Fiber Polymer Composites Research Articles

Effects of Fiber Orientation on the Mechanical Properties of Bidirectional Woven Kevlar Epoxy Composite

Objectives: This study focuses on the mechanical behavior of different fiber orientations of bi-directional woven Kevlar fabric to improve the mechanical properties of the Kevlar epoxy composite materials. Methods: Here in this paper hand moulded composites are fabricated with the Bidirectional plain-woven Kevlar-49, Epoxy resin LY 556 and hardener HT972 and the configuration of the layer was symmetrical and contained 6 plies which arranged as C- (0/45/-45/45/-45/0), B- (0/60/-60/60/-60/0). The standard ASTM D 3039 for tensile test, ASTM D790 for flexural test and ASTM D256 was followed for the laboratory test. F indings: Polymer composite materials are popular due to its weight strength ratio. Bidirectional woven fiber is used for the analysis, where different fiber orientations are compared. From the analysis it is observed that, mechanical properties vary with different fiber orientations. Novelty: In this paper, tensile modulus, flexural modulus, and absorbed impact energy observed in the laboratory to find out the suitability of the Kevlar composite as a building material. The findings of this research are expected to have practical implications for the development of stronger and more durable polymer fiber composites in various structural applications. Keywords Kevlar fiber, Epoxy, Tensile test, Woven fabric, Fiber orientation

Simulation of polymer solution slip motion and composite fiber fabrication in rotary jet spinning

Composite nanofibers are widely used as a novel nanomaterial in various fields, and the key technologies of preparation methods and equipment optimization have become the focus of research. Rotary jet spinning uses the centrifugal force generated by high-speed rotation to produce slip motion of two polymer solutions in the nozzle, and as the slip velocity increases, a rotating jet is eventually formed at the nozzle to eject the composite nanofibers. The slip motion of the polymer solution is one of the important factors affecting the rotating jet composite spinning, which directly affects the velocity distribution and flow stability of the polymer solution, and ultimately affects the morphology and quality of the composite nanofibers. By simulating the flow process of polymer solution inside the nozzle, the effect of slip motion on the flow of polymer solution is verified, which further illustrates that the rotational speed has the greatest influence on the preparation of composite nanofibers. Finally, PEO/PVA composite nanofibers were successfully prepared and collected by using a rotary jet spinning device in the range of 1500–3000 rpm, and the morphology and quality of the fibers were characterized and analyzed by scanning electron microscopy (SEM), which provided experimental bases for the simulation of the slip motion of the polymer solution and the study of composite fiber preparation.

An Experimental Study Incorporating Carbon Fiber Composite Bars and Wraps for Concrete Performance and Failure Insight

Corrosion of conventional steel reinforcement is responsible for numerous structurally deficient bridges, which is a multi-billion-dollar challenge that creates a vicious cycle of maintenance, repair, and replacement of infrastructure. Repair of existing structures with fiber-reinforced polymer (FRP) has become widespread due to multiple advantages. Carbon FRP’s superior tensile strength and stiffness make it particularly effective in shear and flexural strengthening of reinforced concrete (RC) beams. This experimental study incorporates carbon fiber polymer composite bars and wraps to study and report on the flexural behavior of RC beams. By employing a combination of CFRP bar and wrap for strengthening RC beams, this study observed an approximate 95% improvement in flexural load capacity relative to control RC beams without strengthening. This substantial enhancement highlights the effectiveness of integrating CFRP in structural applications. Nevertheless, the key observation is the failure mode due to this combination providing significant insights into the changes facilitated by this combination approach.

Simultaneous measurement of thermal conductivity and emissivity of micro/nanomaterials

Although thermal conductivity of micro/nano scale material has been readily measured, the high specific surface area leads to non-negligible radiative heat transfer. Here, a method for simultaneous measurement of intrinsic thermal conductivity and emissivity of micro/nano materials was developed and verified. The physical model of this measurement principle consisted of two parallel platinum wires, which serve as both heaters and heat flux meters. Thermal conductivity and emissivity can be derived by comparing the changes in the average temperature rise of the heater and sensor platinum wires before and after attaching the test sample. The thermal conductivity and emissivity of an individual platinum wire were determined to 71.7 W/(m·K) and 0.14, which are consistent with the reference values. Subsequently, the thermal conductivity and emissivity of the polymer composite fiber were measured to be 1.45 W/(m·K), 0.73 and 1.87 W/(m·K), 0.8 at different composite filler concentrations. In principle, this method is applicable for accurately measuring the thermal transport properties of any micro/nano wires using appropriate sensors.

