Alkali-treated Fibers Research Articles

Characterisation of alkali-treated novel cellulosic fibres derived from Dombeya Buettneri plant as a potential reinforcement for polymer composites

ABSTRACT The present study evaluates the influence of alkali treatment using 2, 4, and 8 wt.% sodium hydroxide concentration solutions on novel cellulosic fibres manually extracted from the bark of dombeya buettneri plant (DBF). Alkali-treated fibres were characterised through physical and mechanical properties determination, Fourier transform infrared spectroscopy, X-ray diffraction, quantitative chemical analysis, thermogravimetric analysis, and scanning electron microscopy. Quantitative chemical analysis revealed a significant increment in cellulose content, reaching 67 ± 1.7% in DBF treated with 4 wt.% NaOH solution, accompanied by substantial reductions in lignin and hemicelluloses as confirmed by FTIR spectroscopy. XRD analysis showed an improved crystallinity index of 80% and crystallite size of 2.64 nm for 4 wt.% alkali-treated DBF. Additionally, 4 wt.% alkali-treated fibres yielded peak values of breaking force (40 N) and breaking tenacity (181 cN/Tex). SEM analysis confirmed enhanced surface roughness post-treatment, an indication of enhanced fibre/matrix interlocking during composite fabrication, whereas TGA analysis reported improved thermal stability post-treatment. EDX analysis confirmed that the C/O ratio is proportional to alkali solution concentration, indicating effective removal of non-cellulosic contents. In conclusion, treating DBF with 4 wt.% NaOH concentration improves their physical, mechanical, and chemical properties, suggesting their potential for polymer composite applications.

Extraction and characterization of biofunctional lignocellulosic fibers from Pulicaria undulata plant and the effect of alkali treatment on their bio-physicochemical properties

This study aimed to extract and characterize natural fibers from the P. undulata plant and to evaluate their antioxidant and antimicrobial activities, including the influence of alkali treatment on the bio-physicochemical properties. The average yield of raw fibers obtained was 28.1 %. The raw fibers of P. undulata were rich in cellulose (36.2 %), followed by hemicellulose (30.3 %), lignin (16.2 %), moisture (11.1 %), and pectin (3.9 %). However, the alkali treatment removed 75.7 % of hemicellulose and 50.6 % of lignin from the raw fiber sample and also increased its crystallinity and hydrophobicity. Similarly, the degradation temperature of P. undulata fibers also increased from 324.4 °C to 332.6 °C after alkali treatment. The raw fiber showed promising radical scavenging and reducing power properties, and demonstrated antifungal activity against Candida albicans. In contrast, alkali-treated fibers showed a significant decrease in radical scavenging activity (almost 7–8 fold) and reducing power potential (6-fold) and exhibited no antifungal activity, potentially due to the loss of bioactive components such as lignin and essential oils. Overall, the findings of this study highlight the potential applications of raw P. undulata fibers in the healthcare and cosmetics products.

Response of short jute fibre preform based epoxy composites subjected to low-velocity impact loadings

This work aimed to investigate the low velocity impact behaviour of short jute fibre non-woven preform epoxy matrix composites experimentally. Dry fibre preforms were developed using an optimised process and a laboratory made preforming device. The effects of alkali and poly vinyl alcohol (PVA binder) treatments on impact performances of jute composites were investigated and compared at 3 J and 6 J impact energy levels. To identify the failure modes of tested composites, the X-ray µCT tomography was employed. The results demonstrated that the developed untreated short jute fibre preform reinforced composites absorbed a higher impact energy, when they were compared to treated (alkali or PVA binder) composites. For untreated composites, maximum impact forces at 3 J and 6 J energies, were found as ⁓2478 N and ⁓2319 N, respectively; for the PVA treatment these values were measured as ⁓2457 N and ⁓2216 N, while, at same energy levels, alkali treated composites showed the lowest values as ⁓1683 N and ⁓1440 N, respectively. Untreated jute fibre contains natural matrices such as hemicellulose, lignin and waxes, which ensured a positive response to absorb more energy upon impact loading. In contrast, the alkali treatment facilitates a highly fibre packed composite structure, which accelerated the impact crack propagation in tested composites, resulting in lower resistance to impact energy. Although, PVA treated composites showed reduced impact properties compared to untreated composites due to the PVA polymer brittleness on the treated fibre surface during the impact incidents, this treatment demonstrated better impact responses over the alkali treatment. The application of PVA binder on alkali-treated fibres provided an extra support to fibres and a better fibre/matrix interface and hence, this combined treatment demonstrated a slightly better impact resistance (⁓2027 N and ⁓1874 N impact forces at 3 J and 6 J respectively) compared to only alkali treated fibre composites. The SEM fracture images and the X-ray µCT damage analysis revealed different impact damage modes, which supported the observed impact results. The obtained results from this investigation could be helpful for using short jute fibre composites in various load demanding applications where impact incidents are likely to be happened.

