Miracle-dz/UniFAR-FTUs huggingface dataset:
Preparation and Characterization of Regenerated Cellulose Film from a Solution in Lithium Bromide Molten Salt Hydrate

In this study, the molten salt hydrate of lithium bromide (LiBr) was utilized as a non-derivatizing cellulose dissolution solvent to prepare regenerated cellulose films for kraft pulp. The effects of LiBr concentrations (60, 62, and 65 wt %) and dissolving time (from 5 to 40 min with the interval of 5 min) on the structures and the properties of the films were investigated. Fourier transform infrared (FT-IR) and cross-polarization magic-angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C NMR) characterizations verified the breakage of inter- and intra-cellulose hydrogen bonds during the regeneration, resulting in the disruption of the crystalline structure of cellulose. X-ray diffraction (XRD) data indicated that the regeneration converted the polymorphism of cellulose from I to II as well as decreased its crystallinity. Ultraviolet-visible spectra (UV-Vis) and scanning electron microscopy (SEM) analyses revealed the excellent optical transparency of the films to visible light due to the complete dissolution of cellulose fibers as well as the sufficient breaking of the inter- and intra-cellulose hydrogen bonds. In terms of tensile testing, tuning LiBr concentrations and dissolving time could increase the elongation at break and tensile strength of the films. The maximum elongation at break of 26% and tensile strength of 67 MPa were achieved when the films prepared in 65 wt % LiBr for 10 and 15 min, respectively. These results indicated the great potential of the cellulose films for packaging use.
Performance of Plain Woven Jute Fabric-Reinforced Polyester Matrix Composite in Multilayered Ballistic System

The ballistic performance of plain woven jute fabric-reinforced polyester matrix composites was investigated as the second layer in a multilayered armor system (MAS). Volume fractions of jute fabric, up to 30 vol %, were mixed with orthophthalic polyester to fabricate laminate composites. Ballistic tests were conducted using high velocity 7.62 mm ammunition. The depth of penetration caused by the bullet in a block of clay witness, simulating a human body, was used to evaluate the MAS ballistic performance according to the international standard. The fractured materials after tests were analyzed by scanning electron microscopy (SEM). The results indicated that jute fabric composites present a performance similar to that of the much stronger Kevlar™, which is an aramid fabric laminate, as MAS second layer with the same thickness. The mechanism of this similar ballistic behavior as well as the comparative advantages of the jute fabric composites over the Kevlar™ are discussed.
Overcoming the Limits of Flash Nanoprecipitation: Effective Loading of Hydrophilic Drug into Polymeric Nanoparticles with Controlled Structure

Flash nanoprecipitation (FNP) is a widely used technique to prepare particulate carriers based on various polymers, and it was proven to be a promising technology for the industrial production of drug loaded nanoparticles. However, up to now, only its application to hydrophobic compounds has been deeply studied and the encapsulation of some strongly hydrophilic compounds, such as caffeine, remains a challenge. Caffeine loaded poly-ε-caprolactone (PCL) nanoparticles were produced in a confined impinging jet mixer using acetone as the solvent and water as the antisolvent. Caffeine was dissolved either in acetone or in water to assess the effects of two different process conditions. Nanoparticles properties were assessed in terms of loading capacity (LC%), encapsulation efficiency (EE%), and in vitro release kinetics. Samples were further characterized by dynamic light scattering, scanning electron microscopy, X-ray photo electron spectroscopy, and infrared spectroscopy to determine the size, morphology, and structure of nanoparticles. FNP was proved an effective technique for entrapping caffeine in PCL and to control its release behavior. The solvent used to solubilize caffeine influences the final structure of the obtained particles. It was observed that the active principle was preferentially adsorbed at the surface when using acetone, while with water, it was embedded in the matrix structure. The present research highlights the possibility of extending the range of applications of FNP to hydrophilic molecules.
Effect of MAH-g-PLA on the Properties of Wood Fiber/Polylactic Acid Composites

