Reinforced Polymer Composites Research Articles

Determination of shear strength of additively manufactured poly lactic acid/flax fibre bio-composite via the iosipescu test

The need to reduce CO2 emissions is leading to the search for alternatives to the manufacture of products from petrochemical sources. One of these alternatives is polylactic acid a bio-sourced, and biodegradable material, which is expected to be one of the most widely used materials in the forthcoming years. Recently, the feasibility of enhancing the mechanical characteristics of the PLA, by adding the flax fibre was demonstrated. Flax fibers are becoming an ideal alternative in reinforced polymer composites, thanks to the energy-intensive processing required to elaborate synthetic fibers. Flax fibers are not only recyclable and bio-degradable but also have excellent mechanical characteristics. However, the mechanical properties of flax fibre-reinforced polylactic acid composites, obtained by additive manufacturing techniques, are not well known. In the first part of this study, the quality of the Iosipescu shear experiment is examined with full-field strain measurements. In the second part, the in-plane shear response of manufactured flax fibre reinforced polylactic acid composites notched with the machining process and additive manufacturing technique are compared. This last makes it possible to evaluate the influence of the printing conditions and in particular the shell layers (contour) on the mechanical characteristics. It was perceived that the fully 3D printed specimens had a greater shear strength (+50.47%) and shear modulus (+44.68 %) than machined notch specimens. The fully 3D printed specimens count with the presence of a contour that rounds the vertices of the notches, reducing the stress-concentration factor, whereas in machined notch specimens, such contour was removed.

Stress field-aware infill toolpath generation for additive manufacturing of continuous fiber reinforced polymer composites

The infill toolpath utilized in continuous fiber reinforced polymer composites via additive manufacturing (CFRPCs-AM) significantly influences the mechanical performance of printed structures. However, existing infill toolpath for CFRPCs-AM are primarily designed for 2D planar structures and do not account for 3D shell structures with complex shapes or load path dependent characteristics. To address these limitations, this paper proposes an explicit streamline tracing method to convert the stress field into adaptive infill toolpaths for CFRPCs-AM. The method leverages principal stress direction and value fields to control toolpath density and distribution while considering the minimum allowable bead width constraint. Additionally, the geodesic distance is employed to precisely represent the distance between adjacent infill toolpaths on shell structures. Experimental validation on 2D and 3D complex structures under varying conditions demonstrates the effectiveness of the proposed method, which significantly improves stiffness and strength by 200–300% compared to traditional uniform toolpaths for CFRPCs-AM.

Nano-clay treatment of jute fiber for reinforcement in polymer composites: Mechanical, morphological, and thermo-kinetic analysis

Natural fibers have demonstrated exceptional properties that can be utilized as a viable and environmentally reliable material for reinforcement in polymer composites replacing their synthetic counterparts creating numerous environmental problems. Jute fiber is a prominent natural fiber that has been successfully applied for manufacturing noble natural fiber-based composites. This article describes the advantages and comparison between two surface treatment techniques that is alkali treatment and nano-clay treatment of jute fiber to enhance the properties for producing improved composite material. FTIR, SEM, AFM, and TGA have been utilized to compare and study how different surface treatment methods affect jute fiber. Isoconversional methods FWO and KAS are applied for the thermos-kinetic analysis and evaluation of activation energy of thermal decomposition. More than 30% increase in peak activation energy has been observed (120 KJ/mole to 160 KJ/mol). Alkali–nano-clay treated jute fiber exhibits nearly 32% improvement (405 MPa to 535 MPa) in tensile strength, 24% increment (11.85 GPa to 14.69 GPa) in tensile modulus, and 15% improvement (1.4 gm/cm3 to 1.61 gm/cm3) in fiber density as compared to that of untreated jute fiber. This study validates that nano-clay treatment has shown promising results and can improve the overall properties of natural fibers significantly.

