Mohammed Belbachir

Maghnite-H+, an ecocatalyst for cationic polymerization of N-vinyl-2-pyrrolidone

Abstract The polymerization of N -vinyl-2-pyrrolidone catalyzed by the Maghnite-H + (Mag-H) was investigated. Mag-H is a montmorillonite sheet silicate clay, exchanged with protons. It was found that the cationic polymerization of N -vinyl-2-pyrrolidone (NVP) is initiated by Mag-H at 30 °C in bulk and in solution. The effect of the amount of Mag-H, the temperature and the solvent was studied. The polymerization rate increased with increase in the temperature and the proportion of catalyst, and it was larger in nitrobenzene than that in toluene. These results indicated the cationic nature of the polymerization. It may be suggested that the polymerization is initiated by proton addition to monomer from Mag-H.

Synthesis of poly(furfuryl alcohol)/montmorillonite nanocomposites by direct in-situ polymerization

The purpose of this study was to obtain poly(furfuryl alcohol) nanocomposites with Algerian organically modified clay (termed 12-montmorillonite). The formation of poly(furfuryl alcohol) was confirmed by infrared spectroscopy (IR); the prepared nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The evolution of mechanical properties was also studied. The obtained results confirm the intercalation of molecules of salt in the clay layers, and a good interaction with the polymer, showing the formation of intercalated and/or exfoliated structures. The nanocomposites showed higher thermal stability compared to pure polymer, and the mechanical properties presented interesting and promising results.

Preparation of poly(oxybutyleneoxymaleoyl) catalyzed by a proton exchanged montmorillonite clay.

The polycondensation of tetrahydrofuran with maleic anhydride catalyzed by Maghnite-H+ (Mag-H) was investigated. Maghnite is a montmorillonite sheet silicate clay that is exchanged with protons to produce Maghnite-H [1]. It was found that the polymerization in bulk is initiated by Mag-H in the presence of acetic anhydride at 40 degrees C. The effects of the amounts of Mag-H and acetic anhydride were studied. The polymerization yield increased as the proportions of catalyst and acetic anhydride were increased.

Amphiphilic Biodegradable Poly(ϵ-caprolactone)-Poly(ethylene glycol) – Poly(ϵ-caprolactone) Triblock Copolymer Synthesis by Maghnite-H+ as a Green Catalyst

Amphiphilic biodegradable (PCL-PEG-PCL) triblock copolymers have been successfully prepared by the ring opening polymerization of ϵ-caprolactone (CL) in the presence of poly(ethylene glycol) (PEG) at 80°C employing Maghnite-H+ a non-toxic Montmorillonite clay as catalyst. Maghnite-H+ reacts as a solid source of protons to induce ϵ-caprolactone polymerization. The triblock architecture, molecular weight and thermal properties of the copolymers were characterized by NMR spectra, GPC and DSC analyses. The effect of Maghnite-H+ proportion and PEGs on the rate of copolymerization and on average molecular weight of resulting copolymers was studied. A cationic mechanism for the copolymerization reaction was proposed.

Ring opening polymerization of tetrahydrofuran catalysed by maghnite-H+

The cationic ring-opening polymerization of tetrahydrofuran using maghnite-H+ is reported. Maghnite-H+, is a non-toxic solid catalyst issued from proton exchanged montmorillonite clay. Polytetrahydrofuran, also called “poly(butandiol) ether”, with acetate and hydroxyl end groups was successfully synthesized. Effects of reaction temperature, weight ratio of initiator/monomer and reaction time on the conversion of monomer and on the molecular weight are investigated. A cationic mechanism of the reaction was proposed. This chemistry can be considered as a suitable route for preparing poly(THF) as a soft segment for thermoplastic elastomers.

Structural, morphological and thermal properties of nanocomposites poly(GMA)/clay prepared by ultrasound and in-situ polymerization

This work focuses on the preparation and characterization of nanocomposites poly(glycidylmethacrylate)/organoclay. Effect of the organoclays nature and the preparation method were investigated in order to evaluate their structural, morphological and thermal properties. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen sorption at 77 K, scanning and transmission electronic microscopy (SEM, TEM) and thermogravimetric analysis (TGA) were employed to determine the features of the obtained materials. In the first step, the Algerian clay was modified by ultrasonic-assisted method using different concentrations of CTAB or TBAHS in which were used as green nano-filler. A series of nanocomposites were prepared by two different methods. The first deals the in-situ polymerization of GMA within the organoclay galleries and the second pathway involves the use of solution blending of poly(GMA) assisted by ultrasound. The obtained results confirm the intercalation of surfactants within the clay layers, while the nanocomposites obtained by the both methods showed different morphologies and structures in which the exfoliated and intercalated forms were obtained. Both nanocomposites displayed significant enhancement in the thermal stabilities compared to the unmodified poly(GMA). The best results in terms of reaction time, clay dispersion and nanocomposite yield were obtained by the ultrasound method.

