ACETYLATED PLANT-FIBER-REINFORCED POLYESTER COMPOSITES: A STUDY OF MECHANICAL,HYGROTHERMAL, AND AGING CHARACTERISTICS

The potential of acetylation of plant fibers to improve the properties of composites was studied. The chemical modification of oil palm empty fruit bunch (EFB), coconut fiber (Coir), oil palm frond (OPF), jute, and flax using noncatalyzed acetic anhydride were investigated. Proof of acetylation was indicated by the increase in weight percent gain (WPG). Acetylation at a reaction temperature of 120°C had resulted in the reduction in the tensile properties (stress, modulus, and elongation at break) of EFB and Coir composites. However, at 100°C, the acetylated samples exhibited improved properties. The mechanical properties of acetylated EFB- and Coir-fiber-reinforced polyester composites was evaluated at different fiber loadings. The tensile strength and modulus were improved, but elongation at break was slightly reduced upon acetylation, particularly at high fiber loading. Impact properties were moderately increased for those composites with fiber loadings up to 45%. Acetylation exhibited a low moisture absorption, comparable with glass-fiber composites. Acetylated EFB and Coir composites showed superior retention of tensile and impact properties after aging in water up to 12 months.     

Effects of fiber‐surface treatment on the properties of hybrid composites prepared from oil palm empty fruit bunch fibers,glass fibers,and recycled polypropylene

In this article, we report the effects of hybridization and fiber‐surface modification on the properties of hybrid composites prepared from recycled polypropylene (RPP), coupling agents, oil palm empty fruit bunch (EFB), and glass fibers through a twin‐screw extruder and an injection‐molding machine. The surface of the EFB fibers was modified with different concentrations (10–15 wt %) and temperatures (60–90°C) of alkali solutions. The structure and morphology of the fibers were observed with the help of Fourier transform infrared spectroscopy and scanning electron microscopy. Different types of composites were fabricated with untreated, alkali‐treated, and heat‐alkali‐treated fibers. Comparative analysis of the mechanical, structural, morphological, and thermal properties of the composites was carried out to reveal the effects of treatment and hybridization. The analysis results reveal that composites prepared from the alkali‐treated (in the presence of heat) fibers show improved mechanical, thermal, and morphological properties with a remarkably reduced water absorption. Additionally, the crystallinity of RPP also increased with the development of biaxial crystals. The improvement of various properties in relation to the structures and morphologies of the composites is discussed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43049.     

Dynamic mechanical properties of oil palm fiber/phenol formaldehyde and oil palm fiber/glass hybrid phenol formaldehyde composites

The dynamic mechanical properties of oil palm fiber reinforced phenol formaldehyde (PF) composites and oil palm/glass hybrid fiber reinforced PF composites were investigated as a function of fiber content and hybrid fiber ratio. The dynamic modulus of the neat PF sample decreases with decrease in frequency. Glass transition attributed with the α relaxation of the neat PF sample was observed around 140°C. Tanδ values and storage modulus show great enhancement upon fiber addition. The value increases with increase in fiber content. The loss modulus shows a reverse trend with increase in fiber loading. Incorporation of oil palm fiber shifts the glass transition towards lower temperature value. The glass transition temperature of the hybrid composites is lower than that of the unhybridized composites. The highest value of mechanical damping is observed in hybrid composites. Storage modulus of the hybrid composites is lower than unhybridized oil palm fiber/PF composite. A similar trend is observed for loss modulus. Activation energies for the relaxation processes in different composites were calculated. Activation energy is increased upon fibrous reinforcement. Complex modulus variations and phase behavior of the composites were studied from Cole‐Cole plots. Finally, master curves for the viscoelastic properties of the composites were constructed on the basis of time‐temperature superposition principle. POLYM. COMPOS., 26:388–400, 2005. © 2005 Society of Plastics Engineers     

Effect of coir fiber loading on mechanical and morphological properties of oil palm fibers reinforced polypropylene composites