Maleic anhydride (MAH) was used as the grafting monomer, which was prepared by melt grafting reaction in the twin screw extruder with dicumyl peroxide (DCP) as the initiator, polylactic acid grafted with maleic anhydride (MAH-g-PLA) was successfully prepared as the interface compatibilizer. The PLA/Wood fiber/MAH-g-PLA composites were prepared by melt blending and injection molding with different proportions of compatibilizer added, within which PLA was for the matrix phase and wood fiber was for the reinforcing phase. The crystallinity, microstructure, thermal stability and dynamic thermomechanical property of the composites were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), thermo gravimetric analyzer (TGA) and dynamic mechanical thermal analysis (DMA). Furthermore, the mechanical and water absorption properties of the composites were also characterized. Results showed that the tensile strength and flexural strength of the composites attained the highest at 30% MAH-g-PLA added, where the crystallinity of the composites also showed the highest value. DMA results showed that the addition of MAH-g-PLA interfacial compatibilizer increased the loss modulus of the composites and improved the toughness. Scanning electron microscopy (SEM) showed that when the MAH-g-PLA was used, wood fiber is well dispersed in the PLA matrix phase, and that the interfacial compatibility between the matrix and the enhanced phase was improved. Therefore, the addition of MAH-g-PLA could improve the interfacial compatibility of PLA/Wood fiber composites and improve the mechanical properties of the composites.
Effect of PVA Blending on Structural and Ion Transport Properties of CS:AgNt-Based Polymer Electrolyte Membrane

In this work, the role of poly(vinyl alcohol) (PVA) blending on structural and electrical properties of chitosan:silver nitrate systems is studied. The X-ray diffraction (XRD) results show that the crystalline phase of chitosan (CS) is greatly scarified by silver nitrate (AgNt) salt. The crystalline domain of CS:AgNt is more broadened at 10 wt % of PVA. The spike and semicircular arcs can be separated in impedance plots. At high temperatures, the spike regions remained. The direct current (DC) conductivity was calculated from the bulk resistance obtained from the impedance plots. The dielectric constant and DC conductivity versus PVA content exhibited similar behavior. The maximum DC conductivity at ambient temperature was 1.1 × 10−6 S/cm for 10 wt % of PVA. The DC ionic conductivity increased to 9.95 × 10−5 S/cm at 80 °C. Above 10 wt % of PVA, the drop in DC conductivity and dielectric constant were observed due to the increase in viscosity. Shifting of relaxation peaks towards the lower frequency revealed the increase of resistivity of the samples. The linear increase of DC conductivity versus 1000/T indicated that ion transport followed the Arrhenius model. The incomplete semicircular arc in Argand plots indicated the non-Debye type of relaxation process. The Argand plots were used to distinguish between conductivity relaxation and viscoelastic relaxation. Three regions were distinguished in the alternating current (AC) spectra of the blend electrolyte samples. The plateau region in AC spectra was used to estimate the DC conductivity. The estimated DC conductivity from the AC spectra was close to those calculated from the impedance plots.
Flexural Fatigue Properties of Ultra-High Performance Engineered Cementitious Composites (UHP-ECC) Reinforced by Polymer Fibers

In recent years, the application of engineered cementitious composites (ECCs) in structures subjected to cyclic fatigue loading, such as highway bridges, has gained widespread attention. However, most existing ECCs do not have sufficient strength and ductility, which limits their applications, especially in highway bridge structures under high-stress. In this work, an ultra-high performance engineered cementitious composite (UHP-ECC) was configured, which had a compressive strength of approximately 120 MPa, a tensile strength of up to 12 MPa, and a tensile strain capacity of more than 8%. This paper presents a study of the fatigue performance of UHP-ECC at four different fatigue stress levels through the four-point bending test. The mid-span deflection of the specimen was monitored along with the crack opening displacement (COD) of the pure bending section at the bottom of the specimen, and the crack width. In addition, the dissipated energy was calculated at various stress levels. The progressive formation of cracks under static loading was monitored using the digital image correlation (DIC) technique. The fibers at the fractured surface of the specimens were observed and analyzed by environmental scanning electron microscopy, and the morphology of the fibers was obtained at different fatigue stress levels. Eventually, the fatigue life under different stress levels was obtained, and the relationship between the fatigue life and the stress level was established.
Molecular Dynamics Simulations on the Thermal Decomposition of Meta-Aramid Fibers