Measurement of mechanical and thermal performance of cigarette filter fibres/eggshell particles reinforced polymer composite using integrated CRITIC-TODIM approach

The study investigates the development of polyvinyl ester (VE) composites reinforced with day-by-day litter discarded cigarette filter fibre (CFF), utilizing a compression moulding process. Carbonized chicken eggshell powder (ESP) is incorporated as a filler material in the matrix phase, varying in weight percentages (0 %, 3 %, and 5 %). To optimize mechanical properties, a multi-criteria decision-making (MCDM) approach, employing Criteria Importance through Inter-criteria Correlation (CRITIC) integrated with the TODIM (TOmada de Decisao Interativa Multicriterio) methodology, is utilized. Process control factors include CFF (40–60 wt%), fibre length (10–20 mm), and filler (0–5 wt%) at different levels. The CRITIC-TODIM optimization results highlight the significant impact of ESP filler on enhancing tensile, impact, and flexural properties in the fabricated composites. The integrated approach identifies that a combination of CFF at 60 wt%, fibre length of 20 mm, and ESP at 3 wt% yields optimal mechanical characteristics. Furthermore, thermo-gravimetric analysis indicates that the composite developed under these optimal conditions exhibits superior thermal stability compared to the composite without ESP filler.

Experimental Study on Mechanical, Chemical and Acoustical Properties of Waste Tea Leaf Fiber Reinforced Epoxy Composites

Fibre reinforced polymer composites are employed instead of metal and wood because they are stronger, more lightweight, have a favourable strength to weight ratio, and are noncorrosive. In the current research, sisal, carbon fibre, and industrial waste tea leaf fibre (WTLF) reinforced hybrid epoxy composites are being examined for their chemical, mechanical and acoustical properties with experimental study. The sisal and WTLF were chemically treated with 5% sodium hydroxide (NaOH) solution. By modifying the weight percentage of sisal and WTLF with a structure of 40 weight percent fibre and 60 weight percent matrix, five different compositions of natural fibre reinforced hybrid composites were fabricated using an automatic compression moulding technique. As per the ASTM standard the manufactured hybrid composites are tested for mechanical, chemical and acoustic characteristics. According to the experimental findings, sisal fibre with a 25 wt% and WTLF with a 5 wt% demonstrated superior mechanical properties, while these materials also demonstrated an excellent acoustic absorption coefficient (AAC) of 0.62 between the frequency range of 2000 to 6300 Hz. The morphology of failure samples revealed the matrix micro crack, void formation, fiber pullout and layers of fractured fibers which are being examined using Scanning Electron Microscopy (SEM). The superior bonding between fibre and matrix was seen in the FTIR study of 5% alkali treated composites.

Microscale and mesoscale modeling for compressive failure in unidirectional carbon fiber reinforced polymer composites with random distribution of fiber misalignments

AbstractCompressive strength and failure mode of carbon fiber reinforced polymer (CFRP) composites are affected by the severity of fiber misalignment. In this paper, numerical models based on computational micromechanics are proposed to investigate the correlation between fiber misalignment and compression failure. A single‐fiber micromodel including fiber, matrix, and interface phases is first developed to capture the influence of misalignment severity on the material failure mode. The failure longitudinal stress distribution in the fiber predicted by the micromodel indicates that the failure mode depending on the initial misalignment can be identified as uniform compression failure, compression‐bending combination collapse, and fiber buckle. A mesoscale 2D model with multiple fibers is then constructed to investigate the kink band formation. This model takes into account the distribution of fiber misalignments to capture the key geometric features of fiber misalignment that influent the compression failure in realistic composite materials at the structural scale. The results show that fiber misalignment angle amplitude, misalignment dispersion (characterized by the standard deviation), and misalignment wavelength are the key parameters of fiber misalignment, which have significant effects on compression strength and kink band geometry.Highlights Single‐fiber model to capture the effect of misalignment severity on failure mode. Multi‐fiber model with randomly distributed fiber misalignments. Failure mode depending on the severity of initial misalignment was identified. Key parameters of misalignment on compression strength and kink band geometry.