Characterization of novel natural cellulose fiber from Ficus macrocarpa bark for lightweight structural composite application and its effect on chemical treatment

This study investigates Ficus Macrocarpa tree bark fibers (FMB) as a sustainable alternative reinforcement for polymer composites. The Industrial Revolution marked the evolution of polymer composites with synthetic material reinforcement, leading to environmental concerns. Natural fibers have recently gained prominence as efficient alternatives for polymer composites. Despite numerous natural fibers being considered, ensuring a sustainable raw material source remains crucial. In this study, fibers were extracted from FMB and subjected to alkali treatment to evaluate their impact on physical, chemical, and thermal properties. Initially, the extracted fibers measured 253.80 ± 15 μm in diameter, reduced to 223.27 ± 12 μm post-alkali treatment. Chemical analysis showed an increase in cellulose content to 59.7 wt%, a 23.34 % improvement over untreated fibers (48.4 wt%). The crystalline index for untreated and treated fibers measured 80.20 % and 84.75 %, respectively, with no noticeable changes in the cellulose phase. Additionally, the crystalline size increased to 3.21 nm. Thermogravimetric analysis demonstrated enhanced stability of treated fibers up to 378.87 °C, while the kinetic activation energy remained constant at 64.76 kJ/mol for both the treated and the untreated fibers. The alkali treatment further improved surface roughness to 39.26, confirmed by scanning electron microscopic images. These findings highlight the potential of cellulose fibers from Ficus Macrocarpa bark as a sustainable and environmentally friendly replacement for synthetic fibers in polymer composites. The enhanced physical properties and excellent thermal stability make them a promising choice for eco-conscious materials.

Bond–Slip Performance of Steel–Fiber-Reinforced Polymer Composite Bars (SFCBs) and Glass Fiber with Expansion-Agent-Reinforced Seawater Sea-Sand Concrete (GF-EA-SSSC) under Freezing–Thawing Environment

Bond–Slip Performance of Steel–Fiber-Reinforced Polymer Composite Bars (SFCBs) and Glass Fiber with Expansion-Agent-Reinforced Seawater Sea-Sand Concrete (GF-EA-SSSC) under Freezing–Thawing Environment

Core-sheath smart polymer fiber composites with high elasticity and thermal conductivity

Thermal conductive polymer fibers have broad development prospects because of its excellent thermal and mechanical properties. However, currently reported polymer fibers cannot simultaneously possess high thermal conductivity and high resilience, which greatly limits the application of thermal conductive polymer fibers. Therefore, preparing fibers with high thermal conductivity and high resilience is extremely challenging. The thermoplastic polyurethane/boron nitride liquid metal (TPU/BN-LMs) fiber with core sheath structure is prepared by coaxial wet spinning technology, the boron nitride (BN) doped in thermoplastic polyurethane elastomer (TPU) as sheath and the liquid metal (LMs) as core. The maximum tensile strength of the fiber is 3.9 MPa, and the elongation can reach 400 %. After multiple cycles of stretching, it can return to its original state. In addition, the thermal conductivity of the fiber in the horizontal direction and the vertical direction are 10.0 W m−1 K−1 and 4.6 W m−1 K−1, respectively. This work solves the current problem of high thermal conductivity and high resilience of thermally conductive polymer fibers that are difficult to be compatible. And it provides a new research idea for the design and preparation of new high thermal conductivity and high resilience polymer fiber materials.