Enhancing microbial-induced carbonate precipitation (MICP) sand consolidation with alkali-treated jute fibers

Recent research has focused on reinforcing sand consolidated through microbial-induced carbonate precipitation (MICP) with alkali-treated fibers to enhance its mechanical properties and mitigate brittleness. This research investigated how modified fiber affected the microstructure and properties of MICP solid sand. The fiber content (0, 0.5, 1, 3, and 5%), pretreatment concentration (0, 1, 5, 10, and 20%), pretreatment time (0, 0.5, 1, 2, and 4 h), and pretreatment temperature (25, 35, 45, and 55 °C) required for the experiment were determined by MICP testing. The interactions between fiber, sand, and calcium carbonate(CaCO3) were analyzed by calcium carbonate content(CaCO3(%)), unconfined compressive strength (UCS), environmental scanning electron microscopy (ESEM), and X-ray diffraction (XRD). The specimen without added fiber had a UCS of 2.13 MPa, the UCS of the added fiber sample was 2.8 MPa, which was 31.46% more than that of the specimen without added fiber, and the UCS of the specimen with added alkali-treated fiber was 3.62 MPa, which was 70% more than that of the specimen without added fiber and 28.57% more than that of the added untreated fiber. The optimum content of jute fibers was 0.5%, and the optimum concentration of alkali treatment of jute fibers was 10% for one hour.

Sustainable activation of sisal fiber-reinforced slag composites: Mechanical strength and microstructural insights through recycling of alkali-treated wastewaters

An alkali treatment is necessary for natural plant fibers employed as reinforcing additives in inorganic cementitious materials, aiming to diminish moisture sensitivity and facilitate interlocking between the matrix and additives. Recycling alkali-treated fiber wastewaters (ATFWs) is crucial to prevent significant environmental pollution. Sisal fiber (SF)-reinforced alkali-activated slag-based composites incorporating ATFWs were prepared and compared to the control, aiming to investigate the effects of alkali-treated SFs and recycled ATFWs on the long-term mechanical properties and microstructures. Initially, the influence of the treated duration of SFs was examined on the electrical conductivity (EC) of ATFWs. Subsequently, the effects of SFs and ATFWs on the 28-day and 360-day flexural and compressive strengths were investigated, including an observation of failure modes. Furthermore, the effect mechanism of ATFWs in SF-reinforced composites was detected concerning morphology, microstructure, and composition by using diverse analytical techniques such as Scanning Electron Microscopy (SEM), Energy-Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Thermogravimetric-Differential Scanning Calorimetry (TG-DSC). The results show that the inclusion of ATFWs diminishes electrical conductivity (EC) and density while augmenting the flexural and compressive strengths of the composites. When extending the treatment duration of SFs in a 10% NaOH solution from 1 hour to 3 hours for SF-reinforced composites, the 360-day flexural and compressive strengths for samples without SFs show an enhancement of 1.1 times and 0.9 times, those with 1% SFs exhibit an increase of 0.7 times and 0.5 times, and those with 2% SFs demonstrate an improvement of 0.3 times and 0.4 times, respectively. Furthermore, the incorporation of ATFWs enables the physical embedding and sequestration of organic components released from SFs in a matrix without local aggregation. Therefore, recycling ATFWs as an alkaline activator is deemed feasible to produce SF-reinforced SP-based composites. The research outcomes offer an innovative approach for whole-waste utilization in the realm of natural fiber-reinforced composites.

