Rachid Bouhfid

Morphological, Structural, Thermal and Tensile Properties of High Density Polyethylene Composites Reinforced with Treated Argan Nut Shell Particles

High Density Polyethylene (HDPE) composites reinforced with treated bio-filler from Argan-Nut Shell (ANS) at various filler contents are prepared by extrusion and injection molding processes. The microstructures of the composites are characterized by Fourier Transform Infrared Spectroscopy (FTIS) and Scanning Electron Microscopy (SEM); the thermal stability is analyzed by Thermogravimetric Analysis (TGA), and their mechanical properties are investigated by dynamical mechanical analysis and rheological testing. The morphological and structural results indicate an improvement in adhesion between the ANS fillers and HDPE matrix upon alkali treatment. The mechanical properties of the composites show a significant increase in young’s modulus with the addition of filler, a gain of 58% is marked compared to neat polymer. Thermal analysis reveals that the incorporation of bio-filler in polymer results in a decrease in decomposition temperatures. This research offers an ecological alternative to upgrade the valorization of abundant and unexploited Moroccan resources. In addition, the possibility of finding uses for ANS in composite manufacturing will help open new markets for what is normally considered waste or for use in low value products.

Mechanical and Thermal Properties of Polypropylene Reinforced with Almond Shells Particles: Impact of Chemical Treatments

Polypropylene (PP) matrix composites reinforced with chemically treated Almond Shell (AS) particles with and without compatibilizer (PP-g-MA) was prepared by a twin-screw extrusion at loading of 20 wt.% AS particles. Two types of chemical treatments (alkali treatment with sodium hydroxide and etherification with dodecane bromide) of the particles were carried out to improve the interface adhesion between particles and PP matrix. Results show that chemical modifications of AS particles affect the mechanical and viscoelastic properties of AS/PP composites. The composites reinforced with alkali treated particles and the compatibilized matrix lead to a notable increase in the Young’s modulus (14%) compared to the composites with untreated AS particles. The ductility of composite was also evaluated by the yield strain, and results show a notable increase (31%) compared to that of composites with untreated particles. The thermal stability increased with the use of etherification (385 °C), with gains in the temperature up to 23 °C compared to neat PP (362 °C). The achieved results show that the AS/PP composites can be used in several applications. A thermoplastic matrix compsite mixed with treated AS particles appears to be a good alternative to obtain environmentally friendly products.

Biocomposites based on Argan nut shell and a polymer matrix: Effect of filler content and coupling agent.

This study aimed at developing a biocomposite using polypropylene (PP) as the matrix and Argan nut shell (ANS) as reinforcement. Also, styrene-(ethylene-butene)-styrene triblock copolymer grafted with maleic anhydride (SEBS-g-MA) was used as a coupling agent. The samples were prepared by using extrusion compounding followed by injection molding to determine the effect of filler and coupling agent content on the morphological, thermal, mechanical, and hygroscopic properties of the biocomposites. SEM micrographs revealed that good ANS dispersion/distribution into PP was achieved with an important reduction of fiber pull-out, micro-spaces, and voids with coupling agent addition. This led to substantial improvement intension, torsion, and water absorption reduction due to improved interfacial adhesion. Although ANS particles did not significantly modify the thermal stability of PP, the use of a coupling agent increased it. The experimental data were compared with several theoretical models such Voigt, Reuss, Hirsch, and Tsai-Pagano to characterize the interfacial adhesion quality and to determine the elastic modulus of a single ANS particle. Finally, all the results show that Argan waste to produce PP biocomposites is an interesting avenue to effectively deal with agricultural wastes and develop valuable industrial and practical applications.

An Efficient Synthesis of New Spiro[indolo-3(1H),2’(3’H)-oxadiazolyl] and 1-(Triazol-4-ylmethyl)isatin Derivatives

The synthesis and the characterization of new isatin derivatives obtained by 1,3-dipolar cycloaddition reactions on allylisatin and propargylisatin are described. The products thus regiospecifically obtained in good yields bear oxadiazolyles or trizolyles groups, and were characterized by FT-IR spectroscopy, NMR spectroscopy and mass spectrometry.

Hybrid composites based on polyethylene and coir/oil palm fibers

In this work, hybrid composites were produced by blending oil palm fibers with coir fibers and high-density polyethylene for fixed fiber content (40 wt%). The composites were manufactured by twin-screw extrusion followed by compression molding. In particular, the effect of coupling agent (maleated polyethylene) concentration (0, 2, and 4 wt%) was investigated. From the composites obtained, the morphological, structural, and thermal properties were evaluated via scanning electron microscopy, Fourier transformed-infrared spectrometry, and thermogravimetric analysis. The effect of fiber ratio and compatibilization on mechanical performances was studied in tension, flexion, torsion, and impact. The results showed that the compatibilized composites have better fiber dispersion/distribution (homogeneity) due to chemical bonding leading to good interfacial adhesion. All the mechanical properties increased with the presence of fibers and compatibilizer, with non-hybrid composites of coir and oil palm fibers exhibiting the highest and lowest moduli, respectively.

