Showing papers on "SISAL published in 2009"

Effect of fiber surface modification on the mechanical and water absorption characteristics of sisal/polyester composites fabricated by resin transfer molding

Abstract: Sisal fibers were subjected to various chemical and physical modifications such as mercerization, heating at 100 °C, permanganate treatment, benzoylation and silanization to improve the interfacial bonding with matrix. Composites were prepared by these fibers as reinforcement, using resin transfer molding (RTM). The mechanical properties such as tensile, flexural and impact strength were examined. Mercerized fiber-reinforced composites showed 36% of increase in tensile strength and 53% in Young’s modulus while the permanganate treated fiber-reinforced composites performed 25% increase in flexural strength. However, in the case of impact strength, the treatment has been found to cause a reduction. The water absorption study of these composites at different temperature revealed that it is less for the treated fiber-reinforced composites at all temperatures compared to the untreated one. SEM studies have been used to complement the results emanated from the evaluation of mechanical properties.

Effect of glass fiber hybridization on properties of sisal fiber–polypropylene composites

Abstract: Natural fiber reinforced polymer composites became more attractive due to their light weight, high specific strength, and environmental concern. However, some limitations such as low modulus, poor moisture resistance were reported. This study aimed to investigate the effect of glass fiber hybridization on the physical properties of sisal–polypropylene composites. Polypropylene grafted with maleic anhydride (PP-g-MA) was used as a compatibilizer to enhance the compatibility between the fibers and polypropylene. Incorporating glass fiber into the sisal–polypropylene composites enhanced tensile, flexural, and impact strength without having significant effect on tensile and flexural moduli. In addition, adding glass fiber improved thermal properties and water resistance of the composites.

Effect of moisture absorption on the mechanical properties of randomly oriented natural fibers/polyester hybrid composite

Abstract: In this work, the variation of mechanical properties such as tensile, flexural, and impact strengths of roselle and sisal fibers hybrid polyester composite at dry and wet conditions were studied. The composites of roselle/sisal polyester-based hybrid composites with different weight% of fibers were prepared. Roselle and sisal fibers at a ratio of 1:1 had been incorporated in unsaturated polyester resin at various fiber lengths. When the fiber content and length of the roselle and sisal fibers were increased, the tensile and flexural strength of the composite increased. When the samples were subjected to moisture environment, decrease in tensile and flexural strength was observed. The maximum percentage of strength reductions in tensile and flexural strength were observed for the composites having the fiber length of 150 mm and 30 wt% fiber content. For impact strength, it was with the composites of 20 wt% and 150 mm at wet conditions compared to dry conditions. The percentage of strength reductions increased with fiber content and length in wet conditions. A scatter in the impact strength values was identified on both the conditions. The moisture absorption characteristics of the natural fibers are very important to produce the natural fiber hybrid composite materials with the positive hybrid effect. The experimental results are compared with theoretical and empirical or statistical results and found to be in good agreement.

Tensile Testing of Cellulose Based Natural Fibers for Structural Composite Applications

Abstract: A series of tensile tests were conducted on a Lloyd LRX tensile testing machine for numerous natural fibers deemed potential candidates for development in composite applications. The tensile tests were conducted on the fibers jute, kenaf, flax, abaca, sisal, hemp, and coir for samples exposed to moisture conditions of (1) room temperature and humidity, (2) 65% moisture content, (3) 90% moisture content, and (4) soaked fiber. These seven fibers were then tested for the four conditions and the mechanical properties of tensile strength, tensile strain to failure, and Young's modulus were calculated for the results. These results were then compared and verified with those from the literature, with some of the fibers showing distinctly promising potential. Additionally, a study on the effect of alkalization using 3% NaOH solution was carried out on flax, kenaf, abaca, and sisal to observe impact that this common fiber pre-treatment process has on fiber mechanical properties. The result of the investigation indicated that over treatment of natural fibers using NaOH could have a negative effect on the base fiber properties. It is consequently apparent that a treatment time of less than 10 min is sufficient to remove hemicelluloses and to give the optimum effect.