Hybrid composites were fabricated by compounding process with varying the relative weight fraction of oil palm empty fruit bunch (EFB) and coir fibers to assess the effect of hybridization of oil palm EFB with coir fibers in polypropylene (PP) matrix. The mechanical and morphological properties of oil palm/coir hybrid composites were carried out. Tensile and flexural properties of oil EFB‐PP composites enhanced with hybridization of coir fibers except coir/oil palm EFB (25:75) hybrid composite, whereas highest impact properties at oil palm:coir fibers with 50:50 ratios. Results shown that hybrid composites with oil palm:coir fibers with 50:50 ratios display optimum mechanical properties. In this study, scanning electron microscopy (SEM) had been used to study morphology of tensile fractured surface of hybrid composites. Its clear from SEM micrograph that coir/EFB (50:50) hybrid composites display better tensile properties due to strong fiber/matrix bonding as compared with other formulations which lead to even and effective distribution of stress among fibers. The combination of oil palm EFB/coir fibers with PP matrix produced hybrid biocomposites material can be used to produce components such as rear mirrors' holder and window levers, fan blades, mallet, or gavel. POLYM. COMPOS., 35:1418–1425, 2014. © 2013 Society of Plastics Engineers     

Polyurethane composites based on oil palm empty fruit bunches: Effect of isocyanate/hydroxyl ratio and chemical modification of empty fruit bunches with toluene diisocyanate and hexamethylene diisocyanate on mechanical properties

This study focuses on the effect of isocyanate (NCO)/hydroxyl (OH) group ratios and chemical modification of oil palm empty fruit bunches (EFBs) with toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) on the mechanical properties of EFB–polyurethane (PU) composites. The tensile, flexural, and impact properties are affected by the NCO/OH ratios. The tensile strengths, flexural strengths, and toughness increase as the NCO/OH increases; however, the modulus decreases. The reduction in the modulus is attributable to the increased flexibility of the PU linkages. Chemical modification of the EFBs increases the tensile strength, flexural strength, and toughness; however, the modulus is lowered as the percentage of treated EFB is increased. Impact strength results show that the strength increases as the NCO/OH ratio is increased. At NCO/OH ratios of 1.0 and 1.1, the composites with HMDI‐treated fibers exhibit higher impact strength than those with TDI‐treated and untreated fibers, respectively. This may be due to the longer and more flexible chain length of HMDI as compared to TDI, which enables the composites to absorb more energy before failure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effect of layering pattern on the physical,mechanical, and thermal properties of jute/bagasse hybrid fiber‐reinforced epoxy novolac composites

In this study, randomly oriented short jute/bagasse hybrid fiber‐reinforced epoxy novolac composites were prepared by keeping the relative volume ratio of jute and bagasse of 1:3 and the total fiber loading 0.40 volume fractions. The effect of jute fiber hybridization and different layering pattern on the physical, mechanical, and thermal properties of jute/bagasse hybrid fiber‐reinforced epoxy novolac composites was investigated. The hybrid fiber‐reinforced composites exhibited fair water absorption and thickness swelling properties. To investigate the effect of layering pattern on thermomechanical behavior of hybrid composites, the storage modulus and loss factor were determined using dynamic mechanical analyzer from 30 to 200°C at a frequency of 1 Hz. The fracture surface morphology of the tensile samples of the hybrid composites was performed by using scanning electron microscopy. The morphological features of the composites were well corroborated with the mechanical properties. Thermogravimetric analysis indicated an increase in thermal stability of pure bagasse composites with the incorporation of jute fibers. The incorporation of hybrid fibers results better improvement in both thermal and dimensional stable compared with the pure bagasse fiber composites. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

