Showing papers on "SISAL published in 2003"

The thermal and crystallisation studies of short sisal fibre reinforced polypropylene composites

Abstract: The thermal and crystallisation behaviour of sisal/PP composites was studied by thermogravimetry (TG), differential scanning calorimetry (DSC) and polarising optical microscopy. Chemical modifications were made to sisal fibre using a urethane derivative of polypropylene glycol (PPG/TDI), maleic anhydride modified polypropylene (MAPP), and KMnO4 in order to improve the interfacial adhesion between the fibre and matrix. The thermal properties of the blends were analysed by TG analysis. The effects of fibre content and chemical treatments on the thermal properties were evaluated. It was found that treated fibre composites show superior properties compared to the untreated system. DSC measurements exhibited an increase in the crystallisation temperature and crystallinity, upon the addition of fibres to the PP matrix. This is attributed to the nucleating effects of the fibre surfaces, resulting in the formation of transcrystalline regions. On increasing the fibre content, the melting peak of the PP component was shifted to higher temperatures suggesting a constrained melting. The thickness of the transcrystalline layer formed depends on crystallisation temperature and time. The transcrystalline growth rate was slow in the quiescent state. On the other hand, upon the application of stress, transcrystallinity developed quickly. In fact, the shear stress at the polymer/fibre interface initiated the nucleation. Fibre surface modification by PPG/TDI increases the nucleating ability of sisal fibre to a very small extent.

Dynamic mechanical properties of short sisal fibre reinforced polypropylene composites

Abstract: The dynamic mechanical properties of short sisal fibre reinforced polypropylene composites containing both untreated and treated fibres have been studied with reference to fibre loading, fibre length, chemical treatments, frequency and temperature. By the incorporation of short sisal fibre into polypropylene, the storage moduli ( E ′)and loss moduli ( E ″) have been found to be increasing whereas the mechanical loss factor (tan δ ) decreasing. The storage modulus decreases with increase in temperature. The treated fibre composites show better properties compared to untreated system. The Arrhenius relationship has been used to calculate the activation energy for the glass transition. The use and limitations of various theoretical equations to predict the tan δ and storage modulus of the fibre reinforced plastic composites have been discussed. Cole–Cole analysis has been carried out to understand the phase behaviour of the composite samples. A master curve for the modulus of the blend is drawn by applying the time–temperature super position principle.

Mechanical Properties and Water Absorption Behavior of Composites Made from a Biodegradable Matrix and Alkaline-Treated Sisal Fibers

Abstract: Biocomposites were produced using a biodegradable material as matrix, and sisal fibers as reinforcement. The biodegradable material is a commercial product called MaterBi-Y, which is based on a cellulose derivatives and starch system. The characterization of these biocomposites was not done before and it is necessary in order to select a material instead of nonbiodegradable matrices. An alkaline treatment was performed in order to improve the mechanical properties of the fiber. The effect of the treatment on fiber properties and on impact, flexural, and tensile properties of composites were determined. Fiber content enhances the tensile properties of the biodegradable matrix. Water sorption studies were performed. The experimentally observed tensile properties (modulus and tensile strength) of short sisal fiber-reinforced cellulose derivatives/starch composites with different fiber loading are compared with the calculated values obtained from the existing theories of reinforcement.

Potential of alternative fibre cements as building materials for developing areas

Abstract: This project evaluated the performance of thin fibre-cement elements produced from alternative raw materials using the Hatschek process, with a view to their use in low-cost housing. Sisal and banana fibres were prepared using mechanical and kraft pulping procedures while residual Eucalyptus grandis pulp was obtained from a commercial pulp mill. Granulated blast furnace slag (BFS) was used as the major component of an alternative hydraulic binder and ordinary Portland cement as a control. Composites were prepared using a slurry vacuum de-watering process, pressing and air-curing. At fibre contents of 8–12% by mass, moduli of rupture (MOR) up to 23 MPa and fracture toughness (FT) values in the range of 0.6–1.7 kJ/m2 were obtained at 28 days. After 12 months of exposure under temperate and tropical conditions, the MOR of the BFS-based composites had decreased to values in the range of 6.6–10.1 MPa. FT values remained stable or even increased with the weathering exposure. The results indicate that the mechanical performance of the composites being studied is currently satisfactory, but further optimisation of formulation and processing parameters should be investigated.