The impact of chemical treatment and gamma-ray irradiation on the okra hessian cloth reinforced high-density polyethylene composites

Okra hessian cloth-reinforced high-density polyethylene (HDPE) thermoplastic composites were prepared and characterized with both raw and alkali-treated fibers. The fiber contents were optimized for both the raw Okra thermoplastic composites and the alkali-treated Okra thermoplastic composites, and the optimum value of fiber content was 55 wt%. Samples that were alkali-treated and had 55 wt% fibers were subsequently exposed to gamma radiation at doses of 2.5, 5, and 7.5 kGy. Only the sample subjected to 5 kGy showed improved performance. Treated composites exhibited higher crystallinities than the untreated samples as observed by X-Ray diffraction analysis. The rupture surface micrographs of the composites exposed to 5 kGy gamma radiation revealed more compact than others. By using Fourier transform infrared spectroscopy analysis of composites, it was found that 5 kGy dose sample showed enhanced cross-linking between Okra fibers and HDPE matrix. The irradiated composite showed less water intake than the alkali-treated samples. Composites subjected to 5 kGy gamma rays showed improved tensile strength and Young’s modulus of values 66 MPa and 1925 MPa, respectively. Compared to raw and treated composites, the irradiated composites with a radiation dose of 5 kGy showed improved structural, mechanical, and thermal properties.

Investigation on mechanical properties of the green synthesis bamboo fiber/eggshell/coconut shell powder-based hybrid biocomposites under NaOH conditions

Abstract This research delves into the effects of different alkalization treatment approaches on the mechanical characteristics of epoxy matrix composites that are reinforced with natural bamboo fibers and enriched with egg and coconut shell powders as fillers. Various weight ratios of fibers and fillers were investigated, specifically at 5%, 10%, 15%, 20%, 25%, and 30%. The study assessed mechanical properties such as tensile strength, flexural behavior, microhardness, and impact resilience. Findings indicate that composites with alkali-treated fibers demonstrate superior mechanical performance (49.28 MPa of tensile, 57.33 MPa of flexural 89 HV of hardness, and 1.3 kJ·m−2 of impact) compared to untreated counterparts. Particularly noteworthy is the significant improvement in fracture toughness observed with the inclusion of 20% hybrid laminates, surpassing the performance of existing biomaterial-based composites. This heightened toughness is attributed to the optimized composition of fibers and enhanced water absorption capabilities. Conversely, the incorporation of 25% and 30% hybrid composites led to a decrease in mechanical strength (38.65 MPa of tensile, 46.7 MPa of flexural, 72 HV of hardness, and 1.19 kJ·m−2 of impact) due to the formation of additional interfacial contacts, pores, and voids within the polymeric matrix.

Surface modification of bamboo fibers through alkaline treatment: Morphological and physical characterization for composite reinforcement

This study primarily emphasizes the effect of alkaline treatment on the surface morphology, and the physical properties of extracted bamboo fibers were investigated in detail. The bamboo fibers were extracted from raw bamboo culms using a mechanical extraction process followed by roller-milling techniques. The physical properties of the extracted bamboo fibers and their chemical composition were examined based on standard requirements. The extracted and sun-dried bamboo fibers were subjected to surface modifications by treating them with a 5 wt.% NaOH solution. The process involved soaking the extracted bamboo fibers for 1 day at ambient temperature; subsequently, the alkali-treated fibers were washed with distilled water several times to remove alkali content from the fiber surface until it became neutral. Finally, the fibers were dried under the sun for a week. The alkali-treated and untreated extracted bamboo fibers underwent characterization using Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), X-Ray diffraction (XRD) analysis, and Scanning electron microscopy (SEM). The investigation revealed an improvement in the surface morphology of the alkali-treated extracted bamboo fibers, with a significant reduction in surface roughness, as illustrated by SEM. Test results from FTIR, XRD, and TGA indicated that the alkali-treated fibers had removed lignin and hemicellulose from their surface. This study strongly suggests that bamboo fibers prepared using these techniques could be utilized as reinforcing material in composite production.

