on the creation of tribotechnical polymer materials for general purposes are determined. It is shown that increasing the amount of aluminosilicate hollow microspheres in the range from 2 to 8 mass percent to butadiene-styrene and nitrile rubbers contributes to the stabilization of wear intensity values, which is a positive technological factor in the creation of composite materials with an innovative filler.

Comparative Evaluation Of Flexural Strength Of Two Commercially Available Bulk Fill Composite Restorative Materials

Comparative Evaluation Of Flexural Strength Of Two Commercially Available Bulk Fill Composite Restorative Materials

Influence of size classifications on the crystallinity index of Albizia gummifera cellulose

The isolation of cellulose has found considerable applications recently due to its attractive characteristics. Cellulose from Albizia gummifera of different size classifications (425 μm–599 μm and 600 μm–849 μm) was investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analyses. The crystal plane of the preferred orientation was at (020) for the most prominent peaks. The two size classifications have a strong broad peak around 3320 cm−1 (425 μm–599 μm), and 3330 cm−1 (600 μm–849 μm), which corresponds to a different stretching mode of O–H. High percentages of carbon (C) and oxygen (O) were noticed among the elements observed in the two size classifications. The crystallinity index (CrI) obtained for the two sizes were 61.1% for 425–599 μm, and 55.8% for 600 μm–849 μm. The 425 μm–599 μm size classification had a greater crystallinity index than the 600 μm–849 μm size classification, which indicates a stronger capacity for reinforcing. These particles were also effective as fillers in composite materials. The results revealed that Albizia gummifera cellulose possessed promising potential for device applications and capable of being used in the preparation of composite materials.

Carbon Layer Formation on Hexagonal Boron Nitride by Plasma Processing in Hydroquinone Aqueous Solution.

Although hexagonal boron nitride (hBN) is a thermally conductive and electrically insulating filler in composite materials, surface modification remains difficult, which limits its dispersibility and functionalization. In this study, carbon layer formation on hBN particles by plasma processing in hydroquinone aqueous solution was investigated as a surface modification technique. Carbon components with features of polymeric hydrogenated amorphous carbon were found to be uniformly distributed on the hydroquinone-aided plasma-modified hBN (HQpBN) particles. Electron spin resonance measurements revealed abundant unpaired electrons in HQpBN, indicating that defects were formed on hBN by plasma processing and that the carbon layer contained dangling bonds. The defects on hBN could help in the attachment of the carbon layer, whereas the dangling bonds could act as reactive sites for further functionalization. The carbon layer on HQpBN was successfully functionalized with isocyanate groups, thus confirming the ability of this carbon layer to facilitate surface modification. These results demonstrate that the carbon layer formed on hBN can provide a designable interface in organic/inorganic composite materials.

The effect of periodate oxidation, tert-butanol treatment, and starch addition in improving melt dispersion of cellulosic fillers in PBAT

Dispersion in the melt is a very serious issue that affects properties of composites based on cellulosic fillers as these materials tend to form agglomerates. The aim of this study is to test the efficiency of various methods to improve the dispersion of cellulosic fillers in PBAT polymer. First, periodate oxidation treatment was carried out on the fillers in an attempt to reduce the amount of hydroxyl groups responsible of the agglomeration of cellulosic fillers in composite materials. Secondly, as several studies have demonstrated the positive effect of using tert-butanol (TB) as a freeze-drying medium for preventing the aggregation of cellulosic particles, this method was tested to produce composites with reduced amount of agglomerates. Finally, the addition of a third component as a compatibilizer which has a similar chemical structure to cellulose such as starch was also tested. No significant improvement of mechanical properties was noticed in using TB as a freeze-drying medium or with periodate oxidation treatment on the cellulosic fillers at least in improving dispersion in PBAT composites. However, the addition of starch as a compatibilizer has proved its effectiveness through the creation of a percolating network and a better dispersion of the fillers in the polymer matrix.

Calcined hydroxyapatite powders with increased chemical stabilities and dispersibility

Biocompatible hydroxyapatite (HAp) powders have thermodynamically driven tendencies to lower their surface areas due to the formation of irreversible aggregates. To address this challenge, HAp hybrid powders are herein prepared by using a traditional wet-precipitation method with subsequent hydrothermal carbonization for surface modification. The crystallite size, crystallite degree and area ratio of the infrared peak assigned to bonding water against those of free water are determined to investigate the variation of HAp crystallization with processing parameters. The crystallization of HAp is facilitated by enriched water in a stealth layer with water molecules evolved by citrate, nitrogen (N)-containing methylene blue (MB), hydrogen-group-rich β-cyclodextrin (CD) and oxygen-containing organic carbon shells. The low surface areas result in fabrication of nano-sized HAp powders with a uniform size distribution, well-dispersed morphologies and smooth surfaces through calcination of HAp-CD-MB@C. The pH values of acidic buffers increase slowly during incubation of HAp-CD-MB@C powders with chemical stability and a large grain size after calcination at 550°C for 2 h. The present study will shed light on the preparation of nano-sized inorganic powders with a uniform size distribution, well-dispersed morphologies and modulated chemical stability for potential applications as carriers of small molecular substances and fillers in composite materials.

