Composite Reinforcement Research Articles

Development and characterization of a novel AA6061 composite reinforced with titanium aluminide via friction stir processing

Current research work emphasizes on the development of particulate titanium aluminide (TiAl), an intermetallic class of material, through mechanical alloying (MA) from elemental powders and usage of same as reinforcement in AA6061 aluminum matrix to enhance its mechanical and tribological performance. TiAl, being a light weight, strong and abrasion-resistant material, is found to be a suitable candidate to replace dense ceramic-based reinforcements in aluminum composite. Friction stir processing (FSP), a well-established surface severe plastic deformation tool, is used to develop the composite in this study. Several strategies on improving the stirring action and particle distribution during FSP is employed and their scientific effect is studied in detail. Microstructural evolution was studied through scanning electron microscopy (SEM) combined with electron backscattered diffraction (EBSD) analysis which revealed uniform particle distribution of reinforcement in the friction stir processed (FSPed) zone with 88.23 % reduction in grain size of composite as compared to base material. Hardness studied showed an increase in the hardness by 33 % for composite material as compared to un-reinforced FSPed material, showing the positive effect of reinforcement alone on the mechanical strength of the material. Tensile results showed an improvement in yield tensile strength from 156 MPa in base to 186.8 MPa in the composite material without significant compromise in the ductility 26.86 % for composite and 28.14 % for base. Mechanisms aiding uniform particle distribution, and the reasons for improvement in mechanical performance of the developed composite is discussed in detail with the help of microstructural studies and post-deformation fractograph.

Physics-Constrained Neural Network for design and feature-based optimization of weave architectures

Woven fabrics play an essential role in everyday textiles for clothing/sportswear, water filtration, retaining walls, and reinforcements in stiff composites for lightweight structures in aerospace, sporting, automotive, and marine industries. Several possible weave architectures (combinations of weave patterns and material choices) present a challenging question about how they could influence the physical and mechanical properties of woven fabrics and reinforced structures. This paper presents a novel Physics-Constrained Neural Network (PCNN) to predict the mechanical properties (like modulus) of weave architectures and the inverse problem of predicting pattern/material sequence for a design/target modulus value. The inverse problem is particularly challenging as it usually requires many iterations to find the appropriate architecture using traditional optimization approaches. We show that the proposed PCNN can more accurately predict weave architecture for the desired modulus than several baseline models considered. We present a feature-based optimization strategy to improve predictions using features in the Gray Level Co-occurrence Matrix space. We combine PCNN with feature-based optimization to discover near-optimal weave architectures and facilitate the initial design of weave architecture. The proposed frameworks will primarily enable the woven composite analysis and optimization process and be a starting point to introduce knowledge-guided neural networks into the complex structural analysis.

806. MINIMALLY INVASIVE REVISION FUNDOPLICATION, IS IT SAFE AND FEASIBLE? SINGLE CENTER EXPERIENCE

Abstract Introduction Laparoscopic fundoplication has become standard of care for patients with refractory gastroesophageal reflux disease, large and symptomatic hiatal hernia. Failure rate for laparoscopic fundoplication was between 2 to 17%. Doing Revisional Antireflux surgery is technically difficult. Our aim is to analyse symptomatic improvement post surgery, safety and durability of procedure in patients who underwent revision fundoplication at our centre Patients and Methods 22 patients underwent Minimally invasive revision fundoplication between January 2019 to January 2022 were taken into study, of them 12 gentlemen and 10 women were noted. Modified DeMeester score was calculated in all patients preoperatively and on 6 months follow up. Results All patients underwent primary surgery laparoscopically. 14 patients (63.6%)had recurrent reflux symptoms and 8 patients (36.3%) had severe dysphagia. Revision fundoplication was done laparoscopically in 20 patients and 2 patients Robotic surgery was done. Intraoperatively 11 patients had wrap migration, 8 patients had tight wrap, 3 patients had twist of wrap. In the re-do anti-reflux surgery (ARS) procedure, floppy Nissen fundoplication was performed in 86.4% of the patients, which amounts to 19 patients., and 3 patient underwent a 270-degree Toupet fundoplication. In 2 patients, additional composite mesh reinforcement was employed. 13.6 % of patients had intraoperative complications, 9.09 % of patients had pleural injury, 4.7 % had intraoperative bleeding, 9.09% of patients had gallstone disease, for which cholecystectomy was done. All patients anterior and posterior vagus identified and preserved. On follow up 80% of patients had resolution of symptoms, 18% needed intermittent PPI. At a median follow up of 18 months, no surgical failure was noted in endoscopy. Conclusion Laparoscopic revision fundoplication is a safe procedure when operated in a high volume centre by an expert surgeon.

