Effect of silane-based coupling agents and acrylic acid based compatibilizers on mechanical properties of oil palm empty fruit bunch filled high-density polyethylene composites

The mechanical properties of composites consisting of high-density polyethylene (HDPE) and oil palm fibrous wastes—that is, empty fruit bunch (EFB)—have been investigated. Tensile modulus showed an increase, whereas tensile strength, elongation at break, and impact strength decreased with increasing filler loading. The strong tendency of EFB to exist in the form of fiber bundles and the poor filler–matrix interaction is believed to be responsible for the poor strength displayed by the composites. Attempts to improve these properties using two types of coupling agents, that is, 3-aminopropyltrimethoxysilane (3-APM) and 3-aminopropyltriethoxysilane (3-APE) and two types of compatibilizers, poly(propylene–acrylic acid) (PPAA) and poly(propylene–ethylene–acrylic acid), (PPEAA), are described. While almost all chemical treatments increased the stiffness of the composites, limited improvement has been observed in the case of tensile strength. This have been attributed to the presence of fiber bundles that remain intact even after several types of chemical treatment have been carried out. Thus, the role of EFB as reinforcing agent is not fully realized. Scanning electron microscopy (SEM) micrographs revealed that the main energy-absorbing mechanisms contributing towards toughness enhancement is through the fiber bundle pull-out process. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 2189–2203, 1998     

The effect of compounding techniques on the mechanical properties of oil palm empty fruit bunch–polypropylene composites

Oil palm empty fruit bunch–polypropylene (EFB–PP) composites were produced by employing 2 types of compounding techniques, that is, an internal mixer and a single-screw extruder. The mechanical and water absorption properties of both types of composites were investigated. Overall, for both types of composites, the incorporation of the EFB into PP matrix has resulted in the improvement in the tensile modulus. However, the tensile strength, elongation at break, and impact strength decreased with increasing filler loading. Poor filler–matrix interaction or compatibility and, also, the size irregularity of the EFB are believed to be responsible for the poor ultimate performance. Composites produced by an internal mixer (IM) have displayed higher tensile strength, tensile modulus, and impact strength than with those produced by extrusion (EX). The better performance has been attributed to the effectiveness of the IM, which produces better compounding and improves the wetting of the filler surface. Incorporation of compatibilizer and coupling agent, that is, Epolene wax (E-43) and 3-Aminopropyl triethoxysilane (3-APE), respectively, have produced composites with improved tensile strength for both EX and IM composites. In addition, both types of treatment have resulted in an increase in tensile modulus of EX composites and impact strength of IM composites. Water absorption tests have revealed that the presence of coupling agents and compatibilizers have affected the amount of water absorbed, especially for the 3-APE-treated EFB–PP composites. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2647–2655, 1998     

Mechanical properties of polypropylene composite reinforced with oil palm empty fruit bunch pulp

In this study, oil palm empty fruit bunch (EFB) pulp was used as reinforcing agent in polypropylene composite. EFB pulp was prepared using soda pulping with different concentrations of sodium hydroxide (NaOH) solution. Overall, the tensile and flexural properties specifically the strength and the toughness showed improvement as the NaOH content in the treatment was increased. This was attributed to lower probability for EFB pulp to agglomerate and the production of higher aspect ratio pulp fibers. Scanning electron microscopy analysis showed evidence of the reduction in EFB bundles diameter after NaOH treatment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The effect of coupling agents on the mechanical and physical properties of oil palm empty fruit bunch–polypropylene composites

Oil palm empty fruit bunch–polypropylene (EFB‐PP) composites have been produced using a twin‐screw extruder as the compounding equipment. Two levels of EFB were employed, 40 % and 60 % of the total weight of the sample. Three types of coupling agent, maleic anhydride‐modified polypropylene (commercial name Epolene E‐43), polymethylene(polyphenyl isocyanate) (PMPPIC) and 3‐(trimethoxysilyl)‐propylmethacrylate (TPM), were used. Overall, all coupling agents imparted considerable improvements in the flexural properties, E‐43 showing the highest enhancement. However, only E‐43 was observed to improve impact strength and tensile properties of the composites. All composites with coupling agents showed lower water absorption and thickness swelling. The absorption and swelling decreased as the loading of the coupling agents was increased. © 2000 Society of Chemical Industry     

Mechanical properties and fire retardant behavior of polyurethane foam reinforced with oil palm empty fruit bunch

