Extraction and characterization of new natural lignocellulosic fiber Cyperus pangorei

This research is focused on the study of the physical, chemical, mechanical, and thermal properties of a newly identified natural stem fiber, Cyperus pangorei. The chemical composition of Cyperus pangorei fibers (CPF) such as cellulose, lignin, ash, moisture, and wax contents was evaluated. Besides these, the fiber density was determined and the apparent diameter was measured using an optical microscope. Further, tensile, thermal, XRD, and FT-IR studies were performed to evaluate the suitability of the fiber as a reinforcement. The surface topography of CPF was analyzed using scanning electron microscopy (SEM). Encouraging properties such as increased stiffness, fiber texture, and higher thermal stability suggest the suitability of CPF as reinforcement in polymer matrices.     

Monitoring the polymerization process of polypyrrole films by thermogravimetric and X-ray analysis

Bio-composite fibers were developed from wood pulp and polypropylene (PP) by an extrusion process. The thermo-physical and mechanical properties of wood pulp-PP composite fibers, neat PP and wood pulp were studied using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). The thermal stability of bio-composite fibers was found to be significantly higher than pure wood pulp. An understanding into the melting behaviour of the composite system was obtained which would assist in selecting a suitable temperature profile for the extruder during processing. The visco-elastic properties of bio-composite fibers were also revealed from the study. The generated bio-composite fibers were also characterized using Fourier transform infrared spectroscopy (FTIR) to understand the nature of chemical interaction between wood pulp reinforcement and PP matrix. The use of maleated polypropylene (MAPP) as a compatibilizer was investigated in relation to the fiber microstructure. Changes in absorption peaks were observed in FTIR spectra of bio-composite fibers as compared to the pure wood pulp which indicated possible chemical linkages between the fiber and polymer matrix.     

Extraction,modification, and characterization of natural ligno-cellulosic fiber strands from napier grass

Napier grass is a high-productivity perennial grass that is a very important forage for animals in the tropics. In this research work, fiber strands from Napier grass were extracted and the effect of acetic acid treatment on their chemical composition, morphological and structural changes, and tensile and thermal properties was studied. The acid treatment was carried out using glacial acetic acid solution at three different concentrations (5, 10, and 15%) for 2 h. Chemical analysis indicated lowering of amorphous hemicellulose content on acid treatment. FT-IR spectroscopic studies revealed variation of functional groups on acid treatment. Scanning electron micrographs indicated roughening of the surface of the fiber strands due to the removal of the hemicellulose layer on acid treatment. X-ray diffraction analysis indicated an increase in crystallinity of the fiber strands on acid treatment. The thermal stability and tensile properties of the fiber strands increased on acid treatment. This fiber has competitive advantages when evaluated with other natural fibers and can be developed further as a potential reinforcement in polymer matrix composites.     

Extraction and Characterization of Natural Cellulose Fibers from Maize Tassel

This article reports on the extraction and characterization of novel natural cellulose fibers obtained from the maize (tassel) plant. Cellulose was extracted from the agricultural residue (waste biomaterial) of maize tassel. The maize tassel fibers were obtained after treatment with NaOH and were carefully characterized while the chemical composition was determined. The chemical composition of the maize tassel fibers showed that the cellulose content increased from 41% to 56%, following alkali treatment. FT-IR spectroscopic analysis of maize tassel fibers confirmed that this chemical treatment also shows the way to partial elimination of hemicelluloses and lignin from the structure of the maize tassel fibers. X-ray diffraction results indicated that this process resulted in enhanced crystallinity of the maize tassel fibers. The thermal properties of the maize tassel fibers were studied by the TGA technique and were found to have improved significantly. The degradation temperature of the alkali-treated maize tassel fiber is higher than that of the untreated maize tassel fibers. This value convincingly showed the potential of maize tassel fibers for use in reinforced biocomposites and waste water treatment.     