The thermal decomposition mechanism of a meta-aramid fiber was simulated at the atomic level using the ReaxFF reactive force field. The simulation results indicated that the main initial decomposition positions of the meta-aramid fiber elements were Caromatic ring–N and C=O, which could be used as targets for the modification of meta-aramid fibers. The meta-aramid fiber elements first decomposed into C6–C13 and then into smaller segments and micromolecular gases. The temperature was shown to be the key factor affecting the thermal decomposition of the meta-aramid fibers. More complex compositions and stable gases were produced at high temperatures than at lower temperatures. HCN was a decomposition product at high temperature, suggesting that its presence could be used for detecting thermal faults in meta-aramid fibers. Generation path tracing of the thermal decomposition products NH3 and H2O was also performed. NH3 was produced when the NH2 group captured an H atom adjacent to the system. H2O was formed after a carbonyl group captured an H atom, became a hydroxyl group, with subsequent intramolecular dehydration or intermolecular hydrogen abstraction.
Influences of Fluorine Substituents on Iminopyridine Fe(II)- and Co(II)-Catalyzed Isoprene Polymerization

A series of iminopyridine complexes of Fe(II) and Co(II) complexes bearing fluorinated aryl substituents were synthesized for the polymerization of isoprene. The structures of complexes 3a, 2b and 3b were determined by X-ray diffraction analysis. Complex 3a contained two iminopyridine ligands coordinated to the iron metal center forming an octahedral geometry, whereas 2b adopted a chloro-bridged dimer, and 3b featured with two patterns of cobalt centers bridged via chlorine atoms. Complexes 2b and 3b represented rare examples of chlorine bridged bimetallic Co(II) complexes. The fluorine substituents effects, particularly on catalytic activity and polymer properties such as molecular weight and regio-/stereo-selectivity were investigated when these complexes were employed for isoprene polymerization. Among the Fe(II)/methylaluminoxane (MAO) systems, the 4-CF3 substituted iminopyridine Fe(II) complex 1a was found as a highly active isoprene polymerization catalyst exhibiting the highest activity of 106 g·(mol of Fe)−1·h−1. The resultant polymer displayed lower molecular weight (Mn = 3.5 × 104 g/mol) and moderate polydispersity index (PDI = 2.1). Furthermore, the ratio of cis-1,4-/3,4 was not affected by the F substituents. In the series of Co(II)/AlEt2Cl binary systems, complexes containing electron-withdrawing N-aryl substituents (R = 4-CF3, 2,6-2F) afforded higher molecular weights polyisoprene than that was obtained by the complex containing electron-donating N-alkyl substituents (R = octyl). However, ternary components system, complex/MAO/[Ph3C][B(C6F5)4] resulted in low molecular weight polyisoprene (Mn < 2000) with high trans-1,4-unit (>95%).
Vapor-Assisted Crosslinking of a FK/PVA/PEO Nanofiber Membrane

Herein, we demonstrate a three-component FK/PVA/PEO nanofiber membrane by electrospinning and vapor-assisted crosslinking. We have used feather-derived-keratin (FK), poly (vinyl alcohol) (PVA), and poly (ethylene oxide) (PEO) as membrane components and citric acid/glyoxal as the crosslinker. The structural, thermal, hydrophobicity, and mechanical properties of the as-prepared and crosslinked FK/PVA/PEO nanofiber membranes have been systematically investigated. The results suggest that the nanofiber membrane’s vapor-assisted crosslinking by citric acid has shown better performances than that of glyoxal used as a crosslinker. These results exhibit that non-toxic citric acid can be used as a crosslinking agent to modify the performance of keratin-based membranes. This study opens up further avenues for post-synthesis modification of polymeric membranes for a wide range of applications.
Preparation of Compositional Gradient Polymeric Films Based on Gradient Mesh Template

