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     

Properties of silanized nypa fruticans filled polylactic acid/recycled low density polyethylene biocomposites

The biocomposites of Nypa Fruticans (NF) and Polylactic acid (PLA)/recycled low density polyethylene (rLDPE) were prepared using Brabender EC PLUS. The effect of NF content and silane coupling agent on mechanical, thermal, and morphological properties were studied. The results show that addition of NF in PLA/rLDPE biocomposites have decreased the tensile strength, elongation at break, and crystallinity of biocomposites. The Young's modulus of biocomposites and thermal stability increased with the increasing NF content. The surface of NF fillers were silanized to improved the interfacial adhesion between the NF filler and PLA/rLDPE matrix. It was found that the tensile strength, Young's modulus, crystallinity of PLA, and thermal stability of silanized biocomposites higher as compared to untreated biocomposites. The enhancement of the properties of biocomposites with silane treatment was proven by SEM studied. The silanized biocomposites showed better interfacial interaction and adhesion between NF and PLA/rLDPE matrix. POLYM. ENG. SCI., 55:1733–1740, 2015. © 2014 Society of Plastics Engineers     

Mechanical and thermal properties of coconut shell powder filled polylactic acid biocomposites: effects of the filler content and silane coupling agent

The effects of the filler content and the coupling agent 3-aminopropyltriethoxysilane (3-APE) on the mechanical properties, thermal properties, and morphologies of polylactic acid (PLA)/coconut shell powder (CSP) biocomposites were investigated. It was found that increasing the CSP content decreased the tensile strengths and elongations at break of the PLA/CSP biocomposites. However, incorporating CSP increased their modulus of elasticity. The tensile strengths and modulus of elasticity of the PLA/CSP biocomposites were enhanced by the presence of 3-APE, which can be attributed to a stronger filler–matrix interaction. The thermal stabilities of the biocomposites increased with the filler content, and they were enhanced by 3-APE treatment. Meanwhile, the presence of CSP increased the glass transition temperatures (T _g) and crystallinities (X _c) of the PLA/CSP biocomposites at a filler content of 30 php. After 3-APE treatment, T _g and X _c of the PLA/CSP biocomposites increased due to enhanced interfacial bonding. The presence of a peak crystallization temperature (T _c) for the PLA/CSP biocomposites indicated that the CSP has a nucleating effect. The melting temperatures (T _m) and the T _c values of the biocomposites were not significantly affected by the filler content and 3-APE. PLA/CSP biocomposites that had been treated with 3-APE presented the strongest filler–matrix interaction, as confirmed by SEM.     

Hybrid mathematical modeling and multi-objective optimization of mechanical properties of green composites based on starch and modified rice straw fillers

A hybrid mathematical modeling/optimization approach based on the response surface methodology (RSM) and desirability function (DF) capabilities was applied here to imitate and optimize the mechanical properties of thermoplastic starch-based biocomposites. In order to prepare the biodegradable and renewable biocomposites, rice straw (RS) was chemically modified to obtain more effective sustainable reinforcing fillers for starch, having semi-thermoset and core-shell structures. A combination of different RS products was used in the biocomposites and the composition of RS-based fillers was chosen as control variable. A series of experiments, by using RSM, were designed to assess the effects of filler loading and composition on the Young modulus, tensile strength, ultimate strain, and absorbed energy of the biocomposites. The best-fitting regression functions were identified via RSM statistical analysis and transformed into DF to optimize the desired responses concurrently. The findings demonstrate that the starch/RS product biocomposites with optimum elastic modulus (339.3 MPa), tensile strength (9.8 MPa), elongation at break (13.8%), and absorbed energy (1831.2 kJ/m²) were obtained by incorporating RS-based fillers with both semi-thermoset and core-shell structures in combination with each other at loadings of 13.5 and 6.5 phr, respectively.     

Preparation and morphological,thermal, and physicomechanical properties of polypropylene‐potato peel biocomposites

Potato peel powder (POPL), which is biodegradable, has been used as filler material in polypropylene (PP) matrix in varying concentration from 10 to 40% by weight to prepare biocomposites and investigated water absorption, physicomechanical and thermal properties. Scanning electron microscopy and X‐ray diffraction has been used for morphological characterization and crystallization studies. Flexural modulus of biocomposites increased by 40% compared with neat PP at 30% loading of POPL. Flexural strength also increased with increasing filler loading. Tensile strength of biocomposites has been observed to be comparable with neat PP up to 20% filler loading and increase in tensile modulus up to 40% was seen in biocomposites with 20% filler loading. Impact strength of biocomposites up to 20% filler loading was found to be at par with neat PP. Use of MA‐g‐PP compatibilizer in the biocomposites yielded better physico‐mechanical and thermal properties than biocomposites without compatibilizer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42445.     