Influence on the properties of TMCs of ceramic and intermetallic composite reinforcements (B4C, TixAly and TixSiy) fabricated by inductive hot pressing

Ambitious and competitive, the aerospace industry continuously demonstrates to be one of the leading engineering sectors either at exigence and new technologies development. As lightning the weight of aircrafts is one of the main targets, the spotlight is usually on material research by which new ones may be produced to pursue this aim and still offer the necessary performances. The combination of the properties of titanium and other materials as reinforcements provides really interesting results as titanium matrix composite materials, also known as TMCs. Various samples of titanium matrix composite materials with different reinforcements have been under study to determine the influence of the reinforcements and their respective proportions on the properties of the material. These samples composed of grade 1 commercially-pure titanium as matrix and B4C, TixAly and TixSiy as reinforcements, have been manufactured through powder metallurgy in the same conditions of temperature and pressure via Inductive Hot Pressing (IHP). A total of eight composite materials have been arranged in several different groups to confront their compositions. Thus, this analysis reports results for the influence of the powder size of the matrix and the ceramic reinforcement, the effect of varying the volumetric composition of B4C, and the selection of different intermetallic reinforcements. These tests and the obtained information serve for a project in which the main goal is to determine which compositions of the studied composite materials reach a high enough specific stiffness for a suitable application in the aerospace industry.

Characterization and properties of porous red mud–based geopolymer composites reinforced with carbon fiber powders

To obtain porous composites with high porosity and improved performance, porous geopolymer composites (CFP/RMG) were fabricated using alkali-excited red mud and carbon fiber powders (CFPs) using the foaming method. The synergistic effects of CFPs and H2O2 on the microstructure, pore structure, strength, and thermal properties of the porous samples were systematically investigated. CFPs were uniformly distributed on the pore walls of the samples. The total porosity decreased with CFPs and increased with H2O2, the density of CFP/RMG samples ranged from 0.57 ± 0.01 to 1.71 ± 0.05 g/cm3. The compressive strength of the composite samples increased from 0.54 ± 0.09 to 4.16 ± 0.24 MPa with an increase in CFPs from 0 to 12.5 wt%, and it decreased from 4.06 ± 0.23 to 0.47 ± 0.06 MPa with 1–5 wt% H2O2. Fiber bridging and fiber pullout contributed to the strength reinforcement of the whole composite. The porous composites also showed low thermal conductivity (0.176–0.680 W/(m·K)), which revealed that it had potential applications in the field of building materials in the future.

Design and material optimization of carbon fiber composite winding reinforcement layer for vehicle Type-IV hydrogen storage vessels

Due to the safety, reliability, and high hydrogen storage density of vehicle Type-IV composite overwrapped pressure vessels (COPVs), the Type-IV COPVs are currently the preferred choice for vehicle hydrogen storage vessels. The reinforcement layer bears 80 % to 90 % of the internal pressure load, and it accounts for a significant proportion of the total cost and weight of Type-IV COPVs. Thus, the reinforcement layer is the key problem in the design and optimization of the vehicle Type-IV COPVs. Firstly, this paper proposed a design method for vehicle Type-IV COPVs considering the strength and stiffness of reinforcement layer, and created the hydrogen storage vessel scheme. Then, the stress and strain of vehicle Type-IV COPVs under working and blasting internal pressure were analyzed by finite element simulation. Finally, the genetic algorithm was used to find the best carbon fiber for vehicle Type-IV COPVs. The results show that the scheme designed by the method in this paper can meet the requirements of vehicle use; The carbon fiber modulus most suitable for car hydrogen storage bottle winding is 288.8 GPa, and the weight of the reinforcement layer is reduced by 32 % compared to the T700S carbon fiber composite wound vessel.