The objective of this study was to investigate the effects of isocyanate/hydroxyl ratio and ammonium polyphosphate (APP) content on the properties of polyurethane foam. Polyurethane (PU) foam was prepared from polymeric diphenylmethane diisocyanate and polyethylene glycol with molecular weight of 200, reinforced with oil palm empty fruit bunch (EFB) using one shot process. The effect of EFB content on the properties of PU foam was also studied. It was noticed that EFB enhanced the properties of the PU foam. This was due to EFB acting as hard segment in PU foam system. The NCO/OH ratio played an important role in determining the properties of the PU foam produced. However, since EFB is a highly flammable material, APP was introduced to the PU foam system. From the results, APP improved the fire retardant behavior of the PU foam. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Properties of nylon-6-based composite reinforced with coconut shell particles and empty fruit bunch fibres

Novel natural fibre composites of nylon-6 reinforced with coconut shell (CS) particles and empty fruit bunch (EFB) fibres have been investigated. Fillers were alkali treated before melt compounding with nylon-6. Mechanical, thermal and rheological properties of composites were measured. Tensile modulus was found to improve with both fillers up to 16% for nylon-6/CS composite and 10% for nylon-6/EFB composite, whereas a moderate increase in tensile strength was observed only with CS composites. Differences in the strengthening mechanisms were explained by the morphology of the two fillers, empty fruit bunch fibres having a weaker cellular internal structure. Observation of composite morphology using SEM showed that both fillers were highly compatible with nylon-6 due to its hydrophilic nature. Both fillers were found to cause a slight drop in crystallinity of the nylon matrix and to lower melt viscosity at typical injection moulding strain rates. Moisture absorption increased with addition of both fillers.     

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     

The effect of hexamethylene diisocyanate modified ALCELL lignin as a coupling agent on the flexural properties of oil palm empty fruit bunch – polypropylene composites

ALCELL lignin has been employed as a coupling agent in oil palm empty fruit bunch (EFB)–polypropylene (PP) composites. The lignin has been chemically modified with hexamethylene diisocyanate (HMDI). Evidence for the reaction between HMDI and lignin has been observed by using Fourier transform infrared (FTIR) analysis. The effect of lignin as a coupling agent on the flexural properties has been studied. The results show that the HMDI‐modified lignin is able to impart greater compatibility between EFB and PP. This is reflected in the greater flexural strength shown by the composites with HMDI‐modified lignin than those with the unmodified lignin. Scanning electron microscopy studies show that HMDI‐modification of lignin results in a better blending and compatibility between lignin and PP matrix. The glass transition temperature of lignin increases as the level of HMDI modification is increased. © 2001 Society of Chemical Industry     

Swelling properties of chemically modified oil palm empty fruit bunch based polyurethane composites

In this study, the diffusion of various types of solvent in oil palm empty fruit bunch/polyurethane composites, produced from chemically modified empty fruit bunches, was investigated. The solubility parameters and polymer–solvent interaction parameters of the produced composites were determined. The void contents of the composites were also determined before swelling tests to eliminate the free solvent present in the system. From the results obtained, we found that the diffusion of the solvents was dependent on the compatible group available and the voids present in the system. The solubility parameters of the empty fruit bunch/polyurethane composites with different degrees of chemical modification were 11.6 and 11.7 (cal/cm^?3)^1/2. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The effect of glycidyl methacrylate treatment of empty fruit bunch (EFB) on the properties of ultra‐violet radiation cured EFB‐unsaturated polyester composite

In this study, biofiber composites cured by ultra‐violet, were produced using pulp made from empty fruit bunch (EFB) as the reinforcing agent and unsaturated polyester as the matrix. The conversion of EFB fibers into pulp was carried out using organosolv pulping process. The EFB pulp was then chemically treated with glycidyl methacrylate (GMA) to different percentage of weight percent gain and the composites were made with different percentages of pulp loading. Results showed that the Kappa number of EFB decreased as the NaOH concentration in organosolv pulping increased. Composites which were made from GMA‐treated EFB showed better mechanical properties (tensile, flexural, and impact strength) than those of the unmodified. Fourier transform infrared spectroscopy showed peaks that proved the occurrence of grafting between GMA and OH from EFB pulp. Scanning electron microscope analysis showed the evidence of the enhancement of the compatibility between EFB and matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Acoustical,thermal, and morphological properties of zein reinforced oil palm empty fruit bunch fiber bio‐composites