Tensile properties of kenaf/unsaturated polyester composites filled with a montmorillonite filler

Kenaf/unsaturated polyester composites filled with montmorillonite (MMT) filler were produced. Overall, the study showed that, for samples with kenaf filler only, the strength properties decreased as the kenaf filler loading was increased from 40 to 60%. The increase in the kenaf filler loading reduced the amount of matrix material. This subsequently lowered the ability of the sample to absorb energy or distribute stress efficiently. However, with MMT, the tensile properties improved because of the high aspect ratio and surface area of the MMT. The study of the effect of kenaf filler size on the tensile properties showed that the samples with the smallest size (74 μm) displayed the lowest tensile properties compared to the larger ones. This was attributed to the agglomeration of the kenaf fillers. The addition of MMT resulted in an overall increase in the tensile strength of the composites compared to those without MMT. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The use of Bis-(3-triethoxysilylpropyl) tetrasulphane for surface modification of silica,ferrite and kenaf fiber filled natural rubber composites; comparison of aqueous solvent deposition,dry blend and integral blend methods

In this work, Bis-(3-triethoxysilylpropyl) tetrasulphane was employed for surface modification of silica, ferrite and kenaf fiber filled natural rubber composites using aqueous solvent deposition, dry blending and integral blend methods. The efficiency of each method and the preferred modification method for improving the mechanical performance of natural rubber composites was assessed. The appearance of the Fourier transform infrared spectroscopy peak around 1088 cm⁻¹ for all types of fillers provided evidence that silane interaction had occurred between the fillers and rubber and the formation of siloxane linkages were quantitatively determined by the crosslink density measurement. The surface treatment by dry method for silica and ferrite fillers showed significant improvement of tensile performance at approximately 67% and 34% compared to those with untreated fillers. For kenaf fiber-filled rubber composites, the surface treatment by aqueous solvent deposition showed the highest tensile improvement of 59% compared to the dry blending and integral blend method.     

PLA/Kenaf/APP Biocomposites: Effect of Alkali Treatment and Ammonium Polyphosphate (APP) on Dynamic Mechanical and Morphological Properties

Kenaf-filled polylactic acid (PLA) biocomposites were prepared using dry blending, twin screw extrusion and compression molding. PLA was blended with raw and alkali treated kenaf, polyethylene glycol and ammonium polyphosphate (APP). Dynamic mechanical properties of biocomposites were investigated by dynamic mechanical analysis. Storage modulus of composites decreased, while magnitude of damping peaks increased with increase in APP content. The T _g of composites shifted to lower values with APP addition. Alkali treatment improved interfacial adhesion between PLA and kenaf. SEM analysis indicates good dispersion of APP in PLA matrix, however interfacial adhesion between PLA and matrix decreased with increasing APP content.     

Ceramic sheet hybrid kenaf reinforced polypropylene biocomposites

Hybrid biocomposites are one of the emerging fields in polymer composites. The purpose of this study is the development and characterization of ceramic sheet (CS) hybrid polypropylene (PP) biocomposites for broadening of the field of potential applications of biocomposites. Hybrid PP biocomposites were manufactured with 20 wt % loadings of kenaf and the addition of a CS (single or double sided) by melting and compression molding. The effects of the CS on the mechanical and thermal properties of the hybrid PP biocomposites were analyzed in terms of tensile, flexural, and impact properties, and inflammability, smoke optical density, and toxicity of the combustion gas. Also, the surface morphology of fractured hybrid PP biocomposites was observed by SEM and AFM. In spite of the brittle properties of the ceramic, the mechanical properties of the hybrid PP biocomposites were improved and, also, the inflammability of the hybrid PP biocomposites with the CS was highly improved. As a result, full impregnation of CSs into the kenaf reinforced biocomposite can contribute to the improvement of both the mechanical properties and the inflammability of biocomposites, resulting in a broadening of the field of potential applications of biocomposites such as aerospace. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1917–1922, 2013     

