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The tensile behavior of a flexible epoxy resin reinforced with knitted reinforcements from various fiber materials was comprehensively studied in the wale and course direction. By measuring dry yarns, temperature‐treated yarns, dry knitted fabrics and flexible composites, the effect of the fiber material and the knitted fabric on the tensile properties was analyzed. The interlock knit structure strongly affected the deformation behavior of the flexible composites which differed significantly from the dry knitted fabrics. The deformation behavior of the flexible composites was monitored using digital image correlation which revealed the formation of cracks and high local strain differences in the course direction for all fiber materials. This was linked to fiber‐matrix debonding by scanning electron microscope observations. In the wale direction, the deformation of the knitted structure under tensile load led to plastic deformation of the matrix material. Overall, with yarns from recycled thermoplastic fibers, a higher maximum stress and strain at break was achieved compared to bio‐based fibers. However, irreversible damage occurred for all fiber materials at similar strain values. Highlights: Tensile tests on yarns, knitted fabrics and flexible composites.Investigation of the effect of fiber material on mechanical properties.High local strain differences in composites due to knitted structure.Fiber‐matrix debonding in course direction.Plastic deformation of the matrix material in the wale direction. [ABSTRACT FROM AUTHOR]

In this study, the primary factors affecting the performance of PcBN (Polycrystalline cubic boron nitride) tool materials were investigated by high temperature/high pressure sintering through the variation of TiB 2 -Sialon volume ratio, the strength of TiB 2 -Sialon binder itself, as well as the matching of the average coefficient of thermal expansion (CTE) with cBN (Cubic boron nitride). The effects of TiB 2 -Sialon on the phase composition, microstructure, and mechanical properties of PcBN composites were studied by X-ray diffraction (XRD), universal testing machine, scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that the properties of TiB 2 -Sialon binder are analogous to those of the corresponding composites. The phase composition of PcBN composite is not affected by the change of volume ratio. It was found that prepared composite, have TiB 2 rod crystals growing along the (100) plane and Sialon rod crystals growing on the (001) plane. The influence of the volume ratio of TiB 2 -Sialon on the mechanical properties of the composites is principally concerned with the density, mechanical properties, and thermal expansion coefficient of the used binder. The extent to which the binder matches the coefficient of thermal expansion is favorable to the strength of the composite. When the volume ratio of TiB 2 to Sialon was 1:3, the hardness (25.21 GPa, 37.44 GPa) and toughness (7.09 Pa m1/2 and 7.48 Pa m1/2) of TiB 2 -Sialon binder/TiB 2 -Sialon-cBN composites reached the maximum value, and the optimal impact resistance was also achieved. The density of the binder and the composite material was maximized when the volume ratio is 1:4. The average thermal expansion coefficient of the binder hoc tempore matches comparatively with cBN, and the interface bonding is better, displaying the best flexural strength (805.30 MPa and 1059.60 MPa) and wear ratio (2005). Therefore, adjusting the volume ratio of TiB 2 -Sialon within a certain range is beneficial to further enhance the binder's strength and mechanical properties. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) has been widely used in many fields because of its good biodegradability, biocompatibility, and renewability. This work studied the degradation behavior and mechanical properties of cellulose nanofiber (CNF)/PLA composites. In vitro degradation experiments of 3D-printed samples were conducted at elevated temperatures, and the degradation characteristics were evaluated by mechanical tests, gel permeation chromatography (GPC), differential scanning calorimetric (DSC), and scanning electron microscope (SEM). The results indicated that the addition of CNF (0.5 wt%) accelerated the degradation rate of PLA. The decreases in number average molecular weight ( M n ) and weight average molecular weight  (M w)  of composites were 7.96% and 4.91% higher than that of neat PLA, respectively. Furthermore, the tensile modulus of composites was 18.4% higher than that of neat PLA, while the strength was 7.4% lower due to poor interfacial bonding between CNF and PLA. A mapping relationship between accelerated and normal degradation showed that the degradation experienced during 60 days at 37 °C was equivalent to that undergone during 14 days at 50 °C; this was achieved by examining the alteration in  M n . Moreover, the degradation process caused a notable deformation in the samples due to residual stress generated during the 3D printing process. This study provided valuable insights for investigating the in vitro degradation behavior of 3D-printed products. [ABSTRACT FROM AUTHOR]

