Effect of Oil Palm and Jute Fiber Treatment on Mechanical Performance of Epoxy Hybrid Composites

In this work, oil palm empty fruit bunch (EFB) and jute fibers were treated with 2-hydroxy ethyl acrylate (2-HEA) to improve interfacial bonding of oil palm EFB and jute fibers with epoxy matrix. Hybrid composites were fabricated by incorporation of modified oil palm EFB and jute fibers into an epoxy matrix by the hand lay-up technique. Mechanical (flexural and impact) and morphological properties of modified hybrid composites were measured. Results indicated that flexural and impact properties of modified fiber–reinforced hybrid composites improved as compared to untreated hybrid composites due to better fiber/matrix interfacial bonding, which was confirmed by scanning electron microscopy. We confirmed that treated oil palm/jute hybrid composite may be fabricated by advanced techniques such as resin transfer molding, extrusion, and injection molding for industrial applications in the automotive sector.     

Effect of Chemical Modifications of Fibers on Tensile Properties of Epoxy Hybrid Composites

Treatment of oil palm empty fruit bunch (EFB) and jute fibers is carried out by using 2-hydroxy ethyl acrylate (2-HEA) to increase the interfacial bonding of fibers with the epoxy matrix. Fourier transform-infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were used to measure the change of surface composition of the fibers after treatment. Modified oil palm and jute fibers were used as reinforcements for epoxy matrix to fabricate hybrid composites by the hand lay-up technique. Tensile and morphological properties of hybrid composites were studied, and tensile properties of hybrid composites prepared from chemically treated oil palm/jute fibers were found to be better than those of untreated hybrid composites. SEM micrographs disclose that interfacial bonding between fiber and matrix significantly improved in the hybrid composites. Developed hybrid composites can be exploited as alternative materials for development of automotive and structural components instead of synthetic fiber–reinforced polymer composites.     

Characterization of hybrid epoxy composites reinforced by murta and jute fibers

The primary focus of the present work was to fabricate and characterize hybrid epoxy composites using jute and murta bast fibers. Murta and jute fibers with lengths of 35 mm each were mixed randomly with a polymer matrix by varying their relative amounts but keeping the total weight of the fiber mixture fixed at 30%. The hybrid composites were characterized based on values obtained from the experiments carried out to assess properties such as density, thermal stability, water absorption/retention, tensile/flexural/compressive/impact strengths, and hardness. The composite containing equal amounts of the two fibers exhibits synergism and superior properties.     

Experimental investigation on the mechanical properties of Cyperus pangorei fibers and jute fiber-based natural fiber composites

The present era uses natural fibers as a partial replacement for synthetic fibers, thereby utilizing eco-friendly materials in a number of automotive applications (namely, bumpers, wind shields, doors, ceilings, etc.). Although there are many research findings related to natural fiber composites, in this work, a new sandwich layer of Cyperus pangorei fibers and jute fiber epoxy hybrid composites is developed using the hand lay-up technique and compared with the pure Cyperus pangorei fiber and pure jute fiber epoxy composites. The mechanical properties like tensile, flexural, compressive, impact, and hardness are performed as per ASTM standards for the developed composites. The test results show that Cyperus pangorei hybrid composite 3 had a tensile strength of 50.2 MPa, flexural strength of 301.48 N mm^?2, ultimate compression load of 15.03 KN, impact energy of 6.34 J, and Shore D hardness of 82.7, which are superior by 1.1–1.5 times to all the other developed composites. The microstructural characterizations are performed using scanning electron microscope which played a vital role in analyzing the failure morphology of the composites.     

Effect of treatment on the thermal conductivity and thermal diffusivity of oil‐palm‐fiber‐reinforced phenolformaldehyde composites

The thermal conductivity and thermal diffusivity of oil‐palm‐fiber‐reinforced untreated (Sample 1) and differently treated composites were measured with the transient plane source technique at room temperature and under normal pressure. All the composites were 40% oil‐palm fiber by weight. The fibers were treated with alkali (Composite 2), silane (Composite 3), and acetic acid (Composite 4) and reinforced in a phenolformaldehyde matrix. The thermal conductivity and thermal diffusivity of the composites increased after treatment to different extents. The thermal conductivity of the treated fibers as well as of the untreated fibers was calculated theoretically. The model results show that the thermal conductivity of the untreated fiber was smaller than the thermal conductivity of the treated fibers. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 916–921, 2000     

