Kudzu fiber‐reinforced polypropylene composite

Kudzu fiber‐reinforced polypropylene composites were prepared, and their mechanical and thermal properties were determined. To enhance the adhesion between the kudzu fiber and the polypropylene matrix, maleic anhydride‐grafted polypropylene (MAPP) was used as a compatibilizer. A continuous improvement in both tensile modulus and tensile strength was observed up to a MAPP concentration of 35 wt %. Increases of 24 and 54% were obtained for tensile modulus and tensile strength, respectively. Scanning electron microscopy (SEM) showed improved dispersion and adhesion with MAPP. Fourier transform infrared (FTIR) spectroscopy showed an increase in hydrogen bonding with an increase in MAPP content. Differential scanning calorimetry (DSC) analysis indicated little change in the melting temperature of the composites with changes in MAPP content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1961–1969, 2002     

Joining of fiber‐reinforced polymer tubes for high‐pressure applications

Fiber‐reinforced polymer composites offer superior performance particularly in harsh environments; hence, they are recognized as an attractive material, especially for the transportation of pressurized fluids. However, an extensive use of these composites has been hampered, in part due to unsatisfactory solutions for the joining of subcomponents, and insufficient knowledge on the associated damage behavior. A favorable connection design for a piping system can be an adhesively bonded joint. In this study, a unique adhesive injection technique is presented that joins composite pipe sections using filament‐wound overlap sleeve couplers. The purpose of the present study was to characterize the performance and associated damage behavior of a prototype‐size pipe structure joined by the above procedure. Internal pressure and axial traction were applied to specimens at various biaxial ratios. In addition to the experimental investigation, the joint geometry was also modeled numerically employing the finite element technique. This yielded a better understanding of the damage behavior and enabled a parametric study that provided recommendations for an improved joint design. POLYM. COMPOS., 27:99–109, 2006. © 2005 Society of Plastics Engineers     

Investigating the acoustical properties of carbon fiber‐, glass fiber‐, and hemp fiber‐reinforced polyester composites

Wood is one of the main materials used for making musical instruments due to its outstanding acoustical properties. Despite such unique properties, its inferior mechanical properties, moisture sensitivity, and time‐ and cost‐consuming procedure for making instruments in comparison with other materials (e.g., composites) are always considered as its disadvantages in making musical instruments. In this study, the acoustic parameters of three different polyester composites separately reinforced by carbon fiber, glass fiber, and hemp fiber are investigated and are also compared with those obtained for three different types of wood specimens called poplar, walnut, and beech wood, which have been extensively used in making Iranian traditional musical instruments. The acoustical properties such as acoustic coefficient, sound quality factor, and acoustic conversion factor were examined using some non‐destructive tests based on longitudinal and flexural free vibration and also forced vibration methods. Furthermore, the water absorption of these polymeric composites was compared with that of the wood samples. The results reveal that the glass fiber‐reinforced composites could be used as a suitable alternative for some types of wood in musical applications while the carbon fiber‐reinforced composites are high performance materials to be substituted with wood in making musical instruments showing exceptional acoustical properties. POLYM. COMPOS., 35:2103–2111, 2014. © 2014 Society of Plastics Engineers     

Glass fiber‐reinforced composite based on benzoxazine resin

In this study, we aimed to prepare and characterize glass fiber‐reinforced composites (GFRP) based on benzoxazine resins. Therefore, the molten resin from benzoxazine and bisoxazoline with the latent curing agent was used as the matrix resin, and the properties of GFRP based on the molten resins were investigated. The properties of GFRP were estimated by mechanical properties, heat resistance, and flame resistance. As a result, it was found that GFRP based on the molten resins from benzoxazine and bisoxazoline with the latent curing agent showed good heat resistance, flame resistance, and mechanical properties compared with those of the conventional GFRP. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of aluminum alloys on protection performance of metal matrix composite armor reinforced with ceramic particles under ballistic impact

