Flexural Strength Of Composites Research Articles

Fabrication of mechanical durable novolac matrix composites with recycled and cost-effective candle-soot nano particles

Novolac matrix composites are crucial due to their exceptional resistance to heat, chemicals, and mechanical stress. These advanced materials find applications in aerospace, electronics, and automotive industries, providing high-performance solutions for components requiring superior durability and reliability. In this context, the microstructure, thermal, phase, and mechanical properties of the composites obtained as a result of the recycling-oriented reinforcement of the waste candle-soot (CS) reinforcement at the rate of 1 wt% to the pure novolac (PN) and shaping with the hot press method were examined in detail at first time in the literature. While microstructural properties and fracture mechanisms were investigated by scanning electron microscopy (SEM), thermal properties were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results obtained provided critical findings as the composite hardness, tensile strength, and flexural strength values were 3.28, 2.47, and 3.21 times higher than PN, respectively. CS-reinforced novolac composites made a significant contribution to the literature by introducing a novel and eco-friendly approach to enhance material properties. Their use as a filler material provided insights into sustainable novolac composites, offering potential applications in various industries, such as electronics and aerospace, with improved mechanical and thermal properties.

Utilization of Silica Filler as Reinforcement Material of Polylactic Acid (PLA) in 3D Printing Applications: Thermal, Rheological, and Mechanical Performance.

Glass was introduced as an additive to filaments used for the manufacturing of composite materials, employed by Additive Manufacturing applications. Glass accounts for a large waste electric and electronic equipment (WEEE) percentage, and its recovery and recycling can lead to the production of sustainable composite materials. In this work, poly(lactic acid) (PLA)/commercially available silicon oxide composite filaments were manufactured and their structural, thermal, rheological, and mechanical properties were assessed. Scanning Electron Microscopy confirmed the 1:2 ratio of silicon: oxygen, along with the relatively low adhesion between the filler and the matrix. Differential Scanning Calorimetry presented steady glass transition and melting temperatures of composites, whereas a crystallization temperature of 10% wt. and a crystallinity of 15% wt. composite slightly increased. Rheological analysis showcased that the viscosity of the composite filaments decreased compared to PLA (10-100 compared to 300-400 Pa·s), with a more shear-thinning behavior. Dynamic mechanical analysis exhibited increased elastic, flexural moduli, and flexural strength of composites (up to 16, 23, and 11%, respectively), whereas tensile strength and elongation decreased. The affordability of raw materials (with the future introduction of recycled ones) and the minimal processing steps can lead to the potential scaling up of the study.

Valorization of purified agricultural brown eggshell by-product as filler in bio-epoxy composites

This study presents tensile, flexural and water absorption properties of composites made from bio-epoxy resin containing brown eggshell (with membrane), purified brown eggshell (without membrane) and mineral limestone at three filler levels of 5, 10 and 20 wt%. Composites were made by an open silicone mold casting method. Fourier transform infrared (FTIR) spectroscopy was used to demonstrate removal of the membrane. Inductively coupled plasma mass spectrometry (ICP-MS) indicated brown eggshells without membrane had a higher calcium carbonate content suggesting the purification technique worked well. Although composite tensile strengths and flexural strengths were lower than the pure bio-epoxy, the composites containing brown eggshells (with membrane) had slightly better strengths than composites containing purified brown eggshells (without membrane) and mineral limestone for the same particle size of 32 µm. The organic membrane contains proteins on the surface of the eggshells which may be beneficial for chemical bonding to occur with the bio-epoxy resin. Filler contents of 5–10 wt% were acceptable for tensile and flexural strengths. Scanning electron microscopy (SEM) provided visual observations of the fractured surfaces where an increase in surface roughness was related to an increase in filler loading, implying changes occurred within the composite materials. Brown eggshells can be exploited as a waste management opportunity for use as a filler in bio-epoxy composites.