Mechanical,low-velocity impact,and hydrothermal aging properties of flax/carbon hybrid composite plates

A hybrid of flax and carbon fibers was considered as an effective way to enhance the mechanical and hydrothermal resistance of flax-reinforced polymer composites. In this study, hybrid composites based on three layers of cross-ply flax fabrics, two layers of unidirectional carbon fabrics, and an epoxy resin were investigated in terms of the tensile, three-point bending, impact, and water absorption properties. The flax fabric reinforcement of the hybrid composites contributed to an improvement in the toughness, whereas the carbon fabric contributed to an improvement in their hydrothermal resistance and overall strength and stiffness. The hybrid composites with carbon fibers on the surface (CFFFC) exhibited brittle failure in the tensile test, whereas those with alternating layers (FCFCF) exhibited greater plastic deformation. In addition, the failure strain of the CFFFC samples showed a negative hybrid effect, whereas that of the FCFCF samples improved 63.5% compared with that of carbon-fiber-reinforced polymer composites. A positive hybrid effect on the impact performance of hybrid reinforced epoxy composites containing the unidirectional carbon fabric and cross-ply flax fabric was observed. At 40 °C and 80% relative humidity, the diffusion rate of water molecules in the FCFCF samples was 16 times that in the CFFFC samples.     

Dynamic Mechanical Properties of Activated Carbon–Filled Epoxy Nanocomposites

Nano-activated carbons obtained from oil palm empty fiber bunch (AC-EFB), bamboo stem (AC-BS), and coconut shells (AC-CNS) were reinforced in epoxy matrix to fabricate epoxy nanocomposites. The dynamic mechanical analysis of epoxy nanocomposites was carried out, and 5% AC-CNS treated with KOH-filled epoxy composites displayed the highest storage modulus of all the activated carbon–filled epoxy composites. The incorporation of a small amount of AC-BS, AC-EFB, and AC-CNS to the epoxy matrix enhanced the damping characteristics of the epoxy nanocomposites. The 5% AC-EFB treated with H₃PO₄ filled epoxy composites showed the highest glass transition temperature (T_g) in all temperature ranges.     

Enhancement of mechanical and thermal properties of oil palm empty fruit bunch fiber poly(butylene adipate-co-terephtalate) biocomposites by matrix esterification using succinic anhydride

In this work, the oil palm empty fruit bunch (EFB) fiber was used as a source of lignocellulosic filler to fabricate a novel type of cost effective biodegradable composite, based on the aliphatic aromatic co-polyester poly(butylene adipate-co-terephtalate) PBAT (Ecoflex?), as a fully biodegradable thermoplastic polymer matrix. The aim of this research was to improve the new biocomposites' performance by chemical modification using succinic anhydride (SAH) as a coupling agent in the presence and absence of dicumyl peroxide (DCP) and benzoyl peroxide (BPO) as initiators. For the composite preparation, several blends were prepared with varying ratios of filler and matrix using the melt blending technique. The composites were prepared at various fiber contents of 10, 20, 30, 40 and 50 (wt %) and characterized. The effects of fiber loading and coupling agent loading on the thermal properties of biodegradable polymer composites were evaluated using thermal gravimetric analysis (TGA). Scanning Electron Microscopy (SEM) was used for morphological studies. The chemical structure of the new biocomposites was also analyzed using the Fourier Transform Infrared (FTIR) spectroscopy technique. The PBAT biocomposite reinforced with 40 (wt %) of EFB fiber showed the best mechanical properties compared to the other PBAT/EFB fiber biocomposites. Biocomposite treatment with 4 (wt %) succinic anhydride (SAH) and 1 (wt %) dicumyl peroxide (DCP) improved both tensile and flexural strength as well as tensile and flexural modulus. The FTIR analyses proved the mechanical test results by presenting the evidence of successful esterification using SAH/DCP in the biocomposites' spectra. The SEM micrograph of the tensile fractured surfaces showed the improvement of fiber-matrix adhesion after using SAH. The TGA results showed that chemical modification using SAH/DCP improved the thermal stability of the PBAT/EFB biocomposite.     