In this research, the ballistic performance of three series of aluminum alloys in the ceramic-reinforced metal matrix composite plates is investigated for protecting against 7.62 × 39 mm bullet. Twenty seven numerical models of the target combinations are provided by ABAQUS FE code to determine the best armor characteristics and confirmed by three experimental ballistic tests. The parameters which considered in this study are aluminum alloys: AA6061, AA7075 and AA5083 as the matrix, alumina ball weight percentages include 15%, 30% and 45% as reinforcements and the target thickness 20, 25 and 30 mm and the effects of these parameters on the ballistic behavior of the composite armor like depth of penetration, residual velocity, kinetic energy and erosion of the projectile are investigated. The results show that AA6061 is the weakest aluminum alloy for ballistic applications and AA5083 is the best choice to use as the aluminum matrix. Also, it's found that the optimum design of aluminum matrix composite armor against 7.62 × 39 mm projectile is AA5083 with 25 mm thickness and 30% alumina.     

Preparation and mechanical properties of high‐performance short ramie fiber‐reinforced polypropylene composites

Short ramie fiber (RF) was used to reinforce the polypropylene (PP). The composites were prepared in a twin‐screw extruder followed by injection molding. The experimental results showed that both the strength and the modulus of the composites increase considerably with increasing RF content. The tensile strength and flexural strength are as high as 67 and 80 MPa by the incorporation of ramie up to 30 wt %. To the best of our knowledge, this is one of the best results for short natural fiber‐reinforced PP composites. However, the preparation method in this study is more simple and economic. This short RF‐reinforced PP composites extend the application field for short‐nature fiber‐reinforced PP composites. Morphological analysis revealed that it is the high aspect ratio of the fiber and good interfacial compatibility that result in the high performance of the composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Flexural behavior of methyl methacrylate modified unsaturated polyester polymer concrete beams reinforced with glass‐fiber‐reinforced polymer sheets

This study represents the behavior of flexural test of methyl methacrylate modified unsaturated polyester polymer concrete beam reinforced with glass‐fiber‐reinforced polymer (GFRP) sheets. The failure mode, load–deflection, ductility index, and separation load predictions according to the GFRP reinforcement thickness were tested and analyzed. The failure mode was found to occur at the bonded surface of the specimen with 10 layers of GFRP reinforcement. For the load–deflection curve, as the reinforcement thickness of the GFRP sheet increased, the crack load and ultimate load greatly increased, and the ductility index was found to be the highest for the beam with the thickness of the GFRP sheet at 10 layers (6 mm) or 13 layers (7.3 mm). The calculated results of separation load were found to match only the experimental results of the specimens where debonding occurred. The reinforcement effect was found to be most excellent in the polymer concrete with 10 layers of GFRP sheet reinforcement. The appropriate reinforcement ratio for the GFRP concrete beam suggested by this study was a fiber‐reinforced‐plastic cross‐sectional ratio of 0.007–0.008 for a polymer concrete cross‐sectional ratio of 1 (width) : 1.5 (depth). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Ageing studies of pineapple leaf fiber–reinforced polyester composites

This experimental study evaluated the water absorption characteristics of pineapple leaf fiber (PALF)–polyester composites of different fiber content. The degree of water absorption was found to increase with fiber loading. The mechanism of diffusion was analyzed and the effect of fiber loading on the sorption kinetics was studied. The diffusion coefficient was calculated and found to increase with fiber content. Studies were also made to correlate water absorption with the cross‐sectional areas of the specimens. The effects of ageing on the tensile properties and dimensional stability of PALF polyester composites were studied under two different ageing conditions. Ageing studies showed a decrease in tensile strength of the composites. The composite specimens subjected to thermal ageing showed only a slight deterioration in strength. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 503–510, 2004     

