A Review on Synthetic Fibers for Polymer Matrix Composites: Performance, Failure Modes and Applications

Enhancing mechanical properties of mortar with short and thin banana fibers: A sustainable alternative to synthetic fibers

The use of fiber in mortar/concrete is now common for enhancing the flexural and ductility properties of structures. However, the utilization of synthetic fibers contributes to the emission of harmful greenhouse gases. Replacing these synthetic fibers with natural fibers derived from waste plants is imperative for sustainable development. The objective of this study was to evaluate the performance of short and thin banana fibers in enhancing the mechanical properties of fiber-reinforced mortar, specifically in terms of compressive, flexural, and splitting tensile strengths. The base mortar, with a water-cement ratio of 0.30 and a unit water content of 298 kg/m3, was employed. The banana fibers were manually extracted from banana stalks, dried in an oven, and then cut into 10 mm fibers. The fibers were not treated with alkali. The fiber content was varied at 0 %, 0.125 %, 0.25 %, 0.5 %, and 0.75 % by weight of cement. Initially, the fibers were mixed into the viscous mortar along with the first portion of water and a superplasticizer. Subsequently, workability was improved by incorporating the second portion of water. The optimal content of banana fiber was determined to be 0.25 %, which increased the 28-day compressive, flexural, and splitting tensile strengths by 18.7 %, 29.9 %, and 41.1 %, respectively, compared to the base mortar. These findings suggest that the short and thin banana fiber has the potential to serve as a sustainable alternative to synthetic fibers. However, it is essential to conduct a thorough assessment of durability properties before implementing it in actual structures.

Recent advances in reinforced bioplastics for food packaging - A critical review

Recently, diversifying the material, method, and application in food packaging has been massively developed to find more environment-friendly materials. However, the mechanical and barrier properties of the bioplastics are major hurdles to expansion in commercial realization. The compositional variation with the inclusion of different fillers could resolve the lacking performance of the bioplastic. This review summarizes the various reinforcement fillers and their effect on bioplastic development. In this review, we first discussed the status of bioplastics and their definition, advantages, and limitations regarding their performance in the food packaging application. Further, the overview of different fillers and development methods has been discussed thoroughly. The application of reinforced bioplastic for food packaging and its effect on food quality and shelf life are highlighted. The environmental issues, health concerns, and future perspectives of the reinforced bioplastic are also discussed at the end of the manuscript. Adding different fillers into the bioplastic improves physical, mechanical, barrier, and active properties, which render the required protective functions to replace conventional plastic for food packaging applications. Various fillers, such as natural and chemically synthesized, could be incorporated into the bioplastic, and their overall properties improve significantly for the food packaging application.

Experimental Study of a 3D Printing Strategy for Polymer-Based Parts for Drone Equipment Using Bladeless Technology

The present study focuses on an up-to-date topic regarding flying equipment identified within the category of drones that use, for propulsion and air movements, the power generated by electric motors. In this paper, researchers focus on implementing bladeless technology to calculate, develop, and construct flying equipment known in the literature as drones. The entire structure of the prototype, all the needed parts, is to be obtained using additive manufacturing technologies, which assumes practical realization using 3D-printing equipment. Nowadays, the 3D-printing process has been proven to be a reliable solution when it comes to manufacturing complex shape parts in quite a short time and with reduced costs. The practical study within the present research aims to obtain polymer-based, lightweight parts with complex shapes inside to be implemented in the propulsion of a drone. The complex surface geometry of the parts that this research used is influenced by the ventilation technology offered by the "Air Multiplier" technology. The entire structure of the final drone equipment, all the parts, is to be manufactured using fused filament fabrication (FFF). The main purpose of the fusion is to use the advantages offered by this technology in drones to obtain advantages such as augmented values of thrust, a more agreeable and muffled sound signature, or an increased level of safety.

