Alkali-treated Fibers Research Articles

Investigation of Static and Dynamic Mechanical Properties of Short Palmyra Palm Leaf Stalk Fiber (PPLSF) Reinforced Polymer Composites

ABSTRACT The research work is focused toward determining the static and dynamic mechanical properties of the composites made by reinforcing untreated and alkali-treated short palmyra palm leaf stalk fibers (PPLSF) of length 3 mm, , and 10 mm in the polymer matrix. The short palmyra palm leaf stalk fiber reinforced polymer matrix composites are prepared by a compression molding method. The result illustrates that the 7 mm alkali-treated short PPLSF composite exhibited the maximum tensile strength of 45.13 ± 1.57 MPa, the flexural strength of 71.35 ± 2.57 MPa and impact strength 10.21 ± 2.13 kJ/m2. The dynamic mechanical analysis shows that the 7 mm alkali-treated short PPLSF composite has improved the storage and loss modulus compared to 3 mm and 10 mm short untreated and alkali-treated fiber composites. Further thermo-gravimetric analysis carried out for 3 mm, 7 mm, and 10 mm untreated and alkali-treated fiber-reinforced composites showed that the thermal characteristics of the composites have improved due to treatments as well due to increase in fiber length. The tensile-fractured surface of the composites is also examined with SEM to identify the mechanism of failure.

Mechanical refining combined with chemical treatment for the processing of Bamboo fibres to produce efficient cement composites

The effects of chemical (30% sulphidity and 30% alkali active) and mechanical treatments (1500, 2000, 7500 and 10,000 revolutions for different refining and beating rates) on Guadua angustifolia Kunth (Bamboo) fibres are investigated for the first time. The morphological, chemical and physical changes of treated and untreated fibres after refining were characterised and analysed. The macro mechanical and structural properties at 7 and 28 days of curing of fibre-cement composites reinforced with treated fibres are evaluated. Fourier Transformed Infrared (FT-IR) and X-Ray Diffraction (XRD) spectra are performed to investigate structural compound changes. The MOR (Modulus of Rupture), fracture surface and Scanning Electron Microscopy (SEM) images were determined and analysed. The evaluation of manufactured cement composites showed that flexural strength increased by approximately 15% when composites were reinforced with alkali-treated fibres compared to untreated fibres. However, in the case of alkali fibres combined with mechanical refining, the increase reaches 57%. The specific energy (SE) of cement composites is not considerably different between untreated and alkali-treated fibres. Nevertheless, the combination of alkali with mechanical refining results in an increase in SE of more than 7 times. Although the combination of alkali treatment and mechanical refining improves the flexural strength and specific energy of cement composites, the high refining rates have a negative effect on these properties owing to an increase in the fibre fibrillation and a decrease in the swelling capacity, which reduce the fibre–matrix bonding.

Biosorption of copper using nopal fibres: moolooite formation and magnesium role in the reactive crystallization mechanism

In this contribution, we present findings on biosorption of Cu (II) ions using novel alkali-treated nopal fibres. The biosorption data at equilibrium were fitted to several isotherm models and the biosorbent was characterized by XRD and SEM–EDX. The biosorption mechanism was investigated using a holistic approach of pH shifts, apparent colour variations and changes in the concentration of Cu(II) and dissolved hard ions (calcium and magnesium) in the Cu(II) solution. The correlation between the colour, XRD analysis, pH shifts and hard cations released from the biosorbent into the solution suggested the existence of two crystal formations, malachite and moolooite, in what appears to be a microprecipitation mechanism via reactive crystallization. The role of magnesium during the transformation of malachite into moolooite during the copper binding mechanism is analysed. Magnesium cations were released into the solution during malachite growth but were taken up from the solution during the moolooite crystal growth phase. The shift of the molar ratio Mg/Ca was located between the two inflexion points of the crystal growth transition. This specific location at the sorption isotherm was correlated with the colour evolution by a linear discriminant model confirming its association with the polymorphs.Graphic abstract

Morphological, acoustical, mechanical and thermal properties of sustainable green Yucca (Y. gloriosa) fibers: an exploratory investigation.

