Investigation on mechanical and tribological behavior of naturally woven coconut sheath‐reinforced polymer composites

The article presents the results of experimental investigation on mechanical and dry sliding wear behavior of unsaturated polyester resin (USP), reinforced with naturally woven coconut sheath and glass fibers. The mechanical properties of coconut sheath (N) and glass fiber (G) reinforced polyester composites were studied, and the tribological behaviors were tested on pin‐on‐disc sliding wear tester. Mass loss was determined as a function of sliding distance for a sliding velocity of 3.5 m/s and an applied normal load of 40 N. The experimental result revealed that the mechanical properties and wear resistance of the composites depend on the wt% reinforcement of coconut sheath/glass fiber and sliding distance. The hybrid reinforcement (GGN) greatly increased the mechanical properties of USP. At lower sliding distance, the N‐reinforced USP had lower wear loss, whereas at higher sliding distance, the hybrid fiber‐reinforced (GGN) USP composite had lower wear loss. Furthermore, the work showed that the higher sliding distance bring about changes in the worn surface features such as interface separation, inclined fracture of fibers, loss of matrix, and the appearance of debris with the two different fibers. The worn surfaces were also examined by scanning electron microscopy. The study showed differing trends with load for the two types of reinforcements. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

An impact behavior analysis of CNT‐based fiber reinforced composites validated by LS‐DYNA: A review

In last 2 decades use of CNT based‐Fiber Reinforced Polymer (FRP) Composite have revolutionized the aerospace, automobile, marine industry as it have showed exceptional mechanical properties like impact resistant, high energy absorbing capacities, damping properties, etc. The goal of this review is to explore the validation of impact behavior in CNT based FRP composite by LS‐DYNA. Impact behavior depends upon various parameters like velocity of impact, shape of impactor and its weight, environmental conditions as temperature dependency, contact time and damage area and many other considerations. Prediction of impact damage is done using methods like absorbed energy, gross damage produced and/or micro energy dissipation. This article also presents study of variation in impact behavior by varying CNT percentage in composite laminates. POLYM. COMPOS., 38:175–184, 2017. © 2015 Society of Plastics Engineers     

Viscoelastic behavior of epoxy/carbon fiber/Zno nano‐rods hybrid composites

The insufficient viscoelastic resistance of fiber reinforced plastics can be retrofitted by the addition of more rigid nano fillers to the polymer matrix. In this study, carbon fibers plies were grafted with zinc oxide (ZnO) nano‐rods and the hybridized reinforcement was utilized in laminated composites. Flexural creep tests were carried out using dynamic mechanical analysis (DMA) and the time/temperature superposition principle was employed for accelerated testing. To verify the applicability of TTPS, prolonged stress relaxation tests were also carried out in flexural mode. Data from the DMA flexural creep tests revealed that the whiskerization of carbon fibers with ZnO nano rods reduced the creep compliance by 23% at elevated temperatures and prolonged durations. Also, the relaxation data confirmed the applicability of TTPS to these hybrid composites. The stress relaxation modulus improved by 65% in comparison to composites based on neat carbon fibers. POLYM. COMPOS., 36:1967–1972, 2015. © 2014 Society of Plastics Engineer     

Preparation of nano‐reinforced thermal conductive natural rubber composites

Natural rubber (NR) composites highly filled with nano‐α‐alumina (nano‐α‐Al₂O₃) modified in situ by the silane coupling agent bis‐(3‐triethoxysilylpropyl)‐tetrasulfide (Si69) were prepared. The effects of various modification conditions and filler loading on the properties of the nano‐α‐Al₂O₃/NR composites were investigated. The results indicated that the preparation conditions for optimum mechanical (both static and dynamic) properties and thermal conductivity were as follows: 100 phr of nano‐α‐Al₂O₃, 6 phr of Si69, heat‐treatment time of 5 min at 150°C. Furthermore, two other types of fillers were also investigated as thermally conductive reinforcing fillers for the NR systems: (1) hybrid fillers composed of 100 phr of nano‐α‐Al₂O₃ and various amounts of the carbon black (CB) N330 and (2) nano‐γ‐Al₂O₃, the particles of which are smaller than those of nano‐α‐Al₂O₃. The hybrid fillers had better mechanical properties and dynamic performance with higher thermal conductivity, which means that it can be expected to endow the rubber products serving under dynamic conditions with much longer service life. The smaller sized nano‐γ‐Al₂O₃ particles performed better than the larger‐sized nano‐α‐Al₂O₃ particles in reinforcing NR. However, the composites filled with nano‐γ‐Al₂O₃ had lower thermal conductivity than those filled with nano‐α‐Al₂O₃ and badly deteriorated dynamic properties at loadings higher than 50 phr, both indicating that nano‐γ‐Al₂O₃ is not a good candidate for novel thermally conductive reinforcing filler. POLYM. COMPOS., 37:771–781, 2016. © 2014 Society of Plastics Engineers     

