Fiber Biocomposites Research Articles

Influence of the source of starch and plasticizers on the environmental burden of starch-Brazil nut fiber biocomposite production: A life cycle assessment approach

Amidst the global plastic pollution crisis, bio-based polymers have been proposed as a potential substitute to tackle this issue. Owed to their biodegradability, biopolymers are generally regarded as eco-friendly during the post-consumer (disposal) stage. However, the environmental burden of the many production processes biopolymers and their components undergo better reflect the sustainable nature of these materials. Previous studies evaluating the Life Cycle Assessment (LCA) of starch-based composites have focused on commercially available starches, although other non-conventional starches can also be used to produce biopolymers. To address this knowledge gap, in the present study we evaluated the LCA of starch-Brazil nut fiber biocomposites prepared with starch from three different sources, Andean potato, corn, and sweet potato, and applying two different plasticizers, glycerol and sorbitol. Results indicated that the starch-based biocomposites were less impacting than conventional PLA-Brazil nut fiber and PP-glass fiber composites. The type of starch and plasticizer significantly influenced the environmental load of the production of the composites. The main drivers of these differences were the multiple agricultural practices, such as irrigation and fertilization, and the crop efficiency for starch extraction. Sorbitol was found to be many times more impacting than glycerol in most categories, which is due to the complex processing of sorbitol and high content in biocomposites with similar mechanical properties than glycerol. Additionally, Brazil nut fibers are presented as an eco-friendly and low-burden natural filler due to their easy processing and agricultural waste origin. The limitations, applications, and significance of the results were discussed.

Study on properties of polylactic acid/lemongrass fiber biocomposites prepared by fused deposition modeling

AbstractIn this paper, poly(lactic acid) grafted with maleic anhydride (PLA‐g‐MAH) was prepared by melt grafting, and added into poly(lactic acid)/lemongrass fiber (PLA/LF) biocomposites after analyzing the chemical properties of LF. The effect of PLA‐g‐MAH on the properties of PLA/LF biocomposites was studied. Differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), scanning electron microscope (SEM) were used to characterize the crystallinity, isothermal crystallization behavior, thermal stability and microstructure of the biocomposites. In addition, the mechanical properties of biocomposites prepared by fused deposition modeling (FDM) 3D printing technology were also characterized. The results show that, the contents of cellulose, hemicellulose and lignin are 22.5%, 36.4%, and 22.8%, respectively in the composition of LF. With the addition of LF, the flexural modulus, crystallinity and crystallization rate of biocomposites are improved. After PLA‐g‐MAH was added, the crystallization rate of PLA is further slightly increased, but the crystallinity is not changed much. The mechanical properties of the PLA/LF biocomposites are improved to the greatest extent when 5 wt% PLA‐g‐MAH was added. PLA‐g‐MAH can significantly reduce the internal cavity and fiber peeling phenomenon, and there is no obvious gap between phases so that interface compatibility of PLA and LF is improved obviously.

Technological Research of Zinc Extraction from Elazığ Simitsonite Ore

Acrodur, aqueous polyacrylic acid solution and dispersion, has been developed as an alternative wood adhesive to phenolic and urea formaldehyde resins. It has many environmental benefits over the conventional thermoset resins that include its non-corrosive nature and non-emission of carcinogenic gases. It has superior tolerance to moisture during composite fabrication and thus drying of the preforms may be minimised or even eliminated contrary to most resins used in natural fibre biocomposites. The aim of this study was to produce optimised hemp fibre reinforced Acrodur resin biocomposites using nonwoven hemp fibre mats by varying Acrodur solution to dispersion ratio, relative humidity, curing time and temperature. The optimised biocomposites gave the best combination of 26.4MPa-cm3/g specific tensile strength and 4.4GPa-cm3/g specific Young’s modulus with 0.94g/cm3density. Thermogravimetric analysis (TGA) and contact angle measurement showed similar thermal stability and increased hydrophobicity of the biocomposites than those of the fibres. From the water immersion test, the path of wicking of water moleculesinto the biocomposites was believed to be rather straight than tortuous and about 43.5% loss of tensile strength and 57.1% loss of Young’s modulus were observed upon 4-week water immersion of the biocomposites.