The objective of this study was to evaluate the acoustical, morphological, mechanical and thermal properties of fibers extracted from the leaves of Yucca (Y. gloriosa) shrub. Several tests were performed on either untreated or alkali-treated (5% NaOH) fibers. The chemical analysis of the fibers was performed to determine their lignin, cellulose, hemicellulose, wax and moisture content. Fourier transform infrared (FTIR) and thermogravimetric analysis were respectively employed to chemically and thermally analyze the fibers. The microscopic examination was also carried out using scanning electron microscope (SEM). INSTRON universal testing machine and an impedance tube system were employed for measuring the tensile properties of the fibers and the sound absorption coefficient values of the samples fabricated from the same fibers, respectively. The results from the experiments revealed that the fibers have low density (1.32g/cm3) and higher cellulose content (66.36wt.%,). The mechanical characterization of these fibers also confirmed they are similar to the other lignocellulose fibers used for the reinforcement of polymer matrix composites. The tensile strength test conducted on Yucca fibres showed that mechanical properties of alkali treated fibers are superior to the untreated fibers. The thermal analysis also demonstrated that the alkali treated fibres can thermally withstand temperatures of up to 364°C which confirms the fact that the thermal stability of fibers was improved by alkali treatment. Fibers extracted from the leaves of Yucca demonstrated fair amounts of mechanical and thermal resistance and strength. The samples fabricated from Yucca fibers demonstrated fair levels of sound absorption coefficients particularly at higher frequency ranges which are typical to the other natural fibers. The possible use of Yucca fibers as either a reinforcing agent for composites or a sound absorbing medium is highly promising.

Characterization of Alkali-Treated Banana Fiber and its Effects as Web Reinforcement on the Axial Load Capacity of Concrete

The Philippines is an agricultural country due to its location in the tropics. Because of this nature, the agriculture sector tends to produce a huge amount of waste that if not disposed properly could pose a threat to the society and to the environment. Studies have been performed on the possibilities of incorporating agricultural wastes to various construction materials as a form of waste diversion. In order to address the problem with agricultural wastes as well as to improve the property of construction materials, a study on alkali-treated banana fiber as web reinforcement in concrete was done. In this study, a characterization of alkali-treated banana fiber was done in order to assess the characteristics of a possible reinforcement for concrete by tensile strength test on the fiber. The applicability of the treated fiber was then examined as a web reinforcement in concrete in terms of its load capacity. The parametric study was conducted to investigate the effect on the compressive strength of varying bundle diameter (4 mm, 8 mm, 12 mm, 16 mm) while holding the spacing of mesh at 20 mm and also the effect of varying mesh spacing (10 mm, 15 mm, 20 mm and 25 mm) while holding the diameter at 16 mm. Test results show that the 4 mm diameter of treated banana fiber yielded the highest tensile strength at 314 N compared to only 197 N of the untreated banana fiber. The parametric study results the diameter of banana fiber indicate that the increase in diameter also results in the increase in load capacity. With respect to spacing, the smaller the value of spacing results in higher load capacity.

A Study About Water/Alkali Treatments of Hemp Fiber on Ultraviolet Ageing of the Reinforced Polypropylene Composites