Fabrication and mechanical properties of glass fiber‐reinforced wood plastic hybrid composites

To fully utilize the resource in the municipal solid waste (MSW) and improve the strength and toughness of wood plastic composites, glass fiber (GF)‐reinforced wood plastic hybrid composites (GWPCs) were prepared through compounding of recycled high‐density polyethylene (HDPE) from MSW, waste wood fibers, and chopped GF. Mechanical tests of GWPCs specimens with varying amounts of GF content were carried out and the impact fractured surface of GWPCs was observed through scanning electron microscope (SEM). The tensile strength of GWPCs and the efficiency coefficient values were predicted by Kelly‐Tyson method. The results indicated that the tensile strength and impact strength of GWPCs could be improved simultaneously by adding type L chopped GF (L‐GF), and would be dropped down when type S chopped GF (S‐GF) was included. The tensile strength of GWPCs was well accordant with the experimental result. The efficiency coefficient values of S‐GF and L‐GF are ?0.19 and 0.63, respectively. Inspection of SEM micrographs indicated that L‐GF had achieved full adhesion with the plastic matrix through addition of maleic anhydride‐g‐polyethylene. The main fracture modes of GWPCs included pullout of GF, broken of matrix, and interfacial debonding. Because of the synergistic effects between hybrid components in GF/wood fiber/HDPE hybrid system, a special 3D network microstructure was formed, which was the main contribution to the significant improvement in the tensile strength and impact strength of L‐GF‐reinforced hybrid composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical behavior of hybrid fiber‐reinforced composites manufactured by pulse infusion

Epoxy/carbon fiber composites have been manufactured by Pulse Infusion. Pulse Infusion allows to control the pressure of the vacuum bag on the dry fiber reinforcement by using a proper designed pressure distributor that induces a pulsed transverse action and promotes the through thickness resin flow. The adopted one‐component commercial epoxy resin has been preliminary modified by adding 0.05% (w/w) of multiwalled carbon nanotubes, in order to take advantage of carbon nanotubes at low concentration. Both neat and hybrid realized composite panels have been mechanically characterized by performing experimental tests to evaluate tensile, interlaminar, and fracture properties in order to investigate the effect of Pulse Infusion and carbon nanotubes on the mechanical and fracture behavior of composites. Results demonstrated an improvement of 36.2% for the interlaminar shear strength, of 35% for the fracture energy at the crack initiation and of 14% for the fracture toughness in mode II. POLYM. COMPOS., 38:2254–2260, 2017. © 2015 Society of Plastics Engineers     

Erosive wear behavior and dynamic mechanical analysis of textile material reinforced polymer composites

The present analysis intends to look into the needlepunched nonwoven textile material reinforced polymer composites. The solid particle erosion wear behavior of needlepunched nonwoven fabric mat reinforced epoxy composites were assessed using silica sand particles with the size of 250, 350, and 450 μm. Taguchi analysis was also carried out on the basis of design of experiments (DoE) approach to establish the interdependence of operating parameters. Mechanical and physical properties of composites were also evaluated experimentally, and the storage modulus (E′), loss modulus (E″) and damping factor (tan δ) characteristics were analyzed with the help of dynamic mechanical analyzer (DMA) in the temperature range of 20–200°C. Surface morphology of the eroded surfaces of composites were also analyze by scanning electron microscopic (SEM) to discuss the feasible erosion mechanism on composite surfaces. The result reveals that fiber content and impact velocity has an invulnerable impact on the erosion rate of needlepunched nonwoven fabric mat‐epoxy composites. The mechanical and physical properties are meliorating with incorporation of fabric mat weight percentage in composites, and the measured damping factor (tan δ) peaks of T _g for needlepunched nonwoven fabric mat epoxy composites ranged from 100 to 110°C. POLYM. COMPOS., 38:2201–2211, 2017. © 2015 Society of Plastics Engineers     