Acid treatment for functionalizing polyethylene fiber surfaces for enhanced adhesion to epoxy resins

The utility of high-strength, high-modulus polyethylene fibers in fiber-reinforced composites is limited due to its poor interfacial adhesion to various polymeric matrices. One way to overcome this limitation is to introduce reactive functionalities on the fiber surface capable of covalently bonding to matrix resins. Ultra high-strength polyethylene (UHSPE) fibers were treated with chlorosulfonic acid. The surface acid groups were found to considerably improve the interfacial adhesion between polyethylene fibers and epoxy resins as shown by the microbond test. These surface functionalities were found to improve the fiber wettability, as shown by contact angle measurements using the Wilhelmy balance method. Colorimetric measurements of methylene blue absorption were used to quantify the surface concentrations of the acid groups. It was possible to functionalize the UHSPE fiber surfaces using this method to obtain fibers that formed a stronger adhesive bond with epoxy resins; this was achievable without sacrificing other fiber mechanical properties.     

Effect of carbon fiber surface functionality on the moisture absorption behavior of carbon fiber/epoxy resin composites

Polyacrylonitrile (PAN)‐based carbon fibers were electrochemically oxidized in aqueous ammonium bicarbonate with increasing current density. The electrochemical treatment led to significant changes of surface physical properties and chemical structures. The oxidized fibers showed much cleaner surfaces and increased levels of oxygen functionalities. However, it was found that there was no correlation between surface roughness and the fiber/resin bond strength, i.e. mechanical interlocking did not play a major role in fiber/resin adhesion. Increases in surface chemical functionality resulted in improved fiber/resin bonding and increased interlaminar shear strength (ILSS) of carbon fiber reinforced epoxy composites. The relationship between fiber surface functionality and the hydrothermal aging behavior of carbon fiber/epoxy composites was investigated. The existence of free volume resulted from poor wetting of carbon fibers by the epoxy matrix and the interfacial chemical structure were the governing factors in the moisture absorption process of carbon fiber/epoxy composites. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of Chemical Treatment and Fiber Loading on Mechanical Properties of Borassus (Toddy Palm) Fiber/Epoxy Composites

The aim of the present study was to investigate and compare the mechanical properties of untreated and chemically modified Borassus fiber–reinforced epoxy composites. Composites were prepared by the hand lay-up process by reinforcing Borassus fibers with epoxy matrix. To improve the fiber-matrix adhesion properties, alkali (NaOH) and alkali combined with silane (3-aminopropyltriethoxysilane) treatment of the fiber surface was carried out. Examinations through Fourier transform-infrared spectroscopy and scanning electron microscopy (SEM) were conducted to investigate the structural and physical properties of the Borassus fibers. Tensile properties such as modulus and strength of the composites made with chemically modified and untreated Borassus fibers were studied using a universal testing machine. Based on the experimental results, it was found that the tensile properties of the Borassus-reinforced epoxy composites were significantly improved as compared with the neat epoxy. It was also found that the fiber treated with a combination of alkali and silane exhibited superior mechanical properties to alkali-treated and untreated fiber composites. The nature of the fiber/matrix interface was examined through SEM of cryo-fractured samples. Chemical resistance of composites was also found to be improved with chemically modified fiber composites.     

Mechanical property evaluation of glass–jute fiber reinforced polymer composites

The natural fibers such as jute, coir, hemp, sisal etc. are randomly used as reinforcements for composite materials because of its various advantages such as low cost, low densities, low energy consumption over conventional fibers. In addition, they are renewable as well as biodegradable, and indeed wide varieties of fibers are locally available. In this study, glass–jute fiber reinforced polymer composite is fabricated, and the mechanical properties such as tensile, flexural and impact behavior are investigated. The materials selected for the studies were jute fiber and glass fiber as the reinforcement and epoxy resin as the matrix. The hand lay‐out technique was used to fabricate these composites. Fractured surface were comprehensively examined in scanning electron microscope (SEM) to determine the microscopic fracture mode. A numerical procedure based on the finite element method was then applied to evaluate the overall behavior of this composite using the experimentally applied load. Results showed that by incorporating the optimum amount of jute fibers, the overall strength of glass fiber reinforced composite can be increased and cost saving of more than 30% can be achieved. It can thus be inferred that jute fiber can be a very potential candidate in making of composites, especially for partial replacement of high‐cost glass fibers for low load bearing applications. Copyright © 2016 John Wiley & Sons, Ltd.     