Preparation, characterization and application of curcumin based polymeric bio-composite for efficient removal of endotoxins and bacterial cells from therapeutic preparations

Polymer science offers a great insight and a new research dimension for biomedical applications. The synthesis of polymeric materials by the physical ways provides several advantages over the conventional chemical methods. It is though expansive but less toxic, stable, and efficiently reproducible. In the present report, electrospinning was used for bio-composite preparation. The bio-composite was developed using polyvinyl alcohol (PVA) and curcumin. The electrospun fiber bio-composite were analyzed for antibacterial activity, bacterial filtration capability, and endotoxin elimination. The bio-composite was analyzed for physical structure and properties using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray analysis (EDX), and Fourier Transform Infra-Red spectroscopy (FT-IR). PVA solely was not able to exhibit any of the antibacterial or endotoxin removal properties. However, the curcumin-based bio-composite was found to be bactericidal and endotoxin eliminator. The bio-composite was able to remove 100% of endotoxin and nearly 100% of the bacterial cells. The endotoxin removal properties of bio-composite were found to be excellent fit under Langmuir curve with a R2 value of 0.98. Additionally, the effect of bio-composite was also studied over protein content in the sample and L-asparaginase activity. However, the effect observed was negligible.

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.

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.

Effect of Halloysite Nanotube on Mechanical Properties, Thermal Stability and Morphology of Polypropylene and Polypropylene/Short Kenaf Fibers Hybrid Biocomposites.

In this article, the effect of the addition of halloysite nanotube (HNT) on the mechanical and thermal stability of polypropylene (PP) and PP/kenaf fiber biocomposites has been investigated. Different volume contents of HNTs ranging from 1 to 10 vol.% were melt mixed with PP and PP/kenaf fibers. The volume content of kenaf fibers was kept constant at 30%. The morphology of HNTs within the PP matrix has been studied via scanning electron microscopy (SEM). The morphological results revealed that HNT was uniformly dispersed in the PP matrix already at a low concentration of 1 and 2 vol.%. The mechanical properties of the manufactured nanocomposites and hybrid biocomposites such as Young’s modulus, tensile strength, elongation at break, flexural modulus, flexural strength, and notched Izod strength have been measured. The results show that Young’s modulus and strengths have been improved along with the addition of low content of HNTs. Moreover, the gain of notched Izod impact strength obtained by the addition of short kenaf fibers was maintained in hybrids with low concentrations of HNTs. Finally, the thermogravimetric analysis shows that at 10% and 50% weight loss, the thermal degradation rate of the PP and PP/kenaf biocomposites decreased by the addition of HNTs.

Influence of the granulometry and fiber content of palm residues on the diesel S-10 oil sorption in polyurethane /palm fiber biocomposites

The use of technologies with sustainable adsorbents from agro-industrial residues with hydrophobic characteristics has induced the interest of the scientific community, due to the accidents involving spills and leaks of organic pollutants, generating the concern impacts caused to the environment. Thus, in this study was proposed an alternative for palm residues as reinforcing in castor oil-based polyurethane, obtaining eco-friendly biocomposites for sorption of S10 diesel oil. Biocomposites were obtained by mass mixing the polyol with the prepolymer (1:1) and reinforced from 5 to 20% m/m with palm residues and different particle sizes (28 mesh and 35 mesh), to evaluate the influence of same. The palm residues, pure PU, and biocomposites were characterized by techniques scanning electron microscopy (SEM), optical microscopy (OM), apparent density, porosimetry (BET), contact angle, X-ray diffractometry (XRD), thermogravimetry (TGA), and spectroscopy infrared (FTIR). To evaluate the sorption capacity and efficiency as a function of the content and particle size of the fiber added to the polymeric matrix, tests were performed in times of 30–240 ​s in three systems: S10 diesel oil, S10 diesel oil/saline water and S10 diesel oil/mineral water. Results showed that biocomposites presented greater capacity and better sorption efficiency compared to pure PU in the three sorption systems analyzed; however, a greater performance was obtained in the S10 diesel oil system. Besides, the fiber content and particle size directly influenced the results. Biocomposites with higher particle size fibers (28 mesh) and higher content showed the best results with sorption capacity (10.02 ​g/g) and sorption efficiency (24.10%). The contour diagram showed that different particle size fiber (28 and 35 mesh) in the biocomposites presented a linear trend between the sorption/time/fiber fraction. Also, biocomposites presented a reuse efficiency of five cycles, maintaining their hydrophobicity even after the process.