Fabrication and properties of nano‐ZnO/glass‐fiber‐reinforced polypropylene composites

Polypropylene (PP) is widely used in many fields, such as automobiles, medical devices, office equipment, pipe, and architecture. However, its high brittle transformation temperature, low mechanical strength, dyeing properties, antistatic properties, and poor impact resistance, considerably limit its further applications. Nano‐ZnO treated by KH550 coupling agent and glass fibers (GFs) were introduced in order to improve the mechanical performance and flowability of PP in this research. The crystallization behavior and microstructure of nano‐ZnO/GFs/PP hybrid composites were analyzed by differential scanning calorimetry, transmission electron microscopy, and scanning electron microscopy. The effect of crystallization behavior on the mechanical properties of the nanocomposites was investigated and analyzed. The results indicated that nano‐ZnO surface‐coupled by KH550 could be uniformly dispersed in the PP matrix. The incorporation of nano‐ZnO and GFs resulted in increases of the crystallization temperature and crystallization rate of PP and a decrease of the crystallization degree. The introduction of nano‐ZnO and GFs also enhanced the tensile strength and impact toughness of the hybrid composites and improved their fluidity. Composites containing 2% of nano‐ZnO and 40% of GFs possessed the optimum mechanical properties. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers     

Mechanical and shape‐memory behavior of shape‐memory polymer composites with hybrid fillers

Shape‐memory polymer (SMP) materials have several drawbacks such as low strength, low stiffness and natural insulating tendencies, which seriously limit their development and applications. Much effort has been made to improve their mechanical properties by adding particle or fiber fillers to reinforce the polymer matrix. However, this often leads to the mechanical properties being enhanced slightly, but the shape‐memory effect of reinforced SMP composites being drastically reduced. The experimental results reported here suggested that the mechanical resistive loading and thermal conductivity of a composite (with hybrid filler content of 7.0 wt%) were improved by 160 and 200%, respectively, in comparison with those of pure bulk SMP. Also, the glass transition temperature of the composite was enhanced to 57.28 °C from the 46.38 °C of a composite filled with 5.5 wt% hybrid filler, as determined from differential scanning calorimetry measurements. Finally, the temperature distribution and recovery behavior of specimens were recorded with infrared video in a recovery test, where a 28 V direct current circuit was applied. The effectiveness of carbon black and short carbon fibers being incorporated into a SMP with shape recovery activated by electricity has been demonstrated. These hybrid fillers were explored to improve the mechanical and conductive properties of bulk SMP. Copyright © 2010 Society of Chemical Industry     

Thermal conductive composites based on silver‐plating graphite nanosheet and epoxy polymer

Silver plating graphite nanosheet (Ag‐NanoG) prepared by electroless plating method with expanded graphite as starting material is an effective approach to increase thermal conductivity of the filler. Herein, a novel thermal conductive composite was prepared by using Ag‐NanoG as thermal conductive filler and epoxy resin as the polymer matrix. The microstructures of NanoG and Ag‐NanoG were characterized by means of scanning electron microscopy, X‐ray powder diffraction and then the thermal conductivity, impact strength, and thermal stability of the composite were investigated. The results showed that the Ag‐NanoG was successfully obtained and it can be homogeneously dispersed in the epoxy resin. The thermal conductivity of composite increased from 0.328 to 1.847 W/m K with 4 wt% Ag‐NanoG filler content. Moreover, the composite exhibited excellent thermal stability and mechanical property. POLYM. COMPOS., 38:2822–2828, 2017. © 2015 Society of Plastics Engineers     

Crystallinity morphology and dynamic mechanical characteristics of PBT polymer and glass fiber‐reinforced composites