EFFECT OF FILLER CONTENT AND SIZE ON THE FLEXURAL STRENGTH AND HARDNESS OF PURE IRON POWDER FILLED LAMINATED FIBERGLASS EPOXY COMPOSITES

The aim of this work is to evaluate the effect of the amount of pure iron powder (99.9987%), introduced as a filler in a glass-epoxy composite laminate, as well as the variation of its grain dimensions, on its flexure strength and hardness. Contact molding was used to produce laminate plates of 15, 20, and 25% of weight content with three different dimensions 92, 64, and 32 μm, and the fiberglass content was set at 30%. For the bending test, the specimens were prepared according to ISO 14125 standard specification, the test was carried out with three different speeds, and the required number of specimens were manufactured according to Taguchi's orthogonal array L9 (3 × 3) by varying three parameters (iron powder content, grain size, and test speed). The results were studied with the Taguchi method; however, the hardness was measured on plates with the same iron powder content while varying the dimensions of its grains (92, 64, and 32 μm). The results show that the pure iron powder content and dimension variations have a direct and clear influence on the composite material's mechanical characteristics, in such a way that: a specific percentage of filler and grains size reduction could widely increase the hardness as well as the material flexure strength. The results of the elaborated composite material's bending test were compared to a 45% glass-epoxy laminate. Whereas the hardness of the elaborated laminate was compared to a resin plate and the 45% glass-epoxy laminate.

Effect of Al59Cu25.5Fe12.5B3 Quasi-crystals on Microstructure and Flexural Strength of Aluminum Matrix Composites Prepared by Spark Plasma Sintering Method

Effect of Al59Cu25.5Fe12.5B3 Quasi-crystals on Microstructure and Flexural Strength of Aluminum Matrix Composites Prepared by Spark Plasma Sintering Method

Modified Gypsum-Cement-Pozzolan Concrete for 3DCP

3D concrete printing (3DCP) is an innovative and promising method for constructing buildings and structures. Compositions of fine-grained concrete based on Portland cement are widely used as raw material mixtures in this technology. An alternative to the use of cement binder is the use of gypsum-cement-pozzolan binder, which can significantly reduce the cost of the finished product and, accordingly, increase its competitiveness. The raw material mixtures based on gypsum-cement-pozzolan binder presented on the construction market do not fully meet the requirements of 3DCP. Achieving optimal performance of gypsum-cement-pozzolan mixtures in 3DCP is possible by regulating the content of fine aggregate in the composition of fine-grained concrete, as well as the use of multicomponent modifying additives. The purpose of this work is to develop modified gypsum-cement-pozzolan concretes for 3DCP based on optimization of aggregate content and multifunctional additive, providing optimal rheotechnological properties of raw mixtures and technological characteristics of finished products. The formation of samples during experimental studies was carried out using the layer-by-layer extrusion method on a workshop construction 3D printer “AMT S-6044”. Modified gypsum- cement-pozzolan concretes have been developed for 3DCP with increased ultimate shear stress of the mixture (87.6 Pa), dimensional stability (23 cm), average composite density (1920 g/m3), flexural strength (8.4 MPa) and compression (30.6 MPa) and water resistance (0.85). The possibility of targeted regulation of the structure and properties of gypsum-cement- pozzolan mixtures and concrete due to the synergistic effect of the components of the developed multifunctional complex additive, including an aqueous solution of a polycarboxylate ether, a copolymer based on carboxylic acid esters, and a homogeneous mixture of oligoethoxysiloxanes, has been proven. The results obtained are consistent with the results of the differential thermal analysis of modified gypsum-cement-pozzolanic stone.

The Evolution of the Intrinsic Flexural Strength of Jute Strands after a Progressive Delignification Process and Their Contribution to the Flexural Strength of PLA-Based Biocomposites.