In this paper, a template-filling method was found to prepare composition gradient gelatin films by incorporating α-[3-(2,3-epoxypropoxy) propyl]-ω-butyl-polydimethylsiloxane (PDMS–E) grafted gelatin (PGG) into a gradient gelatin mesh template. The method can be used to prepare other composition gradient biopolymer films. Gradient mesh template prepared by the methacrylic anhydride cross-linked gelatin under temperature gradient field. The porosity of the template decreased from 89 to 35% which was accompanied by decrease in average pore size from 160 to 50 µm. Colloidal particles about 0.9~10 µm were formed from PGG after adding them to a mixed solvent system of 9:1 (v/v) of ethanol/water, which were filled in the mesh template under vacuum (0.06 MPa). A gradient film was obtained after drying at room temperature for 48 h. The results of scanning electron microscope-energy dispersive X-ray combined with freezing microtome and Fourier transform infrared spectroscopy suggested that the distribution of the Si element along the thickness showed a typical gradient pattern, which led to hydrophilic/hydrophobic continuous changing along the thickness of film. The water vapor permeability, thermal gravimetric analysis, differential scanning calorimetry and dynamic mechanical tensile results show that the gradient films had excellent water vapor permeability and flexibility, and hence could be used as biomimetic materials and leather finishing agents.
Fabrication of Active Polymer Optical Fibers by Solution Doping and Their Characterization

This paper employs the solution-doping technique for the fabrication of active polymer optical fibers (POFs), in which the dopant molecules are directly incorporated into the core of non-doped uncladded fibers. Firstly, we characterize the insertion of a solution of rhodamine B and methanol into the core of the fiber samples at different temperatures, and we show that better optical characteristics, especially in the attenuation coefficient, are achieved at lower temperatures. Moreover, we also analyze the dependence of the emission features of doped fibers on both the propagation distance and the excitation time. Some of these features and the corresponding ones reported in the literature for typical active POFs doped with the same dopant are quantitatively similar among them. This applies to the spectral location of the absorption and the emission bands, the spectral displacement with propagation distance, and the linear attenuation coefficient. The samples prepared in the way described in this work present higher photostability than typical samples reported in the literature, which are prepared in different ways.
The Drop-in-Drop Encapsulation in Chitosan and Sodium Alginate as a Method of Prolonging the Quality of Linseed Oil

Nowadays, the encapsulation of sensitive products by various techniques has become popular as a promising preservation method. In particular, this applies to oils with a high content of unsaturated fatty acids and a high susceptibility to deterioration. This work presents the possibility of using a chitosan and sodium alginate in the form of a hydrogel membrane to protect food ingredients such as linseed oil, which is stored in an aquatic environment. The obtained results showed the high efficiency of the coaxial method encapsulation, which did not affect the quality of the oil measured after encapsulation. The greatest protective effect was observed in the linseed oil–chitosan membrane system, in which the primary and secondary oxidation products content were 88% and 32% lower than in the control sample, respectively. The smallest changes of the fatty acid profile, conjugated dienes, and trienes were observed in the chitosan capsules with linseed oil compared to the control sample.
A Novel In Situ Self-Assembling Fabrication Method for Bacterial Cellulose-Electrospun Nanofiber Hybrid Structures

Self-assembling fabrication methodology has recently attracted attention for the production of bio-degradable polymer nanocomposites. In this research work, bacterial cellulose/electrospun nanofiber hybrid mats (BC/CA-ENM) were formed by incorporating cellulose acetate electrospun nanofiber membranes (CA-ENMs) in the fermentation media, followed by in situ self-assembly of bacterial cellulose (BC) nanofibers. ENMs exhibit excessive hydrophobicity, attributed to their high crystallinity and reorientation of hydrophobic groups at the air/solid interfaces. We aimed to improve the hydrophilic and other functional properties of ENMs. As-prepared nanohybrid structures were characterized using SEM and FTIR. SEM results revealed that in situ self-assembling of BC nanofibers onto the electrospun membrane’s surface and penetration into pores gradually increased with extended fermentation periods. The surface hydrophilicity and water absorption capacity of as-prepared hybrid mats was also tested and analyzed. Hybrid mats were observably more hydrophilic than an electrospun membrane and more hydrophobic compared to BC films. In addition, the incorporation of CA electrospun membranes in the culture media as a foundation for BC nanofiber growth resulted in improved tensile strength of the hybrid nanocomposites compared to ENMs. Overall, the results indicated the successful fabrication of nanocomposites through a novel approach, with samples demonstrating improved functional properties.
Effect of Operational Conditions on the Behaviour and Associated Costs of Mixed Microbial Cultures for PHA Production

