The current study was performed to synthesize a series of renewable polyamide 614/organoclay nanocomposites (PAC) with the improved structural, mechanical, and thermal properties via in-situ ...polymerization. The uniform dispersion and exfoliation of clay into the PA614 matrix, particularly at a lower loading of organoclay (less than 3%), confirmed via structural analyses (XRD, SEM, and TEM). Furthermore, the mechanical tests revealed remarkable improvement; namely, the tensile strength and storage modulus increased by 27% and 30%, respectively, in the sample contained 2% organoclay. Similarly, the TGA results showed a slight improvement in the thermal stability of the nanocomposite samples. Altogether, these improvements confirmed excellent compatibility between nanofiller and matrix and the organoclay homogenous dispersion into the PA matrix achieved by employing in-situ polymerization. Furthermore, all the samples illustrated a shear-thinning behavior over frequency attributed to the lack of time for the polymer chain to respond to the applied oscillation. Finally, the crystallinity of the samples diminished upon increasing the filler's content, which could be due to the decrease of free volume resulting from the presence of organoclay. To sum up, the current investigation supported the benefit of employing in-situ polymerization to synthesize renewable PA614/clay nanocomposites with enhanced physio-mechanical properties, which could be appropriate candidates for engineering applications.
•Development a series of renewable PA614/organoclay nanocomposites.•In-situ polymerization of exfoliated PA614/organoclay nanocomposites.•Good dispersion of nanofiller and appropriate interaction between fillers and matrix.•Improved mechanical and thermal properties via employed in-situ polymerization.•The acceptable potential of the developed nanocomposites for different engineering applications.
The effects of crystalline morphology and presence of nanoparticles such as cellulose nanofibers (CNFs), organically modified nanoclay (C30B), or a combination of both on water vapor sorption and ...diffusion in polylactide (PLA) were evaluated by a quartz spring microbalance (QSM). It was found that the large spherulite size induced by high-temperature processing leads to an increase in water sorption and a substantial reduction of diffusion with increasing crystallinity. Contrarily, small-sized spherulites, arising after low-temperature processing during solvent-casting, showed a different behavior with a slight decrease in both water vapor sorption and diffusion with increasing crystallinity. These observations suggest that solvent-casting at low temperatures should not be used to predict the properties a material will show after industrial-scale processing. From the analysis of the nanocomposite materials, it was concluded that nanoparticles affected the material′s properties not only by themselves but also by modifying the crystalline morphology. Interestingly, this led to CNF showing similar performance to C30B, decreasing water diffusivity (21 vs 27%) on isothermally crystallized materials despite its less favorable geometry. Additionally, the incorporation of 1 wt % CNF and C30B decreased water vapor transmission rate (WVTR) by 24% under an amorphous state but by 44% in a crystallized state, which makes hybrid CNF/C30B composites a promising food packaging material.
In this paper, for the first time, it is studied the synergetic properties of two different grades of nanocelluloses with different chemical compositions (cellulose nanofibrils-CNF with less than 1% ...of lignin and lignocellulose nanofibrils-LCNF with 16% of lignin). CNF and LCNF were mixed in different ratios to obtain bi-component films. Their performance in terms of transparency, bioactivity, thermo-mechanical and gas barrier properties was evaluated and compared with the performance of the neat CNF films. The presence of LCNF in the formulations conferred antioxidant and UV blocking properties to the films, as well as improved mechanical and barrier properties. Specifically, the incorporation of 25% LCNF to the CNF films increased the mechanical properties (94% increase in tensile stress and a 414% increase in strain at break) and decreased the water vapor transmission rate by 16% and the oxygen transmission rate by 53%. This performance improvement was attributed to the coexistence of nanocelluloses with different chemical composition and morphology. LCNF contributed to increment the interfacial adhesion between cellulose nanofibrils due to the presence of lignin and promote the creation of more tortuous paths for gas molecules. These synergetic properties shown by the CNF/LCNF bi-component films demonstrate high potential to be used as gas barrier packaging solutions.
•CNF and LCNF from residual biomass are used to produce bicomponent nanocellulose films.•LCNF conferred UV-blocking and antioxidant properties to the films.•LCNF presence improved flexibility and tensile strength of CNF films.•All developed bicomponent films display better gas barrier properties than CNF films.•CNF/LCNF formulations have higher potential to be used as barrier coatings/films than CNF.
Direct-ink-writing (DIW) of hydrogels has become an attractive research area due to its capability to fabricate intricate, complex, and highly customizable structures at ambient conditions for ...various applications, including biomedical purposes. In the current study, cellulose nanofibrils reinforced aloe vera bio-hydrogels were utilized to develop 3D geometries through the DIW technique. The hydrogels revealed excellent viscoelastic properties enabled extruding thin filaments through a nozzle with a diameter of 630 μm. Accordingly, the lattice structures were printed precisely with a suitable resolution. The 3D-printed structures demonstrated significant wet stability due to the high aspect ratio of the nano- and microfibrils cellulose, reinforced the hydrogels, and protected the shape from extensive shrinkage upon drying. Furthermore, all printed samples had a porosity higher than 80% and a high-water uptake capacity of up to 46 g/g. Altogether, these fully bio-based, porous, and wet stable 3D structures might have an opportunity in biomedical fields.
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•Development of a bio-hydrogel composed of aloe vera and cellulose nanofibrils•Excellent viscoelastic properties suitable for direct ink writing•Precisely 3D printing of lattice geometry with a suitable resolution•Good mechanical performances and high porosity and water uptake capacity
•Films of aqueous wheat proteins (WP) and alginate (Al) solutions were produced.•Al/WP films production follow a “greener” approach than single WP films.•Al/WP films have UV-blocking behaviour and ...reduced water solubility.•Al/WP films properties can be adjusted with WP concentrations.•Al/WP films provide new insights for further applications of wheat proteins.