Biocomposites from poly-(lactic acid) (PLA) and jute strands were prepared, and their flexural strength was analyzed. Jute strands were submitted to a progressive delignification process and the resulting morphology, composition, and crystallinity index were evaluated. Then, PLA biocomposites comprising 30 wt% of jute strands were produced and characterized under flexural conditions. The delignification processes decreased the lignin content and progressively increased the cellulose content. All this resulted in an enhancement of the composite flexural strength. A modified rule of mixtures, and the relation between tensile and flexural properties were used to determine the intrinsic flexural strength (of the jute strands) and their correlation with their physic-chemical characteristics. Equations correlating the intrinsic flexural strength with the crystallinity index, the cellulose content, and the microfibril angle were proposed. These equations show the impact of these properties over the intrinsic properties of the fibers and can help researchers to select appropriate fibers to obtain accurate properties for the composites. Jute strands show their value as reinforcement by increasing the flexural strength of the matrix by 70% and being less expensive and more environmentally friendly than mineral reinforcements. Together with the profitability and the environmental advantages, the mechanical results suggest that these PLA biocomposites are suitable for specific products of different market sectors.

Assessment of Hydrothermal Treatment Effects on Coir Fibers for Incorporation into Polyurethane Matrix Biocomposites Derived from Castor Oil.

The incorporation of natural lignocellulosic fibers as reinforcements in polymer composites has witnessed significant growth due to their biodegradability, cost-effectiveness, and mechanical properties. This study aims to evaluate castor-oil-based polyurethane (COPU), incorporating different contents of coconut coir fibers, 5, 10, and 15 wt%. The investigation includes analysis of the physical, mechanical, and microstructural properties of these composites. Additionally, this study evaluates the influence of hydrothermal treatment on the fibers, conducted at 120 °C and 98 kPa for 30 min, on the biocomposites' properties. Both coir fibers (CFs) and hydrothermal-treated coir fibers (HTCFs) were subjected to comprehensive characterization, including lignocellulosic composition analysis, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The biocomposites were subjected to water absorption analysis, bending tests, XRD, SEM, FTIR, and TGA. The results indicate that the 30 min hydrothermal treatment reduces the extractive content, enhancing the interfacial adhesion between the fiber and the matrix, as evidenced by SEM. Notably, the composite containing 5 wt% CF exhibits a reduced water absorption, approaching the level observed in pure COPU. The inclusion of 15 wt% HTCF results in a remarkable improvement in the composite's flexural strength (100%), elastic modulus (98%), and toughness (280%) compared to neat COPU. TGA highlights that incorporating CFs into the COPU matrix enhances the material's thermal stability, allowing it to withstand temperatures of up to 500 °C. These findings underscore the potential of CFs as a ductile, lightweight, and cost-effective reinforcement in COPU matrix biocomposites, particularly for engineering applications.

Effects of alkaline treatment and manufacturing process on mechanical and absorption properties of Wild Abyssinia Banana fiber reinforced epoxy composite

To enhance the properties of natural fiber composite, proper selection of an optimum alkaline concentration for fiber surface modifications and composite manufacturing techniques are the main criteria to be considered. This study examined how NaOH and manufacturing methodsaffect the mechanical and absorbency characteristics of a Wild Abyssinia Banana (WAB) epoxy composite. 2 %, 5 %, and 7 % (w/v) NaOH concentrations; hand-layup and hydraulic press manufacturing techniques have been considered. Petroleum, diesel, distilled, and artificial lake water (wastewater) were used for the absorption test. A 5 % NaOH treatment improves composite tensile, flexural, and impact strengths by 14.78 %, 8.59 %, and 29.63 %, respectively. Moreover, the 5 % NaOH treatment reduced the absorption rate of the WAB fiber composite. Hydraulic press manufactured untreated WAB fiber composite was observed to have 26.27 % and 13.45 % higher tensile and flexural strengths than hand layup. The treated WAB fiber-reinforced composite can be utilized in gas stations, home appliances, and finishing materials for construction applications.