Laboratory Study of Asphalt Concrete for Base Course with Reclaimed Asphalt, Recycling Agents, and Jute Fibres

The way we treat materials after their lifespan is changing. We are finding a new, more effective way to deal with waste: using it, rather than depositing it in landfills. Since bitumen mixtures are the most popular paving materials by far, and their lifespan is limited, there is a constant availability of old asphalt pavement or reclaimed asphalt (RA). To restore the aged binder properties, we can use recycling agents. In this study, two commercialized biobased recycling agents were used. Furthermore, jute fibers were used as a reinforcement. The influence of the different fiber content and fiber length was investigated in mixtures without the recycling agents. In addition, alkali-treated fibers were used in some mixes for better fiber compatibility with the bitumen matrix. Air voids content, moisture, freeze–thaw susceptibility, stiffness modulus (IT-CY), resistance to crack propagation, and complex modulus tests were conducted. The addition of recycling agents led to a decrease in stiffness. A lower indirect tensile strength ratio (ITSR), increased stiffness, and best crack propagation results were recorded in some mixtures with fibers and recycling agents.

Thermo-Physical Analysis of natural fiber reinforced phenol formaldehyde biodegradable composites


 
 
 
 Natural fiber reinforced composites are composite materials which contain reinforced fibers from natural sources. Natural fiber composites can provide an effective and renewable solution for environment-friendly construction materials. For example, building insulation materials which are made of natural fibers can improve energy efficiency and reduce material waste generation. The fibers used in these composites are extracted mainly from plant sources such as bamboo, jute, sisal, and flax. Natural fibers have excellent mechanical and energy-dampening properties, making them ideal for manufacturers looking to replace traditional synthetic fiber reinforcements. They are also gaining popularity as replacements for plastic and metal components in many consumer goods. In this paper desert plant prosopis juliflora fibers were used as reinforcement in phenol formaldehyde resin to make composites. TGA, DSC and DMA were performed to analyze the change in thermal stability and mechanical properties of the prosopis juliflora fiber reinforced phenol formaldehyde composites. The alkali-treated fibers were prepared by immersing the PJ fibers in a 1% sodium hydroxide solution for 24 hours. The fibers were washed and dried before being mixed with the phenol formaldehyde resin. The composites were prepared with untreated and alkali-treated reinforced fibers. All specimens were left to cure at room temperature over night.
 
 
 

The Analysis of Fibre Properties of Water Retted Sansevieria trifasciata with Sodium Hydroxide

In the last decade, natural fibres have been in high demand because of their strength, high efficiency, and biodegradability easy availability for nature and improved textile properties than synthetic fibre. So, the increasing preference towards natural and green textile products rather than synthetic products has increased the attraction of tourists to the local as well as outside markets. Therefore, the present paper focused on the analysis of sodium hydroxide on the fibre properties of water-retted S. trifasciata (snake plant) fibres. The extraction of fibres from snake plant leaves was conducted by using water water-retted method. Three different time periods were selected i.e. 10, 15 and 20 days for water retting. After water retting, the selected fibres were treated with an alkali i.e. NaOH. The optimum conditions for alkali were chemical concentration, material to liquor, time durations, treatment temperature and pH for standardization of the process of alkali treatment. The effect of sodium hydroxide was analyzed on fibre properties such as fibre yield, fineness, bundle strength, and elongation at the break. As a result, a gradual fibre yield was to be increased to decrease after being treated with alkali (NaOH). The alkali-treated fibres fibre yield, fineness and bundle strength was recorded (0.84±0.02 g), (23.51±0.39 denier) and (47.97±0.13 g/tex). Elongation of the alkali-treated fibres was 5.02±0.007 per cent. The resulting fibre properties were found suitable for other textile products such as apparel, reinforcement material composite etc.