Microstructural and wear properties of iron slag reinforced aluminum alloy (LM30) based composite prepared through a stir casting method

Aluminum alloys are widely used in various industries due to their as low density, high strength-to-weight ratio, and good corrosion resistance. However, their wear resistance is often inadequate for certain applications. Utilization of industrial waste materials, such as iron slag, as reinforcement in aluminum alloy matrix composites offers a sustainable approach to material development and waste management. The utilization of industrial waste materials for aluminum alloy matrix composite fabrication offers a waste utilization to material development. The loading of this reinforcement varied from 0 to 15 wt.% and different particle size range (220-140, 140-70, and 70-0 µm). A microscopic analysis indicated that the iron slag particles are spread uniformly inside the metallic matrix. There is also a reduction in the size of primary silicon, as well as morphological changes (acicular to globular shape). The wear behavior was calculated using a pin-on-disk wear set up in accordance with ASTM G99 standard. The composites were employed to dry sliding wear test under various operating conditions such as applied pressure (0.2–1.4 MPa), and sliding distance (0–3000 m). The 15F composite outperformed all other composite samples in terms of wear rate under all working conditions. When compared to the base alloy, it demonstrated a remarkable 67% drop in steady state wear rate. The enhancements in wear performance for the 15F composite were attributed to the effects of Fe slag reinforcement. The inclusion of iron slag particles induced strong interfacial bonding between matrix and reinforcement particles improving the durability of the mechanical mixed layer developed during relative motion. Importantly, the wear rate parameters of the 15F composite were similar to those of the brake drum material used in commercial applications. This emphasizes the composite suitability for usage in a variety of automobile components.

Carbon tube‐gypsum reinforced polypropylene: Impact resistance, thermal stability

AbstractThis study investigated the effect of multi‐walled carbon nanotubes (MWCNTs) and reclaimed gypsum of varying contents on the mechanical properties and thermal stability of polypropylene (PP) composite materials. The results indicated that the incorporation of reclaimed gypsum and MWCNTs powder into PP composites could enhance the tensile strength, impact strength, and bending modulus of PP to a certain extent. The above properties of AGY/MWCNTs/PP composites were increased by 14.6%, 131.8%, and 36.2%, respectively, with the impact properties being significantly affected. Univariate analysis of variance revealed that MWCNTs powder and recycled gypsum exerted a significant impact on the mechanical properties of polypropylene composites. Moreover, the initial weight loss temperature of AGY/MWCNTs/PP demonstrated a notable increase, from 318.71 to 398.48°C, while the maximum weight loss temperature exhibited a comparable rise, from 406.85 to 461.54°C.Highlights The impact performance and thermal stability of polypropylene composite materials have been demonstrably augmented. A synergistic effect between reclaimed gypsum and multi‐walled carbon nanotubes in the reinforcement of polypropylene composites was demonstrated. This provides a theoretical framework and practical guidance for the design and preparation of high‐performance and recyclable polymer composites.

Effect of Si3N4 on the in-situ synthetized non-oxide reinforcements in Al-Al2O3 composites under N2 atmosphere

Al-Al2O3 composite is widely used in high-temperature industry due to its excellent properties obtained through in-situ synthesis of non-oxide reinforcing phases. The effect of nitrogen source on the non-oxide reinforcing phases synthesized in-situ in the Al-Al2O3 composites at 1500 °C was investigated. The results show that when N2-gas is the sole nitrogen source, Al4O4C is the major reinforcing phase formed in the composite due to insufficient nitrogen amount provided. Through the construction of an Al@AlN core-shell structure and spontaneous nitrogen introduction by solid Si3N4 and N2-gas, higher amount of AlN mesophase is generated, and the complete transformation of Al to (Al2OC)1-x(AlN)x solid solution is successfully achieved. However, when Si3N4 content is excessive (i.e. Si/C mole ratio ≥ 1, where Si comes from solid nitrogen source Si3N4, C comes from phenolic resin binder), the stability of (Al2OC)1-x(AlN)x solid solution decreases, and more stable AlN-SiC solid solutions and SiAl4O2N4 are generated as reinforcing phases in the composite. This work provides meaningful information for the phase control of Al-Al2O3 composite at high temperature application.

Enhancement of mechanical properties and machinability of aluminium composites by cupola slag reinforcements

AbstractRapid evolution in engineering and manufacturing demands light weight material with enhanced mechanical properties. Aluminium metal matrix composites with ceramic reinforcement particulates serve this demand due to their reduced density, improved strength and hardness along with higher resistance to wear and corrosion. However, the material cost and reduced machinability hinders the full potential of utilization. To overcome these challenges, in this work cupola slag, an industrial waste generated as by product of cast iron production, has been incorporated as reinforcement of aluminium composites using low cost stir casting method. The enhancement of material properties and machinability by cupola slag inclusion on base alloy has been investigated in detail. Moreover, introspection about the underlying mechanisms responsible for the improvement in material properties has been studied using detailed microstructure and fractographic analysis. The results show improvement of in material properties and machinability up to 7 wt.–% cupola slag inclusion, beyond which the reduced wettablity prohibits sound castings. The ultimate tensile strength and specific strength observed to be improved by 18.20 % and 33.23 % respectively for 7 wt.–% slag reinforced composites when compared with base alloy. This work can be a successful addition to the knowledge pool of ongoing research on low‐cost novel material with enhanced properties.