Development of stress-strain models for glass fiber reinforced polymer composites confined sustainable concrete made with natural and recycled aggregates

This study addresses the mechanical limitations of concrete fabricated with recycled brick and concrete as partial replacement of coarse aggregates, which exhibit inferior strength and stiffness compared to those with natural aggregates. To rectify this, a cost-effective approach involving low-cost glass fiber-reinforced polymer composites (LOC-GFRP) is proposed. The key parameters considered were the plain concrete compressive strength and the quantity of LOC-GFRP layers. The compressive strength of LOC-GFRP-confined concrete increased with the number of layers, with greater improvements observed in lower-strength plain concrete. Moreover, the improvement in ultimate strain was more significant than the improvement in compressive strength. The compressive strength and ultimate strain were improved by 271% and 478%, respectively. LOC-GFRP confinement resulted in a bilinear compressive stress vs. strain response, showcasing increased ductility and strength with more LOC-GFRP layers. The study evaluated various existing analytical expressions for fiber-reinforced polymers but found them inadequate in predicting parameters accurately. As a result, nonlinear regression analysis was carried out to propose expressions for predicting compressive strength and ultimate strain of LOC-GFRP-confined concrete for different aggregate types. The calculated coefficient of determination values ≥ 0.90 confirmed the good correlation among experimental and predicted values.

Extraction, purification, and characterization of novel plant fiber from Tabernaemontana divaricate stem to use as reinforcement in polymer composites

Extraction, purification, and characterization of novel plant fiber from Tabernaemontana divaricate stem to use as reinforcement in polymer composites

Pengaruh Penambahan Serat Kulit Jagung Terhadap Sifat Mekanik Komposit Polipropilena (PP) dengan Penambahan Aluminium Oksida (Al2O3) dan Maleat Anhidrida (MAH) sebagai Coupling Agent

The utilization of polymer composites in the automotive field is expanding due to their characteristics such as strength, stiffness, and light weight. Polypropylene (PP) is one of the thermoplastic polymers widely used in composite manufacturing due to its lightweight, corrosion-resistant, and recyclable properties. However, to improve its mechanical properties, modifications using natural reinforcements and coupling agents continue to be made. Corn husk fiber is a natural resource that has potential as a natural reinforcement in polymer composites, it has the advantages of good tensile strength, light weight, and is biodegradable. The addition of Aluminium Oxide (Al2O3) and Maleic Anhydride (MAH) as coupling agent can improve the adhesion between fiber and polymer matrix, support more even load distribution, and optimize the mechanical properties of the composite Al2O3 and MAH on the mechanical properties of PP composites. The composition used was polypropylene: corn husk fiber rasio :Al2O3: MAH, namely 90:5:5:0, 89:5:5:1, 87:5:5:3, and 85:5:5:5% by weight. Tensile strength test using Universal Testing Machine (UTM) and crystallinity test using Differential Scanning Calorimetry (DSC) were conducted to evaluate the material performance. The highest value of tensile strength and crystallinity in the composition with 0 %weight MAH. The results of these tests, showing that the greater the composition of corn husk fiber has an influence on the decrease in tensile strength and crystallinity of the composite.

Effect of Curing Temperature on the Mechanical Properties of Hemp Fiber Reinforced Polymer Composites

Effect of Curing Temperature on the Mechanical Properties of Hemp Fiber Reinforced Polymer Composites

Mechanical recycling of epoxy composites reinforced with short-cut aramid fibers: Surface functionalization – The missing piece of the puzzle