Chitosan‐containing electrospun poly(ethylene oxide)‐polybutadiene‐CNT fibers

AbstractCross‐linked polymer composite fibers are gaining more and more interest in the fields of drug delivery, bone regeneration and biomineralization. This study focuses on the replacement of the radical initiator by photoinitiation via benzophenone, resulting in poly(ethylene oxide)‐polybutadiene‐carbon nanotube (PEO‐PBu‐CNT) nanofibers. The inclusion of small amounts of CNTs increases the rupture temperature and the first glass transition temperature Tg1 of the composite by 28 and 23 K, respectively, while decreasing the second glass transition temperature Tg2 by 20 K determined by dynamic mechanical analysis. A twice higher initial storage modulus of ~44 MPa can be detected for the CNT‐containing samples, indicating the stiffening effect due to CNT addition. Primary X‐ray diffraction peaks of PEO shift by 0.42° towards lower angles by the inclusion of CNTs, accounting for the generation of free volume within the polymer composite. Two orders of magnitude increase in Bode magnitude with a rise in Bode angle from 6° to 56° is detected by electrochemical impedance spectroscopy for the UV‐cured PEO‐PBu‐CNT. Entanglement between the fibers, as well as a rough surface with a rigid structure, is observed upon small CNT additions. Finally, attenuated total reflectance—Fourier transform infrared and Raman spectroscopy allow the detection of the main peaks and intensity changes of these polymer composite structures for the UV‐cured and uncured states.

Mechanistic model for the compression strength prediction of masonry columns strengthened with fibre–polymer composites

A mechanistic model is presented for the strength prediction of squared columns made of masonry with a periodic arrangement and strengthened with a fibre–polymer composite jacketing. The formulation is based on an incremental plasticity theory that relies on equilibrium, compatibility, and kinematic equations. The strength domain of brick units and mortar joints is bounded by a multi-surface yield criterion: a Mohr–Coulomb strength domain with a linear cap in compression and a Rankine cut-off in tension. An elasto-plastic response with limited ductility is assumed for both masonry components. Differently, the FRP response is assumed elastic with a brittle failure governed by a limited tensile strain. Phenomenological-based assumptions are undertaken and justified. Details are also provided for the computational implementation of the procedure. The model accuracy is validated against experimental data on masonry squared columns and compared with existing standard-based formulas. Results demonstrate it provides real-time and accurate compressive strength solutions for squared masonry columns with or without a polymer-based wrapping and yet requiring few input parameters for the masonry constituents and reinforcement.

Optimizing Biomedical Facilities Performance with Dombeya Fiber-Paper Particle Hybrid Reinforced Epoxy Composites

Since the last two decades, the use of natural fiber reinforced polymer composites has garnered significant application considerations over the synthetic fiber reinforced composites due to their numerous advantages and unique properties. Likewise, epoxy resin has attracted the interest of many researchers for composite synthesis, basically because of its chemical stability, thermal and mechanical characteristics. Hence, the primary aim of this study was to investigate the influence of dombeya fiber and paper particulate on the physical and mechanical properties of dombeya fiber and paper particulate-reinforced polymer composites for structural applications. Dombeya fiber and paper particles are renewable and biodegradable materials, thereby making them environmentally friendly materials to replace synthetic materials. Hand lay-up technique was utilized to fabricate the hybrid-reinforced biocomposites after which they were subjected to mechanical, wear, density, and moisture absorption properties. The surface morphology of the fractured surface was also analyzed to investigate its microstructural features. It was discovered from the results that hybrid biocomposites demonstrated improved properties over the unreinforced composite, with composites from 9-wt% dombeya fiber-paper particles reinforced biocomposite exhibiting the most suitable properties with commensurate density with the unreinforced epoxy matrix. These obtained characteristics support the material as a suitable material for biomedical apparatus application such as orthopedic implants, surgical instruments, and bone fixation devices.