POLYSTYRENE-BENZOYLATED EFB REINFORCED COMPOSITES

Reinforced thermoplastics generally are produced by incorporation of reinforcement agents or fillers into thermoplastic resins. The utilization of lignocellulosic material as filler with reinforcement in polymer matrix has received much interest due to its lower price and other properties. A composite of polystyrene reinforced with oil palm empty fruit bunches (EFB) and chemically treated EFB with benzoyl chloride (EFB-benzoylated) as a function of loading and fiber surface modification were prepared. The chemically treated fibers were analyzed with FT-IR to observe the extent of chemical reaction with EFB fiber. The sharp peak at 710 cm^?1 appeared on the spectra, which indicated that the mono-substituted benzene ring has taken place. The strong peak at 1720 cm^?1 has indicated the presence of ester group treated fiber. The flexural test was performed using Instron 4301 testing machine to study flexural properties of the composites with various fiber sizes. The results showed that the flexural properties increased with particle size. The flexural strength of EFB-benzoylated composites was observed to be stronger than untreated EFB fiber. Scanning electron microscope was used to investigate the morphological structure of the fiber surface, fiber pull out, fracture surface, and fiber–matrix interface. The untreated EFB composites showed hole and fiber end, which indicated that most of the fiber have pulled out breaking during the fracture of composites; however, the treated EFB-benzoylated showed a good adhesion between fiber and matrix.     

Dynamic mechanical analysis of oil palm microfibril‐reinforced acrylonitrile butadiene rubber composites

The dynamic mechanical properties of microfibers of oil palm‐reinforced acrylonitrile butadiene rubber (NBR) composites were investigated as a function of fiber content, temperature, treatment, and frequency. The storage modulus (E′) was found to increase with weight fraction of microfibrils due to the increased stiffness imparted by the strong adhesion between the polar matrix and the hydrophilic microfibrils. The damping properties were found to decrease with increase in fiber loading. As the fiber content increases, the damping nature of the composite decreases because of the increased stiffness imparted by the natural fibers. By steam explosion method (STEX), microfibrils are separated from fibers. Natural fibers were undergone treatment such as mercerization, benzoylation, and silane treatment. The NBR is modified by the addition of resorcinol‐hexa‐hydrated silica (HRH) bonding agent. Also dicumyl peroxide (DCP) is used as an alternating vulcanizing agent in the system. In the case of composites containing chemically modified fibers, storage modulus were found to increase. Cole–Cole analysis was made to study the phase behavior of the composite samples. Activation energy for the relaxation processes in different composites was calculated. Morphological studies using scanning electron microscopy of tensile fracture surfaces of treated and untreated composites indicated better fiber matrix/adhesion in the case of treated microfibril‐reinforced composites. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Effect of Fiber Esterification on Fundamental Properties of Oil Palm Empty Fruit Bunch Fiber/Poly(butylene adipate-co-terephthalate) Biocomposites

A new class of biocomposites based on oil palm empty fruit bunch fiber and poly(butylene adipate-co-terephthalate) (PBAT), which is a biodegradable aliphatic aromatic co-polyester, were prepared using melt blending technique. The composites were prepared at various fiber contents of 10, 20, 30, 40 and 50 wt% and characterized. Chemical treatment of oil palm empty fruit bunch (EFB) fiber was successfully done by grafting succinic anhydride (SAH) onto the EFB fiber surface, and the modified fibers were obtained in two levels of grafting (low and high weight percentage gain, WPG) after 5 and 6 h of grafting. The FTIR characterization showed evidence of successful fiber esterification. The results showed that 40 wt% of fiber loading improved the tensile properties of the biocomposite. The effects of EFB fiber chemical treatments and various organic initiators content on mechanical and thermal properties and water absorption of PBAT/EFB 60/40 wt% biocomposites were also examined. The SAH-g-EFB fiber at low WPG in presence of 1 wt% of dicumyl peroxide (DCP) initiator was found to significantly enhance the tensile and flexural properties as well as water resistance of biocomposite (up to 24%) compared with those of untreated fiber reinforced composites. The thermal behavior of the composites was evaluated from thermogravimetric analysis (TGA)/differential thermogravimetric (DTG) thermograms. It was observed that, the chemical treatment has marginally improved the biocomposites' thermal stability in presence of 1 wt% of dicumyl peroxide at the low WPG level of grafting. The improved fiber-matrix surface enhancement in the chemically treated biocomposite was confirmed by SEM analysis of the tensile fractured specimens.     