In this research, biodegradable composites were prepared with zein as a polymer matrix and oil palm empty fruit bunch (OPEFB) as fiber reinforcement. The fibers were treated with sodium hydroxide (NaOH). The effects of sodium hydroxide treatment on sound absorption, thermal stability, and fiber‐polymer matrix interaction in composites were examined. The acoustical sound absorption coefficients of the composites were evaluated using two‐microphone transfer function impedance tube method. The spectral, thermal, and morphological studies of the composites were analyzed and characterized using scanning electron microscope (SEM), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy. It was found that in all the biodegradable composites, the sound absorption coefficients increased as the frequency increased. Increases in fiber loading caused sound absorption coefficients of the composites to increase. The sodium hydroxide treatment showed a better interface adhesion on fiber and zein matrix. It was also found that this treatment increased the sound absorption coefficients. This was supported by qualitative analysis on the SEM micrographs and FTIR spectrum. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44164.     

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     

Thermal and mechanical characterization of linear low‐density polyethylene/wood flour composites

A linear low‐density polyethylene (LLDPE) matrix was modified with an organic peroxide and by a reaction with maleic anhydride (MAn) and was simultaneously compounded with untreated wood flour in a twin‐screw extruder. The thermal and mechanical properties of the modified LLDPE and the resulting composites were evaluated. The degree of crystallinity was reduced in the modified LLDPE, but it increased with the addition of wood flour for the formation of the composites. Significant improvements in the tensile strength, ductility, and creep resistance were obtained for the MAn‐modified composites. This enhancement in the mechanical behavior could be attributed to an improvement in the compatibility between the filler and the matrix. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2775–2784, 2003     

Thermal,dielectric, and mechanical properties of SiC particles filled linear low‐density polyethylene composites

A thermally conductive linear low‐density polyethylene (LLDPE) composite with silicon carbide (SiC) as filler was prepared in a heat press molding. The SiC particles distributions were found to be rather uniform in matrix at both low and high filler content due to a powder mixing process employed. Differential scanning calorimeter results indicated that the SiC filler decreases the degree of crystallinity of LLDPE, and has no obvious influence on the melting temperature of LLDPE. Experimental results demonstrated that the LLDPE composites displays a high thermal conductivity of 1.48 Wm^?1 K^?1 and improved thermal stability at 55 wt % SiC content as compared to pure LLDPE. The surface treatment of SiC particles has a beneficial effect on improving the thermal conductivity. The dielectric constant and loss increased with SiC content, however, they still remained at relatively low levels (<10² Hz); whereas, the composites showed poorer mechanical properties as compared to pure LLDPE. In addition, combined use of small amount of alumina short fiber and SiC gave rise to improved overall properties of LLDPE composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Thermal and mechanical properties of woodflour/tannin adhesive composites

Composite materials formulated with a natural polyphenolic matrix (commercial tannin adhesive made from quebracho tannin extract), pine woodflour as reinforcing material, and hexamethylenetetramine as hardener were prepared and tested. Scanning electron microscopy of fractured samples was used to analyze the efficiency of the wetting and adhesion of the filler to the surrounding matrix. Thermogravimetric analysis was used in the thermal characterization of the woodflour and the tannin extract. Flexural, compression, and dynamic‐mechanical tests were performed on composites to study the relationship of the filler content and particle size with the composite final properties. Moreover, the influence of the moisture content on the physical and mechanical properties of the different composites was analyzed. Results indicated that the mechanical properties were severely affected by the absorbed moisture. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3074–3082, 2004     

Effect of fiber treatment on the mechanical properties of LDPE-henequen cellulosic fiber composites

The degree of mechanical reinforcement that could be obtained by the introduction of henequen cellulosic fibers in a low-density polyethylene, LDPE, matrix was assessed experimentally. Composite materials of LDPE-henequen cellulosic fibers were prepared by mechanical mixing. The concentration of randomly oriented fibers in the composite ranged between 0 and 30% by volume. The tensile strength of these composite materials increased up to 50% compared to that of LDPE. There is also a noticeable increase in Young's modulus for the composite materials that compares favorably with that of LDPE. As expected, the addition of the fibers decreases the ultimate strain values for the composite materials. The thermal behavior of the LDPE-henequen cellulosic fibers materials, studied by differential scanning calorimetry, DSC, showed that the presence of the fibers does not affect the thermal behavior of the LDPE matrix; thus, the interaction between fiber and matrix is probably not very intimate. Preimpregnation of the cellulosic fibers in a LDPE-xylene solution and the use of a silane coupling agent results in a small increment in the mechanical properties of the composites, which is attributed to an improvement in the interface between the fibers and the matrix. The shear properties of the composites also increased with increasing fiber content and fiber surface treatment. It was also noted that the fiber surface treatment improves fiber dispersion in the matrix. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 197–207, 1997     