Ultraviolet (UV) ageing is one main environmental factor affecting the service performance and life of plant fiber reinforced composites. Plant fiber treatment or modification is an essential step in composite preparation to deal with the poor interfacial strength between plant fiber and thermoplastic matrix. Our previous study shows that water treatment is one green fiber treatment method and has potential industrial application. In this paper, effects of water and alkali treatment of hemp fiber on UV resistance of the reinforced polypropylene (PP) composites were studied. Hemp fiber was treated with water and alkali solution firstly, and then blended with PP, respectively. UV ageing of the PP composites was performed. Digital microscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were employed to characterize composite degradation. Water uptake and tensile tests were also conducted to deeply understand the effects of water and alkali treatment on UV ageing of the composites. The surface observation results showed that UV ageing occurs around the fiber locations on composite surface in early stage, both water and alkali treatment of fiber could retard surface whitening and cracking of the composites. After 4 weeks, carbonyl index of the composite reinforced with untreated fiber reached up to 29.3 while that of the composites reinforced with water or alkali treated fiber was only 19.6. The XRD patterns also confirmed that both water and alkali treatment have less crystallization after 8 weeks. Water uptake of composites is greatly decreased from 2.5 to 1.0% by water or alkali treatment of hemp fibers. However, either water or alkali treatment didn’t give obvious contribution to resist the deterioration of composite tensile properties. The hydrophilicity and water absorption of hemp fiber play an important role in UV degradation of composites. Water and alkali treatment could greatly decrease water absorption, which is beneficial to improve UV resistance of plant fiber reinforced composites. This study is helpful to deeply understand UV ageing mechanism and develop related anti-UV ageing technology of plant fiber reinforced composites.

Effect of a Novel Chemical Treatment on the Physico-Thermal Properties of Sugarcane Nanocellulose Fiber Reinforced Epoxy Nanocomposites

Abstract In the present investigation, a novel chemical treatment was introduced for the extraction of nanocellulose fibers from sugarcane bagasse and applied as reinforcement material to enhance the physical properties and thermal stability of epoxy nanocomposites. Epoxy nanocomposites with different weight fractions were fabricated using a wet layup process followed by furnace heating to remove the residual moisture content. The influence of surface modified sugarcane nanocellulose fiber loading on morphological (transmission electron microscope) properties of epoxy nanocomposites was investigated. The porosity and water absorption increase with the increment in fiber weight fraction for both treated and untreated nanocellulose fiber-epoxy composites. Among the various treatment processes, the alkali-treated fibers reinforced epoxy composites showed better thermal stability and water absorption resistance under 10 wt.% of nanocellulose fiber reinforcement.

Tensile, impact and fracture toughness properties of banana fibre-reinforced polymer composites

ABSTRACT In this study, fracture toughness test of short banana fibre-reinforced epoxy composites was carried out. The main interest of this study is to incorporate environmentally friendly biodegradable banana fibres in polymer composites to prove the potential of natural fibres. The short fibres from pseudo-stem part of the banana plant were used to prepare composites. The composite samples were prepared using both alkali-treated and untreated banana fibres. Laminates were prepared from vacuum moulding technique. The effects of alkali-treated fibres on untreated were studied. Since polymer composites are used in many structural applications, these materials because of defects which material failure. The better understanding of material behaviour due to crack growth studies on fracture is essential. In this study, banana fibre-reinforced epoxy composites are developed and their mechanical properties such as tensile strength, impact strength and fracture toughness are evaluated. The fibre matrix adhesion and internal surface of the fractured surfaces are studied by using a scanning electron microscope.

Effect of fibre ratio and chemical treatment on the properties of pineapple leaf and betel nut husk fibre-reinforced hybrid polypropylene composites

ABSTRACT In present research, polypropylene composites were prepared with 10 wt% pineapple and betel nut fibres at ratios of 1:1, 1:3 and 3:1 using compression moulding technique. Both pineapple and betel nut fibre were chemically treated with 5% NaOH. Composite was then prepared with treated pineapple and betel nut fibre at a ratio of 1:3. Mechanical (tensile, flexural and hardness), thermal (thermogravimetric analysis) and morphological (scanning electron microscopy) characterisation of prepared composites were subsequently carried out. Among the fibre ratios, composites containing pineapple and betel nut fibre at a ratio of 1:3 had the best set of mechanical properties. Alkali treatment of pineapple and betel nut fibre decreased tensile and flexural properties of corresponding composites. On the other, the same treatment had opposite effect on hardness. According to scanning electron microscopic analysis, composite containing pineapple and betel nut fibre at a ratio of 1:3 showed more adhesion as compared to other prepared composites. Thermal degradation temperature decreased in alkali-treated fibre- reinforced composite.