Cracking mechanisms in durable sisal fiber reinforced cement composites

Abstract: Fiber reinforced cement composite laminates with long sisal fibers were manufactured using a cast hand lay up technique. A matrix with partial cement replacement by metakaolin and calcined waste crushed clay brick was used in order to improve the durability aspects. Mechanical response was measured under tension and bending tests while crack formation was investigated using a high resolution image capturing procedure. Crack spacing was measured using image analysis and correlated with the applied strain under both the tensile and bending response. Various stages of loading corresponding to initiation, propagation, distribution, opening, and localization of a crack system in the specimen are discussed. The effect of flexural cracking on the location of neutral axis during the bending tests was measured using strain-gages.

Mechanical properties and flammability of sisal/PP composites: Effect of flame retardant type and content

Abstract: In this research, magnesium hydroxide (Mg(OH) 2 ) and zinc borate, as flame retardants, were incorporated into sisal/PP composites. Maleic anhydride grafted polypropylene was also used as a compatibilizer. Adding flame retardants into sisal/PP composites reduced burning rate and increased thermal stability of the composites. No synergistic effect was observed when both magnesium hydroxide and zinc borate were incorporated in the sisal/PP composites. In addition, the sisal/PP composites exhibited insignificant difference of shear viscosity at high shear rate indicating that types of flame retardants used in this study had no impact on the processability of the composites. Good distribution of flame retardants and sisal fiber in PP matrix was also observed. All PP composites had lower impact strength than the neat PP. However, the sisal/PP composites with the addition of Mg(OH) 2 and zinc borate exhibited comparable tensile and flexural properties to the sisal/PP composites without adding those flame retardants. Therefore, the addition of Mg(OH) 2 and zinc borate enhanced flame retardancy of sisal/PP composites without sacrificing their mechanical properties.

Mechanical property improvement of unsaturated polyester composite reinforced with admicellar-treated sisal fibers

Abstract: Sisal fiber was treated by admicellar polymerization with a poly(methyl methacrylate) film coating in order to enhance the interfacial adhesion of the fiber/polymer composite for mechanical property improvement. Properties of the admicellar-treated sisal fiber were investigated by measuring its moisture absorption and electrostatic charge. Thermal stability study by thermogravimetric analysis and film identification by FTIR was also carried out. The treatment was shown to improve the tensile and flexural properties, impact strength, and hardness of the composite. SEM micrographs of the tensile fracture surface of sisal/unsaturated polyester composites also show interfacial adhesion improvement of the composite prepared with admicellar-treated sisal.

Caracterização química e estrutural de fibra de sisal da variedade Agave sisalana

Abstract: In recent years, the interest in the use of natural fibers in polymeric composite materials has increased significantly. In this work were investigated the structural, thermal, chemical, and physical properties of Brazilian sisal fiber from Agave sisalana variety. Our aim was to evaluate the quality and the performance of this fiber for industrial applications. Mechanical properties, chemical composition, X ray diffraction, and scanning electron microscopy (SEM) have been investigated with fibers along their length. The Brazilian sisal fibers studied have exhibited mechanical and thermal properties within the range reported in the literature and were suitable for use in polymeric composites.

A Study on Hardness and Flexural Properties of Kapok/Sisal Composites

Abstract: The natural fiber composites based on kapok/sisal and its hybrid composites with polyester as resin matrix have been prepared and tested for mechanical properties. In this paper hardness and flexural properties of kapok/sisal composites were determined with reference to the fabrics content and varying the volume ratios of fabrics. The maximum strength in the properties determined is observed for the optimum fabric loadings. The effect of alkali treatment of fabrics on polyester composites reinforced with kapok/sisal fabrics was studied. Increasing the sisal fiber content resulted in a reduction in the hardness and flexural properties. The properties were found to increase with alkali treated fabrics used in composite. The properties of kapok/polyester composites are found to be better than those of kapok/sisal polyester composites.

Influence of alkali-treated fibers on the mechanical properties and machinability of roselle and sisal fiber hybrid polyester composite

Abstract: In this work, the alkali-treated roselle and sisal fibers were used as reinforcement fillers for thermosetting matrix with aim of obtaining better mechanical properties and machinability of natural fiber hybrid polyester composite. However, their mechanical properties and machinability were compared with untreated fiber composites. The roselle and the sisal fibers were subjected to a 10% sodium hydroxide solution treatment at different duration of 2, 4, 6, and 8 h. Besides, the fractured surfaces of composite specimen were investigated using scanning electron microscopy. Drill hole profiles were analyzed using profile projector and machine vision inspection system. An improvement in strength and stiffness combined with high toughness was achieved by treating the fibers using 10% NaOH solution. POLYM. COMPOS., 31:723–731, 2010. a 2009 Society of Plastics Engineers