Palm‐based bio‐composites hybridized with kaolinite

This study described the mechanical and thermal properties of hybrid bio‐composites from oil palm empty fruit bunch (EFB) fibers and kaolinite. The polyurethane (PU) used as matrix is formed by reacting palm kernel oil (PKO)‐based polyester with crude isocyanate. The blending ratio of PU to EFB fibers was fixed at 35 : 65 and kaolinite was added at 0, 5, 10, 15, and 20% (by weight). The occurrence of chemical interactions between the hydroxyl terminals in both fillers and the PU system was determined via FTIR spectroscopy. Hybrid bio‐composites showed improved stiffness, strength, and better water resistance with the addition of kaolinite to an extent. At 15% of kaolinite loading, maximum flexural and impact strengths were observed. The interaction between kaolinite with PU matrix and EFB fibers enhanced the mechanical properties of the bio‐composites, which was justified from the FTIR spectrum. However, over‐packing of kaolinite was observed at 20% kaolinite loading, which ruptured the cellular walls and degraded strength of the bio‐composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Recycled milk pouch and virgin LDPE‐LLDPE‐based jute fiber composites

The present investigation deals with the thermo‐mechanical recycling of post consumer milk pouches (LDPE‐LLDPE blend) and its use as jute fiber composite materials for engineering applications. The mechanical, thermal, morphological, and dynamic‐mechanical properties of recycled milk pouch‐based jute fiber composites with different fiber contents were evaluated and compared with those of the virgin LDPE‐LLDPE/jute fiber composites. Effect of artificial weathering on mechanical properties of different formulated composites was determined. The recycled polymer‐based jute fiber composites showed inferior mechanical properties as well as poor thermal stability compared to those observed for virgin polymer/jute fiber composites. However, the jute‐composites made with (50:50) recycled milk pouch‐virgin LDPE‐LLDPE blend as polymer matrix indicated significantly superior properties in comparison to the recycled milk pouch/jute composites. Overall mechanical performances of the recycled and virgin polymeric composites were correlated by scanning electron microscopy (SEM). The dynamic mechanical analysis showed that storage modulus values were lower for recycled LDPE‐LLDPE/jute composites compared to virgin LDPE‐LLDPE/jute composites throughout the entire temperature range, but an increase in the storage modulus was observed for recycled‐virgin LDPE‐LLDPE/jute composites. POLYM. COMPOS. 28:78–88, 2007. © 2007 Society of Plastics Engineers     

Enzyme‐mediated surface modification of jute and its influence on the properties of jute/epoxy composites

Surface modification of jute fibers is necessary to improve the adhesion and interfacial compatibility between fibers and resin matrix before using fibers in polymer composites. In this study, dodecyl gallate (DG) was enzymatically grafted onto the jute fiber by laccase to endow the fiber with hydrophobicity. A hand lay‐up technique was then adopted to prepare jute/epoxy composites. Contact angle and wetting time measurements showed that the surface hydrophobicity of the jute fabric was increased after the enzymatic graft modification. The water absorption and thickness swelling of the DG‐grafted jute fabric/epoxy composite were lower than those of the other composites. The tensile and dynamic mechanical properties of the jute/epoxy composites were enhanced by the surface modification. Scanning electron microscopy images revealed stronger fiber–matrix adhesion in composites with modified fibers. Therefore, the enzymatic graft modification increased the fiber–matrix interface area. The fiber–matrix adhesion was enhanced, and the mechanical properties of the composites were improved. POLYM. COMPOS., 38:1327–1334, 2017. © 2015 Society of Plastics Engineers     

The effect of various anhydride modifications on mechanical properties and water absorption of oil palm empty fruit bunches reinforced polyester composites

The chemical modification of oil palm empty fruit bunches (EFB) using non‐catalysed reaction with acetic, propionic and succinic anhydrides were investigated. Proof of modification was indicated by the increase of weight and was confirmed by Fourier‐transform infrared analysis (FT‐IR). The mechanical and water‐absorption properties of all anhydride‐modified EFB composites were evaluated at different volume fractions (V_f). The properties were improved for these modified fibres, whereas unmodified EFB fibres exhibited poor mechanical properties and higher water absorption. Acetic anhydride modification showed the greatest benefit on composite properties, followed by propionic and succinic anhydride modification. © 2001 Society of Chemical Industry     