Preparation and characterization of biodegradable sugarcane bagasse nano reinforcement for polymer composites using ball milling operation

The present work includes the processing and characterization of nano-based natural reinforcement for polymer composite materials. Sugarcane bagasse has been collected and the fibers were extracted using manual striping process. Undesirable materials present in the extracted fibers were removed by 1% NaOH-based chemical treatment. The macrofibers were reduced to nano scale by using high-energy ball milling process. Nanoparticles from bagasse fibers were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The degree of crystallinity of nano bagasse is 55.2% and it was reported by using XRD. A FTIR spectrum confirms the presence of cellulose functional groups in nano bagasse. The nano bagasse dimensions and morphology were investigated using SEM. The average length and diameter of the nano bagasse is 51.2 and 46.1 nm, respectively. Thermal stability of the nano bagasse was revealed by TGA analysis. The chemical composition of cellulose, lignin, and hemicellulose contents was also investigated.     

Alkali treatment of lignocellulosic fibers extracted from sugarcane bagasse: Composition,structure, properties

Lignocellulosic fibers extracted from sugarcane bagasse were treated with NaOH solutions of different concentration (0-40 wt%) to study the effect of alkali treatment on the composition, structure and properties of the fibers. Composition was determined by the van Soest method, structure was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), while mechanical properties by tensile testing. Hemicellulose and lignin content decrease, while cellulose content goes through a maximum as a function of alkali concentration. Crystallinity changes only slightly and microfibril angle (MFA) remains constant thus structural effects and especially MFA are not the primary reasons for changing properties. The Young's modulus of the fibers shows a slight maximum at around 2-4 wt% NaOH content, while tensile strength goes through a much more pronounced one at around 5-8 wt%. Direct correlation between structure and mechanical properties was not found indicating that composition is more important in the determination of properties than structure. Regression analysis proved that the combination of several compositional variables determines mechanical properties in a non-linear manner. The improvement in fiber properties was explained with the dissolution of weak amorphous fractions and the relative increase of cellulose content.     

偶联剂在改善天然植物纤维/塑料界面相容性的应用

天然植物纤维界面特性十分复杂,其表面表现出很强的化学极性,导致天然植物纤维与塑料基材界面间相容性差,粘结力小,从而影响了植物纤维/塑料复合材料的冲击强度、拉伸强度等物理力学性能。因此,天然植物纤维/塑料界面相容性是决定复合材料性能的关键问题。本文概述了改善天然植物纤维/塑料界面相容性的常用偶联剂的特点和应用,偶联机理以及研究、应用现状,展望了应用于天然植物纤维增强塑料复合材料的偶联剂未来的研究方向。     

Impact of surface adaptation and Acacia nilotica biofiller on static and dynamic properties of sisal fiber composite

Nowadays, the awareness of the public along with strict legitimate forces over the use of polymers, the manufacturing and automotive industries started using the renewable materials. Since, natural fiber reinforced composites play vital role in developing lightweight structural materials, this study focuses on utilizing sisal fiber as reinforcement in polyester matrix along with natural filler. The influence of fiber length and fiber volume fraction on the mechanical properties of sisal fiber was studied initially. Test results revealed that the composite with 20?mm fiber length and 20-volume fraction composite has better mechanical properties. Furthermore, the effect of fiber surface modification has been analyzed using various chemical solutions such as NaOH, KMnO₄, stearic acid, and maleic acid. Of these, NaOH treatment enhances the mechanical properties of composite compared to all other cases. Finally, the influence of Acacia nilotica, a natural filler addition into the alkali-treated sisal fiber composite has been evaluated by mechanical and dynamic mechanical properties. It is found that the addition of natural filler and surface treatment has enhanced the properties of composites due to their synergetic effect. This effect improves the adhesion and uniform stress transfer among the reinforcements. The fiber surface morphology was evaluated using micrographs obtained from scanning electron microscope.     