Mechanically pulped sisal as reinforcement in cementitious matrices

Abstract: The performance as reinforcement of fibres obtained from commercial and by-product sisal (Agave sisalana) by thermomechanical pulping and chemi-thermomechanical pulping (CTMP) processes was investigated. Ordinary Portland cement (OPC) and chemically activated blast furnace slag (BFS) were examined as binders. The flexural strengths of OPC- and BFS-based composites incorporating 8% fibre reinforcement by mass were similar at 28 days and ranged from 18 to 22 MPa. Corresponding modulus of elasticity values were in the region of 11 GPa for the OPC-based composites and 7 GPa for the BFS-based composites. Water absorption values at 8% fibre content lay in the range of 21–31% by mass and density values in the region of 1.5 g/cm3. Fracture toughness increased with fibre content, reaching a value of 1.6 kJ/m2 at a content of 12% in the case of by-product sisal CTMP in the BFS matrix. Scanning electron microscopy provided interfacial bonding information that can be related to the mechanical performance of these fibre-reinforced pastes.

Application of the solvent dimethyl sulfoxide/tetrabutyl-ammonium fluoride trihydrate as reaction medium for the homogeneous acylation of Sisal cellulose

Abstract: Two types of Sisal cellulose were studied as starting material for homogeneous acylation in the solvent dimethyl sulfoxide (DMSO)/tetrabutylammonium fluoride trihydrate (TBAF) The native Sisal cellulose investigated contains 14% hemicellulose (mainly composed of xylose) as confirmed by 13C-NMR spectroscopy in DMSO-d6/TBAF and HPLC analysis after complete polymer degradation Alkali treatment of Sisal cellulose decreases the amount of hemicellulose, the degree of polymerization and the crystallinity Both Sisal cellulose samples can be dissolved in DMSO/TBAF after treatment at elevated temperature GPC measurements showed high aggregation in the solution Different homogeneous acylation reactions using carboxylic acid anhydrides and vinyl esters were carried out, showing a pronounced tendency of the anhydride towards hydrolysis in the solvent This disadvantage can be diminished by decreasing the amount of the salt hydrate (TBAF trihydrate) or by a distillative removal of the majority of water A strong interaction of the polymer with the water in the solvent was observed

Mechanical properties of short sisal fiber-reinforced polypropylene composites: Comparison of experimental data with theoretical predictions

Abstract: Sisal fibers were used for the reinforcement of a polypropylene (pp) matrix. Composites consisting of polypropylene reinforced with short sisal fibers were prepared by melt-mixing and solution-mixing methods. A large amount of fiber breakage was observed during melt mixing. The fiber breakage analysis during composite preparation by melt mixing was carried out using optical microscopy. A polynomial equation was used to model the fiber-length distribution during melt mixing. The experimental mechanical properties of sisal/PP composites were compared with existing theoretical models such as the modified rule of mixtures, parallel and series models, the Hirsch model, and the Bowyer–Baders model. The dependence of the tensile strength on the angle of measurement with respect to fiber orientation also was modeled. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 602–611, 2003

Effect of interface modification on the mechanical properties of polystyrene‐sisal fiber composites

Abstract: The effect of interface modification on the mechanical (tensile, impact and flexural) properties of polystyrene-sisal fiber composites was investigated. The interface modification was performed by treatment of sisal fibers with benzoyl chloride, polystyrene maleic anhydride (PSMA), toluene diisocyanate (TDI), methyl triethoxy silane and triethoxy octyl silane. These interface modifications improve the compatibility of hydrophilic sisal fiber with a hydrophobic polystyrene matrix and change the tensile, impact and flexural properties of the composite, but to varying degrees depending on the fiber modification. The treated fibers were analyzed by spectroscopic techniques. Scanning electron microscopy was used to investigate the fiber surface, fiber pullout, and fiber-matrix interface.

Tire rubber–sisal composites: Effect of mercerization and acetylation on reinforcement

Abstract: Tire rubber particles were mixed randomly with short sisal fibers and hot pressed. Sisal fibers were used as received, mercerized, and mercerized/acetylated. The fibers were characterized by scanning electron microscopy (SEM), thermal gravimetry analysis (TGA), infrared spectroscopy (FTIR), water sorption, and mechanical properties. Thermal stability of the mercerized/acetylated fibers improves (from 200 to 300°C) with respect to the raw fibers, and water sorption is ∼ 20% smaller than for the raw and the mercerized fibers. Tensile strength is unchanged after the chemical treatments. Water sorption, mechanical properties, and SEM evaluated the performance of the tire rubber composites. All composites showed enhanced elastic modulus; increase is dependent on fiber load. Smallest water sorption was obtained in composites with the mercerized/acetylated fibers. With these fibers at 10% load, the best results were obtained with the smaller tire rubber particles (320 μm) and at 5% load with the bigger (740 μm) tire rubber particles. Both composites showed ∼ 50% increase in tensile strength when compared to similar composites with raw fibers. SEM of the surface of fracture showed that the adhesion between fiber and rubber was enhanced after both chemical treatments. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2507–2515, 2003