Evaluation of the mechanical properties of hybrid composites reinforced with plant fibers

The incorporation of plant fibers into the matrix plays an interesting role. Natural fibers have been widely used as reinforcements in polymer matrix composites. Among all reinforcing fibers, natural fiber-based hybrid composites have attracted the attention of researchers as high-potential reinforcing materials for composite materials. These fibers are easily available in the form of agricultural products. Natural fibers are inexpensive, durable and lightweight materials for composite applications. In this experimental work, sisal fibers and date palm fibers were used as reinforcement in different ratios to fabricate hybrid composites by compression molding technique while maintaining a total fiber loading of 20 % by weight. Tensile tests, flexural tests, and impact tests were carried out, water absorption was also determined. The results obtained show that the composite composed of a combination of 16% sisal fibers and 8% date palm fibers has better tensile properties with a stress value of 6.88 N/mm2 and a value of Izod impact of 43.218 J/m. As well as both composites showed a better bending stress value of 67.29 N/mm2, the water absorption test was carried out for four days with 120 hours analysis. This research focuses on the fact that specimen-2 containing 16% sisal and 8% date palm fibers absorbs less water than other composites.

Extraction and characterization of novel Prosopis Juliflora bark and Boehmeria nivea fibre for use as reinforcement in the hybrid composites with the effect of curing temperature, fibre length and weight percentages

The hybrid composite sample based on Prosopis Juliflora (PJ) bark and ramie fibre with different length, weight percentage, and curing temperature were created for the first time in this work. Totally, 120 hybrid composite samples were tested in this study. There were five different fibre lengths: 10 mm, 15 mm, 20 mm, 25 mm, and 30 mm, weight percentages 10 %, 20 %, 30 %, 40 %, and 50 %, and different curing temperatures 80 °C, 90 °C, 100 °C, 110 °C, and 120 °C used to produce the hybrid composite samples. Due to the cross-linking ability with the epoxy matrix, the hybrid composite specimen shows high resistance up to 98 Shore D hardness. The high polarity of the epoxy matrix and the hydrogen bond strengthening effect, increased the composite sample flexural strength by 12 %. The curing temperature of 100 °C, 20 mm fibre length, and 30 % of the hybrid composite sample achieved the highest tensile strength (28.76 MPa), flexural strength (46.54 MPa), impact strength (4.5 J), and hardness strength properties (98 shore D). Thermo gravimetric analysis (TGA) revealed the composite samples initial decomposition temperature (Ti) at 98 °C, maximum decomposition temperature (Tmax) at 320 °C, and the final decomposition temperature (Tf) at 466 °C.

Preliminary Experimental and Numerical Study of the Tensile Behavior of a Composite Based on Sycamore Bark Fibers

In the context of global sustainable development, using natural fibers as reinforcement for composites have become increasingly attractive due to their lightweight, abundant availability, renewability, and comparable specific properties to conventional fibers. This paper investigates the tensile properties of a sycamore bark fiber-reinforced composite. The tensile tests using digital image correlation showed that, by adding 18% by volume of sycamore bark for the polyester matrix, the tensile modulus achieves 4788.4 ± 940.1 MPa. Moreover, the tensile strength of the polyester resin increased by approximately 90% when reinforced with sycamore bark fiber, achieving a tensile strength of 64.5 ± 13.4 MPa. These mechanical properties are determined by the way loads are transferred between the polyester matrix and fibers and by the strength of the bond between the fiber-matrix interfaces. Since it is difficult and time consuming to characterize the mechanical properties of natural fibers, an alternative approach was proposed in this study. The method consists of the identification of the fiber elastic modulus using a finite element analysis approach, based on tensile tests conducted on the sycamore bark fiber-reinforced composites. The model correctly describes the overall composite behavior, a good agreement is found between the experimental, and the finite element predicted stress–strain curves. The identified sycamore bark fiber elastic modulus is 17,763 ± 6051 MPa. These results show that sycamore bark fibers can be used as reinforcements to produce composite materials.