Effect of Processing Conditions on the Mechanical and Morphological Properties of Composites Reinforced by Natural Fibres

In the last years, the exploitation of different natural fibres in the plastic industry has become increasingly essential for the introduction of new composites and products. The properties of polymers reinforced with natural fibre composites are generally governed by the fibre and matrix properties, the compatibility between the compounds, the process of treatment of fibres, and the manufacturing process of composites. Enhancements and innovations in manufacturing technology and assembly of fibre-reinforced polymer composite materials and structures are required to achieve the objectives of cost and performance to allow wider adoption in many sectors. In this chapter, natural fibres from doum, coir, and bagasse were added to polypropylene by twin-screw extrusion and molded by injection machine, to study the influence of manufacturing process especially during the extrusion and injection processes. The influence of extruder screw configuration (corotating and counterrotating), screw speed (60, 80, and 120 rpm), and temperature (190, 200, and 210 °C) was studied on the pressure of matter and torque, and then an optimized configuration was selected to evaluate the mechanical properties of injected composite. On the other hand, the preparation of the injected composite samples was performed by adopting different placing directions according to flow and tensile directions: parallel and transversal placements and the effect of fibre orientation in the mechanical properties of manufactured composites were evaluated. Advanced knowledge of the relationship between structure, composition, and characteristics of material composite based on natural fibres made possible the development of high-performance materials with excellent mechanical properties. We have demonstrated some aspects concerning the influence of the manufacturing process of the fibres in the thermoplastic matrix.

Synthesis of New Spiro[1,4,2-dioxazole-5,3′-indolin]-2′-one by 1,3-Dipolar Cycloaddition

Abstract Novel spiro[1,4,2-dioxazole-5,3′-indolin]-2′-one derivatives were synthesized by 1,3-dipolar cycloaddition reactions of the isatin derivative with aryl nitrile oxide. The cycloadducts were characterized by spectral data including 1H NMR, 13C NMR, infrared, mass spectra, and elementary analysis.

Characterization and Use of Coir, Almond, Apricot, Argan, Shells, and Wood as Reinforcement in the Polymeric Matrix in Order to Valorize These Products

The natural resource materials have an exceptional potential as reinforcement in plastic composites, due to their low cost, good mechanical properties, and biodegradability. This chapter is related to the use of some natural resources (nutshells residues) and their effect on polymer composite with varying filler reinforcement content and type or improving the adhesion between polymer matrix and filler. In this study, the used natural resources as bio-filler were almond shells, coir shells, argan shells, apricot shells, wood powder, and the mixture of these fillers, reinforcing thermoplastic polymer at various filler content (5, 10, and 20 wt.%), through extrusion and injection molding processes. The chemical and physical properties of the bio-filler and bio-filler/polymer composites were defined by using Fourier transform infrared spectroscopy (FT-IR); thermogravimetric analysis (TGA); differential scanning calorimetry (DSC); and tensile, torsional, and rheological tests. Depending on the bio-filler type, there was evidence that some particular difference in the chemical exists and also physical property changes. An increase in the crystallinity of composites is explained by the nucleating agent role of the bio-filler. The thermal, mechanical, and rheological properties of the composites were mostly enhanced with the addition of bio-fillers compared to the neat polymer matrix, and optimal properties were reached. Also, some optimal properties were observed when enhancing the interfacial adhesion by using a coupling agent. As a result, good final properties of the composites were manufactured with low cost. However, a fundamental understanding of the bio-filler structure and chemical composition could be beneficial to reach their full industrial applications.

Bio-composites based on polylactic acid and argan nut shell: Production and properties

The aim of this work is to develop a new bio-composite based on polylactic acid (PLA) reinforced with argan nut shells (ANS). In this study, the effect of ANS chemical surface treatments on the morphological, mechanical, thermal, and rheological properties of PLA was investigated. In particular, a comparison between three chemical treatments (alkali, bleaching, and silane) is made for two filler concentrations (8 and 15% wt.). Scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, dynamic mechanical analysis, and tensile measurements were used to determine the morphology (particle distribution/dispersion/adhesion), thermal stability, mechanical behavior and rheological properties of the bio-composites compared with neat PLA. The results showed that the highest Youngs modulus improvement (16%) was obtained with 15% of bleached ANS particles, while the highest tensile strength (1%) and strain at yield (8.5%) improvements were obtained with a silane treatment. These results were associated with good ANS-PLA interfacial adhesion and distribution in the matrix. Nevertheless, lower thermal stability (onset degradation temperature) for all the bio-composites was observed when compared to neat PLA. To complete the characterizations, water absorption and water contact angle were determined indicating better resistance of the bio-composites when ANS surface treatment was applied.

Natural Fibers Reinforced Polymeric Matrix: Thermal, Mechanical and Interfacial Properties

Natural fibers have recently become attractive to researchers, engineers, and scientists as an alternative reinforcement for fibers–polymer matrix composites. This interest comes from the combination of several advantages of natural fibers such as low cost, low density, non-toxicity, high specific properties, no abrasion during processing, and the possibility of recycling. The lack of compatibility between hydrophilic fibers and hydrophobic polymers (thermoplastics and thermosets), results a poor interfacial adhesion, which may negatively affect the final properties of the resulting composites. The tensile properties of composites based on natural fibers are mainly influenced by the interfacial adhesion, dispersion/distribution of fibers, and fibers loading. Several chemical modifications are used to enhance the interfacial adhesion resulting in an improvement of thermal and mechanical properties of the composites. This chapter presents a description of the natural fiber reinforcement composites/polymer matrix, and the context for the development and use of these products. The fibers used as reinforcement of thermoplastics matrix are Alfa, Doum, Pine cone, Hemp, Coir, and Bagasse. The knowledge of the structure and chemical composition of each component is required to understand the study of interactions between the reinforcing fibers and matrix.