Reinforcement of polypropylene using sisal fibers grafted with poly(methyl methacrylate)

Abstract: Sisal fiber (SF) surface modification was carried out by grafting with methyl methacrylate (MMA) using cerium and ammonium nitrate as initiator. The effects of reaction time, monomer, and initiator concentration on the grafting parameters were systematically investigated. The results showed that MMA was successfully grafted onto the sisal fiber surface. The PMMA-grafted sisal fibers were melt blended with polypropylene (PP) and then injection molded. The PP/SF composites were characterized by means of thermal analysis, mechanical testing, wide-angle X-ray diffraction, and SEM examination. PMMA grafted onto the surface of SF enhanced the intermolecular interaction between the reinforcing SF and PP matrix, improved the dispersion of SF in the PP matrix, and promoted the formation of β-crystalline PP. These enhanced the thermal stability and mechanical properties of PP/SF composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1055–1064, 2003

Polyester moulding compounds of natural fibres and wollastonite

Abstract: Combination of natural fibres and wollastonite whiskers has been attempted as an alternative to glass fibre reinforcement in polyester dough moulding compounds. Natural fibres (sisal) and wollastonite were surface-modified with polyester compatible neo pentyl (diallyl) oxy, tri (dioctyl) pyro-phosphato titanate and gamma-methacryloxy propyl trimethoxy silane coupling agents, respectively. Reinforcing effect of wollastonite to a level of ∼50 wt% in an unsaturated polyester resin reveals a positive indication because of its favourable physico-mechanical properties and microstructural features. The optimization of short sisal and glass fibres in wollastonite/polyester system was carried out to formulate a doughy compound. It was found that ∼11 wt% sisal fibres in wollastonite/polyester and ∼3 to 5 wt% glass fibres in sisal/wollastonite/polyester give the optimum results. The high loss area observed at α and β transitions in dynamic mechanical analyser (DMA) traces supported the elastic behaviour of sisal/wollastonite/polyester moulding compared to corresponding wollastonite/polyester system. Based on these findings, a dough composition has been formulated and its suitability was assessed vis-a-vis to glass fibre–dough moulding compounds. It is observed that polyester dough moulding compound prepared from sisal/wollastonite reinforcement gives satisfactory results.

Influence of fiber volume fraction and aspect ratio in resol–sisal composites

Abstract: Vegetable fibers are being used as reinforcements in polymeric matrices with a wide variety of applications. Among these fibers, sisal is of particular interest due to the high impact strength and moderate tensile and flexural properties of its derivated composites. Because of its low cost and affinity, a phenol–formaldehyde resin, resol, has been selected as the matrix to obtain resol–sisal composites. The influence of fiber length and volume fraction on flexural properties has been studied. An optimum for the fiber length as well as for the fiber volume fraction was found. The improvement of the properties occurred up to a length of about 23 mm. The use of longer fibers lead to reduced properties because they tended to curl and bend during processing. Besides, actual composite densities were lower than theoretical ones mainly due to the presence of voids. This undesirable porosity produced a reduction in flexural properties at high fiber contents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2714–2722, 2003

All-plant fiber composites. II: Water absorption behavior and biodegradability of unidirectional sisal fiber reinforced benzylated wood

Abstract: Sisal fiber reinforced benzylated fir sawdust composites belong to a new category of composite materials, in which both the reinforcement and matrix are based on plant fibers, i.e. renewable resources. The present paper discusses the water absorption behavior of the composites and its influence on the mechanical properties of the composites. In addition, biodegradability of the composites is assessed by using enzyme and fungi tests, respectively. The experimental results indicate that water absorption behavior of the composites is mainly controlled by the reinforcing fiber and the fiber/matrix interfacial characteristics. The inherent biodegradability of the raw materials of the all-plant fiber composites proves to be retained. During the tests of enzymolysis and biodeterioration in soil, damage of the composites was initiated either inside the sisal fiber or at the surface of the composites.