There has been an increasing trend of using natural fibre reinforcements as an alternative to manmade fibre reinforcements for engineered composite applications. Natural fibres are alternative composite reinforcement materials due to their biodegradability, inexpensiveness, abundance and excellent physical properties. This study aims at analysing the mechanical properties of the fabricated bio-composite from polyester resin reinforced with silk waste fabric. The specific objectives of this work are to characterise physical and mechanical properties of silk waste fabric, fabricate a bio-composite from silk waste fabric treated with zinc oxide nanoparticles and polyester resin and to analyse the static mechanical properties (tensile, flexural and impact). The silk waste fabric is characterized and the composite fabricated using hand lay-up technique and a mould with dimensions 360 × 210 × 4 mm. Central composite design is used in the design of experiments, and the fibre weight fraction was varied from 11 to 25%. Treatment with nanoparticles is done by soaking silk waste fabric in a 6% concentration of zinc oxide nanoparticles and 1% citric acid. A sonicator uses to evenly distribute the nanoparticles in the solvent, and the fabric is coated using the pad dry cure method. The fabricated composites are cured at room temperature for 24 h under consolidated pressure of 2.65 kN/m2. The mechanical properties of the composites are determined using D790, D638 and D6110 ASTM standards, whereas the morphology is investigated using a scanning electron microscope. The areal density of the silk waste fabric is 76 g/m2, and its tensile strength was 16.80 MPa. The tensile, flexural and impact strengths of uncoated composites are 27.92 MPa, 52.13 MPa and 32.17 kJ/m2, respectively. The flexural and tensile strengths of the coated bio-composites increase with increasing fibre weight fraction up to peak values of 32.23 MPa and 53.47 MPa, respectively. Bio-composites produced with silk waste fabric treated with nanoparticles had slightly better strengths (tensile 32.23 MPa and flexural 53.47 MPa) compared to bio-composites with non-treated silk waste fabric (tensile 27.92 MPa and flexural 52.13 MPa). The static mechanical properties attained in this study reveal that these bio-composites may be used for non-structural applications for instance partitioning walls and ceiling boards. The study recommended future research studies on increasing the number of plies beyond six with different fabric weave designs of twill, satin, sateen and warp rib and use of thermal evaporation as a coating technique of nanoparticles onto silk waste fabric to establish their effect on mechanical and thermal properties and morphology. [ABSTRACT FROM AUTHOR]

For commercial civil applications of laminated composite material, characterizations to forecast the interlaminar shear behavior and viscoelastic response across a wide temperature range are essential. In this study, the interlaminar shear strength (ILSS) of glass/epoxy (GE) composites dispersed with binary nanofillers nanosilica‐multilayer graphene (NS‐MLG) and nanosilica‐nanoclay (NS‐NC) was analyzed at an in‐situ testing temperature of 20, 70, and 110°C. Further, the viscoelastic property of the composites was studied using a dynamic mechanical thermal analyzer (DMTA) in the temperature range of 35–165°C. An increase in the ILSS value of around 9% and 10% was observed at room temperature for GE/MLG‐NS and GE/NC‐NS, respectively, compared to control GE composites. In contrast, the trend was seen to change at higher temperatures. There was a slight decrement in the storage modulus (E′) of GE/MLG‐NS and GE/NC‐NS composites in the glassy region compared to control GE composites. The mean Tg of the GE composite (control) was nearly 107.3°C when the E′ decline onset temperature was taken into account, but after the addition of MLG‐NS, it was 10.1°C below. The mean Tg of GE/NC‐NS was determined to be 106.3°C, and in the glass transition as well as rubbery regions, it was observed to compete with the E′ value of the control GE composites. Fractography was done using micrographs obtained from environmental scanning electron microscope (ESEM). Traces of polymeric material found at the fiber surface certified the improved interfacial adhesion between glass fiber and polymer in the matrix‐modified composite samples. [ABSTRACT FROM AUTHOR]

The ceramic composites were designed through the regulation of the composition and temperature in the in-situ oxidized SiC/Al–Mg–Si composites process. The evolutions of the phase and microstructure were studied by X-ray Diffraction(XRD), Scanning Electron Microscope (SEM), and Transmission Electron Microscope(TEM) in different alloy addition and heating temperature. The products of in-situ oxidized SiC/Al–Mg–Si composites showed similar compositions due to high oxidation resistance on SiC since the heated temperature was below 1500 °C. Alloy addition dislodges the oxide shell on SiC. It promoted the oxidation of SiC, providing the sustained-release Si source to form the cordierite, mullite, and forsterite. Moissanite/spinel, mullite/spinel, and cordierite/spinel were obtained by controlling temperature or adding alloy. The mullite rods formed in 20% alloy addition samples at 1350 °C was detected. The step-like microstructure revealed that grains abide by a layer growth mechanism. The bending strength was enhanced from 13.83 ± 3.6 MPa to 22.32 ± 4.3 MPa by eutectic melting, which increased with the alloy addition and elevated temperature. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the improvement made on the mechanical properties of the composites by the addition of micro- and nanoparticles to aluminium matrix. The micro- and nano-composites having different weight percentages of particles were fabricated using stir-casting and ultrasonic cavitation probe-assisted casting processes, and they were characterized using metallurgical microscope and scanning electron microscope. The mechanical properties of the composites, such as tensile strength, impact strength, and hardness, were analysed as per the ASTM standards. The analysis indicated that the nanoparticles' reinforcement in aluminium matrix composite significantly improved the mechanical properties compared to the micro-particles owing to their high surface energy. [ABSTRACT FROM AUTHOR]