Wettability of carbon fibers modified by acrylic acid and interface properties of carbon fiber/epoxy

The oxidation-reduction and pre-irradiation induced methods were employed to study the effect of acrylic acid modification on the wetting and adsorption ability of carbon fiber (CF) in epoxy solution and the interfacial properties of CF/epoxy. Systematic experimental work was conducted to determine the surface topography, surface energy, surface chemical composition, absorbability and tensile strength of carbon fibers and interfacial adhesion of CF/epoxy before and after modification. The roughness, surface energy, amount of containing-oxygen functional groups and wetting ability were all found to increase significantly after modifications. The tensile strength of carbon fibers was improved marginally by γ-ray pre-irradiation while was decreased little by oxidation-reduction modification. Consequently, the surface modifications of carbon fibers via both oxidation-reduction and pre-irradiation led to an improvement (more than 15%) of the interlaminar shear strength of CF/epoxy composites. The mechanisms of interfacial improvement of modified CF/epoxy composites are proposed.     

Bio-based polybenzoxazine composites for oil-water separation,sound absorption and corrosion resistance applications

In the present work, an attempt has been made to develop bio-based composites using cardanol and eugenol based benzoxazine matrices with bio-silica as well as natural fibrous materials (coir felt, kapok fabric, jute felt and rice husk) as reinforcements. The bio-composites developed were studied for different applications viz., dielectric, water repellent, oil-water separation, sound-absorption including corrosion resistance use. Among the bio-silica reinforced benzoxazine composites, 7 wt% bio-silica reinforced cardanol composites possesses the highest value of water contact angle (147°) and the lowest value of dielectric constant (2.0) than those of other bio-silica reinforced composites. Further, the cotton fabric was coated with cardanol and eugenol based polybenzoxazines separately, whose values of water contact angles are found to be 159° and 157° with oil-water separation efficiency as 96% and 95% respectively. Furthermore, the cardanol based benzoxazine was separately reinforced with jute felt, coir felt, kapok fabric and rice-husk. The corresponding sound absorption efficiency was found to increase in the following order, Neat polybenzoxazine < rice husk < coir felt < kapok fabric < jute felt. Data resulted from corrosion studies, it was noticed that the mild steel specimen coated with bio-based benzoxazine matrices and bio-silica reinforced benzoxazine composites coated specimens exhibit an excellent resistance to corrosion. Data resulted from different studies, it is suggested that the cardanol and eugenol based bio-composites can be considered as an effective materials for microelectronics insulation, water repellent, oil-water separation, sound absorption and corrosion resistant applications.     

Mechanical Properties,Water Absorption,and Chemical Resistance of Napier Grass Fiber Strand–Reinforced Epoxy Resin Composites

Napier grass fiber strands were used as reinforcement to obtain composites with epoxy resin as matrix. To improve the surface, these fiber strands were treated with alkali solution. The composites were prepared by means of hand lay-up molding, then the effects of Napier grass fiber strand loading on mechanical properties such as tensile, flexural and impact, interfacial bonding, and chemical resistance were investigated. The composite with 20 wt.% Napier grass fiber strands gives excellent mechanical properties and chemical resistance, showing that it has the best bonding and adhesion of the composites. SEM micrographs of fractured and worn surfaces clearly demonstrate the interfacial adhesion between fiber and matrix. Alkali-treated Napier grass fiber strand–reinforced composites have better resistance to water and chemicals than the untreated fiber strand composites.     

Probing the tribological behaviors in water of novel poly(phthalazione ether sulfone ketone) and its composites based on the state of aggregation and the microstructure

In this paper, novel poly(phthalazione ether sulfone ketone) (PPESK) and its composites reinforced with carbon fibers (CFs) were prepared, and their tribological behaviors in pure and sea water were comparatively investigated. Affected by the noncoplanar twisted aromatic structure in the molecular skeleton, the aggregation of the macromolecular chain in PPESK was amorphous, resulting in very high water absorption of PPESK matrix. The invading water molecules led to a sharp decrease in the hardness of PPESK surface, resulting in very high wear rate of PPESK in water. Although CF/PPESK composites had higher water absorption than pure PPESK, their wear processes in water were no longer dominated by high water absorption but by the load‐carrying effect of CFs, ascribed to the good CF/PPESK interfacial adhesion. Therefore, CF/PPESK composites exhibited very low wear rates in the order of 10^?7 mm³/Nm in water, which decreased with the CF content increasing until the content of CFs reached 50%. The results revealed that the most critical factor determining the wear behavior of a fiber‐reinforced polymer composite sliding in water is the fiber/matrix interface but not the water absorption of the polymer matrix. Copyright © 2017 John Wiley & Sons, Ltd.     