Experimental determination of tensile properties of okra, sisal and banana fiber reinforced polyester composites

Abstract: Increasing the needs for different engineering applications invite the development of new materials. In the present research new natural fiber okra was introduced for the preparation of okra fiber reinforced polyester (FRP) composites. Already established fibers sisal and banana were also extracted for the preparation of sisal and banana FRP composites and to determine tensile properties. The tensile properties of okra FRP composites were compared with sisal and banana FRP composites. Hand lay-up technique was used for the preparation of composites. Chemically treated okra fiber reinforced polyester composites at maximum volume fraction showed tensile strength, modulus of 154.17%, 114.13% and specific tensile strength and modulus of 12.26%, 129.82% higher than that of the pure polyester specimen, respectively.

Permeability of Hybrid Reinforcements and Mechanical Properties of their Composites Molded by Resin Transfer Molding

Abstract: The aim of this study was to carry out RTM experiments to determine in-plane permeability of glass mats, non-woven polypropylene flow media (PP) and hybrids (glass þ PP), with different stacking sequences, and to compare these with various sisal mats and hybrids (glass þ sisal). RTM composites were also molded. Permeability decreased for higher fiber content and, for the same fiber volume content, the permeability of the sisal mats was much higher than that of glass mats and also higher than that of the PP non-woven core, often used as an infiltration medium. Besides, a tendency of increasing permeability with sisal fiber length (up to 30 mm) was noticed. The use of the sisal mat as a flow medium increased the permeability of the hybrid reinforcement and slightly improved the mechanical properties of the composite. Hence, the sisal mat may be indicated in engineering applications as a substitute for commercial flow media, widely used in the process called RTM light.

Flexural, Compressive, and Interlaminar Shear Strength Properties of Kapok/Glass Composites:

Abstract: The unsaturated polyester-based hybrid composites were developed by combining the kapok and glass fabrics into polyester matrix. This study describes the flexural, compressive, and interlaminar shear resistance properties of kapok/glass polyester composites with and without alkali treatment of fabrics. These properties increase with increasing glass fabric content in composite. The mechanical performance of kapok/glass composites is excellent. The kapok/glass hybrid composites exhibited higher flexural and compressive values than sisal/glass and kapok/sisal composites.

Natural fiber hybrid composites—A comparison between compression molding and resin transfer molding

Abstract: Short randomly oriented intimately mixed banana and sisal hybrid fiber-reinforced polyester composites having varying volume fraction of fiber were fabricated by compression molding (CM) and resin transfer molding (RTM) techniques by keeping the volume ratio of banana and sisal, 1:1. The static mechanical properties such as tensile, flexural, and impact behavior were studied. The dynamic mechanical properties were also evaluated. Resin transfer molded composites showed enhanced static and dynamic mechanical properties, compared with the compression molded samples. To analyze the fracture surface morphology of the composites, scanning electron microscopy (SEM) was also performed. Water sorption studies revealed that the water uptake of RTM fabricated composites was lower than that of the compression molded composites. The void content of the RTM composites was also found to be lower than that of the other one. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers

Effect of Coconut, Sisal and Jute Fibers on the Properties of Starch/Gluten/Glycerol Matrix

Abstract: Coconut, sisal and jute fibers were added as reinforcement materials in a biodegradable polymer matrix comprised of starch/gluten/glycerol. The content of fibers used in the composites varied from 5% to 30% by weight of the total polymers (starch and gluten). Materials were processed in a Haake torque rheometer (120 °C, 50 rpm) for 6 min. The mixtures obtained were molded by heat compression and further characterized. Addition of lignocellulosic fibers in the matrix decreased the water absorption at equilibrium. The diffusion coefficient decreased sharply around 5% fiber concentration, and further fiber additions caused only small variations. The thermogravimetric (TG) analysis revealed improved thermal stability of matrix upon addition of fibers. The Young’s modulus and ultimate tensile strength increased with fiber content in the matrix. The storage modulus increased with increasing fiber content, whereas tanδ curves decreased, confirming the reinforcing effect of the fibers. Morphology of the composites analyzed under the scanning electron microscope (SEM) exhibited good interfacial adhesion between the matrix and the added fibers. Matrix degraded rapidly in compost, and addition of increased amounts of coconut fiber in the matrix caused a slowdown the biodegradability of the matrix.