Fiber reinforced thermosetting composites are essential materials for present and future technologies. However, their lack of reprocessability puts them far behind in achieving current sustainability targets. The recent development of covalent adaptable networks represents a promising approach to mitigate this. Here, mechanical recycling of short-cut aramid fiber reinforced epoxy composites was evaluated with a special focus on the impact of fiber surface functionality. The introduction of aramid fibers with four different surface chemistries to a covalent adaptable network was shown to influence the mechanical properties before and after reprocessing. Epoxy functionalized fibers enabled 52 % and 36 % retention of the original tensile stress and elongation at break after two recycling cycles. In comparison, the unmodified reference samples could only retain 19 % and 12 % of the original tensile stress and elongation at break. Fiber functionalization was thus proven to be a key piece in the development of more sustainable solutions for short-cut fiber reinforced polymer composites (SCFRPC).

Formulation of a Composite Material for Thermal Comfort from Bamboo Fibers and HDPE Reinforced with Bauxite Red Mud and MAPE: Physico-Mechanical and Thermal Properties

The modern, dynamic world can’t imagine its development without carrying the concept of advancement in composite materials. Various researches are going on in this field to achieve the desired standard. Natural fiber reinforced polymer composite (NFPC) has a huge affinity to interchange the composite made up of synthetic fiber. This is primarily because of the advantages like light-weight, non-toxic, nonabrasive, easy availability, low cost and biodegradable properties. The specific mechanical properties like specific tensile modulus and other specific properties of natural fiber gives a satisfying result for composites as compared to synthetic fiber based composites. The general objective of this work was to develop a composite from bamboo fibers and HDPE reinforced with red bauxite mud residues to ensure good thermal stability and improve the physico-mechanical properties in traction and flexion. The morphology of the composites showed that there was a homogenous dispersion of BF at lower weight fraction, although fibre agglomeration was noticed at higher weight fraction. The results of this study revealed that treated bamboo fibres are suitable for reinforcing HDPE. It appears from these studies that the formulations produced are in accordance with the ASTM standard and can validly be used for the thermal comfort of buildings to improve the comfort of the population in sustainable habitats.

Micromechanics-based modeling of temperature-dependent effective moduli of fiber reinforced polymer composites with interfacial debonding

In this paper, the dimensionless debonding length of fiber at various temperatures was obtained based on the maximum shear stress criterion. Then Hill's stress–strain relations were employed to determine the equivalent elastic moduli of the fiber in the debonding zone. Finally, a micromechanics model of temperature-dependent effective moduli of fiber reinforced polymer composites was developed, which is capable of including the effects of interfacial debonding and its evolution with temperature. To validate this model, temperature-dependent effective moduli of several polymer composites were calculated and benchmarked with experimental results extracted from the published literature, demonstrating the validity of the present model. This study offers an efficient method to forecast the temperature-dependent effective moduli, thereby helping to save considerable time and resources by reducing high-temperature testing. Furthermore, parametric studies were conducted to obtain constructive insights into the sensitivity of the debonding length and effective moduli to the material parameters at different temperatures.

Study Attenuation Parameters and Physical Properties of Silicone Rubber Reinforced with Nano- and Micro-Sized Aluminum Oxide Composites

Theoretical and practical research has been done on reinforced polymer composites, a more recent type of improved shielding material. This study examined the protective qualities of silicone rubber packed with nano- and micro-sized Al2O3. Aspects like the effective atomic number, mean free path, linear attenuation coefficient, and mass attenuation coefficient are used to evaluate these shielding materials. In terms of weight percentage and size, Al2O3 particles have been used to reinforce silicone rubber. Energy dispersive X-ray spectroscopy, X-ray diffraction, UV visible spectrometer, thermal analysis, and Fourier transform infrared spectroscopy have been investigated. The results show that aluminum oxide nanoparticles have a more homogeneous distribution within the samples than micro aluminum oxide particles, which is due to the fact that nanoparticles have a very large surface area-to-volume ratio when compared to the same material in bulk. As a result, the sample containing 40% by weight of nano Al2O3 has the largest attenuation coefficient value and the lowest half value layer (HVL), tenth value layer (TVL), and mean free path (MFP) values. Finally, it can be concluded that the sample containing nano Al2O3 can be utilized to create an innovative and versatile silicone rubber material. This material holds great potential for the manufacturing of gloves and protective jackets, specifically designed for radiation and nuclear shielding applications.