The mechanical and thermal characterization of Moringa oleifera fiber and red mud (RM) reinforced chitosan (CS) based hybrid composite is the subject of this research. By varying the percentages of M. oleifera fiber and RM in the hand lay‐up process, seven types of composite samples were developed. Tensile, flexural, compression, and impact testing were performed in accordance with ASTM standards. A scanning electron microscope was used to examine the cracked surfaces of the tested specimens. Hybridization with M. oleifera fiber and RM increased the characteristics of CS composites, according to the findings. Increase in the percentage composition of RM resulted in better mechanical characteristics of fiber‐reinforced composites. C6 type composite revealed maximum tensile strength of 65.59 MPa and impact strength of 24.86 kJ/m2. It also had better dynamic mechanical qualities, while C6 composite had the best static and dynamic mechanical properties. Overall it may be concluded that composites can be utilized in light weight structural applications. [ABSTRACT FROM AUTHOR]

Kota stone dust (KSD) and fly ash (FA) are the wastes generated from the construction industry and thermal power plant, respectively. In the present work, a novel hybrid composite is developed to utilize KSD and FA as reinforcing phases in the epoxy matrix. The hand lay‐up method is adopted for the fabrication of 12 sets of samples. Four sets are prepared with single filler KSD and eight samples are prepared with a hybrid combination of KSD and FA. The prepared samples are undergone physical and mechanical tests. To understand the compatibility between filler‐matrix and visualize the dispersion of fillers in epoxy, micrographs are taken using the scanning electron microscope. The density and void contents of the material increases with an increase in filler content. The maximum water absorption measured is 0.96% for the combination of epoxy with 40 wt% KSD and 10 wt% FA. From mechanical testing, maximum tensile strength and flexural strength obtained is 34.4 MPa and 65.4 MPa, respectively, for a combination of epoxy with 20 wt% KSD and 5 wt% FA. Compressive strength and hardness increase with either of the content of the filler and reaches 116.28 MPa and 104 Shore D number, respectively, with 40 wt% KSD and 10 wt% FA. From experimentation, it was found that mechanical properties of the hybrid composites are better as compared to that of single filler composites though physical properties are slightly compromised by hybridization of fillers. [ABSTRACT FROM AUTHOR]

The main objective of this research was to study the influence of an enzymatic treatment process of date palm fibers on their chemical and morphological properties as well as the physical and mechanical characteristics of composites filled with raw and treated fibers. To this end, three extraction approaches were considered (a combination of xylanase and pectinase enzymes, xylanase enzymes followed by a pectinase one and pectinase enzyme followed by xylanase). Chemical and morphological analyses were performed on raw and treated fibers. The tensile test of the manufactured composites was achieved, using extrusion and injection molding process. These composites were also subjected to water absorption tests. The results showed that non-cellulosic components decreased after enzymatic treatments while the cellulose content increased significantly. The scanning electron microscope morphological analyses showed that the extraction with the combination of these enzymes is very effective as a fibrillation phenomenon. Composites with high rigidity were observed in the case of enzymatically treated fibers. These composites reveal a better moisture resistance compared to the untreated fibers. Graphical Abstract [ABSTRACT FROM AUTHOR]

Stir casting method has become prominent for fabrication of metal matrix composites in recent years. This method can be adjusted for casting around space holding particles to obtain cellular composite materials. In this study, a specific method which is a combination of stir casting and space holder techniques were used to produce open-celled A360 aluminium-B4C composite foams with regular sized and distributed pores. Weight ratios of reinforcement particles determined as 0.5, 1, 1.5 and 2%. The influences of particle reinforcement on the microstructure and the mechanical behaviour of composite foams were investigated. Microstructures were analysed with optical microscope (OM), scanning electron microscope (SEM). Compression and hardness tests were carried out to observe the effects of reinforcement on mechanical properties. Compression strength properties and hardness of composites increased with the ceramic reinforcement, however the plastic strength of the composite foams showed worsening trend after a certain reinforcement ratio (0.5 wt.%). Energy absorption properties of the composite foams showed parallel trends with compressive strength properties. [ABSTRACT FROM AUTHOR]

