Agave Fibers Research Articles

Compatibilization strategies for PLA biocomposites: a comparative study between extrusion-injection and dry blending-compression molding

ABSTRACT In this work, PLA biocomposites were prepared by two different processing methods to evaluate two coupling agents: maleic anhydride grafted PLA (MA-g-PLA) and glycidyl methacrylate grafted PLA (GMA-g-PLA). Coupling agents were directly incorporated during extrusion before injection molding and through fiber surface treatment before dry-blending (DB) and compression molding. The biocomposites morphology was more homogeneous and with fewer voids using both coupling agents due to a better adhesion. The processing method influenced the coupling efficiency and determined the biocomposites properties. Tensile strength decreased with the agave fibers incorporation to a larger extent in DB-compression molding (from 47 to 34 MPa) than in extrusion-injection (from 55 to 51 MPa) due to the high level of compaction and dispersion achieved with high shear rate. Tensile strength was improved with both surface treatments in DB-compressed samples, while in the extrusion-injected materials, this property increased up to 67 and 59 MPa with GMA-g-PLA and MA-g-PLA, being even higher than the neat PLA. However, the excess of the coupling agent could affect its stiffness. The hydrophobic coating deposited on the surface reduced fibers hydrophilicity, and water diffusivity decreased due to a more compact internal structure, resulting in water absorption lower than 15% in all cases.

Mechanical and Physicochemical Properties of 3D-Printed Agave Fibers/Poly(lactic) Acid Biocomposites.

In order to provide a second economic life to agave fibers, an important waste material from the production of tequila, filaments based on polylactic acid (PLA) were filled with agave fibers (0, 3, 5, 10 wt%), and further utilized to produce biocomposites by fused deposition modeling (FDM)-based 3D printing at two raster angles (−45°/45° and 0°/90°). Differential scanning calorimetry, water uptake, density variation, morphology, and composting of the biocomposites were studied. The mechanical properties of the biocomposites (tensile, flexural, and Charpy impact properties) were determined following ASTM international norms. The addition of agave fibers to the filaments increased the crystallinity value from 23.7 to 44.1%. However, the fibers generated porous structures with a higher content of open cells and lower apparent densities than neat PLA pieces. The printing angle had a low significant effect on flexural and tensile properties, but directly affected the morphology of the printed biocomposites, positively influenced the impact strength, and slightly improved the absorption values for biocomposites printed at −45°/45°. Overall, increasing the concentrations of agave fibers had a detrimental effect on the mechanical properties of the biocomposites. The disintegration of the biocomposites under simulated composting conditions was slowed 1.6-fold with the addition of agave fibers, compared to neat PLA.

Performance of nylon 6 composites reinforced with modified agave fiber: Structural, morphological, and mechanical features

AbstractNylon 6 (Ny6) composites reinforced with treated agave fiber (AF) at different concentrations (5–20 wt%) were achieved by melt mixing process at 250°C, without the addition of any compatibilizing or coupling agents, and characterized in terms of their structural, morphological, and mechanical properties. The alkaline‐ultrasound (NaOH‐U) treatment in AF resulted in the removal of the low thermal stability components (pectin and hemicellulose), concentrating the cellulose fraction, and favoring the crystallinity percentages (Xc) of the Ny/AF composites. Moreover, the interfacial interactions between functional groups of agave fiber and Ny6 resulted in the increase Young's modulus (18.8%), flexural strength (11.3%), and density (3.7%). These findings could be useful when looking for potential applications in the mobility industry.