Effect of fiber surface treatments on the essential work of fracture of HDPE-continuous henequen fiber-reinforced composites

Lignocellulosic fibers, such as henequen, sisal, coconut fiber (coir), jute, palm and bamboo, have been used as reinforcement materials for different thermosetting and thermoplastic resins because of their attractive physical and mechanical properties. Unlike the traditional engineering fibers, e.g. glass and carbon fibers, and mineral fillers, these lignocellulosic fibers are able to impart certain benefits such as low density, less machine wear, no health hazards, and a high degree of flexibility to the composite. The last attribute is especially true because these lignocellulosic fibers will bend rather than fracture, like glass fibers do, during processing of the composite. The mechanical properties and fracture behavior of a natural fiber reinforced polymer composite depend, not only on the properties of constituents, but also on the properties of the region surrounding the fiber, known as the interphase, where the stress transfer takes place. Moreover, the tailoring of the interphase by means of surface treatments, and carefully characterizing it, gives a better understanding of the performance of natural-fiber reinforced composites. The fracture toughness resulting from the use of natural fibers as reinforcing materials is quite different between ductile and brittle polymers, as well as between quasi-static and impact loading rates. The aim of this paper is to study the effect of the interphase properties, resulting from well controlled surface treatment of the natural fibers, on the behavior of a ductile polymer matrix composite under quasi-static loading using the essential work of fracture criteria. Specifically, the contribution of each of the different fiber-matrix interfacial adhesion levels towards the dissipation energy were analyzed and discussed. In the case of the plastic work βw_p, there seems to be a synergy between the frictional and chemical interactions observed for both, low and high strain rates. The nonlinear mechanical behavior of the natural fiber under combined tensile-shear loads has also an effect on the fracture behavior of the composite. Additionally, different fiber surface treatments change the microstructural nature of the natural fiber, further affecting its behavior, particularly under high loading rates.     

Evaluation of liquid ammonia treatment on surface characteristics of hemp fiber

In this study, we investigated the effects of liquid ammonia treatment on the surface characteristics of hemp fibers. We determined the elemental composition, morphological structure, roughness, and wettability of fiber surface using techniques such as electron spectroscopy for chemical analysis, scanning electron microscopy, atomic force microscopy, and contact angle measurements. The lignin coverage on the hemp surface was calculated from the O/C ratio and the C₁ content. The results show that lignin removal from the fiber surface was significantly greater than that from the fiber bulk. After the treatment, the O/C ratio of hemp fibers increased, and cellulose was exposed. The proportion of O₂ species that contributed to formation of hydrogen bonds increased; this further increased the number of hydrophilic groups in the hemp fibers, improving the fiber wettability. The liquid ammonia treatment did not change the large dislocation structures in hemp fibers, but the removal of noncellulosic materials from the fiber surface increased the roughness of the fiber surface.     

EPDM based heat shielding materials for Solid Rocket Motors: A comparative study of different fibrous reinforcements

EPDM/aramid ablatives represent the state of the art heat shielding materials for Solid Rocket Motors. Due to their mechanical properties and excellent thermal stability, aramid fibers or pulp constitute the common reinforcement of EPDM based liners. New generation organic fibers were recently tested as a potential replacement of aramid. In this study, Kynol fiber, a phenolic based reinforcement with high mechanical and thermal properties, was evaluated on this class of ablatives: to date, there are no data available on the use of Kynol fibers in EPDM based ablatives. At the same time, silica fibers which are traditionally used on other classes of ablatives, were also tested: in fact, the use of this type of reinforcement is not well documented on EPDM ablatives. It was found that EPDM/Kynol composition produced the char with the smaller dimensional change and the higher adhesion on the virgin material. EPDM/aramid exhibited the higher insulation properties. At the studied fiber percentage, EPDM/silica showed the worst behavior than the other formulations. The obtained data improved the comprehension of the role of the different fibers on the ablation mechanism of this class of ablatives, thus enabling the possibility to exploit their intrinsic properties.     

Surface modification of ultrahigh‐molecular‐weight polyethylene fibers

To prevent the loss of fiber strength, ultrahigh‐molecular‐weight polyethylene (UHMWPE) fibers were treated with an ultraviolet radiation technique combined with a corona‐discharge treatment. The physical and chemical changes in the fiber surface were examined with scanning electron microscopy and Fourier transform infrared/attenuated total reflectance. The gel contents of the fibers were measured by a standard device. The mechanical properties of the treated fibers and the interfacial adhesion properties of UHMWPE‐fiber‐reinforced vinyl ester resin composites were investigated with tensile testing. After 20 min or so of ultraviolet radiation based on 6‐kW corona treatment, the T‐peel strength of the treated UHMWPE‐fiber composite was one to two times greater than that of the as‐received UHMWPE‐fiber composite, whereas the tensile strength of the treated UHMWPE fibers was still up to 3.5 GPa. The integrated mechanical properties of the treated UHMWPE fibers were also optimum. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 463–472, 2004     