Composites based on eucalyptus tar pitch/castor oil polyurethane and short sisal fibers

Abstract: Polymeric materials are being developed with renewable resources to promote industrial progress with environmentally friendly technologies. For this reason, polyurethane samples were prepared with 4,4′-diphenylmethane diisocyanate (NCO/OH = 1), eucalyptus tar pitch (biopitch), castor oil as a polyol, and dibutyltin dilaurate as a catalyst. These materials were reinforced with different contents of short sisal fibers (0, 2.5, 5.0, 7.5, and 10.0%) and were prepared by resin-transfer molding. The composites were characterized by IR absorption spectroscopy, thermal analysis (thermogravimetry and differential scanning calorimetry), impact resistance, scanning electron microscopy, and water absorption resistance. These materials showed hydrophobic characteristics, despite the addition of sisal fibers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3797–3802, 2003

Mechanical behavior of cold plasma–treated sisal and high‐density polyethylene composites

Abstract: Sisal fibers and finely powdered high-density polyethylene were surface functionalized with dichlorosilane on a RF(radio frequency)-plasma reactor. Composites made from sisal and high-density polyethylene were compounded using a thermokinetic mixer. The discharged mass was cooled, granulated, and injected molded into composite specimens for testing. The mechanical behaviors (tensile, impact and thermal dynamical mechanical properties) of composites made from cold plasma-treated and untreated components are compared and discussed. The best mechanical performance was generally obtained for composites where only the inert thermoplastic matrix was plasma-functionalized. Plasma treatment of lignocellulosic fibers seems to induce decomposition processes of the surface layers structures exposed to the plasma that generally does not contribute to significant improvement on the mechanical behavior of the composite.

Effect of a Two Step Fiber Treatment on the Flexural Mechanical Properties of Sisal-polyester Composites

Abstract: Sisal fibers were chemically treated with a two-step treatment (first sodium sulfide aqueous solution and then acetic anhydride/acetic acid mixture) to promote better adhesion to a polyester resin matrix. The flexural behaviour of the composites was analyzed as a function of the time of immersion in distilled water, and there was an improvement for short times of immersion. The long term behaviour of the treated composites was, however, no better than that of the untreated ones. This could be because of the controlling role of plasticization of both the fibers and the resin matrix for the longer times of immersion.

Machinable light weight sisal-based concrete structural building material

Abstract: A machinable light weight sisal-based concrete structural building material and a method of making the same are disclosed. The material includes short sisal fibers in a range from about 22% (v/v) to about 33% (v/v); a cement in a range from about 12% (v/v) to about 22% (v/v); and perlite in a range from about 51% (v/v) to about 59% (v/v). The method includes the steps of mixing an amount of cement with an amount of perlite to form a solid mixture; adding water and mixing water with the solid mixture to form a sludge; adding an amount of sisal fibers and mixing the sisal fibers into the sludge to form an uniform final composition; and pouring the final composition into a mold and setting the final composition to a solid form structural building material. The produced structural building material can be machined, screwed, cut, and nailed.

Study of hygroscopic properties of some plant fibres under thermal condition

Abstract: The hygroscopic properties such as hygroscopicity, water yielding capacity, capillarity etc of cellulosic plant fibres such as sisal, bowstring hemp (dagger), pineapple, lady's finger and betel-nut annealed from 310 to 430 K have been investigated. The hygroscopicity of the plant fibres at constant relative humidity decreases with an increase in annealing temperature from 310 to 430 K. The bleached and mercerized samples are more hygroscopic than native samples. The rate of sorption of water content at constant relative humidity increases on pre-heating. The water-yielding capacity as well as capillary action at constant relative humidity decreases with increase in annealing temperature.

Material Properties Pull-out and other evaluations in sisal-reinforced polyester biocomposites

Abstract: Although sisal fibers have been used by several authors, the Brazilian variety has not yet been thoroughly characterized. In this work the surface of sisal fibers was modified by treatment with NaOH or N-isopropyl-acrylamide solutions. Lignin content and density of fibers are reduced with the chemical treatment and the N-isopropyl-acrylamide treatment causes a significant reduction in moisture absorption. Tensile tests of NaOH (0.25, 0.5, 1, 2, 5, and 10% w/w) and N-isopropyl-acrylamide (1, 2, and 3% w/w) treated fibers were carried out and a reinforcement effect of the sisal treated with 2% solutions was observed. TGA measurements showed that with the NaOH treatment the fiber becomes more thermally resistant. SEM micrographs and crystallinity index of sisal indicated how different treatments alter the fiber surface. Pull-out tests in polyester resin were performed, evidencing that all treatments were effective in improving interfacial adhesion. The best results were obtained with the 2% N-isopropyl-acrylamide treatment. The main advantages of pull-out tests is that without considering composite processing variables, good performance sisal/polyester composites may be selected before their laborious and material-consuming preparation step.  2002 Elsevier Science Ltd. All rights reserved.