Studies on mechanical properties of sisal fiber/phenol formaldehyde resin in-situ composites

Abstract: Phenol formaldehyde resin (PF) reinforced with short sisal fibers (SF) were obtained by two methods, direct-mixing and polymerization filling. Impact and bending properties of resulting composites were compared. Under the same compression molding conditions, polymerization filled composites showed better mechanical properties than those of direct-mixed composites. The influences of fiber modifications on the mechanical properties of SF/PF in-situ (polymerization filled) composites have been investigated. Treated-SF-reinforced composites have better mechanical properties than those of untreated-SF-reinforced composites. The effects of SF on water absorption tendencies of SF/PF composites have also been studied. In addition, sisal/glass (SF/GF) hybrid PF composites of alkali-treated SF were prepared. Scanning electron microscopic studies were carried out to study the fiber-matrix adhesion. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Sisal organosolv pulp as reinforcement for cement based composites

Abstract: The present work describes non-conventional sisal (Agave sisalana) chemical (organosolv) pulp from residues of cordage as reinforcement to cement based materials. Sisal organosolv pulp was produced in a 1:1 ethanol/water mixture and post chemically and physically characterized in order to compare its properties with sisal kraft pulp. Cement based composites reinforced with organosolv or kraft pulps and combined with polypropylene (PP) fibres were produced by the slurry de-watering and pressing method as a crude simulation of the Hatschek process. Composites were evaluated at 28 days of age, after exposition to accelerated carbonation and after 100 soak/dry cycles. Composites containing organosolv pulp presented lower mechanical strength, water absorption and apparent porosity than composites reinforced with kraft pulp. The best mechanical performance after ageing was also achieved by samples reinforced with kraft pulp. The addition of PP fibres favoured the maintenance of toughness after ageing. Accelerated carbonation promoted the densification of the composites reinforced with sisal organosolv + PP fibres.

Compressive, Chemical Resistance, and Thermal Studies on Kapok/Sisal Fabrics Polyester Composites

Abstract: The naturally occurring fabrics belonging to the species Ceiba pentandra and Agave Vera Cruz were used as reinforcements in the present study. The unsaturated polyester (UP) resin based kapok/sisal...

Plant oil-based biofoam composites with balanced performance

Abstract: BACKGROUND: Biofoam composites were prepared using short sisal fibers as reinforcement and acrylated epoxidized soybean oil as matrix, aiming at replacing traditional unsaturated polyester foams in structural applications. The compressive properties of the composites were examined as a function of fiber loading, fiber length and foam density. RESULTS: The foam composite with 10 phr (parts per hundred of base resin by weight) sisal fiber possessed properties similar to those of commercial unsaturated polyester foams. A study of the failure mechanism revealed that debonding between fiber and matrix was a key issue responsible for catastrophic damage of the composites. According to this finding, surface pre-treatment of the sisal using an alkali or silane coupling agent was carried out. This brought about positive effects on interfacial interaction and compressive strength of the composites, as desired. Also, soil burial tests proved that the foam composites could be biodegraded, and the incorporated sisal fibers accelerated the biodegradation of the composites. CONCLUSION: This work shows the feasibility of making rigid biofoams from natural resources, which could be potential candidates for structural foams. Copyright © 2009 Society of Chemical Industry

Influence of Water Absorption and Pre-drying Conditions on the Tensile Mechanical Properties of Hybrid Lignocellulosic Fiber/Polyester Composites

Abstract: It is well known that humidity can deleteriously affect composite mechanical properties. In the present study the tensile properties of hybrid jute/cotton and sisal/cotton fabrics-polyester matrix composites were analyzed as a function of fiber content, immersion time in distilled water and of fabric drying just prior to composite manufacture. The results indicate that, as expected, tensile properties increase with fiber content, and that sisal reinforced composites were slightly more affected by water exposure than jute reinforced ones. This behavior was attributed to the higher affinity of sisal fibers toward water absorption. Fabric drying immediately before their incorporation onto the composites was shown to play an important role on composite mechanical properties. Fabric pre-drying led to composites with lower water absorption and higher overall mechanical properties. These composites also displayed a smaller strain at rupture, evincing better fiber to polymer matrix interaction. The data obtained suggests that water acts as a plasticizer for the systems investigated and that plasticization occurred in the early stages of composite immersion in water.