Cellulose fiber‐reinforced polylactic acid

Polymer composites from polylactic acid (PLA) and two types of cellulose fibers obtained either by acid hydrolysis of microcrystalline cellulose (HMCC) or by mechanical disintegration of regenerated wood fibers (MF) were prepared and characterized. To enhance the compatibility of the cellulose fibers with PLA matrix, a surface treatment based on 3‐aminopropyltriethoxysilane (APS) was performed. The Fourier Transform Infrared (FTIR) spectroscopy was used to determine the chemical groups involved in the surface modification reaction. The silanization treatment resulted in different modifications on both types of cellulose fibers because of their different structural and morphological characteristics. The composites were prepared by incorporating 2.5% of the treated or untreated HMCC and MF into a PLA matrix using a melt‐compounding technique. An improved adhesion between the two phases of the composite materials was observed by scanning electron microscopy thanks to treatment. The dynamic mechanical thermal analyses showed that both untreated and silane treated fibers led to an improvement of the storage modulus of PLA in the glassy state. A higher enhancement of the storage modulus in the case of PLA/HMCC composites than the composites containing MF was obtained as a result of the high aspect ratio of these fibers which allows better matrix‐to‐filler stress transfer. Furthermore, the storage modulus of PLA composites was enhanced by silanization even at higher temperatures especially after thermal treatment. The cellulose fibers addition in PLA matrix modified significantly the relaxation phenomenon as observed in tan δ curves, emphasizing strongly modified molecular mobility of PLA macromolecules and crystallization changes. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers.     

Sulphur‐vulcanized polybutadiene as a matrix in glass fiber‐reinforced composite materials

The basic material used in this work was a low‐molecular‐weight polybutadiene with isocyanate endgroups in the main chain. The isocyanate groups were used for crosslinking of the oligomeric polybutadiene with glycerol as a three‐functional crosslinker. The prepared polybutadiene‐based polyurethane gel was subsequently vulcanized with sulphur. The effect of sulphur content on mechanical and electrical properties of resulting materials was investigated with the aim to find an optimum matrix composition for the preparation of composite materials. Several types of glass fiber fabric reinforcement differing in fabric weight and fabric ply thickness were tested. Mechanical properties of composites based on the optimum matrix composition and different types of glass fibers were measured and compared. Being vulcanized with sulphur, the polybutadiene was found to possess improved mechanical properties and retain an excellent electroinsulating character. Moreover, the sulphur‐vulcanized polybutadiene was proved good as a matrix for the preparation of glass fiber‐reinforced composite materials having enhanced tensile and flexural properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Kenaf fiber‐reinforced copolyester biocomposites

In this study the morphology and properties of a biodegradable aliphatic–aromatic copolyester mixed with kenaf fiber were investigated. Untreated kenaf fiber, as well as kenaf fiber treated with NaOH, and with NaOH followed by silane coupling agent treatment at various concentrations, were used as fillers in the composites. The biocomposites were prepared by melt‐mixing and a 10 wt% fiber loading was used for all the composites. The properties of the biocomposites were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), tensile properties, environmental scanning electron microscopy (ESEM), and biodegradability. The extent of silane initiated grafting was followed by gel content determination. The presence of fiber and fiber treatment influenced the determined properties in a variety of ways, but the best balance of properties were found for the copolyester mixed with alkali‐treated fiber. This composite showed improved thermal, thermomechanical, and mechanical properties. The introduction of alkali treatment caused increased surface roughness in the fiber, which resulted in mechanical interlocking between the filler and the matrix, while silane treatment slightly reduced the properties. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Preparation and properties of an oxide fiber‐reinforced silica matrix composite

Oxide (Nextel? 440) fiber‐reinforced silica composites, with the density and porosity of 1.97 g/cm³ and 21.8%, were prepared through sol‐gel. Their average flexure strength, elastic modulus, shear strength, and fracture toughness at room temperature were 119.7 MPa, 25.6 GPa, 10.8 MPa, and 4.0 MPa·m^1/2, respectively. The composites showed typical toughened fracture behavior, and distinct pullout fibers were observed at the fracture surface. Their mechanical properties were performant up to 1000°C, with the maximum flexural strength of 132.2 MPa at 900°C. Moreover, the composites showed good thermal stability, even after thermal aging and thermal shock at elevated temperatures.     