Effect of Alkali Treatment of Nettle Fibers on Oil Absorbency

ABSTRACT Nettle is a cellulosic plant fiber with a reasonably large lumen and they are a cheap, easily renewable source of fibers with the potential for oil absorbency. To the author’s best knowledge, there are no published data available on the oil absorbency behavior of alkali-treated nettle fibers. In this work, alkali treatment on nettle fibers was carried out with a view to improve their oil absorbency. The effects of treatment time, temperature, concentration, and solid: liquor ratio of nettle fibers on oil absorbency was assessed. As compared to raw nettle fibers, the oil absorbency of alkali-treated nettle fibers was considerably higher. Nettle fibers were also characterized by FTIR, TGA, SEM, and reusability tests. Oil absorbency capacity of alkali-treated nettle fibers has also been compared with other natural materials.

CHARACTERISTICS OF FIBER TREATMENTS ON TENSILE AND IMPACT STRENGTHS OF PINE RESIN/ARECA HUSK FIBER BIOCOMPOSITES

In this study, alkali treatment was carried out on natural fibers to increase their mechanical strength, change the chemical composition, and clean the fibers of impurities. Areca husk fibers (AHFs) were soaked in an alkaline solution, and dried. Alkali-treated fibers were blended with preheated pine resin, and the tensile and impact strengths of the pine resin/AHFs biocomposites were evaluated. The fibers treatment, the tensile strength increased by about 11% and icreased by about 33% compared with untreated fiber biocomposites. Alkali treatment also increased The value of the Young’s modulus of the fibers by about 9.2%. The impact strength of the pine resin increased by nearly 42% from the presence of 10% by weight AHFc content. For the pine resin/AHFs biocomposites, the impact strength increased 24% compared with untreated AHFs. The mercerization increased the adhesion of the fiber–matrix interface, enabling efficient transfer of tension from the matrix to the AHFs.By the SEM, increased adhesion bonding between the matrix and the fibers was also detected. This is significant, considering that tensile and impact strengths are some of the most important mechanical properties of a composite material thet are affeted by the bonding force between the matrix and the fibers.

Mechanical property evaluation of alkali-treated jute fiber reinforced bio-epoxy composite materials

Natural fiber reinforced polymer composites have proved to be fit for use in several structural and functional applications. Jute fiber reinforced epoxy composites are one of the most preferred natural fiber-based polymer composites. The emerging need for high strength application while considering environmental sustainability and with the advent of bio-composites, the researchers, in recent times, started showing interest in incorporating the various bio-based resins in the composites. The present work thus aims at investigating the possibilities of making jute fiber reinforced epoxy composites with alkali-treated fibers and cashew nut shell liquid blended epoxy resins. The feasibility is tested through the mechanical properties, which is quantified using tensile strength and flexural strength. The modified matrix in the prepared composites is based on the variation in the weight percentage of cashew nut shell liquid (25 and 30%). The results indicate that it is possible to make better composites using the modified matrix and alkaline treated jute fibers as the mechanical properties outperform the jute fiber reinforced epoxy composites made using conventional epoxy resin and untreated jute fibers. The best amongst all the variants made, the one that proved to be the best JFRE composite is having alkaline treated fiber and blend 2, which exhibits an average tensile strength of 679 MPa, and flexural strength of 88.83 MPa.

Effect of Alkali-modified Kenaf Fiber Incorporation on the Biodegradability and Hydrolytic Degradability of Used Polyethylene Material

Polyethylene (PE)-based plastic wastes are non-biodegradable and tend to persistently disturb and destroy the environment. The novel approach in this research is incorporation of alkali-modified kenaf fiber into the used PE material aiming at improving its biodegradability and hydrolytic degradation. The alkaline modification of the kenaf fiber was achieved using 5wt. % sodium hydroxide (NaOH) solution as revealed by chemical composition analysis and Fourier Transformed Infrared Spectroscopy of the alkali-treated fiber. Melt-blending approach was employed to fabricate composites using both treated and un-treated kenaf fibers together with the used low density PE, in the form of table water sachets, at various fiber-to-PE loading formulations. Characterizations of these composites were conducted for their biodegradability using Sandy soil. Additional characterizations conducted included hydrolytic degradation and thermogravimetric analysis respectively. In the results obtained for biodegradation and hydrolytic degradation, the alkali treated kenaf fiber-PE composites revealed a more promising performance than its corresponding un-treated kenaf fiber-PE composites. The higher the kenaf fiber the higher the biodegradation and hydrolytic degradation respectively. These composites also showed higher hydrolytic degradation as well as higher thermal stability in comparison to their corresponding un-treated kenaf fiber-PE composites. The findings on Analysis of Variance (ANOVA) revealed that alkali-modified kenaf fiber incorporated PE composites showed a more statistically significant results for biodegradation and hydrolytic degradation particularly between 60 to 90 days retention periods.