Removal of Cibacron Blue P-3R (RB 49) dye from aqueous solution using chemo-physically activated biochar from Agave fiber waste

This paper presents the use of Agave leaves for the removal of an anionic dye Cibacron Blue P 3R (CB) from aqueous solution. The work reports the preparation of activated material (ALa) by impregnation with H3PO4 and carbon fibers (ALc) by pyrolysis at 800°C, from Agave leaves (AL). The materials were characterized by potentiometric titrations, scanning electron microscope, thermogravimetric analysis, and Fourier transform infrared spectroscopy. Initial pH, contact time, and initial dye concentration were evaluated in batch mode studies. Statistical analysis root-mean-square error (RMSE) was compared in the Langmuir, Freundlich, and kinetic equations. The kinetic investigation was fitted with pseudo-second-order model for both native (AL), calcined (ALc) and activated (ALa) adsorbents with R2 values higher than 0.99. Processes were well described with Langmuir isotherm model at the dye concentration range of 10–250 mg/L for all adsorbents. AL, ALa, and ALc samples exhibited, at pH=2.2, high maximum adsorption capacity of 20.83, 50.76, and 102.04 mg/g respectively. The experimental data are fitted well by the Langmuir in case of native (AL) and activated (ALa) adsorbents, where a high correlation coefficients (R2) and a low root-mean-square errors (RMSE). For the adsorption of CB dye on the calcined material (ALc), the Freundlich mode perfectly describes the adsorption process with a very low-root-mean-squares error (RMSE) = 0.62.

Influence of Ethylene Plasma Treatment of Agave Fiber on the Cellular Morphology and Compressive Properties of Low-Density Polyethylene/Ethylene Vinyl Acetate Copolymer/Agave Fiber Composite Foams

Agave fibers (AF) were incorporated either pristine (AFp) or surface treated by ethylene plasma (AFm) in low-density polyethylene (LDPE)/ethylene vinyl acetate (EVA) blends at a ratio of 1 : 1 and foamed by chemical means. The role of the AF content (3, 6, 9, 12, and 15 wt.%) and its surface modification on the cellular morphology and mechanical properties of LDPE/EVA/AF foams under compression is investigated herein. Fourier transform-infrared spectroscopy, contact angle, and water suspension of AF suggest that plasma treatment using ethylene successfully modifies the surface nature of AF from hydrophilic to hydrophobic. AF and the surface treatment have an important role on the morphological properties of the foams. Composite foams reinforced with 12 wt.% AFm exhibited the highest mechanical properties improvements. At this fiber content, the composite foams enhanced 30% of the compressive modulus and 23% of the energy absorption under compression with respect to the neat polymer blend foam, as a result to the formation of more uniform cells with smaller size and the enhancement of compatibility and spatial distribution of the AFm in the polymer composite foams due to thin clusters of polyethylene-like polymer deposited on the AF surface.

Morphology study of Agave fiber surface by using scanning electron microscopy

Agave plants can grow well in all weather conditions, so that they are very abundant in Indonesia. The appropriate processing technique is needed to develop the utilization of Agave plants, so that they have a higher value. The main purpose of this research is to conduct material engineering of Agave americana species, so that the Agave fiber has good quality when used as a natural composite material. The research method was used by giving 5% alkaline sodium hydroxide (NaOH) treatment for 30 minutes against Agave fiber (called T samples) and the results were compared with normal Agave fiber/not treated with alkaline (called UT samples). The parameters observed were the surface morphology of the fibers which were analyzed using Scanning Electron Microscopy (SEM) at magnifications of 250x, 500x and 1000x. SEM characterization results showed that Agave fiber treated with 5% NaOH alkaline had a denser surface morphology with an average cavity percentage of 9.015%, while untreated Agave fiber had a higher average cavity percentage of 29.795%. In addition, soaking with 5% alkaline NaOH also causes dirt that sticks to the fibers more easily, so the fibers were cleaner. The conclusion of the research shows that 5% alkaline NaOH treatment on Agave fiber could increase the strength and quality of Agave fiber.

Sustainable Biocomposites from Recycled Bale Wrap Plastic and Agave Fiber: Processing and Property Evaluation.