Effect of the Micronization of Pulp Fibers on the Properties of Green Composites

Green composites, composed of bio-based matrices and natural fibers, are a sustainable alternative for composites based on conventional thermoplastics and glass fibers. In this work, micronized bleached Eucalyptus kraft pulp (BEKP) fibers were used as reinforcement in biopolymeric matrices, namely poly(lactic acid) (PLA) and poly(hydroxybutyrate) (PHB). The influence of the load and aspect ratio of the mechanically treated microfibers on the morphology, water uptake, melt flowability, and mechanical and thermal properties of the green composites were investigated. Increasing fiber loads raised the tensile and flexural moduli as well as the tensile strength of the composites, while decreasing their elongation at the break and melt flow rate. The reduced aspect ratio of the micronized fibers (in the range from 11.0 to 28.9) improved their embedment in the matrices, particularly for PHB, leading to superior mechanical performance and lower water uptake when compared with the composites with non-micronized pulp fibers. The overall results show that micronization is a simple and sustainable alternative for conventional chemical treatments in the manufacturing of entirely bio-based composites.     

Physico-chemical,Tensile, and Thermal Characterization of Napier Grass (Native African) Fiber Strands

This article presents the extraction and effect of alkali treatment on the physical, chemical, tensile, and thermal characteristics of fiber strands obtained from Napier grass, a renewable biomass. In order to improve these properties, the Napier grass fiber strands were treated with sodium hydroxide. The alkali treatment was carried out using NaOH solution at three different concentrations (5, 10, and 15%) for 2 h. Characterization of untreated and alkali-treated Napier grass fiber strands was carried out by studying the chemical composition, surface morphology, functional group variation, crystallinity, and tensile and thermal behavior. It was found that untreated fiber strands have lower cellulose content, crystallinity, tensile properties, and thermal stability than alkali-treated fiber strands. Napier grass fiber strands treated with 10% NaOH showed optimum tensile strength, modulus, and percentage elongation with an improvement of 51.9, 47.3, and 12.1% respectively. Based on the properties determined for alkali-treated Napier grass fiber strands, we expect that these fibers will be suitable for use as a reinforcement in natural fiber composites.     

Fragment analysis of different size-reduced lignocellulosic pulps by hydrodynamic fractionation

Micro- and nanocelluloses are typically produced using intensive mechanical treatments such as grinding, milling or refining followed by high-pressure homogenization to liberate individual nano- and microcellulose fragments. Even though chemical and enzymatic pretreatments can be used to promote fiber disintegration, the required mechanical treatments are still highly energy consuming and very costly. Therefore, it is important to understand the kinetics and factors affecting the disintegration tendency of cellulose. In this study, the disintegration tendency of three different wood cellulose pulps with varying chemical composition processed in a PFI mill was examined by analyzing the fractional composition of the microparticles formed. The fractional compositions of the microfibrils and microparticles formed were measured with novel analyzers, which fractionated particles using a continuous water flow in a long tube. The hydrodynamic fractionators used in this study gave valuable information about different size of particles. Results showed that the amount of lignin and hemicelluloses clearly affected the kinetics and the mechanics of cellulose degradation. The P and S1 layers were peeled off from the Kraft fibers, causing the S2 layer to be cropped out. The thermomechanical pulp (TMP) fibers were first degraded by comminution and delamination from the middle lamella and the primary wall. As the refining process progressed, the fibers and fiber fragments began to unravel. Surprisingly, the semi-chemical pulp (SCP) fibers degraded more like Kraft fibers than TMP fibers despite their high lignin and extractive content.     