Plant Fiber Composites for Biomedical Applications: Advances and Prospective.

Plant fibers are strong, robust, flexible, versatile, renewable, and sustainable, making them valuable for many applications. Fibers from plants are now utilized in biomedical applications as reinforcements for biological composites to enhance the mechanical characteristics of composite biological materials including rigidity, tensile strength, and endurance. Reinforcement composites with hybrid components were explored in biodevices for prospective utilization in orthopedics, prosthetics, tissue fabrication, and surgical dressings. This review presents an overview of plant fibers, including their characteristics, influencing variables, and numerous applications. The text explores several methods for creating synthetic composites using common, sustainable fibers and the distinct characteristics of the resulting biological materials. The text also analyses many instances of composite hybrids and their application in the biological field. The results are summarised and suggestions for potential improvements are presented. The current research primarily examines the concept, specifications, efficiency, and potential advancements of composites with hybrid characteristics made from plant fibers.

Effect of adhesive ductility on the bond behavior of CFRP-steel cohesive interfaces made with toughened epoxy resin

The strengthening of steel structures can be effectively performed using carbon fiber-reinforced polymers (CFRP) plates. Specifically, the behavior of corroded and fatigue damaged steel bridges can be significantly improved using externally bonded (EB) or unbonded composite reinforcements. For bonded composites, the bond between the reinforcement and the steel substrate is the weak link of the system. Indeed, cohesive failure within the adhesive layer represents the main failure mode, which makes the selection of a proper adhesive fundamental to achieve an improvement of the system load carrying capacity and fatigue resistance. Within this context, the use of toughened adhesives represents a promising solution. However, research regarding these adhesives is still limited. In this paper, 18 single-lap direct shear tests are performed to evaluate the cohesive behavior of toughened and traditional adhesives. For some specimens, the full-range bond behavior, including the load response snap-back, was experimentally captured. The digital image correlation (DIC) technique is adopted to evaluate the adhesives cohesive material law (CML). The effect of adhesive ductility, plate stiffness, and bonded length on the joint load response is investigated. Finally, experimental results are validated and discussed against the analytical predictions of a cohesive model based on a trapezoidal CML.

Lignocellulose sustainable composites from agro-waste Asparagus bean stem fiber for polymer casting applications: Effect of fiber treatment

In the past decades, lignocellulose fibers have attracted significant attention due to their low density, environmental friendliness, and biodegradability. Consequently, researchers are intensifying their efforts to explore the potential of lignocellulosic fibers as sustainable alternatives to synthetic fibers in polymer composites. Among various natural fibers identified as potential reinforcements, agro-waste from the Asparagus Bean stem (ABS) which has been discarded as landfill after harvest has emerged as a promising source of lignocellulose fibers for promoting sustainability. This study investigates the reinforcement suitability of ABSF in polymer matrices. A water-retting process was used for extraction, followed by treatment with a 5 % alkali solution. Cellulose content was enhanced to 65 wt%, and fiber density increased to 1.13 g/cm3 after chemical treatment. Thermogravimetric analysis indicated improved thermal stability of the treated fibers up to 247 °C. Morphological analysis showed increased surface roughness and impurity removal. To evaluate the reinforcing effect of the chemical treatment, epoxy composites with 10 wt% reinforcement were developed. The mechanical properties of these composites improved significantly, with more than 1.1 times when used alkali-treated ABSF as reinforcement. Flexural properties were substantially enhanced, with flexural strength increasing from 90.53 MPa to 122.71 MPa and flexural modulus from 2.41 GPa to 2.95 GPa due to better fiber-matrix interaction and removal of weak, amorphous constituents. The primary objective of this study is to demonstrate that ABSF is a viable alternative raw material for composite reinforcement, suitable for developing lightweight structural applications.