Effects of Physical and Mechanical Properties of Coir Fiber and Reinforced Epoxy Composites Treated with Acetic Anhydride and Alkali

ABSTRACT Modified coir fiber improves compatibility between fiber and matrix. To explore a better fiber treatment approach and enhance the mechanical properties of composites, this study conducted alkali treatment and acetic anhydride treatment on long and short coir fibers. The effects of different treatments on the properties of coir fibers were characterized using TGA, FTIR, SEM, and stereomicroscopy, and the mechanical properties of the composites were tested. Results showed that the tensile strength of alkali-treated coir fibers (ACF) and acetic anhydride-treated coir fibers (AACF) were remarkably improved. Notably, ACF exhibited a significant 69% increase in tensile strength. The tensile strength of composites with alkali-treated long coir fibers (ALC) and composites with alkali-treated short coir fibers (ASC) reached 34.51 and 21.14 MPa, respectively. The highest flexural strength was found for the acetic anhydride-treated coir fibers, and the flexural strength of composites with acetic anhydride-treated long coir fibers (AALC) and composites with acetic anhydride-treated short coir fibers (AASC) reached 54.38 and 53.46 MPa, respectively. This study presents an improved methodology for enhancing the interfacial bonding ability between coir fibers and the matrix, consequently improving the properties of composites. It offers reference for the investigation of natural fiber composites.

Modifying dental composites to formulate novel methacrylate-based bone cements with improved polymerisation kinetics, and mechanical properties

ObjectivesThe aim was to develop bone composites with similar working times, faster polymerisation and higher final conversion in comparison to Cortoss™. Additionally, low shrinkage/heat generation and improved short and longer-term mechanical properties are desirable. MethodsFour urethane dimethacrylate based composites were prepared using tri-ethylene-glycol dimethacrylate (TEGDMA) or polypropylene dimethacrylate (PPGDMA) diluent and 0 or 20 wt% fibres in the glass filler particles. FTIR was used to determine reaction kinetics, final degrees of conversions, and polymerisation shrinkage/heat generation at 37 °C. Biaxial flexural strength, Young’s modulus and compressive strength were evaluated after 1 or 30 days in water. ResultsExperimental materials all had similar inhibition times to Cortoss™ (140 s) but subsequent maximum polymerisation rate was more than doubled. Average experimental composite final conversion (76%) was higher than that of Cortoss™ (58%) but with less heat generation and shrinkage. Replacement of TEGDMA by PPGDMA gave higher polymerisation rates and conversions while reducing shrinkage. Early and aged flexural strengths of Cortoss™ were 93 and 45 MPa respectively. Corresponding compressive strengths were 164 and 99 MPa. Early and lagged experimental composite flexural strengths were 164–186 and 240–274 MPa whilst compressive strengths were 240–274 MPa and 226–261 MPa. Young’s modulus for Cortoss™ was 3.3 and 2.2 GPa at 1 day and 1 month. Experimental material values were 3.4–4.8 and 3.0–4.1 GPa, respectively. PPGDMA and fibres marginally reduced strength but caused greater reduction in modulus. Fibres also made the composites quasi-ductile instead of brittle. SignificanceThe improved setting and higher strengths of the experimental materials compared to Cortoss™, could reduce monomer leakage from the injection site and material fracture, respectively. Lowering modulus may reduce stress shielding whilst quasi-ductile properties may improve fracture tolerance. The modified dental composites could therefore be a promising approach for future bone cements.

Effect of moisture absorption on the flexural strength of phenolic matrix composites reinforced with glass fibers and aluminum oxide nanoparticles