A 3D architecture carbon fiber preform, specifically fine‐woven cloth and punctured felt preform, is used to manufacture a novel advanced Cf/C‐SiC‐ZrC composite. The composite matrix is produced by chemical vapor infiltration (CVI) plus precursor infiltration and pyrolysis (PIP) process and finalized by using a chemical vapor deposition (CVD) of SiC coating to make the final density of the material reach 1.95 g/cm3. The organic precursors of SiC and ZrC have a weight ratio of 4:1 in a xylene solute. The composite mechanical properties, such as tensile, compression, bending, shear, and Z‐direction load bearing, are introduced under analysis to find possible applications for the composite. What is more, scanning electron microscope (SEM) images are employed to illustrate the failure behavior of the ceramic composite. The results showed that the punctured filament tows will be beneficial, not only for the composite to withstand compression force up to 308.6 MPa and shear strength to 18.14 MPa but also for the alternatively stacked weave piles and short fiber layers to support the punctured bundles, as well as to hold the composite structure under mechanical forces from different orientations, which is believed to reinforce the ceramic matrix for some high pressure and severe ablation applications. [ABSTRACT FROM AUTHOR]

This study investigated the effect of carbon black (CB) filler loading on mechanical and rheological properties of natural rubber (NR)/styrene-butadiene rubber (SBR)/nitrile butadiene rubber (NBR) ternary rubber nanocomposites. The nanocomposites were prepared using a melt mixing method. Four different samples with different filler loadings namely S2 (15 phr), S3 (30 phr), S4 (45 phr), and S5 (60 phr) were prepared in this work. The mechanical properties of these samples were investigated such as tensile strength, stress at 100, 200, and 300% elongations, elongation at break %, tear strength, compression set, compression stress, and crosslink density. Results indicate that minimum torque, maximum torque, tensile strength, stress at 100, 200, and 300% elongations, elongation at break %, tear strength, compression set, compression stress, and crosslink density were increased while the scorch time, cure time, cure rate index, elongation at break %, swelling coefficient, and filler–rubber interaction decrease with increasing CB loading. The higher value of tensile strength for these samples was S4 (loading with 45-phr CB). Therefore, had higher stiffness compared to the other content ratio. Additionally, S4 showed 233.58% increment in tensile strength. These results showed that the optimum filler loading can increase the compatibility between CB and NR/SBR/NBR. These results were confirmed by scanning electron microscope micrography. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the mechanical (tensile, hardness, impact, elongation), microstructure and wear behaviours of aluminium alloy reinforced with mussel shell powder (MSP) at different weight percentages (0 wt. % to 15 wt. %) at 3 wt. % interval. The mussel shell powder was characterized by X-ray fluorescence (XRF). The matrix and the composites' morphology were studied using a scanning electron microscope attached with energy dispersive spectroscopy for the distribution of mussel shell powder particles within the matrix. The wear behaviour of the alloy and composites produced at various reinforcements were carried out using a Taber abrasion wear-testing machine. The XRF showed the compositions of MSP to contain calcium oxide (95.70 %), silica (0.83 %) and others. Mechanical properties showed that tensile values increase with increases in MSP, hardness value increases from 6 wt. % to 15 wt. % of MSP. The impact energy decreased from 42.6 J at 3 wt. % to 22.6 J at 15 wt. %; the percentage elongation also decreased from 37.4 % at 3 wt. % to 20.5 % at 15 wt. % MSP, respectively. The bending stress results increase with increases in the percentage of reinforcement. The morphologies revealed that uniform distribution of MSP within the matrix resulted to improvement in mechanical properties. The wear resistance of the composites increases with increase in the applied load and decreases with increases in the weight percentage of MSP and can be used in the production of brake pads and insulators in the automobile industry. [ABSTRACT FROM AUTHOR]