Water‐sorption kinetics in oil palm fibers

Oil palm fibers represent a very abundant and natural resource for raw materials that can be efficiently utilized as reinforcement in polymers. The sorption characteristics of two types of oil palm fibers—oil palm empty‐fruit‐bunch (OPEFB) fiber and oil palm mesocarp fiber‐in distilled water, mineral water, and water containing salt at four different temperatures were investigated. The uptake of water decreased with an increase in temperature. The OPEFB fiber showed higher sorption than the mesocarp fiber. This was due to the uptake associated with the capillary action in the OPEFB fiber. The thermodynamic parameters of the sorption process were calculated. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1215–1223, 2001     

Surface treatment of ultra‐high molecular weight polyethylene fibers using potassium permanganate and mechanical properties of its composites

Potassium permanganate was applied to improve the surface properties of the ultra‐high molecular weight polyethylene (UHMWPE) fibers. The results suggested that the surface oxygen atoms increased dramatically and the O/C ratio increased from 0.030 to 0.563 after treatment. The increased surface roughness and the O‐containing groups on the treated fiber surface decreased the contact angles with water and ethylene glycol. The crystallinity and the crystallite size of the treated fibers increased, and the DSC results indicated that chain scission and the formation of ―C═O chemical defects in the amorphous region were the main mechanisms of the deterioration of the treated UHMEPE fibers. The breaking strength and the elongation at break of the fibers decreased, but the modulus increased after treatment. The treated fibers exhibited better adhesion with epoxy matrix. An improvement of 27.6% from 101.4 to 129.4 MPa in ILSS confirmed the improvement in the interfacial adhesion strength of composites. The impact and bending strength of composites were both improved.     

Aging behavior of PBO fibers and PBO‐fiber‐reinforced PPESK composite after oxygen plasma treatment

Aging behavior of poly(p‐phenylene benzobisoxazole) (PBO) fibers and PBO‐fiber‐reinforced poly(phthalazinone ether sulfone ketone) (PPESK) composites after oxygen plasma treatment was investigated. Surface chemical composition, surface roughness and surface morphologies of oxygen‐plasma‐treated PBO fibers before and after aging in air for 1, 3, 5 and 10 days were analyzed by XPS and atomic force microscopy (AFM). The effects of aging on the material were examined by interlaminar shear strength (ILSS) and water absorption measurements. The results indicate that the major aging behavior of the fibers and the composite appeared in the first few days after oxygen plasma treatment, whereas minor aging effects were observed with prolonged aging. Copyright © 2008 John Wiley & Sons, Ltd.     

The Role of Lignocellulosic Composition and Residual Lipids in Empty Fruit Bunches on the Production of Humic Acids in Submerged Fermentations

The aim of this research was to study the production of humic acids (HA) by Trichoderma reesei from empty fruit bunches (EFBs) of palm oil processing, with a focus on the effects of lignocellulosic content and residual lipids. EFBs from two different soils and palm oil producers were previously characterized about their lignocellulosic composition. Submerged fermentations were inoculated with T. reesei spores and set up with or without residual lipids. The results showed that the soil and the processing for removal of the palm fresh fruits were crucial to EFB quality. Thus, EFBs were classified as type 1 (higher lignocellulosic and fatty acids composition similar to the palm oil and palm kernel oil) and type 2 (lower lignocellulosic content and fatty acids composition similar to palm oil). Despite the different profiles, the fungal growth was similar for both EFB types. HA production was associated with fungal growth, and it was higher without lipids for both EFBs. The highest HA productivity was obtained from type 1 EFB (approximately 90 mg L⁻¹ at 48 h). Therefore, the lignocellulosic composition and the nature of the residual lipids in EFBs play an important role in HA production by submerged fermentation.