AbstractIn this research, the effect of adding aluminum oxide nanoparticles on the flexural strength of glass/phenolic composites that were exposed to water environment was experimentally investigated. To make glass/phenolic composites, IL‐800 phenolic resin, H002 hardener, T400 bidirectional glass fibers and Al2O3 nanoparticles were used. Four‐layer composite plates were made by hand layup method. Beam‐shaped samples were extracted from the plates with the help of laser cutting method. Rectangular composite beams made of glass/phenolic and Al2O3/glass/phenolic were subjected to three‐point flexural test. The moisture absorption test was continued until the amount of water absorption reached a constant level. Bending test was performed on the samples before and after immersion in water. Based on the results, the average flexural strength of the samples after water absorption shows a decrease of about 15%. This parameter is equal to 118.96 MPa for glass/phenolic composite samples immersed in water, and by adding 0.25 wt% of Al2O3 nanoparticles into the matrix material of glass/phenolic composite samples, the flexural strength reaches 142.54 MPa, which shows an increase of 19.82% compared to samples without nanoparticles. Furthermore, the amount of flexural modulus decreases after water absorption, and the addition of nanoparticles in the base material can compensate this reduction. Scanning electron microscopy images illustrate that the addition of Al2O3 nanoparticles into the phenolic resin can enhance the strength of matrix material and improve the adhesion of glass fibers to the resin.Highlights Addition of nano Al2O3 reduces water absorption of glass/phenolic composites. Nano Al2O3 improves composite flexural strength after water absorption. Addition of nano Al2O3 increases the adhesion between the layers of the specimens.

Influence of interfacial microstructure on the mechanical properties of SiC/SiBCN composites

SiC/SiBCN composites were prepared via polymer infiltration and pyrolysis technique (PIP) and the influence of the interfacial microstructure on the mechanical properties of the composites was investigated. In this paper, an amorphous SiOC layer was observed at the fiber-matrix interface for the first time. Formation of the SiOC layer stems from SiO gas formed inside the ceramic matrix may diffused towards the interface and reacted with the carbon-rich layer of SiC fibers to form Si atom. Si atom dissolved in the O–C molecular network to form a 100 nm chemical bonding SiOC layer, which caused the SiC fibers to pull out in a whole bundle and the pull-out length was short, leading to a composite flexural strength of only 143 ± 30 MPa. By introducing SiC coating, SiC fibers were effectively protected from chemical reactions, and the coating acted as a barrier to the diffusion and migration of the matrix elements to the interface and weakened the interfacial bonding strength (IFBs), in which IFBs decreased from 266 ± 19 MPa to 170 ± 10 MPa. Hence, the flexural strength of composites increased up from 143 ± 30 MPa to 388 ± 16 MPa.

Mechanical Interlocking Approaches to the Prediction of Mechanical and Tribological Behavior of Natural Fiber-Reinforced Polymer Hybrid Nanocomposites or Automotive Applications

Polymer matrix composites synthesized with biodegradable natural fiber obtain a predominant structure with specific properties at a low-processing cost. The unique characteristics of polymer matrix composites were magnetized in automotive parts like top roof, panel, and seat frame applications. American Society for Testing and Materials (ASTM) G99 analyzed the wear characteristics of synthesized composites through a pin-on-disc wear tester with an EN32 steel disc. The epoxy hybrid composites have been synthesized via a conventional casting process assisted with a mechanical interlock technique to obtain a predominant structure with specific properties at a low-processing cost. The advanced composite contained different jute weights (50, 25, 50, and 75 g) and coconut coir (50, 70, 45, and 20 g) hybridized with graphite particles. ASTM D2240, D638, and D790 standards evaluated the fabricated composite hardness, tensile, and flexural strength. The Sample 4 hybrid composite found maximum hardness, tensile, and flexural strength of 27.41 ± 0.99 Hv, 51.69 ± 1.01MPa, and 55.94 ± 0.78 MPa, respectively. Sample 4 offered good wear resistance of their volumetric wear rate of 0.043 cm3 on 40 N average load at 0.25 m/s sliding speed. It is increased by 12% compared to Sample 1 at 40 N applied load on 2.5 m/s sliding speed.