Comparison of interfacial shear strength from fibre pull out and mechanical testing in polypropylene sisal composites

Abstract: In this work we investigated the interfacial shear strength for the system sisal polypropylene. Composites containing different chop lengths were produced via extrusion and injection moulding. These test specimens were investigated for tensile and impact properties, as well as the final fibre length in the composite was determined. A simple rule of mixtures model was applied to evaluate the mechanical testing for the interfacial shear strength, which was compared with the one retrieved from single fibre pull out tests. We found good applicability of the rule of mixtures to evaluate the composite for the interfacial shear strength.

Performance of a sisal fibre fixed-bed anaerobic digester for biogas production from sisal pulp waste

Abstract: A single stage anaerobic digester employing a sisal fibre waste fixed bed was studied for biogas production from sisal pulp waste. The fibre was colonized by microorganisms involved in biogas production. The sisal pulp waste to be digested was fed from the top and was sprinkled intermittently with recirculating leachate from the material. Organic loading rates of 0.1-10 kg volatile solids (VS) m-3d-1 could be applied and methane yields in the range of 0.13-0.48 m3 CH4 kg-1 VS added were obtained. The average methane content in the biogas produced from sisal pulp waste was 55%, and the biogas production rate was 0.15-0.54 m3m-3d-1. The methane yield obtained and the highest organic loading rate that could be sustained by this simple, fixed-bed digester are indications of an attractive system in terms of performance and reliability. It is concluded that the sisal fibre waste fixed bed is a promising carrier for microbes and can be employed for long-term operation without changing the bed.

Advances in Natural Fiber Cement Composites: A Material for the Sustainable Construction Industry

Abstract: The need for economical, sustainable, safe, and secure shelter is an inherent global problem and numerous challenges remain in order to produce environmentally friendly construction products which are structurally safe and durable. The use of sisal, a natural fiber with enhanced mechanical performance, as reinforcement in a cement based matrix has shown to be a promising opportunity. This work addresses the development and advances of strain hardening cement composites using sisal fiber as reinforcement. Sisal fibers were used as a fabric to reinforce a multi-layer cementitious composite with a low content of Portland cement. Monotonic direct tensile tests were performed in the composites. The crack spacing during tension was measured by image analysis and correlated to strain. Local and global deformation was addressed. To demonstrate the high performance of the developed composite in long term applications, its resistance to tensile fatigue cycles was investigated. The composites were subjected to tensile fatigue load with maximum stresses ranging from 4 to 9.6 MPa at a frequency of 2 Hz. The composites did not fatigue below a maximum fatigue level of 6 MPa up to 10 cycles. Monotonic tensile testing was performed for composites that survived 10 cycles to determine its residual strength.

Stretch Properties of Cotton Hollow Yarns Made by Hybrid Open-End Rotor Spinning Frame

Abstract: Many yarns are made from chemical fibers with various kinds of functional properties, and filament yarn surpasses spun yarn in terms of mechanical properties. However, in this century, “comfort”, “safety”, “user-friendly” and “green” are key concepts. The Food and Agriculture Organization of the United Nations (FAO) officially launched the International Year of Natural Fibers (IYNF) 2009 to celebrate the virtues of cotton, flax, sisal and hemp, and also those of wool, alpaca, camel hair and angora. In order to make effective use of natural fibers and reduce carbon dioxide emission, it is worthwhile to design and develop new spun yarns from vegetable fibers.It is also known that, in comparison with ring spun yarn, open-end spun yarn is inferior in quality. So, to produce open-end rotor spun yarn with novel functional properties, we investigated how to give it greater extension (and/or stretch), as in synthetic filament yarn. Thus, 100% cotton hollow yarns were produced using a hybrid open-end rotor spinning frame and an experimental covering machine, and the resulting mechanical properties were assessed.

Amethod for preparing kenaf and polypropylene biocomposites

Abstract: PURPOSE: A method for producing natural fiber and polypropylene biocomposites is provided to introduce natural single fiber into polypropylene through biaxial extrusion technology. CONSTITUTION: A method for producing natural fiber and polypropylene biocomposites comprises the following steps of: reforming the surface of natural fiber such as kenaf, jute, coir, rice straw, sisal, flax, hemp, and banana using electron beam; mixing the surface-treated natural fiber and polypropylene composite in a biaxial extruder; and compression-molding or extruding the mixed composites in order to produce biocomposites.