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.

PLA/flax fiber bio-composites: effect of polyphenol-based surface treatment on interfacial adhesion and durability

ABSTRACT Fiber treatments to enhance interfacial adhesion in natural fiber-reinforced composites generally induce the use of many chemicals. To address this issue, the present work aimed to develop innovative and ecological fiber treatments to produce 100%-green composites, by investigating interfacial adhesion between modified flax fibers and polylactic acid (PLA) using lignin and tannin, two types of eco-friendly polyphenolic compounds derived from waste or paper industry byproducts. The surface modification of flax fibers was performed using a dip-coating method and solutions of condensed tannin or Kraft lignin at different concentrations ranging from 1% to 7% (wt/V). The results showed that the use of coating solutions composed of 1% (wt/V) tannin or lignin significantly improved the interfacial adhesion of composites. Tannin showed better compatibility with PLA and flax fibers with a 17% and 29% increase in the ultimate flexural strength and interlaminar shear strength of the composites, respectively. These results were explained by tannin higher concentration of hydroxyl functions as compared to lignin and thus, good reactivity with cellulose and PLA. Coating solutions rich in lignin or tannin have reduced the mechanical properties of composites due to the thicker coating layers and the migration of lignin or tannin molecules into the PLA bulk.

Effect of [C2mim][OTf] Ionic Liquid on Tensile Properties of HDPE/KCF Biocomposites: A Primary Research

In this primary research, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid ([C2mim][OTf]) was added to the high-density polyethylene/kenaf core fiber (HDPE/KCF) biocomposites by using an internal mixer at 150°C, followed by compression molding at the same temperature. The [C2mim][OTf] contents were varied from 0 to 10wt.%. The tensile properties of the prepared biocomposites have been determined by using a universal testing machine. The tensile results of the HDPE/KCF biocomposites indicated that the tensile strength and tensile modulus have decreased with the addition of [C2mim][OTf]. However, the presence of [C2mim][OTf] has significantly increased the tensile extension at break of the biocomposites. This research concluded that the addition of [C2mim][OTf] at the lower content (≈ 10wt.%) could act as a plasticizer for improving the flexibility of HDPE/KCF biocomposites.

Physical and Environmental Properties of Thermoplastics Corn Starch TPCS Reinforced Pineapple Leaf Fibre PALF Composite

The purpose of this research is to study the physical and environmental properties of thermoplastic corn starch (TPCS) reinforced with 2 mm length of pineapple leaf fibre (PALF) bio-composites. Weight percentages of PALF ranging from 20 wt.% to 60 wt.% were used in this investigation. Hot compression moulding technique was used to produce samples of TPCS with different wt.% of PALF at the temperature of 165 °C for the duration of 15 minutes. The physical tests that had been performed were density, moisture content, moisture absorption and water absorption while the environmental tests were water solubility and soil burial testing. The moisture content results showed a decreasing trend by increasing the PALF content. However, moisture absorption and water absorption revealed an increased yield with the increase in PALF content. Meanwhile, density results did not show much change even when the fibre content was raised up to 60 wt.%. In addition, the water solubility results showed an increasing trend as the fibre was increased from 20 wt.% to 60 wt.%. On the other hand, soil burial results revealed vice versa whereby an increasing fibre content caused the weight loss of bio-composites to gradually decrease from 20 wt.% of fibre loading to the maximum of fibre loading. In conclusion, the physical and environmental properties of TPCS/PALF bio-composites obtained from this study can be used to develop biodegradable products such as containers or disposable trays.

From fabric to tissue: Recovered wool keratin/polyvinylpyrrolidone biocomposite fibers as artificial scaffold platform.

