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Seed coating ensures the targeted delivery of various compounds from the early stages of development to increase crop quality and yield. Silicon and alginate are known to have plant biostimulant effects. Rice husk (RH) is a significant source of biosilica. In this study, we coated mung bean seeds with an alginate–glycerol–sorbitol (AGS) film with embedded biogenic nanosilica (SiNPs) from RH, with significant plant biostimulant activity. After dilute acid hydrolysis of ground RH in a temperature-controlled hermetic reactor, the resulting RH substrate was neutralized and calcined at 650°C. The structural and compositional characteristics of the native RH, the intermediate substrate, and SiNPs, as well as the release of soluble Si from SiNPs, were investigated. The film for seed coating was optimized using a mixture design with three factors. The physiological properties were assessed in the absence and the presence of 50 mM salt added from the beginning. The main parameters investigated were the growth, development, metabolic activity, reactive oxygen species (ROS) metabolism, and the Si content of seedlings. The results evidenced a homogeneous AGS film formation embedding 50-nm amorphous SiNPs having Si–O–Si and Si–OH bonds, 0.347 cm 3 /g CPV (cumulative pore volume), and 240 m 2 /g SSA (specific surface area). The coating film has remarkable properties of enhancing the metabolic, proton pump activities and ROS scavenging of mung seedlings under salt stress. The study shows that the RH biogenic SiNPs can be efficiently applied, together with the optimized, beneficial alginate-based film, as plant biostimulants that alleviate saline stress from the first stages of plant development.

Biodegradable blends and nanocomposites were produced from polylactic acid (PLA), poly(3-hydroxybutyrate) (PHB) and cellulose nanocrystals (NC) by a single step reactive blending process using dicumyl peroxide (DCP) as a cross-linking agent. With the aim of gaining more insight into the impact of processing methods upon the morphological, thermal and mechanical properties of these nanocomposites, three different processing techniques were employed: compression molding, extrusion, and 3D printing. The addition of DCP improved interfacial adhesion and the dispersion of NC in nanocomposites as observed by scanning electron microscopy and atomic force microscopy. The carbonyl index calculated from Fourier transform infrared spectroscopy showed increased crystallinity after DCP addition in PLA/PHB and PLA/PHB/NC, also confirmed by differential scanning calorimetry analyses. NC and DCP showed nucleating activity and favored the crystallization of PLA, increasing its crystallinity from 16% in PLA/PHB to 38% in DCP crosslinked blend and to 43% in crosslinked PLA/PHB/NC nanocomposite. The addition of DCP also influenced the melting-recrystallization processes due to the generation of lower molecular weight products with increased mobility. The thermo-mechanical characterization of uncross-linked and cross-linked PLA/PHB blends and nanocomposites showed the influence of the processing technique. Higher storage modulus values were obtained for filaments obtained by extrusion and 3D printed meshes compared to compression molded films. Similarly, the thermogravimetric analysis showed an increase of the onset degradation temperature, even with more than 10 °C for PLA/PHB blends and nanocomposites after extrusion and 3D-printing, compared with compression molding. This study shows that PLA/PHB products with enhanced interfacial adhesion, improved thermal stability, and mechanical properties can be obtained by the right choice of the processing method and conditions using NC and DCP for balancing the properties.

The growing concern about environmental pollution has generated an increased demand for biobased and biodegradable materials intended particularly for the packaging sector. Thus, this study focuses on the effect of two different cellulosic reinforcements and plasticized poly(3-hydroxybutyrate) (PHB) on the properties of poly(lactic acid) (PLA). The cellulose fibers containing lignin (CFw) were isolated from wood waste by mechanical treatment, while the ones without lignin (CF) were obtained from pure cellulose by acid hydrolysis. The biocomposites were prepared by means of a melt compounding-masterbatch technique for the better dispersion of additives. The effect of the presence or absence of lignin and of the size of the cellulosic fibers on the properties of PLA and PLA/PHB was emphasized by using in situ X-ray diffraction, polarized optical microscopy, atomic force microscopy, and mechanical and thermal analyses. An improvement of the mechanical properties of PLA and PLA/PHB was achieved in the presence of CF fibers due to their smaller size, while CFw fibers promoted an increased thermal stability of PLA/PHB, owing to the presence of lignin. The overall thermal and mechanical results show the great potential of using cheap cellulose fibers from wood waste to obtain PLA/PHB-based materials for packaging applications as an alternative to using fossil based materials. In addition, in situ X-ray diffraction analysis over a large temperature range has proven to be a useful technique to better understand changes in the crystal structure of complex biomaterials.