Natural rubber composites reinforced with sisal/oil palm hybrid fibers: Tensile and cure characteristics

Natural rubber was reinforced with untreated sisal and oil palm fibers chopped to different fiber lengths. The influence of fiber length on the mechanical properties of the hybrid composites was determined. Increasing the fiber length resulted in a decrease in the properties. The effects of concentration on the rubber composites reinforced with sisal/oil palm hybrid fibers were studied. Increasing the concentration of fibers resulted in a reduction in the tensile strength properties and tear strength but an increase in the modulus of the composites. Fiber breakage analysis was evaluated. The vulcanization parameters, processability characteristics, and stress–strain properties of these composites were analyzed. The extent of fiber alignment and the strength of the fiber–rubber interface adhesion were analyzed from the anisotropic swelling measurements. Scanning electron microscopy studies were performed to analyze the fiber/matrix interactions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2305–2312, 2004     

Effect of chemical treatment on the thermal properties of hybrid natural fiber-reinforced composites

The main objective of this work is to study the effect of chemical treatment on the thermal properties of hybrid natural fiber-reinforced composites (NFRCs). Different chemical treatments [i.e., alkalized and mixed (alkalized+ silanized)] were used to improve the adhesion between the natural fibers (jute, ramie, sisal, and curauá) and the polymer matrix. A differential scanning calorimetry, thermogravimetry, and a dynamic mechanical analysis were performed to study the thermal properties of hybrid NFRC. It was found that the chemical treatments increased the thermal stability of the composites. Scanning electron microscopy images showed that the chemical treatments altered the morphology of the natural fibers. A rougher surface was observed in case of alkali treated fiber, whereas a thin coating layer was formed on the fiber surface during the mixed treatment. However, for some fibers (i.e., sisal and rami), the chemical treatment has a positive impact on the composite properties, whereas for the jute and curauá composites, the best behavior was found for untreated fibers. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47154.     

Mechanical and viscoelastic properties of soybean oil thermoset reinforced with jute fabrics and carded lyocell fiber

Composites and hybrid composites were manufactured from renewable materials based on jute fibers, regenerated cellulose fibers (Lyocell), and thermosetting polymer from soybean oil. Three different types of jute fabrics with biaxial weave architecture but different surface weights, and carded Lyocell fiber were used as reinforcements. Hybrid composites were also manufactured by combining the jute reinforcements with the Lyocell. The Lyocell composite was found to have better mechanical properties than other composites. It has tensile strength and modulus of about 144 MPa and 18 GPa, respectively. The jute composites also have relatively good mechanical properties, as their tensile strengths and moduli were found to be between 65 and 84 MPa, and between 14 and 19 GPa, respectively. The Lyocell‐reinforced composite showed the highest flexural strength and modulus, of about 217 MPa and 13 GPa, respectively. In all cases, the hybrid composites in this study showed improved mechanical properties but lower storage modulus. The Lyocell fiber gave the highest impact strength of about 35 kJ/m², which could be a result of its morphology. Dynamic mechanical analysis showed that the Lyocell reinforced composite has the best viscoelastic properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Improved thermal properties of jute fiber‐reinforced polyethylene nanocomposites

The thermal behavior of chemically modified jute fiber‐reinforced polyethylene (PE) nanocomposites was investigated. Nanocomposites were prepared by hot press molding technique using different fiber loadings (5, 10, 15, and 20 wt%) for both treated and untreated fibers. Jute fibers were chemically modified with benzene diazonium salt to increase their compatibility with the PE matrix. Surface and thermal properties were subsequently characterized. Fourier transform infrared spectroscopy and scanning electron microscopy analysis were used to study the surface morphology. Thermogravimetric analysis (TGA) and differential scanning calorimetry were carried out for thermal characterization. Fourier transform infrared spectroscopy and scanning electron microscopy study showed interfacial interaction among jute fiber, PE, and nanoclay. It was observed that, at optimum fiber content (15 wt%), treated jute fiber‐reinforced composites showed better thermal properties compared with that of untreated ones and also that nanoclay‐incorporated composites showed enhanced higher thermal properties compared with those without nanoclay. POLYM. COMPOS., 38:1266–1272, 2017. © 2015 Society of Plastics Engineers     