Hemp‐fiber‐reinforced unsaturated polyester composites: Optimization of processing and improvement of interfacial adhesion

The processing variables for making hemp‐fiber‐reinforced unsaturated polyester (UPE) composites were optimized through orthogonal experiments. It was found that the usage of initiator, methyl ethyl ketone peroxide, had the most significant effect on the tensile strength of the composites. The treatment of hemp fibers with a combination of 1,6‐diisocyanatohexane (DIH) and 2‐hydroxyethyl acrylate (HEA) significantly increased tensile strength, flexural modulus of rupture, and flexural modulus of elasticity, and water resistance of the resulting hemp‐UPE composites. FTIR spectra revealed that DIH and HEA were covalently bonded to hemp fibers. Scanning electron microscopy graphs of the fractured hemp‐UPE composites demonstrated that treatment of hemp fibers with a combination of DIH and HEA greatly improved the interfacial adhesion between hemp fibers and UPE. The mechanism of improving the interfacial adhesion is proposed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Barrier properties for short‐fiber‐reinforced epoxy foams

The barrier properties of short‐fiber‐reinforced epoxy foam are characterized and compared with unreinforced epoxy foam in terms of moisture absorption, flammability properties, and impact properties. Compression and shear properties are also included to place in perspective the mechanical behavior of these materials. Compared with conventional epoxy foam, foam reinforced with aramid fibers exhibits higher moisture absorption and lower diffusion, while glass‐fiber‐reinforced foam is significantly stiffer and stronger. In addition, the polymeric foam composites studied present superior fire‐resistance compared with conventional epoxy foam systems. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3266–3272, 2006     

Evaluation of tribological performance of surface‐treated carbon fiber‐reinforced thermoplastic polyimide composite

The effect of surface treatment [rare earth solution (RES) and air oxidation] of carbon fibers (CFs) on the mechanical and tribological properties of carbon fiber‐reinforced polyimide (CF/PI) composites was comparatively investigated. Experimental results revealed that surface treatment can effectively improve the interfacial adhesion between carbon fiber and PI matrix. Thus, the flexural strength and wear resistance were significantly improved. The RES surface treatment is superior to air oxidation treatment in promoting interfacial adhesion between carbon fiber and PI matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

The scratch behavior of accelerated aged carbon fiber‐reinforced epoxy matrix composite

This paper deals with the effect of accelerated aging on the scratch behavior of carbon/epoxy composites. Carbon/epoxy composite is one the most important type used in aircraft structural parts and exposed to drastic service conditions under various temperatures resulted with scratch damage. Four different type of accelerated aging procedure applied and scratch behavior of carbon/epoxy composites were evaluated using coefficient of friction and penetration depth. Scratch damage morphologies of both original and accelerated aged samples were determined by optical and scanning electron microscope. POLYM. COMPOS., 37:3527–3534, 2016. © 2015 Society of Plastics Engineers     

Vibration joining of fiber‐reinforced thermosets

Adhesive bonding is known to be particularly suitable for thermoset composites with continuous fiber reinforcement as it does not interrupt the fibers because of drilled holes. The frequently used two‐part adhesives often require long curing times for the chemical reaction. At the Institute of Polymer Technology (LKT), a vibration‐assisted hot melt bonding technique (vibration joining) was developed, which offers short cycle times and represents a modification of hot melt bonding, using the machine technology from vibration welding. It is suitable to join thermoplastics with thermoset materials or thermosets using a thermoplastic interlayer, by taking advantage of short cycle time and good lap shear strength, compared to bonding with reactive adhesives. Polym Compos 2009 POLYM. COMPOS., 31:1205–1212, 2010. © 2009 Society of Plastics Engineers     