Thermal and mechanical properties of polypropylene/wood‐flour composites

In this research, polypropylene/wood‐flour composites (WPCs) were blended with different contents of wood and/or maleated polypropylene (MAPP) and clay. We found that the addition of MAPP or clay in the formulation greatly improved the dispersion of the wood fibers in the composite; this suggested that MAPP or clay may have played the role of an adhesion promoter in the WPCs. The results obtained with clay indicate that it also acted as a flame retardant. The thermal tests carried out with the produced samples showed an increased crystallization temperature (T_c), crystallinity, and melting temperature (T_m) with wood loading. The increase of the two former parameters was explained by the incorporation of wood flour, which played the role of nucleating agent and induced the crystallization of the matrix polymer. On the other hand, the T_m increase was ascribed to the insulating properties of wood, which hindered the movement of heat conduction. The effects of UV irradiation on T_m and T_c were also examined. T_c increased with UV exposure time; this implied that UV degradation generated short chains with low molecular weight that could move easily in the bulk of the sample and, thus, catalyze early crystallization. The flexural strength and modulus increased with increasing wood‐flour content. In contrast, the impact strength and tensile strength and strain decreased with increasing wood‐flour content. All of these changes were related to the level of dispersion of the wood flour in the polymeric matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermal expansion and mechanical properties of phenolic resin/ZrW2O8 composites

Phenolic resin/ZrW₂O₈ composites were successfully fabricated and their coefficient of thermal expansion (CTE) as well as mechanical properties was investigated. The CTE of the composites decreases from 46 × 10^–6 to 14 × 10^–6 K^?1 when the ZrW₂O₈ volume fraction increases from 0 to 52 vol %. The CTE of the composites is analyzed by some theoretical models; Schapery's upper bound provides the best estimate of the reduction in CTE. The Barcol hardness of the composites increases with an increase in the ZrW₂O₈ volume fraction. The bending strength of the composites with 19–25 vol % of ZrW₂O₈ fillers shows a maximum value of 130 MPa, which is 45% larger than that of phenolic resin without fillers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effect of ZnO type and concentration on the mophology,thermal, and mechanical properties of poly(ether ester)/ZnO composites

Poly(ether ester) (PEE) copolymers were synthesized in a two‐stage process involving transesterification and polycondensation. The synthesized copolymer and the zinc oxide (ZnO) were used in composite preparation by melt compounding. The influence of ZnO type and concentration on the morphology, thermal and mechanical properties of the composites were studied. DSC and XRD analyses indicated that crystallinity of composites was slightly reduced with ZnO content. Homogeneous dispersion of fillers in the polymer matrix was observed through morphological analyses. While in general tensile strength and elongation at break values of the composites decreased with increasing ZnO content, elastic modulus values increased with the addition of ZnO. Moreover, ZnO particles were modified with poly(N‐vinyl pyrrolidone) and a slight improvement in mechanical properties was observed, respectively over the composites containing unmodified particles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Modification of oil palm empty fruit bunches with maleic anhydride: The effect on the tensile and dimensional stability properties of empty fruit bunch/polypropylene composites

Oil palm empty fruit bunch (EFB)‐filled polypropylene (PP) composites were produced. The EFB filler was chemically modified with maleic anhydride (MAH). The effects of the filler size and chemical modification of EFBs on the tensile and dimensional stability properties of EFB–PP composites were studied. The composites with MAH‐treated EFBs showed higher tensile strengths than those with untreated EFBs. This was attributed to the enhanced compatibility between the MAH‐treated EFBs and PP matrix, as shown in a scanning electron microscopy study. Fourier transform infrared analysis showed evidence of C?C and C?O bonds from MAH at 1630 and 1730 cm^?1, respectively. The MAH‐treated PP composites showed lower water absorption and thickness swelling than those with untreated EFBs. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 827–835, 2003