This study investigated the valorization of keratin extracted from sheep wool waste for the preparation of PLA/SBS/Keratin composites as potential adsorbents for the removal of chromium (Cr) from synthetic water. A flexible formulation containing 75 wt% PLA and 25 wt% SBS was selected for the incorporation of 10 wt%, 20 wt%, and 30 wt% keratin. The morphology and structural characteristics of keratin and PLA-based composites were analyzed using SEM and FT-IR spectroscopy. The mechanical and thermal properties of the prepared composites were investigated using TGA and DMA analyses. The adsorption experiments revealed that keratin exhibited an adsorption capacity of 57.57 mg g of Cr(VI) removal efficiency, while the PLA/SBS formulation containing 10 wt% keratin achieved a removal efficiency of total Cr of 55.41%. After three regeneration cycles, the removal efficiency decreased by approximately half of the total Cr removal.

Hybrid nanomaterials based on zinc oxide were synthesized via the sol–gel method, using different silane coupling agents: (3-glycidyloxypropyl)trimethoxysilane (GPTMS), phenyltriethoxysilane (PhTES), octyltriethoxysilane (OTES), and octadecyltriethoxysilane (ODTES). Morphological properties and the silane precursor type effect on the particle size were investigated using dynamic light scattering (DLS), environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The bonding characteristics of modified ZnO materials were investigated using Fourier transform infrared spectroscopy (FTIR). The final solutions were deposited on metallic substrate (aluminum) in order to realize coatings with various wettability and roughness. The morphological studies, obtained by ESEM and TEM analysis, showed that the sizes of the ZnO nanoparticles are changed as function of silane precursor used in synthesis. The thermal stability of modified ZnO materials showed that the degradation of the alkyl groups takes place in the 300–500 °C range. Water wettability study revealed a contact angle of 142 ± 5° for the surface covered with ZnO material modified with ODTES and showed that the water contact angle increases as the alkyl chain from the silica precursor increases. These modified ZnO materials, therefore, can be easily incorporated in coatings for various applications such as anti-corrosion and anti-icing.

The medical sector is one of the biggest consumers of single-use materials, and while the insurance of sterile media is non-negotiable, the environmental aspect is a chronic problem. Nanocellulose (NC) is one of the safest and most promising materials that can be used in medical applications due to its valuable properties like biocompatibility and biodegradability, along with its good mechanical properties and high water uptake capacity. However, NC has no bactericidal activity, which is a critical need for the effective prevention of infections in chronic diabetic wound dressing applications. Therefore, in this work, a natural product, propolis extract (PE), was used as an antibacterial agent, in different amounts, together with NC to obtain sponge-like structures (NC/PE). The scanning electron microscope (SEM) images showed well-impregnated cellulose fibers and a more compact structure with the addition of PE. According to the thermogravimetric analysis (TGA), the samples containing PE underwent thermal degradation before the unmodified NC due to the presence of volatile compounds in the extract. However, the peak degradation temperature in the first derivative thermogravimetric curves was higher for all the sponges containing PE when compared to the unmodified NC. The antibacterial efficacy of the samples was tested against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, as well as on two clinically resistant isolates. The samples completely inhibited the development of Staphylococcus aureus, and Pseudomonas aeruginosa was partially inhibited, while Escherichia coli was resistant to the PE action. Considering the physical and biological properties along with the environmental and economic benefits, the development of an NC/PE wound dressing seems promising.