• The optical and mechanical properties of pure zirconia are affected by low temperature degradation. • First and second generation 3Y-TZP subjected to autoclave aging undergoes significant t-m phase transformation. • t-m Phase transformation in ZTA composites is limited after hydrothermal aging. • ZTA's optical and mechanical properties remain stable after aging. To synthesize a zirconia toughened alumina (ZTA) composite with 70% alumina reinforced by 30% zirconia for dental applications and to characterize its microstructure and optical properties for comparison with the isolated counterpart materials and a first-generation 3Y-TZP. Disc-shaped specimens were divided in four groups (n = 70/material): (1) 3YSB-E (first generation 3Y-TZP), (2) Zpex (second generation 3Y-TZP), (3) alumina, and (4) ZTA-Zpex 70/30. After synthesis, ceramic powders were pressed, and green-body samples sintered following a predetermined protocol. Specimens were polished to obtain a mirror surface finish. Apparent density was measured by Archimedes principle. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the crystalline content and microstructure. Reflectance tests were performed to determine the contrast-ratio (CR) and translucency-parameter (TP). Mechanical properties were assessed by biaxial flexural strength (BFS) test. All analyses were conducted before and after artificial aging (20 h, 134 °C, 2.2 bar). Optical parameters were evaluated through repeated-measures analysis of variance and Tukey tests (p < 0.05). BFS data were analyzed using Weibull statistics (95% CI). High density values (95–99%) were found for all ceramic materials and SEM images exhibited a dense microstructure. While XRD patterns revealed the preservation of crystalline content in the ZTA composite, an increase in the monoclinic peak was observed for pure zirconias after aging. Significantly higher CR and lower TP values were observed for the ZTA composite, followed by alumina, 3YSB-E, and Zpex. The highest characteristic stress was recorded for 3YSB-E, followed by intermediate values between ZTA and Zpex, and the lowest for alumina. Aging affected the optical and mechanical properties of both zirconias, while remained stable for ZTA composite and alumina. The synthesis of experimental 70−30% ZTA composite was successful and its relevance for dental applications relies on its higher masking ability, aging resistance, and strength similar to zirconia. [ABSTRACT FROM AUTHOR]

ZnS‐reinforced ZnS/ZnSe composites are prepared by chemical vapor deposition. Scanning electron microscope, transmittance, and bending strength are used to characterize the samples. The schematic diagram of the transmittance model of the double‐layer composite window is used to calculate the theoretical transmittance, and the measured value of the transmittance of ZnS/ZnSe composite material is in good agreement with the calculated value. The effects of interface layer on the optical and mechanical properties of materials are studied in detail. It is found that the interface can affect the transmittance of the composites, but it still maintains a high transmittance, and the influence of interface layer on the transmittance of visible band is more serious than that of infrared band. Moreover, the mechanical properties of the new composite material are significantly improved (35%). [ABSTRACT FROM AUTHOR]

In the present study, the reinforcing effect of aluminum silicon carbide (Al‐SiC) nanoparticles and chemically treated nanocellulose fiber on thermomechanical and corrosion characteristics of polymer nanocomposites have been investigated. The experimental design was selected as per response surface methodology (RSM) to optimize the effect of Al‐SiC (1.59 to 18.41 wt%), nanocellulose fiber concentration (1.59 to 18.41 wt%) and sonication time (39.55 to 140.45 minutes). From the analysis of variance (ANOVA) results, it was found that the Al‐SiC, nanocellulose fiber concentration and sonication time played a significant role in the mechanical properties. In order to simultaneously maximize the flexural strength, the optimal values of nanocellulose fiber, Al‐SiC nanoparticles, and sonication time was found to be 5 wt%, 5 wt%, and 120 minutes, respectively. From the normal distribution plot, it is found that there is a good agreement between experimental results and developed RSM model. Addition of Al‐SiC (5 wt%) and nanocellulose fiber (5 wt%) in epoxy polymer improved the physical, mechanical, thermal and corrosion resistance properties. The scanning electron microscope analysis on Al‐SiC and nanocellulose fiber reinforced epoxy nanocomposites revealed uniform dispersion of nanocellulose fiber and Al‐SiC in the polymer matrix, which caused for the improved mechanical, and corrosion resistance characteristics. [ABSTRACT FROM AUTHOR]

Chemically reduced graphene (C- r GO) nanosheets were first prepared from graphene oxide (GO), and then the polypropylene (PP) composites synergistically reinforced–toughened by styrene–butadiene rubber (SBR), and C- r GO nanosheets were fabricated via melt blending. The mechanical properties of PP can be considerably improved by synergistically filling with C- r GO nanosheets and SBR, especially for the notched Izod impact strength (IS). The results from the X-ray diffraction, polarizing optical micrographs, scanning electron microscope, differential scanning calorimetric, dynamic mechanical analysis, and thermogravimetric analysis measurements reveal that: (1) the β -phase crystal structure of the PP is formed when the C- r GO and SBR are synergistically filled with PP and its formation plays a role for the enhancement of the impact strength for PP/SBR/C- r GO composites; (2) the dispersion of the C- r GO and SBR in the PP/SBR/C- r GO composites is homogeneous, indicating that synergistic incorporating method decreases the aggregation of nanosheets and thus increases the sites for dissipation of shock for impact energy in the PP/SBR/C- r GO composites; and (3) the thermal analysis shows high thermal stability for the PP/SBR/C- r GO composites. [ABSTRACT FROM AUTHOR]