Massive production and disposal of petrochemical derived plastics represent relevant environmental problems. Polyhydroxyalkanoates (PHA) are a renewable alternative that can even be produced from wastes. The production of PHA from acetate using mixed microbial cultures was studied. The effect of two key operational conditions was evaluated, i.e., substrate concentration and cycle length. The effects of these factors on several responses were studied using a surface response methodology. Several reactors were operated under selected conditions for at least 10 solids retention times to ensure stable operation. Results show that conditions providing higher PHA content involve lower biomass productivities. This has a great impact on biomass production costs. Results suggest then that PHA content alone may not be a reasonable criterion for determining optimal conditions for PHB production. If production costs need to be reduced, conditions that provide a lower PHA content in the selection reactor, but a higher biomass productivity may be of interest.
Isothermal and Nonisothermal Crystallization Kinetics of Poly(ε-caprolactone) Blended with a Novel Ionic Liquid, 1-Ethyl-3-propylimidazolium Bis(trifluoromethanesulfonyl)imide

Recently, ionic liquids (ILs) and biodegradable polymers have become crucial functional materials in green sustainable science and technology. In this study, we investigated the influence of a novel IL, 1-ethyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide ([EPrI][TFSI]), on the crystallization kinetics of a widely studied biodegradable polymer, poly(ε-caprolactone) (PCL). To obtain a comprehensive understanding, both the isothermal and nonisothermal crystallization kinetics of the PCL blends were studied. Incorporating [EPrI][TFSI] reduced the isothermal and nonisothermal crystallization rates of PCL. Regarding isothermal crystallization, the small k and 1/t0.5 values of the blend, estimated using the Avrami equation, indicated that [EPrI][TFSI] decreased the rate of isothermal crystallization of PCL. The Mo model adequately described the nonisothermal crystallization kinetics of the blends. Increasing the [EPrI][TFSI] content caused the rate-related parameter F(T) to increase. This indicated that the crystallization rate of PCL decreased when [EPrI][TFSI] was incorporated. The spherulite appearance temperature of the blending sample was found to be lower than that of neat PCL under a constant cooling rate. The analysis of the effective activation energy proposed that the nonisothermal crystallization of PCL would not be favorited when the [EPrI][TFSI] was incorporated into the blends. The addition of [EPrI][TFSI] would not change the crystal structures of PCL according to the results of wide angle X-ray diffraction. Fourier transform infrared spectroscopy suggested that interactions occurred between [EPrI][TFSI] and PCL. The crystallization kinetics of PCL were inhibited when [EPrI][TFSI] was incorporated.
A Pseudopeptide Polymer Micelle Used for Asymmetric Catalysis of the Aldol Reaction in Water

Micelles assembled from amphiphilic molecules have proved to be ideal scaffolds to construct artificial catalysts mimicking enzymatic catalytic behavior. In this paper, we describe the synthesis of amphiphilic poly(2-oxazoline) derivatives with l-prolinamide units in the side chain and their application in asymmetric aldol reactions. Upon dissolution in water, the pseudopeptide polymers self-assembled into particles with different sizes, relying on the copolymer composition and distribution of hydrophilic/hydrophobic segments in the polymer chain. A preliminary study has demonstrated that the catalytic activity of these polymeric organocatalysts are strongly dependent on the aggregated architecture. The micelle-type assemblies can act as nanoreactors to efficiently promote the direct aldolisation of cyclohexanone with aromatic aldehydes in aqueous media, affording anti-aldol products in excellent yields (88–99%) and higher stereoselectivities (90/10 dr, 86% ee) compared to their nonmicellar systems under identical conditions.