Utilization of Festuca arundinacea Schreb. Biomass with Different Salt Contents for Bioethanol and Biocomposite Production

Soil salinity is one of the particularly important environmental factors, which limits the growth and development of plants, reduces the amount of crops and causes serious economic damage. The study found that Festuca arundinacea can be successfully used for the management and bioremediation of saline habitats, and it is characterized by a very well-developed root system and an average high biomass production of approx. 14.8 Mg∙ha−1, which can be used for industrial applications. Tall fescue biomass from soils with different levels of salinity was used to obtain bioethanol using 1.5% NaOH pretreatment and for the process of simultaneous enzymatic hydrolysis and ethanol fermentation (SSF). It was found that the content of Na+ ions in the tall fescue biomass had no significant effect on the amount of ethanol obtained (the average 19.32 g∙100 g−1 of raw material). F. arundinacea biomass was also used as a natural filler to obtain green composites using a biodegradable polylactide (PLA) matrix. It has been shown that tall fescue biomass with the lowest sodium content in biomass (approx. 2.5 mg∙g−1) from an area with high saline (above 6 g NaCl∙L−1) has the smallest effect on reducing the tensile and flexural strength of composites. Moreover, the highest value of bioethanol concentration (21.2 g∙100 g−1 of raw material) for this biomass sample was obtained.

Bio-Based White Eggshell as a Value-Added Filler in Poly(Lactic Acid) Composites

Based on its positive environmental impact, poly(lactic acid) (PLA) has been a gradual substitute for synthetic plastics used in diverse applications. The use of industrial limestone (ILS) as a filler in polymers can have advantages of changing the properties of pure polymers. Waste eggshells (WE) can be seen as an alternative filler to ILS as they are also a source of calcium carbonate. To assess the feasibility of both filler types and sizes, PLA composites were manufactured by injection molding with filler contents of 5, 10, and 20 wt.%. Tensile, flexural, and impact mechanical properties were evaluated in addition to water absorption. One-way analysis of variance (ANOVA) was performed to determine whether statistically significant differences among the measured mechanical properties existed. Scanning electron microscopy (SEM) was used to view the morphology of the fillers and fractured surfaces. The composite tensile strengths and flexural strengths performed the best when filler loadings were 5 wt.% and 10 wt.%, respectively, for both filler types. The tensile and flexural modulus both increased with filler loadings. The impact strength for the composites was obtained at a threshold level of 5 wt.% filler loadings for both filler types and slightly better for smaller particles sizes. ANOVA identified statistically significant differences for the mean mechanical property values evaluated. SEM showed the fractured surfaces of the PLA composites were different from the pure PLA indicating some transformation occurred to the matrix. The weight gains due to water absorption were observed to increase with increase in content of both filler types while the smaller particles had slightly higher water weight gains. Although the composites containing ILS fillers had somewhat enhanced mechanical properties over the WE-filled composites, the end application will dictate which filler type to use in PLA.

Tensile and Flexural Behaviors of Basalt Textile Reinforced Sprayed Glass Fiber Mortar Composites.

The proposed study combines sprayed glass fiber-reinforced mortar and basalt textile-reinforcement to harness the favorable properties of each component to obtain a composite material that can be used for strengthening of existing structures. This includes crack resistance and a bridging effect of glass fiber-reinforced mortar and the strength provided by the basalt mesh. In terms of weight, mortars containing two different glass fiber ratios (3.5% and 5%) were designed, and tensile and flexural tests were conducted on these mortar configurations. Moreover, the tensile and flexural tests were performed on the composite configurations containing one, two, and three layers of basalt fiber textile reinforcement in addition to 3.5% glass fiber. Maximum stress, cracked and uncracked modulus of elasticity, failure mode, and average tensile stress curve results were compared to determine each system's mechanical parameters. When the glass fiber content increased from 3.5% to 5%, the composite system without basalt textiles' tensile behavior slightly improved. The increase in tensile strength of composite configurations with one, two, and three layers of basalt textile reinforcement was 28%, 21%, and 49%, respectively. As the number of basalt textile reinforcements increased, the slope of the hardening part of the curve after cracking clearly increased. Parallel to the tensile tests, four-point bending tests showed that the composite's flexural strength and deformation capacities increase as the number of basalt textile reinforcement layers increase from one to two.