Study of the Mechanical and Physical Properties of Pervious Concrete Modified with Treated and Untreated Natural Coconut Fiber for Pavement

Pervious concrete pavements (PCP) are a novel material that numerous researchers are studying and focusing on. Its inexpensive cost, quick construction, and simple implementation are gaining favour. The aim of this study is to investigate the mechanical properties of pervious concrete pavement as well as the effects of modifying it with natural fibres such as coconut fibre. In this study, two types of coconut fibre were used: untreated (raw) fibre and alkali-treated fibre, as well as aggregates of various grades. By varying the amount of coconut fibre added by volume fractions of 3%, 6%, and 9%, the PCP mixes were generated. The fibre was treated with sodium hydroxide (NaOH) and is 2.5–3.5 cm long. The results showed that a 3% addition of treated natural fibre improved the mechanical properties of the PCP. Natural coconut fibre is able to be used as a concrete modification to improve its flexural behaviour and strength. According to the findings of this study, using 3% coconut fibre in the mix design of PCP at the age of 28 days improves tensile strength by 1.3 MPa, compressive strength by 4.8 MPa, and flexural strength by 1.92 MPa, whereas using 6% and higher fibres decreases flexural and split tensile and compressive strengths.

Thermal, chemical, tensile and morphological characterization studies of bamboo fibre extracted from the indian species bambusa bambos

The objective of this research is to investigate the extraction and characterization of a particular kind of Indian bamboo family plant known as Bambusa bambos. The fibres were extracted from the bamboo plant in the form of strips using the retting process and separated as thin fibres after the stamping process. The extracted raw bamboo fibres were chemically modified in a 5% alkali solution. The thermogravimetric analysis (TGA), x-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to investigate the thermal, crystalinity, and morphological properties of untreated and alkali (NaOH) treated bamboo fibres. The ASTM standard was followed for the chemical composition and tensile testing of raw and chemically treated bamboo fibres. In contrast to raw bamboo fibres, alkali-treated bamboo fibres had a 5% drop in hemicellulose concentration. In the alkali-treated state, weakly bonded containments were removed from the fiber's surface, exposing the cellulose over a wider surface area. As a result, the thermal stability of the alkali-treated fibres was enhanced as compared to raw bamboo fibres. The increased amount of cellulose content and decreasing aspect ratio of the alkali-treated bamboo fibers lead to increased tensile strength. A significant improvement in the crystallinity index (broad band width of the second peak) was observed in the alkali-treated condition, which may occur due to the removal of hemicelluloses. Based on their performance, the chemically treated bamboo fibres can be used as effective reinforcement elements for the development of polymer matrix composites in the automobile and construction industries.

Investigation of physical, Di-electric and hydrophobicity properties of roystonea regia/banana fibre polyester composites in both alkali treated and untreated conditions

Natural fibre-based hybrid composites have attracted a lot of attention in recent years due to their potential as environmentally friendly substitutes for synthetic fibres. When two or more types of natural fibres are combined to form a hybrid, the resulting material can have novel electrical properties. The study of Roystonea Regia fibre with other natural fibres as hybridization is very scarce, so in this context, the physical, di-electric and hydrophobicity properties of Roystonea Regia/Banana fibre hybrid composites have been studied. Experiments are conducted to demonstrate the dielectric strength, hardness, and hydrophobicity of polyester composites reinforced with a hybrid of Roystonea-Regia fibres and banana fibres in both treated and untreated conditions. This goal is reached through the fabrication of hybrid composites with varying proportions via the hand-lay-up technique and subsequent testing. The composition of 15% Roystonea-Regia alkali-treated polyester composites has a dielectric strength of 2.5 kV mm−1 in air, which is much lower than that of the untreated composites, which is 12.2 kV mm−1. Due to the increase in soaking time, percentage of hydroxyl group in treated fibres increases, which in turn reduced the dielectric strength. And also, the dielectric constant and electrical conductivity vary with the change in frequency. The alkali-treated fibre shows an increase in Shore D hardness when compared with the untreated fibres. The highest contact angle of 88.85° for 10% Roystonea-Regia fibre and 5% Banana fibre was observed, whereas the lowest contact angle of 65.14° was observed for 5% Roystonea-Regia fibre and 10% Banana fibre.

