The fields of polymer composites integrating new natural fibers, as well as the development of more sophisticated fiber treatment methods, are expected to promote the production of natural reinforcements with more desirable properties and broaden their application to new areas. The present work aims to investigate the chemical properties of two lignocellulosic fibers extracted from date palm trees using an environmentally friendly technique and to evaluate the thermal, rheological, mechanical, and long-term behavior of the resulting composites. The extraction technique utilizes an enzymatic cocktail containing xylanase and pectinase. The resulting composites exhibited good thermal stability and a much higher level of crystallinity than the virgin polymer, particularly with treated palm fibers. Tensile testing revealed that enzyme-treated fibers induced greater stiffness and strength in the elaborated composites compared to raw fibers. After aging, the treated palm fiber composites retained their mechanical strength and maintained better flexibility compared to composites with treated trunk fibers. This new class of treated fiber-based composite materials is characterized by enhanced long-term performance, their lightweight nature, and reduced environmental impact. As a result, they can be widely applied in various industries, contributing to their sustainable development.

Natural fiber-reinforced composites have garnered significant attention from researchers seeking to produce environmentally friendly materials and promote sustainable industrial development. The characteristics of the final composites, tailored for specific applications, depend not only on the properties of their constituents but also on the fiber/matrix interface. This is why soft fiber treatments are often recommended. This study aimed to assess the influence of the introduction of date palm fibers, having undergone an enzymatic treatment, on the mechanical characteristics of PBS/palm fiber biocomposites. The optimal enzymatic fiber treatment method and duration were determined based on reducing sugars released analysis. Fiber structure changes were determined by spectroscopic and morphologic analysis. The results showed that combined treatment with xylanase and pectinase for 8h contributed to higher amounts of reducing sugars released, indicating efficient removal of hydrophilic fractions. Microstructure tests showed an exposure of cellulose micro-fibrils that could enhance interfacial interaction fiber/matrix in the composite. Mechanically, composites with enzymatically treated fibers exhibited significantly increased stiffness modulus compared to the case of untreated fibers. The improvement in the composites rigidity is explained by the increase in the fibers cellulose rate with the biological treatment, which acts on the non-cellulosic components. The enzymatic treatment maintained the fibers natural morphology, enhancing fiber/matrix adhesion through increased contact surfaces.

This work aims to study the bioactivity of glass-ceramic powders obtained by thermal treatment of a 45S5 bioactive glass synthesized by the sol-gel process. The effect of two experimental protocols is explored. The first one is a thermal treatment in air at atmospheric pressure (called THAIR), and the second one is carried out at low pressure under a controlled atmosphere (called THUCA). Both treatment conditions result in partial crystallization of the bioactive glass into a mixture of three bioactive crystalline phases, namely combeite (Na2Ca2Si3O9), devitrite (Na2Ca3Si6O16), and a third sodium calcium silicate phase (Na2CaSi2O6). The two glass-ceramic powders are chemically similar but differ in their morphology, specific surface area, and porosity. The bioactivity of the two glass-ceramic powders is studied by immersion in a physiological medium at 37 degrees C for 30 min, 1 h, 2 h, and 4 h. The results show that the THUCA protocol produces a glass-ceramic powder with a higher specific surface area, more porosity, and improved bioactivity in a physiological environment.

Natural fibers, when used as reinforcement, offer a wide range of attractive characteristics and provide an alternative solution for waste materials. To investigate the performance of natural fiber-reinforced composites in outdoor applications, it is essential to analyze their environmental degradation properties, particularly under UV conditions. In this study, biocomposites based on date palm fibers were fabricated using the injection molding process. An enzymatic hydrolysis process, employing a synergistic activities effect of xylanase and pectinase enzymes, was applied to treat date palm fibers and compare the resulting composites. Tensile testing and SEM analysis were served for this evaluation. Additionally, the impact of accelerated UV environmental aging on the mechanical properties of all the fabricated composites was assessed. The results obtained revealed that UV aging caused a certain reduction in the tensile properties of composites loaded with raw fibers. This reduction was attributed to weak interfacial bonding, as evidenced by SEM images, which may have been further degraded after artificial aging. In contrast, composites filled with treated fibers exhibited improved preservation of their tensile properties, suggesting a more robust interfacial interaction between the treated fibers and the matrix material.