Flexural and flame retardance properties of multi-walled carbon nanotubes/glass fibre/epoxy hybrid composites

The effect of different multi-walled carbon nanotubes (MWCNTs) wt.% loading on the flammability, water absorption, thermal stability and flexural properties of glass fabric reinforced epoxy composites is reported in this paper. The pristine MWCNTs were dispersed in water, using arabic gum (GA) as a dispersing agent. Then, the suspension was sprayed onto the glass fibre (GF). Hybrid composites with and without MWCNTs were fabricated using hand lay-up and vacuum bagging techniques. Based on standard fire testings such as limiting oxygen index (LOI) and horizontal burning (UL94HB), it was observed that the composites were able to self-extinguish, even at low amounts of MWCNTs. Increase in the MWCNTs content produced a concurrent increase in the LOI of the composites which reached a maximum value of 31.30 ± 1.22% at 1 wt% MWCNT. The thermal stability was investigated using thermogravimetric analysis (TGA) and it was found that the addition of MWCNTs improved thermal stability, and increased the fire-retardance of the glass fabric reinforced epoxy (GF/EP) composites. The highest composite flexural strength (150 MPa) and flexural modulus (12 GPa) were attained at 0.5 wt% MWCNT. Above 0.5 wt%, a drop in strength and modulus was observed. The results from this study showed that the use of hybrid reinforcement containing MWCNTs can help to significantly improve the flame retardance, water absorption, and mechanical properties of reinforced composites by incorporating optimum amount of MWCNTs.

Nontraditional Natural Filler-Based Biocomposites for Sustainable Structures

In recent years, there has been a growing awareness and demand for global sustainability, as well as a mandate for the use of renewable and environmentally sustainable materials and processes. Due to which, massive efforts are being made to develop and nurture the next generation of composite materials that are energy efficient, environmentally friendly, and biodegradable. Light weight, lower coefficient of thermal expansion, and comparable tensile strength exhibited by natural fibers render them the choice for use in several industrial products and applications over the last decade. Natural fibers as the reinforcing entity are pitted against their synthetic variants primarily because of the superior aspects like biodegradability and excellent strength-to-weight ratio. This article presents the review on various nonconventional natural fibers such as tamarind seed and shell, Luffa cylindrica, groundnut shell, coconut coir, papaya bast, okra, and Ashoka tree seed. The flow of the chapter includes the introduction, extraction methodologies, and fabrication, and investigations of mechanical properties, applications, and sustainability are dealt in detail for nontraditional natural fibers. The okra fibers possess greater tensile strength of up to 262.8 MPa in comparison with other fibers, while the Ashoka tree seed fibers are known to possess a maximum flexural strength of up to 125 MPa. Further, these fibers are used as reinforcements in potential applications in interiors and automobile and aircraft panels and wood-based particle board composites owing to the increase in tensile and flexural strengths of composites.

Evaluation of rheological and mechanical properties of bottom ash based masonry mortar with graphene oxide

This paper evaluates the rheological and mechanical properties of lignite based bottom ash as fine aggregate in cement mortar with GO as an additive. The annual extraction of such a huge amount of bottom ash needs a massive transfer to the field, as it constitutes a threat to the environment. The utilization of such residue as a partial replacement of fine aggregate in masonry mortar is not fully explored. Hence, an attempt has been made to utilize the bottom ash as FA in cement mortar composites, and studied the influence of graphene oxide (GO) in the properties of mortar matrix. In this study, bottom ash replacement from 0 to 60% and GO at dosage of 0.1, 0.15 and 0.20% by weight of cement were used. Compressive and flexural strengths of composites were improved significantly at GO = 0.15%. Mechanical properties at 40% bottom ash replacement level only have shown minor improvement. It was observed from the flow table test that addition of bottom ash leads to reduction in workability of masonry mortar, and GO enhanced both the rheological and mechanical properties of mortar matrix.