Assessing Extraction Methods and Mechanical and Physicochemical Properties of Algerian Yucca Fibers for Sustainable Composite Reinforcement

Assessing Extraction Methods and Mechanical and Physicochemical Properties of Algerian Yucca Fibers for Sustainable Composite Reinforcement

A type of multifunctional cellulose nanocrystal composite silicone-based polymer coating for marine antibiofouling

Nanocomposite polymer coatings are being used as a new generation of marine antibiofouling coatings because of their toxin-free chemical composition and ease of large-scale adoption. Cellulose nanocrystal (CN) exhibits significant potential for composite reinforcement. Herein, CN was surface-modified via α,ω-bis(3-(2-hydroxyl-terminated polydimethylsiloxane (HTPDMS), resulting in dihydroxyl-terminated poly(dimethylsiloxane)-grafted CN (HP-g-CN). The amine-terminated PDMS as the foundational component was sequentially reacted with isophorone diisocyanate, isophthalaldehyde, and carbon disulfide to produce PDMS-based poly (urea-thiourea-imine) (PDMS-PUTI). Subsequently, a composite (PDMS-PUTI/HP-g-CN) was produced through physical blending. The intrinsic imine bonds and dynamic hydrogen-bonding network were responsible for the self-healing properties, which achieved a healing efficiency of up to 89.2 %. HP-g-CN was grafted with the non-leaching lubricant, HTPDMS, resulting in improved mechanical properties (1.38 MPa of ultimate strength) and adhesion strength (2.43 MPa), along with the self-cleaning and self-lubricating performance (0.700 coefficient) of the coating. Additionally, the fouling resistance to bovine serum albumin (BSA, 10.44 μg cm−2), bacteria (∼97.08 % and ∼ 98.05 % reduction for Pseudomonas sp. (P. sp.) and Shewanella sp. (S. sp.), respectively), and diatoms (∼27 cells mm−2) was further enhanced. Marine field tests conducted over 90 days revealed that the coatings were static fouling-resistant for an extended period. This study demonstrated a multifunctional, high-performance, and environmentally friendly nanocomposite polymer coating for preventing marine biofouling.

Characterisation of alkali-treated novel cellulosic fibres derived from Dombeya Buettneri plant as a potential reinforcement for polymer composites

ABSTRACT The present study evaluates the influence of alkali treatment using 2, 4, and 8 wt.% sodium hydroxide concentration solutions on novel cellulosic fibres manually extracted from the bark of dombeya buettneri plant (DBF). Alkali-treated fibres were characterised through physical and mechanical properties determination, Fourier transform infrared spectroscopy, X-ray diffraction, quantitative chemical analysis, thermogravimetric analysis, and scanning electron microscopy. Quantitative chemical analysis revealed a significant increment in cellulose content, reaching 67 ± 1.7% in DBF treated with 4 wt.% NaOH solution, accompanied by substantial reductions in lignin and hemicelluloses as confirmed by FTIR spectroscopy. XRD analysis showed an improved crystallinity index of 80% and crystallite size of 2.64 nm for 4 wt.% alkali-treated DBF. Additionally, 4 wt.% alkali-treated fibres yielded peak values of breaking force (40 N) and breaking tenacity (181 cN/Tex). SEM analysis confirmed enhanced surface roughness post-treatment, an indication of enhanced fibre/matrix interlocking during composite fabrication, whereas TGA analysis reported improved thermal stability post-treatment. EDX analysis confirmed that the C/O ratio is proportional to alkali solution concentration, indicating effective removal of non-cellulosic contents. In conclusion, treating DBF with 4 wt.% NaOH concentration improves their physical, mechanical, and chemical properties, suggesting their potential for polymer composite applications.

Mechanical property enhancement of flax fibers via supercritical fluid treatment

The desire for lightweight, carbon-negative materials has been increasing in recent years, particularly as the transportation sector reduces its global carbon footprint. Natural fibers, such as flax fiber and their composites, offer a compelling combination of properties including low density, high specific strength, and carbon negativity. However, because of the low modulus and high variability in performance, natural fibers can’t compete with glass fibers as structural reinforcements in polymer composites. In this study, flax technical fibers were treated in supercritical CO2 (scCO2), and the effects of this treatment on the morphology and properties of flax fibers are reported. Treatment in scCO2 successfully resulted in higher fiber modulus and strength by 33% and 40%, respectively. Fiber porosity was reduced by 50% and morphological changes to the fibers were observed. Specifically, fiber lumen collapsed during treatment and micro/mesoporosity was reduced by 27%. Treated flax fibers were used to create 30 vol% unidirectional flax-epoxy composites. ScCO2 treatment raised composite modulus and strength by 33% and 25%, respectively. Because of the dependence between technical fiber size and mechanical properties, the relationship between fiber modulus and fiber size were created and applied to the rule-of-mixtures. This relationship were found to be viable representations of the fiber performance within each composite. Overall, the treatment developed in this study has the potential to significantly improve natural fiber properties, enabling their consideration for use in lightweight, semi-structural composites.