Thermal stability of PP with acetylated sisal fiber: Romero García kinetic method

Abstract: This work deals the effect of acetylated and non-acetylated sisal fiber 011 thermal degradation of polypropylene. Applying the R-G method at constant conversion levels of 0.1, 0.3, 0.5, 0.7 and 0.9 to thermograms of the ”PP/untreated sisal fiber” blend, E, values of 99, 213, 224, 187, and 145 kJ/mol were obtained, whereas they were 99, 299, 255, 205, 154 kJ/mol for the “PP/treated sisal fiber” blend. On the other hand, with the R-G method at constant temperature, activation energies within the range of 156-417 kJ/mol were obtained for the “PP/treated sisal fiber” blend and within the range of 126-344 kJ/mol for the “PP/untreated sisal fiber” blend. Additionally, the method establishes as dominant the following decomposition mechanisms: three-dimension limiting surface reaction between both phases, diffusion in two and three dimeiisions and first-order random nucleation and nuclei growth.

Enzyme degradability of benzylated sisal and its self-reinforced composites

Abstract: To produce natural polymer based composite materials, sisal fibers were slightly benzylated and then molded into sheets. Because the modified skin portions of the fibers acquired certain thermoplasticity and the unmodified core parts remain constant, the resultant composites fall into the category of self-reinforced ones. The present article is devoted to the evaluation of the materials biodegradability with the help of cellulase. It was found that the inherent biodegradability of plant fibers is still associated with the benzylated sisal and the molded composites, as characterized by structural variation, weight loss and deterioration of mechanical performance of the materials. Reaction temperature and time, pH value of the enzyme solution, and dosage of the enzyme had significant influences on the decomposition behavior of the materials. In principle, the enzymolysis of sisal and its self-reinforced composites is a diffusion-controlled process. Due to the insusceptibility of lignin to cellulase and the hindrance of it to the cellulase solution, the degradation rates of the materials are gradually slowed down with an increase in time. Copyright © 2003 John Wiley & Sons, Ltd.

Tcf bleached sisal market pulp: potential reinforcing fibre for commodity papers - part 1

Abstract: Sisal pulp has physical characteristics superior to softwood kraft pulp. Depending on the furnish components and paper quality requirements, sisal pulp can replace softwood kraft at a rate of up to 2.8:1. This offers many opportunities for sisal pulp. For example, sisal pulp may be used as a reinforcing fibre in high recycle content papers, or its use may permit basis weight reductions while maintaining product quality. Sisal pulp as a value added replacement to softwood kraft in commodity papers is considered a viable alternative market. Part 1 of this paper reviews the laboratory work to establish conditions for producing TCF bleached sisal pulp, and discusses the results of a pilot scale trial and tests on pulp samples which were distributed to paper companies for testing in various furnishes. Part 2 reviews a sisal estate plan to provide pulping fibre, tentative flowsheets for fibre preprocessing stations and a sisal market pulp mill using processes and equipment which are currently available on the market, and the estimated capital and manufacturing costs and economic analysis for a 50,000 metric ton per year sisal market pulp mill.

Sisal hemp extractive, preparing method and use thereof

Abstract: A sisal hemp extract is prepared from sisal hemp through extracting and separating, and features that it contains common saponin (30-80%). It can be used to prepare the medicine for treating hyperlipomia, diabetes and lipoidosis.

Influences of Treatment Methods for Sisal Stems on Properties of Sisal Fiber/Formaldehyde Resin Composites

Abstract: Sisal fiber/UF composites were made by blending sisal stems treated by alkali,coupling agents and acetic acid with UF resin synthesized by the author and molded at certain temperatureEffects of different treatment conditions by the alkali and treatment ways on the mechanical properties,wear resistance,water absorption,electrical properties and thermal performance were studied and compared with those of wood powder/UF compositesResults showed that the techniques treating sisal stems had little effect on electric properties,thermal performance and water absorption of the compositesWhen the sisal stems were treated by acetylation, the composites had higher strength and better wear resistance,and properties of sisal fiber/UF are close to those of wood powder/UF composites