Effective mechanical properties of polyvinylalcohol biocomposites with reinforcement of date palm leaf fibers

Polyvinylalcohol/date palm leaf fiber (PVA/DPL) biocomposites were prepared by the melt mixing fabrication technique with various proportions of fibers. DPL fibers were chemically modified with the purpose of improving the dispersion and better compatibility with PVA matrix. Different chemical processes of modification were adopted and the tensile strengths of both treated and untreated fibers were compared. It was noticed that the tensile strength of acrylic acid treated fiber was optimum in comparison to other methods. The interaction of DPL fibers with PVA matrix were studied by Fourier transforms infrared spectroscopy (FTIR). Field emission scanning electron microscope (FESEM) was used to study the morphology of biocomposites. The tensile strength, Young's modulus, elongation at break, flexural strength, and impact strength of PVA/DPL biocomposites were investigated and compared with that of virgin PVA matrix. It was found that the above properties were first increased with fiber loading and then decreased. The optimum properties were obtained at 28 wt% of DPL fiber. The storage modulus and tan delta values of PVA/DPL biocomposites were analyzed. The thermal properties of biocomposites were also studied through the results of thermogravimetric (TGA). POLYM. COMPOS., 34:959–966, 2013. © 2013 Society of Plastics Engineers     

Formulation‐properties versatility of wood fiber biocomposites based on polylactide and polylactide/thermoplastic starch blends

This article discusses the interrelation between formulation, processing, and properties of biocomposites composed of a bioplastic reinforced with wood fibers. Polylactide (PLA) and polylactide/thermoplastic starch blends (PLA/TPS) were used as polymeric matrices. Two grades of PLA, an amorphous and a semicrystalline one, were studied. TPS content in the PLA/TPS blends was set at 30, 50, and 70 wt%. Two types of wood fiber were selected, a hardwood (HW) and a softwood (SW), to investigate the effect of the fiber type on the biocomposite properties. Finally, the impact of different additives on biocomposite properties was studied with the purpose to enhance the bioplastic/wood fiber adhesion and, therefore, the final mechanical performance. The biocomposites containing 30 wt% of wood fibers were obtained by twin‐screw extrusion. The properties of the biocomposites are described in terms of morphology, thermal, rheological, and mechanical properties. Furthermore, the biocomposites were tested for humidity and water absorption and biodegradability. An almost 100% increase in elastic modulus and 25% in tensile strength were observed for PLA/wood fiber biocomposite with the best compatibilization strategy used. The presence of the TPS in the biocomposites at 30 and 50 wt% maintained the tensile strength higher or at least equal as for the virgin PLA. These superior tensile results were due to the inherent affinity between the matrices and wood fibers improved by the addition of a combination of coupling and a branching agent. In addition to their outstanding mechanical performance, the biocomposites showed high biodegradation within 60 days. POLYM. ENG. SCI., 54:1325–1340, 2014. © Her Majesty the Queen in Right of Canada 2013 ¹      

Thermal pretreatment of kudzu biomass (pueraria lobata) as filler in cost‐effective pla biocomposite fabrication process

This article aims on the fabrication of cost‐effective polylactic acid (PLA) biocomposites using kudzu biomass derivatives as new filler. In this way, it has been realized that pretreatment of the filler was an essential requirement. We demonstrated thermal pyrolysis process that targeted to extraction and isolation of all extractable and unnecessary compounds such as intracellular water and bio‐oil from the biomass. Also, to further improve the compatibility of the filler with PLA, noncatalytic thermal esterification reactions of kudzu after thermal pyrolysis (called char) were carried out as second pretreatment stage in the presence of phthalic anhydride. Kudzu derivatives obtained from either first or second pretreatment reactions were melt‐blended with PLA in various rates. The blends were then compression molded into dumbbell specimens. Physicomechanical properties of the prepared biocomposites were evaluated using several analytical techniques. It was found that biocomposites containing treated biomass had higher values of physicomechanical properties than untreated ones. The final rate of filler to PLA with acceptable properties was set up to 50%. Obviously, the cost of PLA can be reduced using higher rates of low‐cost filler on a finished‐product basis. Extracted valuable compounds from biomass via thermal pyrolysis could be another benefit of the process. POLYM. ENG. SCI., 55:340–348, 2015. © 2014 Society of Plastics Engineers     