New approach for synthesis of poly(ethylglyoxylate) using Maghnite-H+, an Algerian proton exchanged montmorillonite clay, as an eco-catalyst

ABSTRACT In this works, we have explored a new method for a green synthesis of poly(ethylglyoxylate) (PEtG). This method consists on using a montmorillonite clay called “Maghnite-H+” as an eco-catalyst to replace triethylamine which is toxic. Cationic polymerization experiments are performed in bulk conditions at three temperatures (−40°C, 25°C, 80°C) and in THF solutions at room temperature (25°C). At 25°C, an optimum ratio of 5 wt% of catalyst leads to molar masses up to 22000 g/mol in THF solutions. Polymerizations in bulk conditions lead to slightly lower masses than experiments conducted in THF solutions. However, bulk polymerization of ethyleglyoxylate remains a preferable method in order to avoid the use of a solvent and therefore to stay in the context of green chemistry. The structure of obtained polymers are characterized and confirmed by 1H and 13C NMR. Thermogravimetric Analysis (TGA) shows an enhanced thermal stability for end-capped PEtG compared to non-terminated PEtG. The best conversion rate (92%) is observed in bulk conditions at 25°C for a reaction time of 48h. An activation energy could be calculated from bulk experiments (Ea = 6.9 kJ/mol). An interesting advantage of Maghnite-H+ is an easy recoverage by a simple filtration from the polymer solution.

Synthesis and Characterization of New Organometallic Hybrid Material LCP-1 Based on MOF (Metal–Organic Framework) and Maghnite-H+, a Protons Exchanged Montmorillonite Clay, as Catalytic Support

In this work, a new 3D crystalline metal–organic framework formulated as [Zn2(BTC)4, (BTC: 1,2,4,5-Benzenetetracarboxylate)] and called LCP-1 (LCP: Laboratoire de Chimie des Polymères), with unsaturated coordinated Zn(II) sites as metal ion and pyromellitic acid (H4BTC: 1,2,4,5-Benzenetetracarboxylic acid) as organic ligand, has been successfully synthesized under solvothermal conditions. In-Situ polymerization of this material was also carried out using an amount of clay called Maghnite-H+, an acid-exchanged montmorillonite, as an eco-catalyst with the aim to respect the principles of green chemistry, to give a new hybrid composite material LCP-1/Mag-H+ with a better yield, a significantly reduced time and temperature reaction than those of LCP-1. LCP-1 and LCP-1/Mag-H+ have been structurally characterized and established by fourier transform infrared spectroscopy (FT-IR). The morphology of these compounds was studied by the X-ray diffraction (XRD) and revealed a highly crystalline and ordered structure for both LCP-1 and LCP-1/Mag-H+. FT-IR and XRD spectra showed also that the stability and structural integrity of LCP-1 and LCP-1/Mag-H+ was maintained even after being evacuated from the DMF solvent molecules. The thermal stability identified by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed that Maghnite-H+, as inorganic support, has also improved the thermal stability of LCP-1 compound.

Destructive and Non-Destructive Testing of an Industrial Screed Mortar Made with Lightweight Composite Aggregates WPLA

Today, only a very small portion of plastic waste is recycled, while huge quantities remain untreated and are becoming increasingly worrying. The search for other alternatives is still an urgent necessity so that these wastes can be reduced to the maximum; their valorization may be the best solution. This study concerns a new technique for the valorization of polyethylene terephthalate (PET) plastic bottle wastes, in order to design a composite material, i.e. siliceous sand-PET, which then gives a Waste Plastic Lightweight Aggregate “WPLA”. Our hope is to provide solutions to specific and general applications in the field of construction. Some observations are noted on the effects of this composite on destructive and non-destructive testing, such as the physical properties and mechanical behaviors of an industrial composite screed, by substituting 0, 25, 50, 75 and 100% by weight of natural aggregate by this composite. Scanning electron microscope (SEM), FT-IR and X-ray diffraction analyses were used to better understand the cement hydration products of the composite mortars. Some possible uses of this screed, or even of the composite itself, can subsequently be recommended. Encouraging results were obtained regarding the usage of this composite aggregate as an eco-material in the field of construction for sustainable development. In addition, it provides environmental-friendly and cost-effective solutions in using recycled materials for concrete construction applications.

The Characteristics of Poly Propylene Oxide/MontmorilloniteNanocomposites

The aim of our study is based to produce the Poly propylene oxyde /clay nanocomposites [3,5,7 and 10% (w/w) Maghnite - CTAB based on the propylene oxyde content] were synthesized by in situ polymerization. Maghnite-CTAB is montmorillonite-CTAB silicate sheet clay was prepared through a straight forward exchange process, polymer composites based on modified montmorillonite (montmorillonite-CTAB) and Poly Propylene Oxyde were prepared with different compositions by melt processing. The maghnite used was obtained with a cation exchange, using a green natural clay from Maghnia which is situated in the west of Algeria. This work is based also to demonstrate a morphology, which is obtained by combining AFM and MEB. The polymer composites were characterized using differenttechniques such as X-ray diffraction (XRD), differential scanning calorimetery (DSC), infrared spectrophotometery (IR),and Microscopic electronics with sweeping (MEB) and Atomic force microscopy (AFM). The results were showed that, the basal space of the silicate layer increased, as determined by XRD, from 12.97 A° to 32.60 A°. The addition of PPO shows distribution of platelets perparticules, and improve the interaction between clay and polymer matrix. The microstructure was detected by X-ray patterns and Microscopic electronics with sweeping (MEB) and Atomic force microscopy (AFM) at 5wt% MMt-CTAB, however, higher than 3 wt% MMt-CTAB reveals partial intercalation structure. The results confirm the presence of several intercalation of molecules salt in the clay layers, and it also shows a good interaction with the polymer.