Study of jute fiber reinforced polyester composites by dynamic mechanical analysis

Cyanoethylation of jute fibers in the form of nonwoven fabric was studied, and these chemically modified fibers were used to make jute–polyester composites. The dynamic mechanical thermal properties of unsaturated polyester resin (cured) and composites of unmodified and chemically modified jute–polyester were studied by using a dynamic mechanical analyzer over a wide temperature range. The data suggest that the storage modulus and thermal transition temperature of the composites increased enormously due to cyanoethylation of fiber. An increase of the storage modulus of composites, prepared from chemically modified fiber, indicates its higher stiffness as compared to a composite prepared from unmodified fiber. It is also observed that incorporation of jute fiber (both unmodified and modified) with the unsaturated resin reduced the tan δ peak height remarkably. Composites prepared from cyanoethylated jute show better creep resistance at comparatively lower temperatures. On the contrary, a reversed phenomenon is observed at higher temperatures (120°C and above). Scanning electron micrographs of tensile fracture surfaces of unmodified and modified jute–polyester composites clearly demonstrate better fiber–matrix bonding in the case of the latter. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1505–1513, 1999     

Dynamic mechanical properties of oil palm microfibril‐reinforced natural rubber composites

The dynamic mechanical properties of macro and microfibers of oil palm‐reinforced natural rubber (NR) composites were investigated as a function of fiber content, temperature, treatment, and frequency. By the incorporation of macrofiber to NR, the storage modulus (E') value increases while the damping factor (tan δ) shifts toward higher temperature region. As the fiber content increases the damping nature of the composite decreases because of the increased stiffness imparted by the natural fibers. By using the steam explosion method, the microfibrils were separated from the oil palm fibers. These fibers were subjected to treatments such as mercerization, benzoylation, and silane treatment. Resorcinol‐hexamethylenetetramine‐hydrated silica was also used as bonding agent to increase the fiber/matrix adhesion. The storage modulus value of untreated and treated microfibril‐reinforced composites was higher than that of macrofiber‐reinforced composites. The T_g value obtained for this microfibril‐reinforced composites were slightly higher than that of macrofiber‐reinforced composites. The activation energy for the relaxation processes in different composites was also calculated. The morphological studies using scanning electron microscopy of tensile fracture surfaces of treated and untreated composites indicated better fiber/matrix adhesion in the case of treated microfibril‐reinforced composites. Finally, attempts were made to correlate the experimental dynamic properties with the theoretical predictions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The Effect of Oil Extraction of the Oil Palm Empty Fruit Bunch on the Processability,Impact, and Flexural Properties of PVC-U Composites

The use of oil palm empty fruit bunch fiber (EFB) as reinforcement in the unplasticized poly(vinyl chloride) (PVC-U) is a new attraction in the thermoplastic composite technology. The objectives of this study are to investigate the effects of extracted EFB on processability, impact, and flexural properties of PVC-U composites. A soxhlet extraction was used to extract the extractives from the EFB fibers. The identification of the related functional groups present in the concentrated extract was analyzed using FTIR. To produce composites, PVC resin, EFB fiber, and other additives were first dry-blended using a heavy-duty laboratory mixer before being milled into sheets on a two-roll mill. Test specimens were then hot pressed after which the impact and flexural properties were determined. The processability studies of dry blends were carried out using a Brabender Torque Rheometer model PL2200. The FTIR analysis showed that the oil residue was successfully extracted from EFB fibers. Both the extracted and unextracted fibers decreased the fusion time and melt viscosity of PVC-U. However, the extracted fiber was found to increase the fusion time of PVC as the fiber content increased from 10 to 40 phr. The impact and flexural properties of composites were not significantly affected by the fiber extraction.