Effects of kenaf contents and fiber orientation on physical,mechanical, and morphological properties of hybrid laminated composites for vehicle spall liners

The aim of this work is to study the effect of kenaf volume content and fiber orientation on tensile and flexural properties of kenaf/Kevlar hybrid composites. Hybrid composites were prepared by laminating aramid fabric (Kevlar 29) with kenaf in three orientations (woven, 0^o/90^o cross ply uni‐directional (UD), and non‐woven mat) with different kenaf fiber loadings from 15 to 20% and total fiber loading (Kenaf and Kevlar) of 27–49%. The void content varies between 11.5–37.7% to laminate with UD and non‐woven mat, respectively. The void content in a woven kenaf structure is 16.2%. Tensile and flexural properties of kenaf/Kevlar hybrid composites were evaluated. Results indicate that UD kenaf fibers reinforced composites display better tensile and flexural properties as compared to woven and non‐woven mat reinforced hybrid composites. It is also noticed that increasing volume fraction of kenaf fiber in hybrid composites reduces tensile and flexural properties. Tensile fracture of hybrid composites was morphologically analysed by scanning electron microscopy (SEM). SEM micrographs of Kevlar composite failed in two major modes; fiber fracture by the typical splitting process along with, extensive longitudinal matrix and interfacial shear fracture. UD kenaf structure observed a good interlayer bonding and low matrix cracking/debonding. Damage in composite with woven kenaf shows weak kenaf‐matrix bonding. Composite with kenaf mat contains the high void in laminates and poor interfacial bonding. These results motivate us to further study the potential of using kenaf in woven and UD structure in hybrid composites to improve the ballistic application, for example, vehicle spall‐liner. POLYM. COMPOS., 36:1469–1476, 2015. © 2014 Society of Plastics Engineers     

Development and study of fully biodegradable composite materials based on poly(butylene succinate) and hemp fibers or hemp shives

The use of natural fibers to reinforce polymers is an established practice, and biocomposites have gained an increased interest in areas such as automotive, construction, and agriculture. The purpose of the present work was the preparation and study of fully biodegradable (“green”) composite materials using poly(butylene succinate) (PBSu) as polymeric matrix and hemp fibers and shives as fillers. Composites containing 15, 30, 50, 60, and 70 wt% of fillers were prepared by melt mixing in a twin screw extruder. The composites were studied using Fourier transform infrared spectroscopy, X‐ray diffraction, and differential scanning calorimeter while the dispersion and interfacial adhesion were studied with scanning electron microscopy. From mechanical properties measurements, it was found that tensile and impact strength are both affected by the type and the amount of the used filler. The degree of crystallinity of PBSu was found to decrease by increasing the filler content, although that both fillers can act as nucleating agents. Finally, the degradation rate during enzymatic hydrolysis and soil burial increased in all biocomposites by increasing the filler content. PBSu/hemp shive composites showed higher biodegradation rates than PBSu/hemp fiber composites. POLYM. COMPOS., 37:407–421, 2016. © 2014 Society of Plastics Engineers     

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     

Rubber-Wood Composites from Chemically Modified Olive Husk Powder and Carboxylated Nitrile Butadiene Rubber: Cure Characteristics,Tensile Behavior,and Morphological Studies

Abstract

Olive husk powder (OHP) was chemically treated using sodium hydroxide, silane coupling agent, and stearic acid. The treatment was performed to improve both the dispersion of the OHP as well as the degree of interactions between the filler and the matrix. The treated OHP was mixed with carboxylated nitrile butadiene rubber (XNBR) using a lab-scale two roll mill. The potential of the treated filler on the cure characteristics and tensile performance of the fabricated samples was monitored. We found that the cure characteristics and the tensile properties were increased after the incorporation of the modified OHP into the matrix. The interactions between the treated OHP and the XNBR were inspected by attenuated total reflectance infrared spectroscopy (ATR-IR). The spectra revealed the emergence of a new peak at 1770 cm^?1. This suggests the occurrence of a condensation reaction between the modified OHP and the carboxylic group of the XNBR. The morphology of the fractured surfaces of the samples was inspected under scanning electron microscope (SEM). The images revealed an improved filler dispersion and better degree of interaction with the matrix after chemical modification.     