Large amount of wheat proteins by-products are produced during wheat starch manufacture. This work aimed to develop edible films of cast aqueous wheat proteins (WP) and alginate (Al) solutions. The investigation of the microstructure of Al/WP films revealed a more compacted cross-section and homogeneous surface, comparatively to Al films. Those properties could be modified with the increase of WP concentration from 4 to 8 % w/v, as result of electrostatic interactions between WP and Al. Furthermore, the incorporation of WP provided UltraViolet-blocking behaviour (4-fold decrease in the Ultra-Violet-B region). Additionally, the incorporation of WP in the films reduced the water solubility of the Al films. It was also found that by incorporating different amounts of WP the mechanical and Water Vapor Transmission rate (WVTR) properties could also be modified, so the film composition could be adjusted to suit different types of foods and applications (e.g. coatings and packaging).
In the present work, transparent films were obtained by the solution casting method from faba bean protein isolate (FBP), reinforced with different cellulose nanocrystals (CNCs) content (1, 3, 5 and ...7 wt%), obtained by acid hydrolysis of pine cone, and using glycerol as plasticizer. The influence of different CNCs loadings on the mechanical, thermal, barrier, optical, and morphological properties was discussed. Microstructurally, the FTIR and FESEM results corroborated the formation of intramolecular interactions between the CNCs and proteins that lead to more compact and homogeneous films. These interactions had a positive influence on the mechanical strength properties, which is reflected in higher tensile strength and Young's modulus in reinforced films with respect to the control film, resulting in stiffer films as the CNCs content increases. Thermal stability of the FBP films was also improved with the presence of CNCs, by increasing the characteristic onset degradation temperature. In addition, the linkages formed between the CNCs, and proteins reduced the water affinity of the reinforced films, leading to a reduction in their moisture content and water solubility, and an increase in their water contact angle, obtaining more hydrophobic films as the CNCs content in the matrix increased. The addition of CNCs in the FBP film also considerably improved its barrier properties, reducing its water vapour transmission rate (WVTR) and oxygen transmission rate (OTR). The present work shows the possibility of obtaining biobased and biodegradable films of CNC-reinforced FBP with improved mechanical, thermal and barrier properties, and low water susceptibility, which can be of great interest in the food packaging sector as edible food packaging material.
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•Faba beans protein films reinforced with different CNCs contents were studied.•Addition of CNCs improved the strength properties of the Faba beans protein films.•Faba beans protein films reinforced with CNCs showed improved barrier properties.•Addition of CNCs decreases the water susceptibility of the Faba beans protein film.
In the present work, faba bean protein (FBP) films plasticized with glycerol and reinforced with different amounts (2.5, 5.0, 7.5 and 10% by weight of FBP) of lignin extracted from pine cones (PL) ...have been obtained by solution casting. The results obtained showed an elongation at break of 111.7% with the addition of 5% PL to the FBP film, which represents an increase of 107% compared to the FBP control film. On the other hand, it was observed by thermogravimetric analysis (TGA) that the incorporation of lignin improved the thermal stability of the FBP film, leading to an increase in the protein degradation temperature, being this increase higher in the sample film reinforced with 10% PL. The barrier properties of the FBP films were also affected by the presence of lignin, leading to a decrease in water vapor permeability (WVP) in comparison to the unreinforced film. The results show that the sample reinforced with 2.5% PL had the lowest WVP value, with a reduction of 25% compared to the control film. Chemical analysis by Fourier transform infrared spectroscopy (FTIR) confirmed the formation of intramolecular interactions between lignin and proteins which, together with the inherent hydrophobicity of lignin, resulted in a decrease of the moisture content in the films reinforced with PL. This research work has allowed the development of biobased and biodegradable films with attractive properties that could be of potential use in sectors such as packaging.
•Addition of 5% pine cone lignin in FBP films increased its elongation by 107%.•Addition of lignin to FBP films increases their tensile strength and stiffness.•Addition of 10% lignin delayed the degradation temperature of FBP films around 14 °C.•Low contents of pine cone lignin improve the water vapor permeability of FBP film.•Intramolecular interactions between lignin and proteins decrease the moisture content of films.
Presented herein is the integral valorization of residual biomass to film composites by their fractionation into building blocks in a multicomponent cascade isolation approach. First, pine cones were ...subjected to alkaline pretreatment, followed by soda pulping. Two different hemicellulose/lignin-based fractions were recovered from the extractives of these treatments, with a yield of 19%. Then, chloride- and peroxide-based bleaching methods were proposed to treat the soda-pulped samples, obtaining two cellulose-rich fractions with different chemical compositions and recovery yields (32% and 44%, respectively). From these cellulose fractions, two types of nanocelluloses with different lignin contents were obtained: cellulose nanofibrils (CNF), with a lignin content of 1%, and lignocellulose nanofibrils (LCNF), with a lignin content of 16%. The LCNF displayed lower crystallinity and viscosity but greater diameter and thermal stability than the CNF. The reinforcing capability of different amounts of both nanocelluloses on the first hemicellulose/lignin-based fraction (PCA-L) to form films was evaluated. The thermomechanical, barrier, antioxidant, moisture sorption, and mechanical properties were assessed and compared. In general, the LCNF films showed less moisture sorption and better thermomechanical and antioxidant properties than the CNF films. These results reveal LCNF to be a promising reinforcing agent for designing all-lignocellulose-based composite films to be used in food packaging applications.
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