Plastic recycling to make sustainable materials is considered one of the biggest initiatives toward a greener environment and socioeconomic development. This research aims to investigate the properties of a blend of recycled bale wrap linear low-density polyethylene (rLLDPE) and polypropylene (PP) (rLLDPE/PP 50:50 wt % matrix), which was further reinforced with 25 wt % agave fiber prepared by injection-molding. Different ratios of a combined industrial compatibilizer (maleic anhydride-grafted PP/PE) were used (1–3 wt %), which were compared with a synthesized compatibilizer made from maleic anhydride–PP/rLLDPE in terms of mechanical and thermomechanical properties of the biocomposites. Incorporation of the compatibilizer in the composite improved the interfacial adhesion between the hydrophobic matrix and the hydrophilic agave fiber, which further increased the mechanical properties and heat deflection temperature of the composite. Scanning electron microscopy showed enhanced compatibility and adhesion between the fiber and the matrix by inclusion of 2 wt % compatibilizer. The synthesized compatibilizer-blended composite showed better mechanical properties than the industrial one, which indicates the potential application of this composite (around 62% recycled material) in the manufacture of packaging materials and commodity products.

Up-cycling of agave tequilana bagasse-fibres: A study on the effect of fibre-surface treatments on interfacial bonding and mechanical properties

The aim of this study was to assess the feasibility of upcycling fibre residues from the harvesting and production of tequila to green composites. Specifically, four different surface-modified natural fibres were assessed as raw material for green composite production. Before any surface treatment, the morphology and tensile properties of agave bagasse fibres from the tequila production batches were determined by optical and environmental scanning electron microscopy (ESEM) and single fibre tensile test, respectively. Further to this, agave fibres were exposed by immersion to four surface treatments including alkali, acetylation, enzymatic and silane treatments, in order to improve their morphology and compatibility with polylactic acid (PLA). The effects of these treatments on fibres’ morphology, mechanical properties (i.e. Youngs modulus and ultimate tensile strength), interfacial shear strength (IFSS), and water absorption were assessed. Overall, surface treatments showed improvements in agave bagasse fibre properties with the best results for alkali treated fibres with an ultimate tensile strength of 119.10 ​MPa, Young modulus of 3.05 ​GPa, and an IFSS of up to ~60% higher (5.21 ​MPa) to that performed by untreated samples. These tests allowed to identify alkali treatment as the most suitable for agave bagasse fibres. These results shed light on the interfacial interaction between agave bagasse fibres and PLA and the potential to up-cycle these residue agave fibres to manufacture PLA-based green composites.

Effect of Fiber Pre-treatment Methods on Hygrothermal Aging Behavior of Agave Fiber Reinforced Polymer Composites

ABSTRACT Three different pre-treatment methods, that is, alkali hornification, water hornification, and alkali treatment, are evaluated for the improvement in durability of agave natural fiber-reinforced polymer composites under the hygrothermal aging conditions. The composite specimens were prepared following the standard test procedures laid for moisture diffusion analysis. To analyze the effect of different treatment conditions, the standard test specimens were subjected to different hygrothermal aging conditions in the accelerated environments. After four subsequent hornification cycles, the alkali hornification resulted in about 27% lower water retention value in the agave fibers. Under similar conditions, water hornification leads to a meager 6% loss of water retention. Under the direct exposure to water, the alkali-hornified composites had a mass gain of 4.1%, 4.3%, and 4.7%, respectively, at 25°C, 50°C, and 75°C. The mass gain of alkali-treated composites was 4.3%, 4.5%, and 5.1%. and water hornification resulted in a mass gain of 5.5%, 5.9%, and 6.1% at similar temperatures. Under the humidity conditions, the alkali-hornified composites had a mass gain of 0.9%, 1.3%, and 1.1%, respectively, at 25°C, 50°C, and 75°C. The mass gain of alkali-treated composites was 0.6%, 1.05%, and 1.2%. and water hornification resulted in the mass gain of 0.66%, 1.07%, and 1.3% at similar temperatures. The present study reveals the influence of fiber pre-treatment methods on moisture durability of agave natural fiber composites. The results are further supported through microstructural investigations.