Alkali Treatment Effect on the Tensile and Impact Properties of Recycled High-Density Polyethylene Composites Reinforced with Short Cantala Fiber

In this study, an environmentally friendly composite was prepared from cantala fiber and recycled high-density polyethylene. Alkali treatment was utilized to improve the fiber–matrix interface of cantala fiber. The alkali treatment was carried out with a 2% NaOH solution for periods of 0, 4, 8, 12, 16, 20, and 24 hours. Various recycled high-density polyethylene composites reinforced with treated and untreated short cantala fiber were produced by hot press. The tensile and impact properties of the composites were examined to reveal the effect of alkali treatment. Changes in fiber–matrix bonding were investigated via composite fractography using scanning electron microscopy. A study of fiber morphology and other supporting tests, such as the fiber tensile test, X-ray diffraction, and Fourier transform infrared microscopy were also carried out. The results show that the addition of alkali-treated fiber to recycled high-density polyethylene composites enhanced the composites’ tensile and impact performance: Tensile strength improved by 15.5% and impact strength by 24.8%.

Microwaved cement boards with alkali-treated pineapple and water hyacinth fibers

Pineapple fibers (PFs) and water hyacinth fibers (WHFs) were treated with sodium carbonate (Na2CO3) and sodium hydroxide (NaOH) solutions for soaking times of 0·5, 1·0, 1·5 and 2·0 h. Analyses showed that the best treatment parameters for PFs were 2·0 M sodium carbonate for 1·5 h and 2·0 M sodium hydroxide for 0·5 h; those for WHFs were 1·5 M sodium carbonate for 0·5 h and 1·0 M sodium hydroxide for 1 h. The untreated and treated PFs showed similar Fourier transform infrared spectra ranging from 2924 to 2926 cm−1, which signify the presence of acidic oxygen (O)–hydrogen (H) stretching vibrations on a carbonyl group. The sodium hydroxide-treated WHFs had the 2926 cm−1 transmittance peak absent compared with the untreated WHFs. The acetylation process on both fibers resulted in increased roughness of fibers, which were analyzed under scanning electron microscopy of 10 μm magnification. The fibers treated under the determined best parameters were then used in the fabrication of cement boards. The specimens underwent microwave curing with regimes under 119 and 280 W. The cement board with aligned sodium carbonate-treated combined PFs and WHFs performed 16–41% better than the cement board with non-woven oriented fibers in terms of flexural strength.

Optimization Studies on Improving the Dielectric Properties of Alkali Treated Fibers from Phaseolus Vulgaris Reinforced Polyester Composites by Central Composite Design

ABSTRACT This study investigates the dielectric efficiency of a composite prepared using a fiber extracted from Phaseolus vulgaris. The extraction of fiber was statistically modeled using face-centered central composite design. The concentration of NaOH and extraction time was taken as the process variables and dielectric strength was taken as the response. The numerically optimized model for the extraction of fiber from Phaseolus vulgaris of alkali treatment showed 14.325 kV/cm as dielectric strength of initial NaOH concentration of 3% and time period of 51 min. The model was significant with R2 = 0.9323 and adjusted R2 = 0.884. The linear, quadratic & interactive relationship between the response (dielectric strength) and variables (NaOH & time) was also established. This study explains the importance of NaOH and time period in establishing the fiber extraction by the alkali treatment process.