Increased concern for human health and the environment has pushed various industries to adopt new approaches towards satisfying modern regulations. Strategies to achieve these approaches include utilizing lightweight materials, repurposing waste materials, and substituting synthetic polymers with bio-based counterparts. This study investigates the effects of treated fly ash (C) and bio-based polyamide 10.10 (PA10) on the thermal, morphological, and mechanical properties of glass fiber (GF)-reinforced polyamide 6 (PA6). Our main objective was to develop a composite that would allow for the partial replacement of glass fiber in reinforced polyamide 6 composites (PA6-30G) while maintaining a favorable balance of mechanical properties. Composites processed via melt processing demonstrated enhanced mechanical properties compared to PA6-30G. Notably, significant improvements were observed in impact strength and tensile strain at break. The addition of PA10 resulted in increases of 18% in impact strength and 35% in tensile strain relative to PA6-30G. Complementary, structural and morphological analyses confirmed strong interfacial interactions within the composite matrix. These findings indicate that a PA6/PA10 hybrid composite may represent a viable alternative material for potential automotive applications.

In this work, some physical properties of a commercial Ni–Ti (nitinol) shape-memory alloy with cylindrical geometry (wire) were investigated; the focus was on the thermomechanical, calorimetric and magnetic characterization. By dynamical mechanical analysis, the range of elasticity, the elasticity–viscoelasticity coexistence domain and the domain in which a maximum force is applied were determined for the SMA wire. By using the temperature-modulated differential scanning calorimetry method, a multi-step temperature variation program was applied to the wire with cylindrical geometry, in two stages (heating–cooling) and through the interpretation of heat fluxes (reversible, nonreversible and total), and the phase transitions in the formation of martensite, austenite and rhombohedral phase (R-phase) were identified and correlated with those observed during the thermomechanical study; also, the formation of austenite and martensite was evidenced by the regular differential scanning calorimetry method; by magnetic measurements, it was established that the SMA wire had magnetic properties at room temperature, and the nitinol sample is paramagnetic and linear in the intensity of the magnetizing magnetic field; these results were compared with those previously obtained for the investigation of the nitinol SMA stripe.

Photocatalytic coatings are difficult to obtain on textile materials because of the sometimes contradictory properties that must be achieved. In order to obtain a high efficiency of a photocatalytic effect, the metal–oxide semiconductor must be found in the vicinity of the coating–air interface in order to come into direct contact with the contaminant species and allow light radiation access to its surface. Another necessary condition is related to the properties of the covering textile material as well as to the stability of the xerogel films to light and wet treatments. In this sense, we proposed a solution based on hybrid silica films generated by sol–gel processes, coatings that contain as a photocatalyst TiO2 sensitized with tetracarboxylic acid of iron (III) phthalocyanine (FeTCPc). The coatings were made by the pad–dry–cure process, using in the composition a bifunctional anchoring agent (3-glycidoxipropyltrimethoxysilane, GLYMO), a crosslinking agent (sodium tetraborate, BORAX), and a catalyst (N-methylimidazole, MIM) for the polymerization of epoxy groups. The photodegradation experiments performed on methylene blue (MB), utilized as a model contaminant, using LED or xenon arc as light sources, showed that the treatment with BORAX improves the resistance of the coatings to wet treatments but worsens their photocatalytic performances.

Polymer nanodielectrics characterized by good flexibility, processability, low dielectric loss and high dielectric permittivity are materials of interest for wearable electronic devices and intelligent textiles, and are highly in demand in robotics. In this study, an easily scalable and environmentally friendly method was applied to obtain polysiloxane/nanosilica nanocomposites with a large content of nanofiller, of up to 30% by weight. Nanosilica was dispersed both as individual particles and as agglomerates; in nanocomposites with a lower amount of filler, the former prevailed, and at over 20 wt% nanosilica the agglomerates predominated. An improvement of both the tensile strength and modulus was observed for nanocomposites with 5–15 wt% nanosilica, and a strong increase of the storage modulus was observed with the increase of nanofiller concentration. Furthermore, an increase of the storage modulus of up to seven times was observed in the nanocomposites with 30 wt% nanosilica. The tensile modulus was well fitted by models that consider the aggregation of nanoparticles and the role of the interface. The dielectric spectra showed an increase of the real part of the complex relative permittivity with 33% for 30 wt% nanosilica in nanocomposites at a frequency of 1 KHz, whereas the loss tangent values were lower than 0.02 for all tested nanodielectrics in the radio frequency range between 1 KHz and 1 MHz. The polysiloxane–nanosilica nanocomposites developed in this work showed good flexibility; however, they also showed increased stiffness along with a stronger dielectric response than the unfilled polysiloxane, which recommends them as dielectric substrates for wearable electronic devices.