Biodegradability and improved mechanical performance of polyhydroxyalkanoates/agave fiber biocomposites compatibilized by different strategies

AbstractIn this work, biocomposites made of polyhydroxyalkanoates (PHA) with natural fibers were produced via compression molding. In particular, polyhydroxybutyrate (PHB) and polyhydroxybutyrate‐co‐hydroxyvalerate (PHBV) were reinforced with 20 wt% of agave fibers. Different compatibilization strategies were investigated to improve the fiber‐matrix interaction: fiber surface treatment in PHA solution, fiber surface treatment in maleated PHA solution, fiber propionylation, and extrusion with maleated PHA. The biocomposites were characterized in terms of morphology, mechanical properties, water absorption, and biodegradability by CO2production tracking. In general, fiber propionylation was the best strategy for mechanical properties enhancement and water uptake decreasing. Biocomposites with propionylated fibers showed improved flexural strength (170% for PHB and 84% for PHBV). The flexural modulus was also enhanced with propionylated fibers up to 19% and 18% compared to uncompatibilized biocomposites (PHB and PHBV, respectively). Tensile strength increased by 16% (PHB) and 14% (PHBV), and the water absorption was reduced using propionylated fibers going from 6.6% to 4.4% compared with biocomposites with untreated fibers. Most importantly, the impact strength was also improved for all biocomposites by up to 96% compared with the neat PHA matrices. Finally, it was found that the compatibilization did not negatively modify the PHA biodegradability.

Mechanical properties and fracture behaviour of agave fibers bio-based epoxy laminates reinforced with zinc oxide

Biolaminates of Ixtle and Henequen natural fibers reinforced bio-based epoxy resin were prepared using Vacuum Assisted Resin Infusion process. ZnO nanoparticles were added to the bio-based epoxy resin at 1, 2 and 3 wt. % content before impregnation process. The viscoelastic and mechanical properties, as well as the fracture behavior, were evaluated and related to the nature of the fibers and filler content. The viscoelastic results indicated the ZnO particles are effective fillers just at low concentrations, and induce different reinforcement mechanisms attributed to the interaction between the nature of fibers and nanoparticles. The mechanical properties of the Ixtle biolaminates decreased at higher filler concentrations, while Henequen biolaminates showed better mechanical properties just above the 2 wt. % of ZnO. The fracture behavior in mode I registered moderate changes in toughness, related to the ZnO fraction, which promoted different behaviors on the interlaminar adherence of the layers. The results point to the need to continue evaluating the potential application of these green composites for their use in construction and automotive industries.

Accelerated Weathering of Polylactic Acid/Agave Fiber Biocomposites and the Effect of Fiber–Matrix Adhesion

In this study, the accelerated weathering of PLA and its biocomposites produced with agro-industrial waste agave fibers was evaluated to better understand the lifetime of these materials. The effects of the fiber content, the fiber treatment with glycidyl methacrylate grafted PLA, and the fiber/matrix adhesion on the degradation of the materials were also analyzed. The biocomposites were prepared by dry blending, followed by compression molding using untreated and chemically modified agave fibers. The chemical treatment promoted a better fiber–matrix adhesion and lower fiber pull-outs resulting in high tensile and flexural strength values (similar to the neat PLA even with 40 wt% of fiber). Once the modification of the fiber–matrix was observed to be effective, the effect of accelerated weathering over compatibilized and uncompatibilized biocomposites was evaluated. The results showed that after accelerated weathering, the crystallinity of the biocomposites increased significantly, causing that the impact strength remains constant and, in some cases, even improved. At the same time, tensile and flexural properties were noticeably decreased. Nevertheless, the treated fibers which have better adhesion to the matrix led a better resistance to weathering degradation, which is confirmed by higher dimensional stability and lower decreases in tensile and flexural properties than biocomposites with untreated fibers.