Potential of Agave angustifolia marginata for composite and textile applications – A new source of natural fibre

This study explored the properties of Agave angustifolia marginata leaves derived lignocellulose fibres, including their strength, flexibility, and durability, as well as their potential applications in composite and textile manufacturing. Commercial natural fibre standards used for quality assessment of the extracted fibre. According to National Standard 08–1113–1989, the fibre length was measured to be 60–90 cm. According to IS 271 (2003), bundle strength, colour, fineness, and bulk density were 20.46 g tex −1, 47.8%, 2.28 tex, and 0.413 g cc −1, respectively, and the textile grade was estimated. Results indicated that these are viable alternatives to a few textile fibres and can be easily blended with W-3 to W-6 jute fibres. On the other hand, for better interfacial strength of composite, a simple chemical treatment was performed on the fibres (2% NaOH solution for 4 h). A liquid digital density metre showed 980.4 kg m−3 and 1385 kg m−3 densities for raw and alkali-treated fibres according ASTM D792–20, respectively. ASTM D3379–75 tensile testing of fibres showcased superior Alkali-treated fibre characteristics. The Sieko TG/DTA instrument thermograms' revealed the thermal stability of raw fibre (240° C) and alkali-treated fibre (275° C). For a better understanding of the results, morphological investigations were also carried out. Alkali-treated fibres performed better than raw fibres, suggesting they could be employed as ecologically friendly reinforcement in polymeric composites.

Effect of Alkaline Treatment on Mechanical and Thermal Properties of Miswak (Salvadora persica) Fiber-Reinforced Polylactic Acid.

This study examines the effects of alkaline treatment on the mechanical and thermal properties of miswak fiber-reinforced polylactic acid. The treatment was performed with three distinct concentrations of sodium hydroxide (NaOH): 1 wt %, 2 wt %, and 3 wt %. The difficulties of interaction between the surface of the fiber and the matrix, which led to this treatment, is caused by miswak fiber's hydrophilic character, which impedes its ability to bind with hydrophobic polylactic acid. FTIR, tensile, TGA, and DMA measurements were used to characterize the composite samples. A scanning electron microscope (SEM) was used to examine the microstructures of many broken samples. The treatment is not yet especially effective in enhancing interfacial bonding, as seen by the uneven tensile strength data. The effect of the treated fiber surface significantly improves the tensile strength of miswak fiber-reinforced PLA composites. Tensile strength improves by 18.01%, 6.48%, and 14.50%, respectively, for 1 wt %, 2 wt %, and 3 wt %. Only 2 wt %-treated fiber exhibits an increase of 0.7% in tensile modulus. The modulus decreases by 4.15 % at 1 wt % and by 19.7% at 3 wt %, respectively. The TGA curve for alkali-treated fiber composites demonstrates a slight increase in thermal stability when compared to untreated fiber composites at high temperatures. For DMA, the composites with surface treatment have higher storage moduli than the composite with untreated miswak fiber, especially for the PLA reinforced with 2 wt % alkali miswak fiber, proving the effectiveness of the treatment.