Review on Properties of Natural Fiber Reinforced Polymer Composites: Effect of Gamma Radiation and Nano particles.

Materials comprised of a polymer matrix with natural fiber reinforcement are known as natural fiber reinforcement polymer composites (NFRCs). Scientists have recently become quite interested in these composite materials because they provide improved properties over conventional synthetic fiber reinforced polymer composites at a lower cost and with benefits to the environment. However, a number of factors, including gamma radiation exposure and the addition of nanoparticles, can impact the properties of NFRCs. This review will focus on the effects of gamma radiation and nanoparticles on the mechanical, thermal, and water-resistance properties of NFRCs. In order to help in the creation of new and improved NFRCs for diverse applications, this review seeks to provide a thorough understanding of the characteristics of NFRCs and how they might be impacted by gamma radiation and nanoparticles.

Investigation of UV Aging and Compatibilizer Effects on Glass Sphere Reinforced Polymer Composites

Maleik anhidrit aşılı polipropilen (MAPP) oranı ve UV (Ultraviyole) yaşlandırma işleminin polipropilen (PP)/cam küreler (GS) polimer kompozitlerinin mekanik ve morfolojik özellikleri üzerindeki etkileri üzerine bir araştırma yapılmıştır. UV yaşlandırma, 70 C sıcaklıkta 0, 15, 30 gün olacak şekilde üç farklı bekletme süresinde gerçekleştirilmiştir. Polipropilen matris içerisine %1, 5, 10 ve 15 oranlarında katılan cam küre parçacıkları ekstrüderde karıştırılarak homojen bir karışım elde edilmiştir. Ekstrüderde elde edilen karışım kırıcıdan geçirilerek granül formuna getirilmiştir, ardından enjeksiyon makinesinde standartlara uygun şekilde test numuneleri kalıplanmıştır. MAPP ve UV tutma süresinin, PP/cam küreler kompozitlerinin elastik modülü, akma mukavemeti, kopmadaki çekme mukavemetleri, %uzama, İzod darbe mukavemeti, sertlik, yoğunluk ve morfolojik özelliklerine etkileri araştırılmıştır. MAPP ve UV tutma süresinin, kompozitlerin elastiklik modülü ve yoğunluğu gibi mekanik özellikleri üzerinde marjinal etkileri vardır. Sonuçlar, artan MAPP içeriğinin ve UV tutma süresinin elastiklik modülü ve yoğunluğunun artmasına neden olduğunu, buna karşın UV tutma süresi arttıkça İzod darbe dayanımı ve %uzamanın azaldığını göstermiştir. MAPP içeriği kompozitin termal davranışına etki ederek vicat yumuşama sıcaklığı ve ısıl çarpılma sıcaklığı-HDT değerlerinde önemli derecede artışa sebep olmuştur. Ayrıca, bu deneylerde cam küre parçacıklarının mikro yapısını ve malzeme dağılımını değerlendirmek için taramalı elektron mikroskobu (SEM) incelemesi yapılmıştır.

Post lightning strike residual compressive strength prediction in unidirectional carbon reinforced polymer composites

Post lightning strike residual compressive strength prediction in unidirectional carbon reinforced polymer composites

Constructing a new multiscale “soft-rigid-soft” interfacial structure at the interphase to improve the interfacial performance of carbon fiber reinforced polymer composites