Purificación de la fibra de agave por un método hidrotérmico

The bagasse of agave tequilana Weber is a lignocellulosic waste generated by the tequila production process. Purification of agave fiber was carried out by evaluating the effect of temperature and reaction time on the hydrothermal process. Hydrolysis was carried out in a high pressure digester, temperature 140°C, the process was standardized using 3.5 g of fiber previously dried, a solution of 0.5 M nitric acid (HNO3) in deionized water and reaction time of 6 h, the developed pressure inside the system caused the release of organic material such as hemicellulose and lignin from the cellulose microfiber grid that forms the structure of agave bagasse. Overall, a yield of 326 g/kg dry matter was obtained; equivalent to 48% of the theoretical value, this method is a promising alternative to treat this type of waste.

Fiber-matrix interface improvement via glycidyl methacrylate compatibilization for rotomolded poly(lactic acid)/agave fiber biocomposites

The growing interest in research and development of eco-friendlier materials makes attractive the use of bio-based and biodegradable polymers such as polylactic acid (PLA). However, the higher cost of PLA compared to conventional polymers limits its applications. Moreover, raw materials for rotational molding must be in a powder form, which further increases their cost. So, the main objective of this study was to use agave fibers to produce lower-cost PLA based rotomolded biocomposites (BC) without compromising its bio-sourced origin and to compare with a standard rotomolding resin: linear medium density polyethylene (LMDPE). To improve the fiber-matrix interface, a chemical surface treatment of the fibers with glycidyl methacrylate grafted polylactic acid (GMA-g-PLA) in solution was evaluated. The results showed that a better biocomposites’ morphology was obtained, especially with the fibers treated twice. The surface treatment was also shown to substantially improve the flexural and tensile properties of treated fiber biocomposites at higher fiber content (25% wt.) compared to those with untreated fiber. The surface treatment also led to a substantial reduction of the biocomposites porosity and water absorption. Overall, the samples were shown to have better mechanical properties than neat LMDPE while being eco-friendlier due to their bio-nature.

Phenolic Constitution, Phytochemical and Macronutrient Content in Three Species of Microgreens as Modulated by Natural Fiber and Synthetic Substrates.

The present study examined the modulatory effects of natural fiber substrates (agave fiber, coconut fiber and peat moss) and synthetic alternatives (capillary mat and cellulose sponge) on the nutritive and phytochemical composition of select microgreens species (coriander, kohlrabi and pak choi) grown in a controlled environment. Polyphenols were analyzed by UHPLC-Q-Orbitrap-HRMS, major carotenoids by HPLC-DAD, and macro-minerals by ion chromatography. Microgreens grown on peat moss had outstanding fresh and dry yield but low dry matter content. Natural fiber substrates increased nitrate and overall macro-mineral concentrations in microgreens compared to synthetic substrates. The concentrations of chlorophylls, carotenoids and ascorbate were influenced primarily by species. On the contrary, variability in polyphenols content was wider between substrates than species. Out of twenty phenolic compounds identified, chlorogenic acid and quercetin-3-O-rutinoside were most abundant. Hydroxycinnamic acids and their derivatives accounted for 49.8% of mean phenolic content across species, flavonol glycosides for 48.4% and flavone glycosides for 1.8%. Peat moss provided optimal physicochemical conditions that enhanced microgreens growth rate and biomass production at the expense of phenolic content. In this respect, the application of controlled stress (eustress) on microgreens growing on peat moss warrants investigation as a means of enhancing phytochemical composition without substantial compromise in crop performance and production turnover. Finally, nitrate deprivation practices should be considered for microgreens grown on natural fiber substrates in order to minimize consumer exposure to nitrate.

Morphological and Mechanical Properties of Bilayers Wood-Plastic Composites and Foams Obtained by Rotational Molding.