Effect of mercerization on the properties and biodegradation behavior of LDPE and LDPE/PHB hybrid composites filled with castor bean cake

ABSTRACT The aim of this study is to evaluate the effect of mercerization of castor cake on the tensile and biodegradation behaviour of LDPE and LDPE/PHB composites. Polymer composites filled with raw castor cake (CC) and castor cake treated with 5% NaOH solution (MCC) were developed and the tensile and biodegradation behaviour of the materials obtained were evaluated. The incorporation of mercerized fibers to polymeric matrices generated materials with an elastic modulus superior to that of LDPE and tensile strength values close to that of LDPE. The biodegradation rates of the polymer composites increased the addition of fibers. However, alkali-treated fibres had a less pronounced effect biodegradation rates of the polimeric composites, due to the lower tendency of mercerized fibers to absorb water. The 85/10/5 LDPE/PHB/CC composite showed greater mass loss, 3.1%, than the 85/10/5 LDPE/PHB/ MCC composite, respectively, 0.9%, in 180 days.

Physico-Chemical Properties of Alkali Treated Cellulosic Fibers from Fragrant Screw Pine Prop Root

ABSTRACT The purpose of this study is to characterize alkali-treated fibers from the prop root of fragrant screw pine (FSP) plant in order to determine their suitability as a substitute for man-made fiber in preparation of lightweight bio-based composite materials. The physical, chemical, mechanical, morphological, and thermal properties of alkali-treated FSP fibers (AFSPF) were reported and compared to those of other natural fibers used as reinforcement in polymer composites. Cellulose content (80.53 wt.%), wax content (0.21 wt.%), density (1.41 g/cm3), tensile strength (619–1038 MPa), and young’s modulus (23–41 GPa) of AFSPF were determined. Thermal analysis (TGA and DTG) confirms the thermal stability of these fibers up to 257°C. The characterized properties demonstrate that AFSPF can be used as reinforcement in the preparation of polymer-based bio-composites for applications requiring low weight and high specific strength that meet technical and environmental requirements.

Effect of alkali treatment on physical–chemical properties of sisal fibers and adhesion towards cement-based matrices

This work aims to evaluate the effect of alkali treatment on sisal fibers to improve the fiber properties and the effectiveness of their use as reinforcement in cement-based matrices. Alkaline solution concentration (1, 5 and 10 wt% NaOH) and post-treatment protocol (use of distilled water or acetic acid) influence were evaluated. The physical, chemical, thermal, wettability and surface characteristics were analyzed. Also, single-fiber direct tensile and pullout tests were performed. Results showed an increase in cellulose proportion with a reduction in hemicellulose and lignin content upon alkali treatment. Consequently, enhanced thermal stability and a decrease on the water uptake tendency were reached. Additionally, improved tensile properties, as well as an enhanced bond with the cementitious matrix, were found for alkali-treated fibers. Also, fibers became more stable when subjected to alkaline aggressive conditions. Thus, the alkali-treated sisal fiber seems to be an adequate and sustainable alternative as reinforcement for cement-based matrices.

Alkali treatment influence on cellulosic fiber from Furcraea foetida leaves as potential reinforcement of polymeric composites

The present study explores the potential of the alkali-treated Furcraea foetida (FF) fibers as reinforcement materials in polymeric composites. The fibers were treated and soaked for 3 h in an alkali solution of different concentrations (3, 6, 9, 12, and 15 wt.%). The untreated and alkali-treated fibers were characterized, and their physical and mechanical properties were determined. The results revealed that the 9 wt.% alkali-treated FF fiber yielded superior mechanical strength and Young's modulus because of its relatively high cellulose fraction after removing non-cellulosic materials. The twisting behavior and increasing microfibril angle of the FF fiber were attributed to a non-linear region in the stress–strain curves after the alkali treatment. The Fourier-transform infrared and X-ray diffraction studies endorsed the removal of non-cellulosic materials on optimally treated fiber. Thermogravimetric analysis of the 9 wt.% alkali-treated FF fiber confirmed the increase in the degradation temperature (358 °C) and activation energy (145.29 kJ/mol). Scanning electron microscopy results confirmed that the fiber surface roughness is proportional to the alkali solution concentration. Then the results were compared with others previous studies. Thus, treating FF fibers with optimized alkali concentration at specified soaking period can enhance their performance as a viable reinforcement material in polymeric composites for low-load applications.