Effect of elastomeric filler content on the acoustic and mechanical response of natural fiber-based hybrid composites

The environmental threat of discarded tires needs to be addressed through alternative applications with the enormous increase in the global vehicle population. When tire rubber particles are combined with environmentally friendly, and biodegradable natural fibers in polymer composites, such materials have a lot of potential for use in a variety of applications of insulating structures. The current work explores the effect of adding waste tire rubber particles (TRP) to natural fiber-based hybrid composites, on mechanical and acoustic properties and investigate the possibility of a potential insulating structural material. Tire rubber particles were employed as fillers and chopped banana fibers as reinforcing fibers (particle size less than 400 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu$$\\end{document}m) with epoxy resin as the matrix in this work. Five compositions were formulated in which the TRP content was varied from 0 to 36 wt.%, compensating for the fiber wt.%. The different compositions prepared by compression molding technique were subjected to compressive, impact, and acoustic characterization. In the natural fiber composites, the compressive strength was observed to dip with increase in TRP content while impact strength was found to rise till 15 wt.% TRP content. Beyond 15 wt.% TRP fillers, the impact strength and brittleness declined. The optimal acoustic response in terms of the sound transmission loss was observed for the composition with 15 wt.% TRP fillers. Polymer composites with natural fiber reinforcing and elastomeric fillers create excellent interior lining materials for buildings, automobiles, and aircrafts, because of their superior mechanical properties and acoustic proofing.

Investigation of Physical Properties of Polymer Composites Filled with Sheep Wool.

Sheep farmers are currently facing an oversupply of wool and a lack of willing buyers. Due to low prices, sheep wool is often either dumped, burned, or sent to landfills, which are unsustainable and environmentally unfriendly practices. One potential solution is the utilization of sheep wool fibers in polymer composites. This paper focuses on the study of mechanical vibration damping properties, sound absorption, light transmission, electrical conductivity of epoxy (EP), polyurethane (PU), and polyester (PES) resins, each filled with three different concentrations of sheep wool (i.e., 0%, 3%, and 5% by weight). It can be concluded that the sheep wool content in the polymer composites significantly influenced their physical properties. The impact of light transmission through the tested sheep wool fiber-filled polymer composites on the quality of daylight in a reference room was also mathematically simulated using Wdls 5.0 software.

Waste natural fibers for polymer toughening and biodegradability of epoxy-based polymer composite through toughness and thermal analysis

Polymeric materials are being increasingly used to replace many metallic components due to their beneficial properties such as higher strength-to-weight ratio and corrosion resistance. However, the widespread use of polymers poses a risk to the environment as they are not biodegradable. The addition of the waste jute fiber and sawdust fiber as reinforcement to the epoxy resin improved its toughness and induced the biodegradability of the polymer. To examine the effect of the jute fiber and sawdust fiber on biodegradability, the composites were then kept in the drainage system for one year, and the impact energy and fracture morphology of the as-cast and weathered samples were examined using a drop ball impact test and a Charpy impact test. During the weathering period, weight gain was initially observed due to the water absorption by the porous fibers, but after three months, the composites started to lose weight due to the degradation of the fiber by swelling and microbial attacks. Microorganisms in the drainage system used the fiber as their energy source, which resulted in the deterioration of the fiber and the production of CO2. The production of CO2 was identified by the FTIR analysis of the weathered composite samples. TGA analysis of the as-cast and weathered samples reveals the reduction of the onset thermal degradation temperature of the weathered composites due to the degradation of the composites. The fiber disintegrated through microbial attack and the fiber swelling caused by the absorption of water by jute fiber and sawdust fiber is identified through SEM imaging. The SEM image also reveals the formation of biofilms and the growth of microorganisms at the fibers. A higher growth rate of the microorganisms was observed in the jute fiber composite than in the sawdust fiber composite, as sawdust contains a high level of lignin that protects it from degradation. The results of this study suggest that both sawdust fiber and jute fiber composites induce biodegradability in the epoxy matrix, but jute fiber was more prominent in this regard. The discovery paves the way for using natural fibers in biodegradable polymer composites, reducing polymeric pollution in the environment.