This work deals with the synthesis of biodegradable and UV resistant wood polymer composites (WPCs) via compression moulding technique. As outdoor applications become more widespread, durability becomes an issue. Ultraviolet exposure can lead to photodegradation, which results in a change in appearance and mechanical properties. In this study, we examined the performance of WPCs after UV exposure and microbial attack. The rate of degradation was found to decrease by the addition of a higher percentage of rosin derivatives. The bacterial growth on the samples and morphological features of the bacterial-degraded samples were investigated by UV spectrophotometry and Scanning Electron Microscope (SEM) study, respectively. The UV-degraded samples were also analysed by Fourier Transform Infrared (FTIR) spectroscopy and SEM study. It was observed that with the incorporation of 40 wt-% of divinylacrylicpimaric acid (DAPA) significantly improved the UV stability, mechanical, thermal and other physical properties of the WPCs. [ABSTRACT FROM AUTHOR]

The present research venture focuses on utilization of food and agricultural waste Citrus limetta (musambi) peel by using it as a filler material to develop novel epoxy (EP) composites. Experimental investigation has been performed to analyse the influence of C limetta (musambi) peel particles (CLPP) on mechanical properties (tensile, flexural and impact strength) of the developed composites. Different loadings by weight percentages (0, 5, 10 and 15 wt%) of filler have been used to explain the variation in mechanical properties. Along with effect of different filler percentages, failure characteristics of the prepared samples have also been studied. The results indicate that higher CLPP content in EP matrix has a detrimental effect on mechanical properties of manufactured biocomposites. Thermal characterization was performed to analyse the degradation behaviour and the onset temperature. Morphological analysis of the fractured surfaces was also conducted with the help of a scanning electron microscope. The current experimental investigation has revealed that CLPP can be used as a potential filler for manufacturing biocomposites with applications in general purpose interior fitments in addition to various non-structural components. [ABSTRACT FROM AUTHOR]

In the last decade, natural plant fibers (jute, sisal, coir, banana, hemp, kenaf, flax, etc.) are getting attention from many researchers and academicians to utilize it as an alternate reinforcement of synthetic fiber reinforced polymer composites. These fibers are becoming a great replacement of conventional fibers (such as glass, carbon, and aramid) due to their light weight, low cost, carbon neutrality, fairly good mechanical properties, high specific strength, and biodegradability characteristics. Some chemical treatments are required to enhance the fiber matrix interfacial strength and to minimize the moisture absorption by these fibers which would ultimately improve physico-mechanical properties of these fiber reinforced composites. This paper is a review on mechanical properties of the natural plant fiber reinforced polymer composites and various factors affecting the mechanical performance of it. The tribological behavior of natural fiber reinforced polymer composites and scanning electron microscope analysis are also discussed. Some mathematical models are mentioned which are useful to predict mechanical behavior of the composites. It is found that Halpin–Tsai equation is the most effective equation amongst others in predicting Young's modulus for short-fiber reinforced composites with minimum error. The applications of natural plant fiber reinforced polymer composites in various engineering fields are discussed. [ABSTRACT FROM AUTHOR]

Present investigation elucidates the effect of surface treatment on the mechanical response of carbon fiber (CF)/polyimide (PI) composite loaded with a range of graphene oxide (GO) content. Incorporation of 0.5 wt% GO in CF/PI exhibited 21.1% improvement in flexural strength. The state of interface and its impact on the tensile behavior at various testing temperatures have been discussed. Scanning electron microscope (SEM) analysis of fractured surfaces has been carried out to comprehend various interfacial strengthening and failure micromechanisms. Surface-treated CFs were incorporated into PI matrix to fabricate a high-performance multiscale composite. To improve the stress transfer between PI and CFs, GO was also grown on fibers to produce GO-grown short CFs. The synergic reinforcing effects of combined fillers were analyzed on the fracture surface of composites through SEM. [ABSTRACT FROM AUTHOR]