The use of natural fiber-reinforced polymer materials has become increasingly common in various applications. However, the performance and durability of these composites in outdoor applications are not fully understood. Therefore, the objective of this study is to investigate the impact of an artificial ultraviolet radiation on the degradation behavior of composites based on a Poly Butylene Succinate (PBS) matrix. The reinforcement materials used in this research were the trunk and palm fibers obtained from date palm trees. Specifically, the effect of modifying the fiber surface with an enzymatic treatment on the interfacial adhesion fiber/matrix as well as on the rate of deterioration of the resulted composites, under accelerated aging, was assessed. Changes in the composite's thermal stability, surface morphology and mechanical properties were determined after aging. A sharp transition in the behavior of the PBS matrix was observed after UV exposure, shifting from slight ductility following 100 h to brittleness after 700 h. The aging process resulted in a decrease in the thermal stability of all composites. However, the composites containing treated fibers exhibited better thermal stability compared to those with untreated fibers. Additionally, the use of enzyme-treated fibers in the composites promoted greater stability in the mechanical properties even after aging. The reinforcement of the composites with palm fibers yielded better interfacial adhesion compared to the use of trunk fibers, and resulted in better retention in the tensile strength property after aging. The enzymatic treatment facilitated stronger physical attachment between the fibers and the matrix, preventing any fiber or interface degradation.

In the present work, the effects of an accelerated aging process on the rheological and mechanical behavior of enzymatically treated date palm fiber reinforced poly butylene succinate (PBS) composite materials were evaluated. The bio-composite compounds were manufactured by twin-screw extrusion and, then, injected to obtain normalized simples. These samples were then exposed to UV radiation in an accelerated aging chamber for 100 h. The rheological analyses were conducted using multi-wave tests, by sweeping the frequency. The composite’s mechanical behavior was evaluated through tensile tests in order to determine any physical degradation of the material after aging. The results showed an enhance-ment of the composite stability imparted by the addition of the fibers, and particularly the treated ones, into the PBS matrix. Tensile tests revealed better resistance of the mechanical characteristics, after artificial aging, by adding raw fibers to the pure polymer. Compared to the composites based on untreated fibers, those having modified ones exhibited better rigidity, with almost a 40

Over the past few decades, biodegradable polymers based on natural fibers, such as date palm fibers, have become increasingly popular as an alternative to traditional composites using inorganic fillers. These composites' properties determine their application in various fields; however, when exposed to ultraviolet (UV) rays in outdoor environments, their structure may change, leading to a decrease in their overall properties. Therefore, understanding the long-term behavior of composites following UV aging is of great importance. The aim of this study was to investigate the effect of UV irradiation on the performance of poly (butylene succinate) (PBS) biocomposites reinforced with different mass content of raw date palm fibers (Phoenix dactylifera L.). The impact of enzymatically treated fibers, using a combination of pectinase and xylanase enzymes, on the properties of the biocomposites after being exposed to an accelerated aging process was also highlighted. All of the specimens were sampled after 100 h and 700 h of accelerated aging for laboratory characterizations. Their mechanical properties were determined by tensile tests. Rheological analyses were conducted by multi-wave tests and revealed two main phenomena resulting from UV aging; molecular chain scission and crosslinking. Tensile tests showed that the addition of raw fibers to the reference matrix resulted in a better resistance of the mechanical properties to the accelerated aging process. It was also found that the rigidity of the composites based on enzymatically modified fibers was approximately 37% higher than those loaded with raw fibers, at the same charge rate (20%) and after the same aging period (700 h).

The rheological properties of biocomposites can change depending on the polymer, fiber type, fiber size and processing conditions. In this work, biodegradable PBS composites filled with raw and enzymatically treated date palm fibers were processed using an internal mixer. The influence of the processing conditions, namely filler concentration, rotor of the mixer rotational speed, as well as the type of the enzymatic fiber treatment on PBS (Poly Butylene Succinate)/date palm fiber composites were studied by measuring the torque and the temperature in real time during melt processing. A rheological analysis was also carried out by performing time and multi-wave-frequency sweeps. It was found that the stabilization torque increased with increasing fiber loading and rotor rotational speed, indicating a higher viscosity. An enhancement of the melting process occurred with modified fibers, which was explained by the decrease in the fiber diameter, denoting cellulose micro-fibrils separation by enzymes action. These composites were characterized by a better thermal resistance and mechanical stiffness compared to those based on raw fibers at the same loading rate.