Scanning Electron Microscopy Analysis of Kenaf Coir Epoxy Reinforced Carbon Nanotubes Nanoparticles Hybrid Composite

Ecological awareness and sustainable development have attracted researchers’ focus on composites developed using natural fibers. Consequently, natural fiber polymer composites are flattering and increasingly prominent for use and research. Fiber-reinforced composites inhibit considerable benefits, in conjunction with high strength and lesser weight, simpler fabrication, biodegradability, lesser cost of production, and so on. Natural fiber offers good properties, but it requires proper matrix interface bonding along with effective synergy amongst each matrix-fibre combination. In the case of the hybrid composite proposed in this research, analytical modeling has been carried out and compared with the previous literature, in our previously published research [Parashar, S. and Chawla, V., 2022. Kenaf-coir based hybrid nanocomposite: AN analytical and representative volume element analysis. Engineering Solid Mechanics, 11(1), pp.103–118]. The present paper investigates the composite proposed in the research for scanning electron microscopy examinations, using an S3400M Scanning Electron Microscope. Each of the specimens has been cut to the necessary dimensions for SEM examination. The micrographs have been created with a high voltage of 20 kV. The broken surface of the tensile specimens of the composite samples was investigated using SEM. According to the findings of SEM and analytical modeling it has been observed that, combining nanoparticles of CNT as filler and kenaf-coir as fiber reinforcement results in a composite material with good interfacial adhesion betwixt matrix and fibers, high strength, and mechanical capabilities, to make hybrid composites for various industrial and automotive applications compared to composite present in the previous literature. The hybridization effect has also been evaluated for the composite, which depicts the higher tensile failure strain of the proposed hybrid composite.

Low-high-low cyclic performance of screw connections for fibre-polymer composites

This study examines the cyclic performance of screw connections for joining fibre polymer composite members. Cyclic tensile experiments were conducted on connection specimens consisting of a flat panel (FP) and a square hollow section (SHS) at a right angle. A low-high-low (LHL) cyclic loading program was employed, consisting of seven varying-amplitude loading sequences spanning over 10,361 cycles, in order to simulate wind actions according to relevant standards. Four types of specimens, connected using screws or/and adhesive bonding, were examined, under three load amplitude levels corresponding to 50%, 80%, or 100% of the monotonic ultimate load. All specimens loaded under the LHL amplitude levels of 50% and 80% of the monotonic ultimate load survived after all LHL cycles. These survived specimens were subsequently loaded to determine their retention capacity. The results revealed that no less than 89% of the monotonic strength was preserved. In the LHL loading process, the specimens with adhesive bonding showed more severe degradation of stiffness than their screw-only counterparts, due to the initiation of delamination near the bonded side edges on the FP in the early stage of cycles, with further propagation as the number of cycles increased. The screw-only specimens also demonstrated comparable retention capacity in comparison to the adhesively-bonded specimens.

Adhesion characteristics of plasma-treated flax fabrics and elastoplastic properties of their biocomposites

ABSTRACT Recently, there has been growing interest in replacing synthetic fibers with natural fibers in polymer composites due to several advantages of natural fibers over synthetic ones, such as low cost, low density, sustainability, and biodegradability. However, a significant drawback of natural fibers is their high capillary water absorption, worsened by waxes and atmospheric pollutants, resulting in weak adhesion with polymer matrices. Surface treatments, including plasma treatments, have shown promise in improving this interfacial bonding. In this study, woven flax fabrics (FFs) were treated with two plasma techniques: atmospheric pressure plasma torch (APPT) and low-pressure plasma (LPP). The plasma effects on the fibers’ surface, wettability, and surface energy were assessed through X-ray photoelectron spectroscopy and contact angle measurements, respectively. Subsequently, the treated fibers were utilized to fabricate biopolymer composites using polyamide1 (PA11), green low-density polyethylene (GPE), and polybutylene succinate (PBS) as matrices. The adhesion strength and elastoplastic behavior of the biocomposites were compared by peel-off test and plasticity index measurement. The results indicated that both treatments successfully improved the FFs’ surface characteristics, resulting in increased wettability and surface energy. The higher peeling strengths and lower plasticity indices confirmed the improvement in the adhesion of treated FFs with the biopolymer matrices.