The effect of granite powder on mechanical,structural and water absorption characteristics of alkali treated cordia dichotoma fiber reinforced polyester composite

Environmental and societal concerns such as pollution, disposal of solid waste, requirement of different conflicting properties for materials in varied applications and cost are the main reasons for the development of new materials from the existing materials. The concerns may possibly be overcome by substituting natural fibers for synthetic fibers. In this study, a hybrid composite was developed by reinforcing the natural fiber “cordia dichotoma” and filler “granite powder” into polyester resin. This composite was fabricated using hand lay-up method. Cordia dichotoma fibers were surface treated with NaOH for reducing the hydrophilic nature of the fiber. Unused industrial waste in the form of granite powder obtained from the granite polishing industry is utilized as reinforcement in polymer composite. The hybrid composite was prepared by reinforcing a constant cordia dichotoma fiber content of 20 wt % and varying the granite powder weight (wt. %) percentages (0, 5, 10, 15, and 20) into polyester resin. Mechanical properties (tensile, flexural and impact) of hybrid composites were investigated. The novelty of this work lies in utilization of granite powder sourced from industrial waste utilized as filler material. Granite, as one of the hard materials, may improve wear and other mechanical properties. Following the results obtained, granite powder could be evidenced as a good filler material for the betterment of composites mechanical properties. Also, the ability of this filler material is proved in decreasing water absorption and chemical resistance. Scanning electron microscope (SEM) analysis was performed to investigate the bonding and distribution of granite powder within both the fiber as well as resin in the composite. Besides, the presence of chemical functional groups in the composite was traced by Fourier transform Infrared spectroscopy (FTIR). Also, Thermo-gravimetric analysis (TGA) was carried out and the composite was found to be thermally stable up to 415 °C.     

Mechanical Properties and Chemical Resistance of Short Tamarind Fiber/Unsaturated Polyester Composites: Influence of Fiber Modification and Fiber Content

In the present work, tamarind fibers were extracted from ripened fruits by the water retting process. Using these fibers as reinforcement and unsaturated polyester as matrix, composite samples were prepared by the hand lay-up technique. The effect of chemical surface treatments (alkali and silane) of tamarind fibers on the mechanical properties, chemical resistance, and interfacial bonding was studied. The mechanical properties of the composites with surface modified fibers were found to be higher than those with unmodified fibers. Morphological studies indicated improvement of interfacial bonding by alkali and silane coupling agent treatments of the fibers. The composites were found to be resistant to many chemicals.     

Very-high-strength (60-GPa) carbon nanotube fiber design based on molecular dynamics simulations

The mechanical properties of carbon nanotubes such as low density, high stiffness, and exceptional strength make them ideal candidates for reinforcement material in a wide range of high-performance composites. Molecular dynamics simulations are used to predict the tensile response of fibers composed of aligned carbon nanotubes with intermolecular bonds of interstitial carbon atoms. The effects of bond density and carbon nanotube length distribution on fiber strength and stiffness are investigated. The interstitial carbon bonds significantly increase load transfer between the carbon nanotubes over that obtained with van der Waals forces. The simulation results indicate that fibers with tensile strengths to 60 GPa could be produced by employing interstitial cross-link atoms. The elastic modulus of the fibers is also increased by the bonds.     

Comparative study of pineapple leaf microfiber and aramid fiber reinforced natural rubbers using dynamic mechanical analysis

Natural fiber is often considered inadequate for high performance reinforcement of polymer matrix composites. However, some natural fibers have relatively high mechanical properties with modulus close to that of high-performance synthetic fibers. Since the reinforcing efficiency of a short fiber is determined not only by the fiber modulus, but also by other physical properties such as the length to diameter ratio. Here it is shown, for the first time, that pineapple leaf fiber, whose modulus is somewhat lower than that of aramid fiber, can be used to reinforce natural rubber more effectively than aramid fiber. The situation was achieved by breaking down the fiber bundles into the constituent microfibers to gain very high aspect ratio. Comparisons were made at fiber contents of 2, 5 and 10 parts (by weight) per hundred of rubber (phr) using dynamic mechanical analysis over a range of temperature. The results reveals that at temperature below the glass transition of the matrix rubber and low fiber contents of 2 and 5 phrs, aramid fiber displays slightly better reinforcement efficiency. At high temperatures of 25 and 60 °C and high fiber content of 10 phr, pineapple leaf microfiber clearly displays higher reinforcement efficiency than does aramid fiber. Surface modification of the fiber by silane treatment provides a slight improvement in reinforcing efficiency.