A metal/UHMWPE/SiC multi-layered composite armor against ballistic impact of flat-nosed projectile

A novel multi-layered composite armor system is proposed for ballistic protection in the present study. The composite armor is composed of a ductile metal front, followed by a ceramic/UHMWPE laminate composite as the intermediate layer, and a ductile metal back layer. The ballistic performance of the composite armor against flat-nosed projectile was investigated experimentally and numerically. Experimental results show that the proposed composite armor exhibited several failure modes, including ductile hole enlargement of metallic face sheets, fragmentations and cracks of the ceramic layer, delamination, fiber fracture and bulge deformation of UHMWPE laminates. Three-dimensional numerical model was established to analyze the evolution of the whole ballistic response, and to discuss the effect of the ceramic layer placement and the mass allocation between the ceramic layer and UHMWPE laminate layer on the ballistic performance. Simulation results reveal the evident reduction in residual velocity that results from the optimal placement of the ceramic layer. Good balance among the contributions of the target components can be achieved to maximize the total energy absorption of composite armor by optimizing the ceramic placement strategy. The projectile residual velocity and the total energy absorption are insensitive to the mass ratio of ceramic layer to UHMWPE laminate layer within a certain range. Under the condition of a higher mass ratio, the specific energy absorption of UHMWPE layer can be significantly improved due to the full development of its bulging deformation. Consequently, it would benefit the energy absorption capability of the composite armor.     

Investigation of unsaturated polyester composites reinforced by aspen high‐yield pulp fibers

Aspen chemithermomechanical pulp fiber‐reinforced unsaturated polyester (UPE) composites were fabricated using premade paper handsheets. The effects of handsheet wet‐pressing pressure, grammage, and subsequent fabrication methods on the composite properties were evaluated. The composites obtained using the optimum process parameters had tensile moduli and tensile strengths comparable with those of traditional glass fiber‐reinforced UPE composites. The pressed composites had very consistent tensile moduli that were well fitted by the Halpin–Tsai and Tsai–Pagano models. The classical Kelly‐Tyson and Bowyer‐Bader models significantly underestimated the composite tensile strengths and the potential reasons for this discrepancy are discussed. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Influence of fly ash cenospheres on performance of coir fiber‐reinforced recycled high‐density polyethylene biocomposites

Recycled high‐density polyethylene (RHDPE)/coir fiber (CF)‐reinforced biocomposites were fabricated using melt blending technique in a twin‐screw extruder and the test specimens were prepared in an automatic injection molding machine. Variation in mechanical properties, crystallization behavior, water absorption, and thermal stability with the addition of fly ash cenospheres (FACS) in RHDPE/CF composites were investigated. It was observed that the tensile modulus, flexural strength, flexural modulus, and hardness properties of RHDPE increase with an increase in fiber loading from 10 to 30 wt %. Composites prepared using 30 wt % CF and 1 wt % MA‐g‐HDPE exhibited optimum mechanical performance with an increase in tensile modulus to 217%, flexural strength to 30%, flexural modulus to 97%, and hardness to 27% when compared with the RHDPE matrix. Addition of FACS results in a significant increase in the flexural modulus and hardness of the RHDPE/CF composites. Dynamic mechanical analysis tests of the RHDPE/CF/FACS biocomposites in presence of MA‐g‐HDPE revealed an increase in storage (E′) and loss (E″) modulus with reduction in damping factor (tan δ), confirming a strong influence between the fiber/FACS and MA‐g‐HDPE in the RHDPE matrix. Differential scanning calorimetry, thermogravimetric analysis thermograms also showed improved thermal properties in the composites when compared with RHDPE matrix. The main motivation of this study was to prepare a value added and low‐cost composite material with optimum properties from consumer and industrial wastes as matrix and filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42237.