Preparation and properties of ultra-high performance lightweight concrete

Based on orthogonal experiments, an ordinary Portland cement (OPC)-fly ash (FA)-silica fume (SF) ternary cementitious material system was developed. The ultra-high-strength lightweight concrete (UHPLC) with a strength exceeding 100 MPa was prepared using pottery sand (PS) and hollow glass microspheres (HGM) as the weight-reducing material and steel fibers as reinforcement. Through workability, apparent density, strength, and early autogenous shrinkage tests, as well as SEM examinations, the effect of various material parameters on the basic performance of UHPLC was investigated, and their mechanisms were explored. The results revealed the optimal mix ratio of OPC : FA : SF : PS : HGM = 1 : 0.200 : 0.133 : 0.533 : 0.067, a water-binder ratio of 0.16, and a volume ratio of steel fibers of 2%. Under steam curing at 90°C for 48 h, the prepared UHPLC had an apparent density of 2031 kg/m3, compressive/flexural strengths of 112/16 MPa, a slump/expansion of 260/590 mm, and specific strength of 0.055, achieving the goal of light weight and high strength. As the filler of composite materials, HGM can achieve lightweight and high strengthening of cement-based materials. HGM had a large water demand, increasing the autogenous shrinkage of UHPLC to a certain extent. The incorporation of steel fibers significantly increased the strength and apparent density of UHPLC, and its high elastic modulus inhibited the UHPLC shrinkage.

Deformable dispersed particles, calculation of compositions and technology for obtaining highly filled polymer composite materials

The main methods for determining the maximum content of the dispersed phase and designing the compositions of polymer composite materials (PCM) with different types of dispersed structure are considered on the example of rice straw powder (RSP) particles deforming under pressure.It is shown that different methods for determining the maximum content of RSP in PCM make it possible to obtain data on the packing and internal porosity of RSP particles.It has been established that dispersed RSP particles deform under pressure, and at a pressure of ~500 MPa their density almost reaches the value of the true density of the substance (~1.55 g/cm3).The maximum content of RSP with deformable particles in dispersed PCM can reach ~95 vol.%, which significantly expands the possibilities of polymer materials science and makes it possible to practically solve the environmental problem of using agricultural waste in the form of rice straw.

Recycling of polymer materials using ethylene vinyl acetate and styrene block copolymer

The technology for obtaining highly filled composite materials based on ethylene vinyl acetate (EVA) and styrene block copolymer (SBS) is presented. Crumb rubber from recycling tires was used as a filler. The working temperature of rubber crumb activation has been determined, namely, the vulcanization temperature of the non-crosslinked part is 170°C. The amount of noncrosslinked part in the rubber crumb was established to be not less than 2%.

The Effect of Different Light Curing Units and Tip Distances on Translucency Parameters of Bulk fill Materials

ObjectivesTo evaluate the effect of light curing unit (LCU) types and distance from light curing unit tip on the translucency parameters (TP) of bulk fill composite materials. Materials and MethodsTwo bulk-fill resin composites and one nanohybrid composite were used in this study. The specimens were divided into groups based on the type of curing unit used, and further subdivided based on the distance of the curing source to the surface of the resin composite. Translucency was evaluated at 4 mm thickness (for the bulk-fill) and 2 mm thickness (for nanohybrid) after curing using two different light curing units at zero, 2 mm, and 4 mm distance. The results were analyzed using two-way ANOVA at the significance level of a p-value of < 0.05. ResultsAmong all the tested materials, Filtek Bulk Fill Posterior RBC showed the highest TP at 0 mm distance when cured with Blue phase G2 LED LCU and it was the least affected by the differences in distances. However, Filtek Z350 nanohybrid composite had no significant differences between the three distances when cured with Blue phase G2 LCU. ConclusionTranslucency values among the studied bulk-fill materials are affected by material composition, curing units and the distance of the tip of the light source to the restoration surface.

Covalent adaptable networks impart smart processability to multifunctional highly filled polymer composites

To tackle the challenge of manufacturing highly filled composite materials via melt compounding and injection molding, the authors proposed a novel approach based on Diels-Alder (DA) chemistry. Polycaprolactone oligomers (PCLolig, Mw = 2000 g/mol) were firstly crosslinked by DA bonds, and then the resultant network PCLolig-DA was also connected to maleimide functionalized Al2O3 particles (Al2O3-M) via DA bonds. Upon being heated to the retro-DA reaction temperature, the covalent adaptable composite network exhibited low viscosity due to de-crosslinking, enabling melt processing and well dispersion of high-concentration fillers. During the subsequent cooling, the composite network was regained because of DA reaction, benefiting increase of the composite’s strength. Consequently, the contradictory requirements for molecular weight of matrix polymer under the circumstances, which had better to be as low as possible during the manufacturing but as high as possible in the ultimate composites, were skillfully satisfied.