This study focuses on the thermal properties and structural features of blends consisting of thermoplastic starch (TPS) and poly(ethylene-co-methacrylic acid) copolymer (EMAA) or its ionomer form (EMAA-54Na). The aim is to investigate how carboxylate functional groups of the ionomer form intervene in blends compatibility at the interface of the two materials and how this impacts their properties. Two series of blends (TPS/EMAA and TPS/EMAA-54Na) were produced with an internal mixer, with TPS compositions between 5 and 90 wt%. Thermogravimetry shows two main weight losses, indicating that TPS and the two copolymers are primarily immiscible. However, a small weight loss existing at intermediate degradation temperature between those of the two pristine components reveals specific interactions at the interface. At a mesoscale level, scanning electron microscopy confirmed thermogravimetry results and showed a two-phase domain morphology, with a phase inversion at around 80 wt% TPS, but also revealed a different surface appearance evolution between the two series. Fourier-transformed infrared spectroscopy analysis also revealed discrepancies in fingerprint between the two series of blends, analysed in terms of additional interactions in TPS/EMAA-54Na coming from the supplementary sodium neutralized carboxylate functions of the ionomer.

This work aims to study the thermal properties of biocomposites based on surface modified date palm fibers (DPF) using a combined action of xylanase and pectinase enzymes. Fibers treatment was effected as composites components (i.e. fibers and matrix) as well as their characteristics are the two principal parameters that determine its applications in any field. Thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC) of the composites materials were carried out. It was found that the addition of raw fibers to the poly (butylene succinate) (PBS) matrix increase the composite crystallinity. The results have shown a significant improvement in the crystallinity rate with the composites having enzymatically treated fibers. This increase is about 30% by comparing it with the non-improved PBS, which is due to the presence of a very high percentage of crystalline material which is the cellulose. The addition of raw fibers to the PBS matrix induced a three main degradation phases as a function of the temperature. This was explained by the thermosensibility difference of the fibers components (hemicellulose, lignin,…). An increase in the degradation onset temperature was revealed with composites filled with enzmatically treated fibers, which proved that these composites exhibited a better thermal resistance.

An experimental study on corona discharge effect on hydrophobicity of Polymethyl methacylate (PMMA) and Styrene acrylonitrile (SAN) insulating solids is presented here. Contact angle evaluation of water deposited on the corona aged sample allows evolution of the surface condition to be characterized. More, time variation of adhesion energy, under electrical stress is calculated. We observe that contact angle and adhesion energy depend on of the surface’sphysico-chemical characteristics, and onapplied electrical stress duration.. State of degradation of these insulators is analysed usingFourier transform infrared spectrometry (FTIR).

A contactless method based on energy shift of high-energy cut-off of the x-ray bremsstrahlung, the so-called Duane Hunt Limit and a conventional low voltage electrical technique (three-probes technique) is applied on thermal and corona aged silicone rubber (SiR) to measure, respectively, the surface potential, V-s, and the surface resistivity, rho(s). The effect of aging on these quantities, representing the dielectric properties, is studied. The results are highly reproducible and highlight a good correlation between V-s and rho(s). It was observed that thermal aging combined with electrical aging deteriorates more the electrical properties of the polymer than thermal aging alone. Explanations for electrical characteristics (V-s, rho(s)) change with aging are supported by attenuated total reflection Fourier transform infrared spectroscopy spectra analysis and a chemical mechanism of aging in three steps (i.e., oxidation-polycondensation, degradation, and thermal cracking). The surface degradation of the polymer is revealed by images of surface morphology obtained by using scanning electron microscopy (SEM). Roughness is greater for combined thermal and corona aging mode compared to thermal aging alone. In addition, the surface degradation of SiR polymer is confirmed by the loss of its hydrophobicity.

This study aims to assess the viability of nanocomposites in fused filament fabrication. Polylactide/organo-modified layered silicate materials have been studied in terms of structure and properties evolution through the whole manufacturing chain, and for thermomechanical optimisation. The method included the optimisation by the composite formulation and by the additive manufacturing process by experimental designs. A competition between flow thinning of the molten composite and stiffness of the input filament with the addition of filler allows an enhanced printability at intermediate loadings. The method provides an optimisation of the final parts, enabling similar or greater tensile properties, while providing better thermal stability, with additively manufactured nanocomposite materials compared to conventionally manufactured polymers.