The crystalline morphologies of PBT (poly butylene terephthalate) and its glass fiber reinforced composite systems were investigated in a thin‐film form by polarized optical microscopy and wide‐angle X‐ray diffraction. Three different types of PBT morphology were identified in the Maltese cross pattern: 45° cross pattern (usual type) by solvent crystallization, 90° cross pattern (unusual type) by melt crystallization at low crystallization temperature, and mixed type by melt crystallization at crystallization temperatures higher than 160°C. The glass fibers increased the number density of spherulites and decreased the size of crystallites acting as crystallization nucleation sites without exhibiting trans‐crystallinity at the vicinity of the glass fiber surfaces. Finally, the storage modulus was analyzed by using a dual‐phase continuity model describing the modulus by the power‐law sum of the amorphous‐ and crystalline‐phase moduli. The crystalline‐phase modulus was extracted out from the PBT polymer and composite systems containing different amount of crystallinity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 478–488, 2002     

High‐temperature mechanical behavior of ZrB2‐based composites with micrometer‐ and nano‐sized SiC particles

Using micrometer‐ and nano‐sized SiC particles as reinforcement phase, two ZrB₂‐SiC composites with high strength up to 1600°C were prepared using high‐energy ball milling, followed by hot pressing. The composite microstructure comprised finer equiaxed ZrB₂ and SiC grains and intergranular amorphous phase. The temperature dependency of flexure strength related to the initial particle size of SiC. In the case of micrometer‐sized SiC, the high‐temperature strength was improved up to 1500°C compared to room‐temperature strength, but the strength degraded at 1600°C, with strength values of 600‐770 MPa. In the case of nano‐sized SiC, the enhanced high‐temperature strength was observed up to 1600°C, with strength values of 680‐840 MPa.     

Fabrication of functionally graded nano‐TiO2‐reinforced epoxy matrix composites

Functionally graded nano‐TiO₂ epoxy matrix composites were successfully fabricated using a centrifugal method. In the preparation of the composite, the aggregation of nano‐TiO₂ occurred during curing, which had a negative effect on the composite performance. To solve this problem, we introduced a silane coupling agent to modify the surface of the nano‐TiO₂, thereby improving the performance and mechanical properties simultaneously. The modified nano‐TiO₂ (s‐TiO₂) had better dispersion in the epoxy resin, making it possible to produce depth gradients of the mechanical properties of functionally graded materials (FGMs). The s‐TiO₂ was characterized with respect to functional groups, morphology, and chemical elements using transmission electron microscopy, X‐ray photoelectron spectroscopy, and Fourier‐transform infrared spectroscopy. The results show that a silane layer was successfully coated on the surface. Also, the gradients of the mechanical and permittivity properties of the FGM indicated that by modifying the surface of the nano‐filler, it is possible to fabricate nano‐filler‐reinforced epoxy matrix FGMs using a centrifugal method. POLYM. COMPOS., 35:557–563, 2014. © 2013 Society of Plastics Engineers     

Mechanical and tribological behavior of alumina and alumina‐CNT reinforced hybrid unsaturated polyester composites

Micro‐ and nano‐scale wear behavior of alumina vis‐á‐vis alumina‐carbon nanotube‐reinforced hybrid composites has been studied. In comparison to the pristine alumina, the alumina‐carbon nanotube hybrid reinforcement resulted in reduced scratch depth and lower frictional coefficient. Addition of carbon nanotube has effectively modified the pristine alumina into a superior wear resistant filler. POLYM. COMPOS., 37:1577–1586, 2016. © 2014 Society of Plastics Engineers     

Mechanical properties study of micro‐ and nano‐hydroxyapatite reinforced ultrahigh molecular weight polyethylene composites