Experimental and Numerical Study of Printing Strategy Impact on the Mechanical Properties of Sustainable PLA Materials

This article is focused on a mechanical properties investigation of three types of sustainable poly lactic acid materials manufactured using the fused filament fabrication process. The purpose of this work was to study the impact of printing strategies on the mechanical properties and predict mechanical behavior under tensile loading using finite element analysis. The testing of mechanical properties was conducted according to the ISO 527 standard. The numerical simulations were conducted in Simufact Forming 2022 software. Analysis of the experimental data showed a dependance of mechanical properties on the used printing strategy. The Clear PLA samples printed in the XY plane exhibited a 43% reduction in tensile strength and a 49% reduction in elongation compared to samples printed from the same material in YZ plane. The experimental results show the influence of the printing orientation on the mechanical properties of 3D-printed samples.

Mechanical Properties and Microstructure of Rice Husk Ash-Rubber-Fiber Concrete under Hygrothermal Environment

In order to study the mechanical properties of rice husk ash-rubber-fiber concrete (RRFC) under hygrothermal environment, the optimal group was selected by orthogonal test. The mass loss, relative dynamic elastic modulus analysis, strength analysis, degradation degree analysis after cyclic loading and internal microstructure analysis of the optimal group of RRFC samples after dry-wet cycles under different environments and temperatures were compared and analyzed. The results show that the large specific surface area of rice husk ash optimizes the particle size distribution of RRFC specimens, reacts to form C-S-H gel, enhances the compactness of concrete, and forms a dense structure as a whole. The presence of rubber particles and PVA fibers effectively improves the mechanical properties and fatigue resistance of RRFC. The comprehensive mechanical properties of RRFC with rubber particle size of 1-3 mm, PVA fiber content of 1.2 kg·m^-3 and rice husk ash content of 15% are the best. The compressive strength of the specimens after dry-wet cycles in different environments generally increased first and then decreased, reaching a peak at the seventh dry-wet cycle, and the compressive strength of the specimens under chloride salt solution decreased more than that under clear water solution. Thes provided new concrete materials for the construction of highways and tunnels in coastal areas. Under the premise of ensuring the strength and durability of concrete, it is of great practical significance to explore new roads for energy conservation and emission reduction.

Parameter Optimization of RB-SiC Polishing by Femtosecond Laser

Reaction-boned silicon carbide (RB-SiC) is considered a new material for large lightweight ground-based space telescopes due to its high specific stiffness, low thermal deformation, and excellent optical quality. The excellent mechanical properties of RB-SiC result in the low efficiency of traditional polishing and mechanical polishing. In this paper, a polishing method for RB-SiC based on a femtosecond laser is proposed to improve surface quality. A theoretical heat conduction model was established in the process of femtosecond laser irradiation of SiC. We analyzed the ablation type and calculated the single-pulse ablation threshold of SiC, which verified the feasibility of femtosecond laser polishing. Further, the effects of polishing parameters on the polished surface quality were analyzed by a series of experiments, and the optimal parameters were selected. It was observed to improve polishing efficiency and can replace the intermediate steps of traditional mechanical polishing.

Influence of the Addition of Alumina Nanofibers on the Strength of Epoxy Resins

The paper describes the effect of the addition of alumina nanofibers on the mechanical properties of the epoxy resin. Alumina nanofibers functionalized with epoxypropyl functional groups are used in this work. The dependence of the mechanical characteristics on the amount of the additive, as well as the features of its distribution in the material, is investigated. In the work, nanocomposites were obtained, which are epoxy resin with aluminum oxide nanofibers. The mechanical properties of the samples were studied by bending tests and differential mechanical analysis (DMA). It has been shown that the addition of alumina nanofibers leads to an increase in ultimate flexural strength. The maximum of this increase is near the percolation threshold of alumina nanofibers in epoxy resin. With the addition of 0.2% alumina nanofibers, the ultimate flexural strength increases from 41 to 71 MPa. It is shown that after exceeding the percolation threshold of nanofibers, the ultimate strength decreases. In this case, the elastic modulus increases from 0.643 to 0.862 GPa. DMA is shown that the glass transition temperature decreases with increasing amount of the additive. This indicates a decrease in the molecular weight of the polymer. By implication, this suggests that the hardener connects the epoxypropyl functional groups on the nanofibers and the epoxy groups in the resin, and as a result of this process, the nanofibers become natural polymer chain length limiters. The data obtained from mechanical testing and differential mechanical analysis can be used to strengthen epoxy resins in polymer composite materials and molding compositions.