In the context of sustainable development and natural products valorization, new ecological materials enter a logic aimed at removing the causes of pollution generated by synthetic dyes presented in food packaging. Natural dyes gain more attention to substitute the synthetic dyes in plastic materials. Therefore, we developed a new packaging biodegradable material by melting a natural dye and Polybutylene succinate (PBS) and varying the concentrations of dye. Thermal and morphological properties of the colored material have been studied. Colorimetric properties were investigated. The aging test was done to see the effect of UV irradiation on the colored mixture. The results show that the incorporation of the dye in polymer facilities their crystallization. Morphology of material shows a good dispersion of the dye in PBS. The irradiation under UV after one week shows that the material is resistant. Feasibility and results of dye incorporation in PBS are compared to those of a previous study using an amorphous Polyacid lactid (PLA) as a matrix and under similar conditions. Dye is well solubilized in the two matrix. With PLA, blends shows degradation at 130 °C while PBS blend’s is stable. The semi-crystalline polymer PBS gives to blend shades of deeper color compared to those with the amorphous PLA that is more transparent.

In this work, ethylene propylene diene monomer (EPDM) used in power cables insulation was exposed to a thermal aging at different temperatures ranging from $80^{\circ}C$ to $140^{\circ}C$. Two complementary characterization techniques were used to track changes in EPDM crystalline structure during thermal aging. Differential scanning calorimetry (DSC) analysis was performed to measure the variation of the melting enthalpy $\Delta H_{m}$. To highlight the modifications induced on the crystalline and amorphous fractions of the EPDM structure, we carried out X-ray diffraction (XRD) measurements. The results of both methods agree in the time and temperature dependence of the aging process. The results show that the crystallinity is improved when aging is carried out at a low temperature. When temperature increases, minor changes in the crystallinity occur at the end of the aging process. At the highest aging temperature, a drop in the crystallinity occurs from the first hours of aging, indicating a degradation of the molecular structure of the polymer.

ABSTRACT This article deals within the study of the effect of artificial radiations on physical and chemical properties of the crosslinked polyethylene (XLPE) material, widely used for manufacturing high‐voltage cables. Within this framework, several experimental tests, using essential characterization techniques, were performed to study XLPE behavior under ultraviolet (UV) aging. Attenuated total reflection Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, X‐ray diffraction, and scanning electron microscopy were thus carried out to identify the main structure changes of the material before and after exposure to UV. In addition, appearance changes and DC (Direct Current) volume resistivity were evaluated. The obtained results showed that UV radiation has a great effect on the physicochemical properties of XLPE cable insulation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137 , 48575.

The aim of this study was to assess the physical phenomena that influence the rheological behaviour of polylactide/organo-modified clay nanocomposites. A model was proposed to explain the decrease in non-linear viscosity at high clay contents. Several variables were studied, including shear rate, temperature, clay volume fraction, and polymer molar mass. When the effects of the molar mass and temperature were separated from that of the clay volume fraction, the results suggested a decrease in viscosity compared with that of neat polylactide, which was mostly assigned to molar mass degradation and partially assigned to enhanced temperature dependency. The time–temperature superposition principle was employed for this purpose and highlighted two distinct trends in the activation energies with the clay volume fraction. Ultimately, rheological measurements were corroborated by morphological observations to reveal a non-monotonic evolution of viscosity with the clay volume fraction. These results help provide insight into simulation of the flow behaviour of a nanocomposite based on layered silicate.

In the context of raw materials valorization, reducing pollution and producing more energy, the world is undergoing a revolutionary shift towards biodegradable materials. Biosourced materials used for biocomposites gain more and more attention regarding different properties and are means of improving properties, especially mechanical ones. The aim of this research was to evaluate the effect of various enzymatic treatments (xylanase, pectinase and xylanase + pectinase) on chemical structures, morphology and mechanical properties of date palm fiber (DPF) and reinforced DPF composites. Two types of palm residues, namely: palm and trunk, were subject of several experiments. The reaction time of fiber-enzyme treatments and enzyme activities were optimized by measuring the liberated reduced sugar. The treatments effect on the fibers surface was also examined by a Scanning Electron Microscope. Different fiber contents and fiber treatments substantially improved mechanical properties (Tension and impact resistance). Results have shown that an enzyme treatment for 8 h is enough to liberate the maximum of amorphous components. The treatment combining pectinase + xylanase enzymes contributed to more fibrillose structures and proper surface which indicates an effective elimination of lignin, hemicellulose and extractive fractions. The palm variety exhibits relatively high values of cellulose compared to trunk fiber. It was found that enzymatically treated date palm fibers enhance the composite materials rigidity by about 42 % and 29 % for trunk and palm fibers, respectively. Sustainable products with such characteristics could enhance the development and progress of sustainable industries.