Keratin extracted from wool fibers has recently gained attention as an abundant source of renewable, biocompatible material for tissue engineering and drug delivery applications. However, keratin extraction and processing generally require a copious use of chemicals, not only bearing consequences for the environment but also possibly compromising the envisioned biological outcome. In this study, we present, for the first time, keratin-PVP biocomposite fibers obtained via an all-water co-electrospinning process and explored their properties modulation as a result of different thermal crosslinking treatments. The protein-based fibers featured homogenous morphologies and average diameters in the range of 170-290nm. The thermomechanical stability and response to a wet environment can be tuned by acting on the curing time; this can be achieved without affecting the 3D fibrous network nor the intrinsic hydrophilic behavior of the material. More interestingly, our protein-based membranes treated at 170°C for 18h successfully sustained the attachment and growth of primary human dermal fibroblasts, a cellular model which can recapitulate more faithfully the physiological human tissue conditions. Our proposed approach can be viewed as pivotal in designing tunable protein-based scaffolds for the next generation of skin tissue growth devices.

FTIR Spectroscopy Analysis of PLA Biocomposites Reinforced with Hemp Fibers

In this study, Fourier-transform infrared spectroscopy (FTIR) of polylactide (PLA) biocomposites reinforced with hemp fibers were analyzed. Three samples of biocomposites with different proportions of hemp fibers in the PLA matrix were compared. Hemp and PLA fibers in biocomposite were evenly blended using carding technology. Samples before and after water absorption were compared using scanning electron microscopy (SEM). Thermoset treated polylactide and hemp fiber biocomposites have high mechanical properties, that allow to reduce the number of materials in the product. The developed biocomposite can be used as a slab material and for molded parts of furniture, etc.

Controlling interfacial interactions in LDPE/flax fibre biocomposites by a combined chemical and radiation-induced grafting approach

By combining chemical and gamma radiation treatments, we show that it is possible to improve the interfacial adhesion between natural fibres and a non-polar and non-reactive matrix such as low density polyethylene (LDPE), and the resulting mechanical performances of their biocomposites. To this aim, flax fibres are first functionalized with octadecylphosphonic acid (ODPA) and the quantity, effective grafting and localization of ODPA molecules on flax fibres are characterized by ICP-AES, solid state 31P NMR and SEM-EDX. ODPA molecules are effectively grafted onto flax fibres at a content of roughly 2.5 wt% and mostly localized at the fibre surface. Moreover, contact angle measurements as well as water sorption kinetics give evidence for increased hydrophobic and oleophilic character of ODPA treated fibres. Pellets of LDPE/flax fibre biocomposites obtained by melt extrusion are then submitted to gamma radiation and processed by injection moulding. Based on Soxhlet extraction experiments and SEM observations, it is shown that LDPE cross-linking rate induced by gamma radiation is locally enhanced at the fibre/matrix interface, suggesting that regio-selective cross-linking occurred between LDPE chains and the alkyl chain of ODPA grafted on flax fibre surface. Consequently, the uniaxial tensile performances of the biocomposites are enhanced by this combined chemical and radiation-induced grafting approach, especially their ultimate properties (up to 40% increase in the work of rupture). These results evidence an enhanced interfacial adhesion that is also supported by more cohesive interfacial failure and higher work of rupture through in-situ micro-mechanical tensile SEM experiments.

Influence of Filler Loading and in Situ Salicylic Acid Treatment on Corn Husk Fiber Filled Poly(Hydroxybutyrate-Co-Valerate)

The effect of filler loading and in situ salicylic acid treatment on the mechanical properties and morphology of poly(hydroxybutyrate-co-valerate)/corn husk fiber (PHBV/CHF) biocomposites was studied. Both untreated and salicylic acid treated PHBV/CHF biocomposites were prepared by using heated two roll mill followed by compression moulding. It was found that the addition of CHF to PHBV biocomposites increased the tensile strength and Young’s modulus while the elongation at break decreased. Salicylic acid treated PHBV/CHF biocomposite display superior tensile strength and Young’s modulus than untreated PHBV/CHF biocomposite due to the enhanced filler–matrix interaction. The better interfacial adhesion between CHF and PHBV matrix was confirmed through scanning electron microscope (SEM) analysis.