This is a comparative study between ultrahigh molecular weight polyethylene (UHMWPE) reinforced with micro‐ and nano‐hydroxyapatite (HA) under different filler content. The micro‐ and nano‐HA/UHMWPE composites were prepared by hot‐pressing method, and then compression strength, ball indentation hardness, creep resistance, friction, and wear properties were investigated. To explore mechanisms of these properties, differential scanning calorimetry, infrared spectrum, wettability, and scanning electron microscopy with energy dispersive spectrometry analysis were carried out on the samples. The results demonstrated that UHMWPE reinforced with micro‐ and nano‐HA would improve the ball indentation hardness, compression strength, creep resistance, wettability, and wear behavior. The mechanical properties for both micro‐ and nano‐HA/UHMWPE composites were comparable with pure UHMWPE. The mechanical properties of nano‐HA/UHMWPE composites are better compared with micro‐HA/UHMWPE composites and pure UHMWPE. The optimum filler quantity of micro‐ and nano‐HA/UHMWPE composites is found to be at 15 wt % and 10 wt %, separately. The micro‐ and nano‐HA/UHMWPE composites exhibit a low friction coefficient and good wear resistance at this content. The worn surface of HA/UHMWPE composites shows the wear mechanisms changed from furrow and scratch to surface rupture and delamination when the weight percent of micro‐ and nano‐HA exceed 15 wt % and 10 wt %. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42869.     

Physical and mechanical behavior of unidirectional banana/jute fiber reinforced epoxy based hybrid composites

During the last few years, natural fiber composites are replacing synthetic fiber composites for practical applications due to their advantages like low density, light weight, low cost, biodegradability and high specific mechanical properties. In this connection, the present investigation deals with the fabrication and mechanical properties of unidirectional banana/jute hybrid fiber reinforced composites and compares with the single natural fiber reinforced composites. The physical and mechanical properties of the natural fiber composites were obtained by testing the composite for density, tensile, flexural, inter‐laminar shear, impact, and hardness properties. The composite specimens with different weight percentages of fibers were fabricated by using hand lay‐up technique and testing were carried out as per ASTM standards. Incorporation of both the fibers into epoxy matrix resulted in an increase in mechanical properties up to 30 wt% of fiber loading. It is found that the hybrid composite give encouraging results when compared with the individual fiber composites. The morphologies of the composites are also studied by scanning electron microscope. POLYM. COMPOS., 38:1396–1403, 2017. © 2015 Society of Plastics Engineers     

Dynamical mechanical analysis of sisal/oil palm hybrid fiber‐reinforced natural rubber composites

Natural rubber was reinforced with sisal and oil palm fibers and was subjected to dynamic mechanical analysis to determine the dynamic properties as a function of temperature. The storage modulus E′ was found to increase with weight fraction of fiber. This is due to the increased stiffness imparted by the natural fibers. Loss modulus increased with loading while the damping property was found to decrease. The fibers were subjected to alkali treatment of different concentrations namely 0.5, 1, 2, and 4% and the dynamic properties were studied. In the case of composites containing chemically modified fibers, storage modulus and loss modulus were found to increase. Scanning electron micrographs of tensile fracture surfaces of treated and untreated composites demonstrated better fiber–matrix bonding in the case of the former. POLYM. COMPOS., 27: 671–680, 2006. © 2006 Society of Plastics Engineers     

Friction properties of sisal fiber/nano‐silica reinforced phenol formaldehyde composites

The friction‐resistant sisal fiber/nano‐silica phenol formaldehyde resin composites were prepared through compression molding. To enhance the bonding between the sisal fiber (SF) and polymer matrix, SF were treated with different surface modifiers. The worn surfaces of composites were observed by scanning electron microscope (SEM). The result shows that the matrix of nano‐silica phenol formaldehyde resin can relieve the heat fade of the friction materials. Meanwhile sisal fibers treated with borax have effectively improved the friction and wear properties of the composites when the fiber content was 15%. POLYM. COMPOS. 36:433–438, 2015. © 2014 Society of Plastics Engineers     

Investigation of mechanical properties of alumina nanoparticle‐loaded hybrid glass/carbon‐fiber‐reinforced epoxy composites

This research work investigates the tensile strength and elastic modulus of the alumina nanoparticles, glass fiber, and carbon fiber reinforced epoxy composites. The first type composites were made by adding 1–5 wt % (in the interval of 1%) of alumina to the epoxy matrix, whereas the second and third categories of composites were made by adding 1–5 wt % short glass, carbon fibers to the matrix. A fourth type of composite has also been synthesized by incorporating both alumina particles (2 wt %) and fibers to the epoxy. Results showed that the longitudinal modulus has significantly improved because of the filler additions. Both tensile strength and modulus are further better for hybrid composites consisting both alumina particles and glass fibers or carbon fibers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39749.