This study deals with the investigation on mechanical properties of aluminium alloy (AA 6082) composites reinforced with tungsten carbide particles. Stir casting process was employed to fabricate the aluminium composite specimen by varying tungsten carbide in 2, 4, 6, 8 and 10% by weight. The composites were exposed to density, hardness, tensile and impact studies. Scanning electron microscope was used to investigate the mechanism of the fractured tensile and impact test specimen. The density, impact strength and elongation of the composites decreased with increase in addition of tungsten carbide, while the hardness of composites increased with increase in tungsten carbide. The tensile strength of the composites increased initially and then tends to decrease. Fracture of the composites is characterized by dimples, voids, cracks, ridges, pits and particle fracture. Brittle fracture of composites in the form of cracks and particle fracture are due to the strong interfacial bonding between the tungsten carbide and aluminium matrix at high strain rate. High impact strength of composites are due to ductile failure in the form of dimples, while low impact strength are due to brittle and plastic deformation characterized by micro and macro cracks, particle fracture. [ABSTRACT FROM AUTHOR]

The aim of this work is to develop a natural fiber composites that can become a substitute for plywood and medium density fiber boards used in packaging application. In this work, the composite was fabricated with randomly oriented chopped coir and cotton fiber reinforced with unsaturated polyester resin. The different types of composite materials were prepared with different quantity of coir fiber and cotton fiber reinforced with unsaturated polyester by using hand lay-up technique. Mechanical properties such as tensile, flexural and impact strength are evaluated. Scanning Electron Microscope (SEM) was conducted on the fabricated composite to analysis the interfacial properties, internal cracks and internal structure of the fractured surfaces. Based on the results, cotton fiber reinforced with unsaturated polyester has better mechanical properties to be used for packaging applications compared with other combinations of coir/cotton fiber reinforced with unsaturated polyester. [ABSTRACT FROM AUTHOR]

Green/bio-based composites of poly(lactic acid) and lignin were prepared by melt blending in a twin-screw extruder. Thermal and mechanical properties, phase interaction, and morphology of the composites have been investigated. Fourier transform infrared studies elucidated the existence of intermolecular hydrogen bonding between poly(lactic acid) and lignin. Scanning electron microscopy studies revealed an extent of diffused phase boundaries between poly(lactic acid) and lignin which also indicated significant interaction between them. Tensile properties showed significant increase over neat poly(lactic acid) with lignin loading (0–0.28 volume fraction) which further justified using theoretical models. Izod impact strength decreased with lignin content. [ABSTRACT FROM AUTHOR]

This study focuses on the development of epoxy/luffa composites and the investigation of their mechanical and acoustical properties. The fibers underwent an alkalization treatment, and its effects on the mechanical and sound absorption properties of the composites were measured utilizing a universal testing machine and two-microphone transfer function impedance tube methods. The effects of chemical modifications on the fibers were studied using a scanning electron microscope (SEM). The thermal analyses of composites were conducted using thermo-gravimetric analysis (TGA). The composite's functional group was identified and evaluated using Fourier transform infrared spectroscopy (FTIR). The sound absorption coefficient of untreated and treated composites across a range of frequencies was very similar. Untreated composites appeared to perform better than those that were treated. Compared with untreated fiber composites, there was an improvement in the tensile strength of the treated fiber composites. The SEM characterization showed that the alkaline treatment changed the morphology of the fibers, resulting in a decrease in the sound absorption coefficients of the composites. The thermal characterization of composites showed that dehydration and degradation of lignin occurred in a temperature range of 40 to 260 °C, and the maximum percentage of cellulose was found to decompose at 380 °C. [ABSTRACT FROM AUTHOR]

Abstract: In the current work, flexural properties of unidirectional long kenaf fibre reinforced epoxy (KFRE) composites are studied. The kenaf fibres were prepared into two types as untreated and treated (with 6% NaOH). The failure mechanism and damage features of the materials were categorized with the surface observation by scanning electron microscope (SEM). The results revealed that reinforcement of epoxy with treated kenaf fibres increased the flexural strength of the composite by about 36%, while, untreated fibres introduced 20% improvement. This was mainly due to the high improvement of the chemical treatment (NaOH) on the interfacial adhesion of the fibres and the porosity of the composites which prevented the debonding, detachments or pull out of fibres. For untreated KFRE, the fracture mechanisms were debonding, tearing, detachments and pull out of fibres. The developed composite exhibited superior properties compared to the previous composites based on natural and synthetic fibres. [Copyright &y& Elsevier]