The Mechanical Properties of Nanocomposites Reinforced with PA6 Electrospun Nanofibers

Electrospun nanofibers are very popular in polymer nanocomposites because they have a high aspect ratio, a large surface area, and good mechanical properties, which gives them a broad range of uses. The application of nonwoven structures of electrospun nanofiber mats has historically been limited to enhancing the interlaminar responses of fiber-reinforced composites. However, the potential of oriented nanofibers to improve the characteristics of bulk matrices cannot be overstated. In this research, a multilayered laminate composite was created by introducing polyamide (PA6)-oriented nanofibers into an epoxy matrix in order to examine the effect of the nanofibers on the tensile and thermal characteristics of the nanocomposite. The specimens' fracture surfaces were examined using scanning electron microscopy (SEM). Using differential scanning calorimetry (DSC) analysis, the thermal characteristics of the nanofiber-layered composites were investigated. The results demonstrated a 10.58% peak in the nanocomposites' elastic modulus, which was compared to the numerical simulation and the analytical model. This work proposes a technique for the development of lightweight high-performance nanocomposites.

Covid-19 waste facemask conundrum: A facile way of utilization through fabricating composite material with unsaturated polyester resin and evaluation of its mechanical properties

Since the outbreak of novel coronavirus (COVID-19), the use of personal protective equipment (PPE) has increased profusely. Among all the PPEs, face masks are the most picked ones by the mass people for protective purpose. This spawned extensive daily use of face masks and production of masks had to augment to keep up this booming demand. Such extensive use of face masks has resulted in a huge waste generation. Lack of proper disposal, waste management and waste recycling have already led this waste to pervade in the environment. In quest of finding a solution, here in this research, a composite material was fabricated utilizing waste face mask (WFM) with unsaturated polyester resin (UPR) and the mechanical properties were evaluated. The composites were fabricated by incorporating 1%, 2%, 3%, 4% and 5% WFM (by weight) within the UPR matrix in the shredded form following hand lay-up technique. Tensile properties, i.e., tensile strength (TS), tensile modulus (TM) and percentage elongation at break (% EB) as well as flexural properties, i.e., bending strength (BS) and bending modulus (BM) were evaluated for the fabricated composites. According to the results obtained, the 2% WFM loaded composites showed highest values of TS, TM, BS and BM which are 31.61 N/mm², 1551.41 N/mm², 66.53 N/mm² and 4632.71 N/mm² respectively. These values of 2% WFM loaded composite are 69.58%, 107.78%, 129.49% and 152% higher than the values of the control sample (UPR). Such results depict the successfulness of WFM's incorporation as a reinforcing material in the composite materials. Attenuated Total Reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), water uptake and thickness swelling tests were also carried out for the fabricated composites. FTIR of the collected WFM revealed the fiber to be of polypropylene and the existing functional groups were also identified. The SEM images confirmed the proper adhesion of WFM and UPR in terms of mechanical bonding rather than chemical bonding. Water absorption and dimension change was investigated by water uptake and thickness swelling test. To sum up, the way we have utilized WFM as a reinforcing agent in a composite material, this could be a possible solution for the face mask's waste conundrum.