In this work, the suitability for the production of sustainable and lightweight materials with specific mechanical properties and potentially lower costs was studied. Agave fiber (AF), an agro-industrial waste, was used as a reinforcement and azodicarbonamide (ACA) as a chemical blowing agent (CBA) in the production of bilayer materials via rotational molding. The external layer was a composite of linear medium density polyethylene (LMDPE) with different AF contents (0–15 wt %), while the internal layer was foamed LMDPE (using 0–0.75 wt % ACA). The samples were characterized in terms of thermal, morphological and mechanical properties to obtain a complete understanding of the structure-properties relationships. Increases in the thicknesses of the parts (up to 127%) and a bulk density reduction were obtained by using ACA (0.75 wt %) and AF (15 wt %). Further, the addition of AF increased the tensile (23%) and flexural (29%) moduli compared to the neat LMDPE, but when ACA was used, lower values (75% and 56% for the tensile and flexural moduli, respectively) were obtained. Based on these results, a balance between mechanical properties and lightweight can be achieved by selecting the AF and ACA contents, as well as the performance and aesthetics properties of the rotomolded parts.

Synthesis and characterization of nano-fibrillated cellulose derived from green Agave americana L. fiber

Excessive exploitation of petroleum-based plastics and synthetic fibers is harming the environment. This study isolated nano-fibrillated cellulose (NFC) from plant fiber (Agave americana). The as-extracted Agave fibers were chemically treated (alkali, bleaching, and acid hydrolysis coupled with ultrasonication). Functional and structural analysis were performed using Fourier-transform infrared spectroscopy and X-ray diffraction. The surface morphological changes and thermal decomposition behavior were studied by scanning electron microscopy and by thermogravimetry and derivative thermogravimetry, respectively. Fourier-transform infrared peaks confirmed the absence of lignin and hemicellulose in the NFC samples. X-ray diffraction data revealed that the crystallinity index increased from 50.1% to 64.1% from the raw fiber to the NFC. Thermogravimetry and derivative thermogravimetry showed that the stability increased notably from the raw fiber to the NFC stage. The average particle size was 18.2 nm ± 10.14 nm in the NFC sample, which was confirmed by transmission electron microscopy.

Sustainable composites from poly(3-hydroxybutyrate) (PHB) bioplastic and agave natural fibre

A sustainable composite based on poly(3-hydroxybutyrate) PHB and agave fibre was produced.

Diet analysis reveals pre-historic meals among the Loma San Gabriel at La Cueva de Los Muertos Chiquitos, Rio Zape, Mexico (600–800 CE)

Coprolites have been a source of study for archeologists due to several reasons: they not only provide information on the life and nutritional habits of ancient individuals but also on their health. In this paper, we processed 10 coprolites collected at La Cueva de Los Muertos Chiquitos (600–800 CE), Rio Zape, Mexico, with acetolysis solution for pollen analysis. The number of pollen grains/gram of each coprolite sample was quantified along with the macroscopic remains of these samples. The main food item ingested by the population was maize, followed by Agave. Squash blossoms were also part of their food source determined by the presence of pollen grains. In macroremains, we identified rodent bones, plant seeds, and Agave fibers. The macroscopic analysis of the samples fits with the analysis of smaller remains, giving an idea of the meal represented by each coprolite analyzed. We relate these results to previous microbiome studies of coprolite samples from the same archeological site and provide a discussion on the relevancy of studying macro- and microremains that can be applied to microbiome interpretation analysis.

Eco-friendly Extraction of Fibrils with Hierarchical Structure Assisted by Freeze-Drying Using Agave Salmiana Leaves as a Raw Material

Agave fibers were extracted mechanically without the use of solvents or water, through a lyophilization-assisted method. Then, the internal arrangement of the fibrils was studied in order to elaborate a hierarchical growing model, using this information to explain the outstanding properties of these natural fibers. We found that the lyophilized fibers have an initial modulus of 36.7 g/den, a breaking tenacity of 1.45 g/den and an elongation of 17 %, while the fibers washed with water after extraction presented a similar value of initial modulus (31.1 g/den), but the breaking tenacity (2.59 g/den), and the elongation (34 %) increased nearly two times, showing the embrittling effect of the freeze-drying on the fibers behavior.