Abstract: Thermoplastic starch (TPS)/luffa fiber composites were prepared using compression molding. The luffa fiber contents ranged from 0wt.% to 20wt.%. The tensile strength of the TPS/luffa fiber composite with 10wt.% of luffa fiber had a twofold increase compared to TPS. The temperature values of maximum weight loss of the TPS/luffa fiber composites were higher than for TPS. The water absorption of the TPS/luffa fiber composites decreased significantly when the luffa fiber contents increased. The strength of adhesion between the luffa fiber and the TPS matrix was clearly demonstrated by their compatibility presumably due to their similar chemical structures as shown by scanning electron microscope (SEM) micrographs and Fourier transform infrared (FTIR) spectra. [Copyright &y& Elsevier]

The poplar biochar (PB) was prepared at different pyrolysis temperatures and the hot pressing method was applied to prepare composites with PB based on high-density polyethylene (HDPE). The effects of pyrolysis temperature on the characterizations of PB were analyzed and the PB/HDPE composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), Scanning electron microscope (SEM), and their mechanical properties. The results showed that the specific surface area and pore volume increased, polar functional groups and the polarity of PB decreased with the increase of pyrolysis temperatures. Moreover, the addition of PB had no effect on the microcrystalline structure but the intensity of the peaks of PB/HDPE composites was reduced. FTIR analysis of PB/HDPE composites showed no new functional groups which indicated that PB and HDPE did not react chemically with each other. Besides, the addition of PB did not change the melting temperature of HDPE but it promoted the early crystallization of PB/HDPE composites. The mechanical analysis showed that the flexural strength improved and the impact strength decreased of PB/HDPE composites by the addition of PB. Image 1 • The poplar biochar (PB) prepared at 600 °C has the most significant pore characteristics and least polar functional groups. • PB/high-density polyethylene (HDPE) composites were prepared through the process of hot pressing. • The addition of PB had an important influence on the basic characterization of PB/HDPE composites. • The pores of PB allowed HDPE to flow in creating an interlocking and improving the mechanical properties. [ABSTRACT FROM AUTHOR]

Paper fibers have gained broad attention in natural fiber reinforced composites in recent years. The specific problem in preparing paper fiber reinforced composites is that paper fibers easily become flocculent after pulverization, which increases difficulties during melt-compounding with polymer matrix and results in non-uniform dispersion of paper fibers in the matrix. In this study, old newspaper (ONP) was treated with a low dosage of gaseous methyltrichlorosilane (MTCS) to solve the flocculation. The modified ONP fibers were characterized by Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Thermogravimetric Analysis (TG). Then the modified ONP fibers and high-density polyethylene (HDPE) were extruded and pelletized to prepare ONP/HDPE composites via injection molding. Maleic anhydride-grafted polyethylene (MAPE) was added to enhance the interfacial bonding performance with the ultimate purpose of improving the mechanical strength of the composites. The mechanical properties such as tensile, flexural, and impact strength and the water absorption properties of the composite were tested. The results showed that the formation of hydrogen bonding between ONP fibers was effectively prevented after MTCS treatment due to the reduction of exposed –OH groups at the fiber surface. Excessive dosage of MTCS led to severe fiber degradation and dramatically reduced the aspect ratio of ONP fibers. Composites prepared with ONP fibers modified with 4% (v/w) MTCS showed the best mechanical properties due to reduced polarity between the fibers and the matrix, and the relatively long aspect ratio of treated ONP fibers. The composite with or without MAPE showed satisfactory water resistance properties. MTCS was proven to be a cheap and efficient way to pretreat old newspaper for preparing paper fiber reinforced composites. [ABSTRACT FROM AUTHOR]

A comprehensive and comparative experimental study has been conducted to investigate the effect of thermal-oil ageing on mechanical, thermal and internal structural properties of E-glass fibre/epoxy composite materials. E-glass fibre/epoxy composite specimens were divided into 8 groups according to the certain experimental ageing temperatures. The temperature values were selected as −10, 25, 50, 80, 100, 120 and 140 °C, while the values of the ageing duration were selected as 24, 168, 360, 720 and 1080 h. Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) tests were performed to determine the thermal properties, tensile tests were used to detect the mechanical properties and a Scanning Electron Microscope (SEM) was used to illustrate the changes in the internal structure of the composites. As a result of this work, unexpectedly no alteration was observed in the mechanical properties of the specimens aged at −10 °C; however, ageing at 120 and 140 °C reduced the maximum load carrying capacities (LCCs) of the specimens especially for further ageing exposure times. Furthermore, the thermal stability of the specimens aged at −10 °C increased with the increasing thermal ageing duration while, for the other thermal ageing temperatures, the thermal stability showed a decreasing trend as the thermal ageing exposure time increased. [ABSTRACT FROM AUTHOR]