3D-Printed Fiber-Reinforced Polymer Composites by Fused Deposition Modelling (FDM): Fiber Length and Fiber Implementation Techniques

Fused Deposition Modelling (FDM) is an actively growing additive manufacturing (AM) technology due to its ability to produce complex shapes in a short time. AM, also known as 3-dimensional printing (3DP), creates the desired shape by adding material, preferably by layering contoured layers on top of each other. The need for low cost, design flexibility and automated manufacturing processes in industry has triggered the development of FDM. However, the mechanical properties of FDM printed parts are still weaker compared to conventionally manufactured products. Numerous studies and research have already been carried out to improve the mechanical properties of FDM printed parts. Reinforce polymer matrix with fiber is one of the possible solutions. Furthermore, reinforcement can enhance the thermal and electrical properties of FDM printed parts. Various types of fibers and manufacturing methods can be adopted to reinforce the polymer matrix for different desired outcomes. This review emphasizes the fiber types and fiber insertion techniques of FDM 3D printed fiber reinforcement polymer composites. A brief overview of fused deposition modelling, polymer sintering and voids formation during FDM printing is provided, followed by the basis of fiber reinforced polymer composites, type of fibers (synthetic fibers vs. natural fibers, continuous vs. discontinuous fiber) and the composites' performance. In addition, three different manufacturing methods of fiber reinforced thermoplastics based on the timing and location of embedding the fibers, namely 'embedding before the printing process (M1)', 'embedding in the nozzle (M2)', and 'embedding on the component (M3)', are also briefly reviewed. The performance of the composites produced by three different methods were then discussed.

Elastic Properties of Jute Fiber Reinforced Polymer Composites with Different Hierarchical Structures

A two-stage micromechanics technique is used to predict the elastic modulus, as well as the major and minor Poisson's ratio of unidirectional natural fiber (NF) reinforced composites. The actual NF microstructure consists of cellulose, hemicellulose, lignin, lumen, etc., and these constituents and their contributions are neglected in classical models while quantifying their mechanical properties. The present paper addresses the effect of the real microstructure of the natural jute fiber (JF) by applying a micromechanics approach with the Finite Element Method. Six different hierarchically micro-structured JFs are considered to quantify the JF elastic properties in the first level of homogenization. Later, the JF reinforced polypropylene matrix properties are investigated in the second stage by adopting a homogenization approach. Taking into account the different hierarchical structures (HS), the fiber direction modulus (E₁), transverse modulus (E₂ and E₃), in-plane and out-of-plane shear modulus (G₁₂ and G₂₃), and major (ν₁₂, ν₁₃) and minor (ν₂₃, ν₂₁) Poisson's ratios are estimated for JF and JF reinforced polypropylene composites. The predicted elastic modulus from micromechanics models is validated against the analytical results and experimental predictions. From the present work, it is observed that the HS of NF needs to be considered while addressing the elastic properties of the NF-reinforced composite for their effective design, particularly at a higher volume fraction of NF.

Conductivity Prediction Method of Carbon Nanotube Resin Composites Considering the Quantum Tunnelling Effect

Understanding and predicting the conductivity of carbon nanotube resin composites are essential for structural health detection and monitoring applications. Due to the complexity in the composition of carbon nanotube resin composites, it is of practical significance to develop a method for predicting the conductivity with a view to design and making of the composite. In this paper, the influence of carbon nanotube tunnelling on the conductivity was investigated thoroughly, where the tunnelling conductivity effect is considered as an independent conductive phase. Then, the effective medium model and the Hashin-Shtrikman (H-S) boundary model are used to predict the conductivity of carbon nanotube resin composites. The results presented in this paper show that the developed method can reduce the prediction range of the H-S boundary model and improve the prediction accuracy of the lower bound of the H-S boundary model. The results also show that the tunnelling has little effect on conductivity prediction based on the effective medium model. Based on the results, the effects of nanotube conductivity, the aspect ratio and the barrier height on the prediction of the effective conductivity are discussed to provide a guidance for the design and making of the composites.