Bioepoxy based advanced lightweight hybrid composites from hemp fibers: Towards greener production

Over the past few decades, the widespread use of composite materials has become prominent, particularly following the industrial revolution. In response to environmental concerns, natural fiber polymer composites have found extensive applications, notably in the automotive industry and various versatile applications. However, pure natural fiber polymer composites face challenges in matching the performance of synthetic fiber-reinforced polymer composites. To address this issue, natural fibers are hybridized with synthetic fibers to enhance the performance characteristics. In this study, hemp fibers were hybridized with Innegra fibers through a stacking sequence and subjected to weathering. Both the weathered and unweathered composites underwent mechanical, thermal, and viscoelastic analysis to assess their performance under harsh environmental conditions. The mechanical analysis revealed that the tensile strength of the composite with Innegra as the skin layer was 76.56 MPa, reducing to 67.73 MPa after the weathering process. The flexural strength showed values of 111.01 MPa and 101.61 MPa before and after the weathering process, respectively. Thermomechanical analysis indicated that pure hemp composites exhibited lower thermal expansion at 1.45%, with the composite featuring hemp fibers in the outer layer performing better at 2.34% compared to hybrid composites. Additionally, SEM images demonstrated good interfacial adhesion between fibers and the matrix. Overall, the results suggest that the developed composites have the potential for use in lightweight semi structural applications.

Investigating the Impact of Carbon Fiber as a Wheelchair Frame Material on Its Ability to Dissipate Kinetic Energy and Reduce Vibrations.

Using a wheelchair over uneven terrain generates vibrations of the human body. These vibrations result from mechanical energy impulses transferred from the ground through the wheelchair components to the user's body, which may negatively affect the quality of the wheelchair use and the user's health. This energy can be dissipated through the structure of the wheelchair frame, such as polymer and carbon fiber composites. This article aims to compare a wheelchair with an aluminum alloy frame and a carbon fiber frame in terms of reducing kinematic excitation acting on the user's body. Three wheelchairs were used in the study, one with an aluminum alloy frame (reference) and two innovative ones with composite frames. The user was sitting in the tested wheelchairs and had an accelerometer attached to their forehead. The vibrations were generated by applying impulses to the rear wheels of the wheelchair. The obtained results were analyzed and compared, especially regarding differences in the damping decrement. The research shows that using modern materials in the wheelchair frame has a beneficial effect on vibration damping. Although the frame structure and material did not significantly impact the reduction in the acceleration vector, the material and geometry had a beneficial effect on the short dissipation time of the mechanical energy generated by the kinematic excitation. Research has shown that modern construction materials, especially carbon fiber-reinforced composites, may be an alternative to traditional wheelchair suspension modules, effectively damping vibrations.

The influence of different fiber sizes on the flexural strength of natural fiber-reinforced polymer composites

This experiment aimed to investigate the impact of varying fiber lengths on the flexural strength of coconut fiber composites with epoxy resin. Coconut fiber composite panels were produced using rectangular molds. The effects of various fiber sizes, especially 2, 4, and 6 mm, respectively, were compared with fiberless and continuous fiber polymer composites on the flexural strength of Natural Fiber-reinforced Polymer Composites (NFPC). The lowest flexural strength is 10.04 MPa, was obtained for the NFPC sample with a fiber length of 2 mm, while the highest flexural strength value was 10.70 MPa with a fiber length of 6 mm. Generally, flexural strength is influenced by variations in fiber size but not significantly. The flexural modulus and flexural strength values exhibit the same trend. Fiber pullouts are visible on the fracture surface of the sample, and voids in the form of trapped gas are also apparent on the sample surface. Short fiber size is one of the causes of fiber pullout, which can reduce the flexural strength of short fiber polymers.

Green Polymer Composites for Aerospace Engineering Applications : A Review

In the last decade, Study on the use of natural fibers as synthetic substitute materials or green polymer composites is growing. The growth of green polymer composites has had a significant impact on polymer composite research and innovation. This rapid growth provides advantages over low-cost synthetic fiber composites and reduces adverse impacts on the environment. Because of its potential, this material is applied in various engineering fields, including in the aerospace engineering.
 In recent years, various improvements have been made to natural fiber composite materials to improve physical, mechanical and chemical properties. The aim of this review is to highlight trends in the use of natural fiber polymer composites applied to the aerospace engineering. This review article explains the latest research activities regarding green polymer composite fabrication, advantages of green polymer composites, and applications in the aerospace engineering