The high strength and toughness of Carbon Fiber-Reinforced Polymers (CFRPs) are the main requirements for their properties in various fields. Herein, the “soft-rigid-soft” structure has been designed by us to achieve the aim of the improvement for the CFRP strength and toughness simultaneously. The soft-rigid-soft structural interface layer of CF was firstly constructed by carbon nanotubes (CNT) and Tannin/Aminopropyl isobutyl POSS (TA/NH2-POSS). The interfacial shear strength (IFSS) of the modified carbon fiber composite was 111.94 MPa, which was 84.08 % higher than that of the untreated fiber (60.81 MPa). Moreover the interlaminar shear strength(ILSS) and impact strength were increased by 50.43 % and 80.37 %. Enhancement of interface performance is mainly ascribed to CNT and TA/NH2-POSS, because they can effectively which is more effective to consume energy and decentralize stress. In this paper, the strength and toughness of CFRPs ware effectively improved by the in-depth and detailed design of the “soft-rigid-soft” multi-scale structure.

Ballistic and Charpy impact performance of basalt fiber reinforced polymer composites

AbstractIn this study, the behavior of composite material produced using basalt, a natural fabric, under ballistic and Charpy impact loads was investigated. The damage resistance of target plates under ballistic loads is an important design parameter in the structures that will be exposed to these loads. Cross‐ply fiber‐reinforced composite plates were produced with different numbers of layers. The composite specimens are produced using the vacuum infusion method, cross‐ply laminated with 3, 6, 9, and 12 layers ([0/90]3, [0/90]6, [0/90]9, and [0/90]12). Carbon/Epoxy specimens were also produced in identical sequences to be used as comparison material. The study aimed to understand the absorbed energy under ballistic loads and the required energy level under the Charpy impact loads of Basalt/Epoxy composite specimens with different thicknesses. Ballistic loads are applied to the specimens using a test set‐up including the sample holder mechanism and a firing system. Charpy impact tests were conducted using a standard test machine. According to the results, for 12‐layer specimens, the residual velocity difference between Basalt/Epoxy and Carbon/Epoxy is approximately 1.5 times. For the Basalt/Epoxy plate, increasing number of layers from 3 to 12 increases the amount of energy absorbed approximately 13 times. Although this increase is approximately 19 times for the Carbon/epoxy plate, when Basalt/Epoxy and Carbon/Epoxy plates are compared, Basalt/Epoxy absorbs more energy for all layer numbers. For the Charpy impact cases, it has been observed that Basalt/Epoxy absorbs approximately 34% more energy for flat wise impact and approximately 24% more energy for edgewise impact.Highlights The behavior of composite material produced using basalt, a natural fabric. Cross‐ply fiber‐reinforced composite plates. Effect of different number of layers considered. The damage resistance of target plates under ballistic loads. Comparison of basalt and carbon‐reinforced composites.

Constructing quasi-vertical carbon nanotubes fiber bridging on aluminum alloy with micro-channels to improve adhesive bonding with carbon fiber reinforced polymer composites

The poor wettability and compatibility, and weak mechanical interaction of bonding interface are main concerns for adhesive bonding of aluminum (Al) alloy and carbon fiber reinforced polymer (CFRP) composite, limiting its high strength developing and industrialization. In this study, the united treatments of anodizing, chemical vapor deposition (CVD) and resin pre-coating (RPC) were adopted to construct the quasi-vertically distributed carbon nanotube (CNT) fiber bridging for reinforcing the adhesive bonding joints. The results exhibited that better surface properties including morphology, roughness and wettability were obtained after anodizing. CNTs could be in-situ grown via the novel CVD method in the channels or micro-cavities formed by anodizing treatment. Acetone-diluted epoxy resin solution enabled to flow into the root of micro-cavities or the gap of growing CNT fibers to reduce potential void defects. Single lap shear test results indicated that Al-CFRP composites treated by anodizing, CVD and RPC performed up to 136.1 % increment in strength compared to the base. While the original debonding failure on Al alloy surface was changed into the complete delamination failure of CFRP composites, verifying the stronger bonding interface and strength. Thus, the novel united treatments were effective and might be an alternative solution in developing high-performance Al-CFRP composites.