Kenaf‐filled biodegradable composites: rheological and mechanical behaviour

Biodegradable polymer composites, typically based on biodegradable polymer matrices and natural‐organic fillers, are gaining rising interest and importance over the last few years. Several natural‐organic fillers can be used but the most widespread so far is wood, in the form of fibres or flour. Alternative cellulosic fillers can ensure advantages in terms of resource utilization and properties of the final composite. In this work, Mater‐Bi^® based biodegradable composites were prepared with two kinds of wood flour, and directly compared with alternative composites containing kenaf fibres. The use of kenaf fibres allowed improved elastic modulus, tensile strength and interaction with the polymer matrix to be obtained, although the filler dispersion was worse. Rheological measurements evidenced higher viscosity and an increasingly elastic behaviour of the melt. Copyright © 2012 Society of Chemical Industry     

Effect of modification conditions of coal gangue on properties of natural rubber composites

The purpose of this work is to study the reinforcement effect of modified coal gangue (CG) on natural rubber (NR); carbon black (CB) was taken as reference filler. The addition of CG and CB to NR with the total filler loading fixed at 35 phr. The orthogonal experiment was employed to reveal the modification conditions on reinforcing properties. The results show that modification conditions such as weight ratio of coupling agent (CA), calcining temperature (CT), and calcining time (CM) affect the strengthening properties of CG, and CA is the most important factor influencing the tensile strength of NR, the order of influence can be expressed as CA > CT > CM. The optimum modification conditions are CT 800°C, CM 1 hr, and CA 2%. 300% modulus of NR composites filled with modified CG (17.5 phr)/CB (17.5phr) hybrid filler is similar to NR filled with CB alone at same filler loading, while elongation at break increases significantly for existent of CG. The effect of heat treatment and modification conditions of CG were tested by particle size distribution, scanning electron microscopy, Fourier transform infrared spectra, and X‐ray diffraction. The results show that the specific surface area of CG increased and hydroxyl group in crystal structure of CG removed under heat treatment. Dynamic mechanical analysis results show that the storage modulus and tan δ of CG filled NR composites are higher while T_g is less than that of CB, indicating the existence of a strong and stiff interface between filler and NR matrix. POLYM. COMPOS., 35:1911–1917, 2014. © 2014 Society of Plastics Engineers     

Biocomposites based on poly(lactic acid) and seaweed wastes from agar extraction: Evaluation of physicochemical properties

Seaweed waste (SWW) is a residue or by‐product from the filtration step of the agar extraction process, and it has been explored as an inexpensive and effective filler for incorporation by melt blending into a poly(lactic acid) (PLA) matrix. PLA‐SWW biocomposites were manufactured with various contents of SWW (0, 5, 10, 15, and 20 wt %) using a sheet extrusion process. PLA was functionalized with maleic anhydride (MAH) by reactive extrusion using dicumyl peroxide (DCP) as an initiator, and it was extruded using 0, 5, and 20 wt %. SWW content. The mechanical, thermal, structural, and morphological properties of the processed biocomposites were investigated. Regarding the mechanical behavior, a slight increase in the tensile modulus was observed at low SWW content. The thermal properties indicated that the rigid amorphous phase content was enhanced in the biocomposites. This work suggests that SWW can be used as filler to develop environmental friendly biocomposites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42320.     

The Properties of Woven Kenaf and Betel Palm (Areca catechu) Reinforced Unsaturated Polyester Composites

The use of woven betel palm and kenaf lignocellulosic fibers as a reinforcing phase in unsaturated polyester was reported. The morphology, physical properties, and mechanical properties of the natural fibers and resulting woven composites were evaluated. Kenaf fibers exhibit higher tensile properties than betel palm fibers due to the higher amount of cellulose content. From the morphology observation, it is found that the alkaline treatment of the fibers effectively clean the fiber surface and increase the fiber surface roughness. Comparison between treated and untreated woven betel palm and kenaf composites at 7 vol% of fiber content was carried out. Interestingly, untreated woven kenaf composites exhibit comparable flexural strength with those of untreated woven betel palm composites. However, untreated kenaf composites exhibit superior flexural modulus to those of betel palm composites. In general, mechanical properties of the woven composites made from alkali-treated fibers were superior to the untreated fibers.