Studies on the Effect of Hybridization on Sound Insulation of Coir-banana-polypropylene Hybrid Biocomposites

ABSTRACT Natural fiber-based hybrid composites have been explored in this study as possible structural materials. Detailed investigation of sound insulation property of a series of hybrid and nonhybrid composites has been carried out using impedance tube having four microphones. Hybrid biocomposites were prepared with chopped and randomly oriented coir and banana fibers. Polypropylene was used as a matrix and compression molding technique was used for composite fabrication. The ratio of both fibers in hybrid biocomposites was maintained at 1:1. The effect of fiber loading and arrangement of fibers on sound insulation property of composites was investigated. It was found that fiber loading and hybridization bear a significant role in improving sound insulation property of hybrid composites. Experimental results showed that increase in fiber loading considerably improved the sound insulation up to a certain limit. The sound insulation property of hybrid and nonhybrid composites has been subsequently discussed. The results showed that sound insulation performance can be customized by structural parameters such as volume fraction, dispersion, ratio, and placement of fibers with respect to sound source, without necessitating a change in raw material.

Physical–chemical and structural stability of PHBV/wheat straw fibers based biocomposites under food contact conditions

AbstractThis aricle aims at investigating for the first time the ability of using poly(3‐hydroxylbutyrate‐co‐3‐hydroxyvalerate) (PHBV)/wheat straw fibers (WSF) biocomposites as food contact materials for packaging applications. For that purpose, the impact of the filler size and content on overall migration and mechanical properties was assessed under standardized testing conditions using the food simulant liquids (FSL). Very high overall migration values were noticed in the case of hydrophilic FSL, that is, water, acetic acid 3% (wt/vol), ethanol 20% (vol/vol), and ethanol 95% (vol/vol), related to the leaching of water extractable components of WSF. Low migration values were obtained in contact with isooctane and olive oil, demonstrating the possibility of using biocomposites in contact with fatty products. To answer the lack of methodologies to simulate different types of food for which PHBV‐based composites could be more specifically dedicated, including food products of low or intermediate water activity such as fruits and vegetable, bread, and cheese, a new range of new solid food models based on agar‐agar gels have been developed. Results showed that the water activity (aw) was the main parameter governing the overall migration of PHBV/WSF materials, suggesting that such composite materials could only be used as food contact materials in the case of food products with an awequal or lower than 0.90.

Development and evaluation of zinc oxide-blended kenaf fiber biocomposite for automotive applications

There is an increasing environmental concern of using glass-fiber sheet molding compound (GF-SMC) in automobiles. Here, a zinc oxide (ZnO) blended natural fiber-reinforced biocomposite (NFRBC) was developed and evaluated to replace the commercial automotive GF-SMC (Meridian’s SLI 323IF) due to its superior properties and environmental friendliness. The NFRBC consists of kenaf (Hibiscus cannabinus) fibers blended with ZnO nanoparticles to obtain a fiber-mat preform used to manufacture the final NFRBC using a vacuum-assisted resin transfer molding process. Adding 12.4 % ZnO nanoparticles increased flexural strength (121 %), tensile strengths (38 %) and water resistance (76 %). The ZnO12.4 %-NFRBC had comparable mechanical properties as GF-SMC while the production consumed 9% less energy and reduced the environmental burden by 33 % from life-cycle assessment (LCA). Although the water-resistance of ZnO12.4 %-NFRBC was significantly improved, further adjustments are needed to fully meet the requirements for GF-SMC replacement.

Physical and rheological properties of biodegradable poly(butylene succinate)/Alfa fiber composites

Biodegradable poly(butylene succinate) (PBS)/Alfa fiber biocomposites were prepared through the compression molding method. Scanning electron microscopy images were acquired to assess the effects of reinforcement and homogenization of mixtures and to determine the characteristics of the microstructure. The rheological properties, melting, and crystallization behavior of neat PBS and its biocomposites were investigated. Regarding the thermal properties, it was observed that the presence of Alfa fibers facilitates the crystallization of the PBS matrix, which suggests that Alfa cellulose fiber acts as a nucleating agent. The rheological analysis suggests that the biocomposites show a better dynamic behavior with the addition of Alfa fibers. Indeed, the incorporation of fibers increased the complex modulus and complex viscosity of the composites. Also, increasing the percentage of fibers in the matrix induces percolation, the shift and change in the slope of Cole–Cole curve of the PBS/Alfa fiber composite compared to that of neat PBS indicate that the PBS microstructure has changed with the addition of fibers. Moreover, the improvement of biocomposites properties is believed to be largely attributable to the homogeneous dispersion of the Alfa fibers within the polymer matrix and also to the strong interfacial interactions between the two constituents.