Investigation of bio-waste natural fiber–reinforced polymer hybrid composite: effect on mechanical and tribological characteristics of biodegradable composites

The global energy crises and environmental pollution have encouraged investigators, scientist, and engineers to develop a substitute material for the conventional material. Since the availability of the natural fibers is abundant, many researchers in the worldwide are focusing their attention on the improvement of natural fiber–reinforced composites, which act as a substitute material for the synthetic natural fibers. This work examines the study of mechanical and tribological properties of tensile, flexural, impact, wear rate, and friction coefficient of the banana/hemp hybrid composites, which are calculated with the aid of NaOH-treated composite specimens. Composites were fabricated for various wt.% of the fiber content, different length of the fiber and matrix. Surface morphology of the fractured specimen of the alkali-treated fibers composites is studied by using SEM images. The effect of water absorption behavior on the mechanical properties of banana/hemp fiber composites was also determined.

Prevention of Postoperative Adhesion Bands by Alkali-treated Cellulosic Luffa Fibers

ABSTRACT The formation of postsurgical intra-abdomen adhesion bands can cause severe complications. The luffa fibers were alkali treated to produce the desire hydrophobic and microfibrous structure. The scanning electron microscope and X-ray diffraction results have demonstrated that this treatment furnished a fine and hydrophobic fibrous structure. Moreover, the crystallinity of luffa increased from 17.4% to 63.32% by alkali treatment. Moreover, the in vivo results represented a significant reduction of inflammatory cells and adhesion bands after one week of luffa fibers implantation. These results suggest that the luffa fibers have the potential to act as a barrier for prevention of adhesion bands.

Tailoring the Effective Properties of Typha Fiber Reinforced Polymer Composite via Alkali Treatment

Typha fibers were chemically retted in 5% sodium hydroxide solution for 1 h, 2 h, 4 h, and 8 h. Changes in chemical compositions of the untreated and treated fibers were monitored with Fourier transmission infrared spectroscopy, while changes in the crystallinity index were studied via X-ray diffraction. The FTIR spectra and scanning electron microscope images corroborated the successful removal of amorphous portions from the Typha leaf fibers during alkali treatment, which resulted in an enhanced crystallinity index for alkali-treated fibers. The alkali-treated Typha fiber for 1 h showed the highest water contact angle of 87.5°, while the untreated composite showed the lowest contact angle. Typha fiber treated for 4 h had high tensile strength, Young’s modulus, and elongation at break of 158 MPa, 1600 MPa, and 7%, respectively. The results showed that there was a general increase in the interfacial shear strength of Typha fiber with epoxy resin and polyester resin with increased time. Both the mechanical properties and crystallinity index of the Typha leaf fibers increased with increased time of retting until 4 h, after which further alkaline retting resulted in decreased values. The overall results showed that alkaline-extracted Typha leaf fibers are suitable for biodegradable film composites.

Rheological behavior of short Alfa fibers reinforced Mater-Bi® biocomposites

This paper investigates the viscoelastic behavior in the melt of biocomposites of Alfa fibers dispersed in a polyester-starch bioplastic of the Mater-Bi® type. Biocomposites with three kinds of short Alfa fibers (untreated or treated with alkali solutions at 1% or 5%) and at various filler contents were prepared by means of twin screw extrusion. The rheological properties of such biocomposites have been studied in oscillatory shear at 140, 160 and 180 °C at frequencies varying from 100 to 0.01 rad/s in the viscoelastic linear domain. The influence of fiber loading, alkali treatment of fibers, and temperature on the viscoelasticity of biocomposites was examined. Dynamic moduli increase with increasing fibers content. In addition, biocomposites exhibit a plateau of the storage moduli at low frequencies, indicating a percolated fibers network. This low frequency elastic behavior is enhanced by the treatment of the fibers.The ratio of storage modulus of biocomposites to that of the neat matrix at low and high frequency is used to characterize the influence of the fiber content and of the concentration of alkali treatment of Alfa fibers on both percolation and hydrodynamic effects. This made it possible to sense the effect of these parameters on the dispersion process of Alfa fibers in the biopolymer matrix.