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Matrix Assisted Laser Desorption Ionization Time of Flight(MALDI-TOF)-Mass Spectrometry and^(13)C-NMR-Identified New Compounds in Paraberlinia bifoliolata(Ekop-Beli)Bark Tannins

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Journal of Renewable Materials 2024年第3期12卷 553-568页

作者： Liliane Nga benoit ndiwe Achille Bernard Biwolé Antonio Pizzi Jean Jalin Eyinga Biwole Joseph Zobo Mfomo Laboratory of Forest Resources and Wood Valorization Training Unit in Engineering SciencesPost Graduate School of Fundamental and Applied SciencesUniversity of DoualaP.O.Box 1872DoualaCameroun Laboratory of Mechanics Training Unit in Engineering SciencesPost Graduate School of Fundamental and Applied SciencesUniversity of DoualaP.O.Box 2701DoualaCameroun Laboratory of Studies and Research on Wood Material(LERMAB) University of LorraineNancyFrance

Extracts of plant origin,particularly tannins,are attracting growing interest for the sustainable development of materials in the industrial sector.The discovery of new tannins is therefore necessary.The aim of this work was to contribute to the understanding of the properties of Paraberlinia bifoliolata tannin by Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectroscopy MALDI-TOF/MS and Carbon 13 Nuclear Magnetic Resonance(13C NMR).The chemical composition of tannin extracted from Paraberlinia bifoliolata bark was determined,as was the mechanical strength of the resin hardened with Acacia nilotica extracts.Yield by successive water extraction was 35%.MALDI-TOF/MS analysis revealed the presence of three new compounds in this tannin,previously unknown in this family of extracts.These are 3-hydroxyproline acid,N-methyl-4-hydroxypipecolic acid and N-methyl-5-dihydroxypipecolic acid.The identification of the above molecules means that this tannin can be used for industrial applications,as a resin in the manufacture of particleboard and in the formulation of green corrosion inhibitors.This information is reinforced by 13C NMR spectrometry,which indicates the presence of several polyflavonoid units,confirming the condensed nature of the tannin.Thermomechanical analysis of the resin formed by the purified tannin of Paraberlinia bifoliolata to which a vegetal biohardener has been added provided a Modulus of Elasticity(MOE)value of 4840 MPa at 150℃,confirming its possible use as a binder resin in the manufacture of wood panels as well as for the formulation of a corrosion inhibitor.

关键词： Tannin Paraberlinia bifoliolata Central African wood species MALDI-TOF/MS 13C NMR bark extracts thermomechanical behaviour wood-binder

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Desorption Behavior and Thermogravimetric Analysis of Bio-Hardeners

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Journal of Renewable Materials 2022年第8期10卷 2015-2027页

作者： benoit ndiwe Antonio Pizzi Hubert Chapuis Noel Konai Lionel Karga Pierre Girods Raidandi Danwe Department of Mechanical Engineering Higher Technical Teacher Training College Douala(ENSET)University of DoualaDoualaCameroon Laboratory of Forest Resources and Wood Valorization(Larefob) ENSET of DoualaDoualaCameroon Department of Engineering Science West UniversityTrollhättanSweden LERMAB-ENSTIB University of LorraineEpinal88051France Laboratoire D’Etudes et de Recherche sur le Matériau Bois LERMAB Facultédes Sciences et TechnologiesUniversitéde LorraineNancyFrance Laboratory of Materials Mechanics Structures and Integrated ManufacturingNational Advanced School of EngineeringYaoundé1 UniversityYaoundéCameroon Department of Mechanical Petroleum and Gas Engineering Faculty of Mines and Petroleum IndustriesUniversity of MarouaKaéléCameroon Laboratory of Mechanic Materials and BuildingSahel Institute of Maroua UniversityMarouaCameroon

In this work,the thermal degradation and drying of bio-hardeners are investigated.Four bio-hardeners based on exudates of Senegalia senegal,Vachellia nilotica,Vachellia seyal,and Acacia siebteriana were analyzed by FTIR and thermogravimetric analysis,and a desorption study was also conducted.The analysis by infrared spectroscopy indicates the existence of oligomers of different types all giving 5-hydroxy-2-hydroxymethylfuran and 2,5-dihydroxymethylfuran which are then the real hardening molecules.The pyrolysis of these extracts reveals three main regions of mass loss,a first region is located between 25℃and 110℃reflecting the loss of water from the adhesive and the formation of some traces of volatile organic compounds such as CO_(2)and CO,a second zone characterized by the release of CO,CO_(2)and CH4 gases with peaks between 110°and 798.8℃.At the end of the analysis,about 22%of the initial mass remains undecomposed,this mass corresponds to the rigid segments of the bio-hardener which are not completely decomposed.

关键词： Exudates pyrolysis FTIR bio-hardener desorption

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Physico-Mechanical Properties of Bio-Based Bricks

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Journal of Materials Science and Chemical Engineering 2022年第4期10卷 16-29页

作者： Valentin Makomra Lionel Karga Tapsia benoit ndiwe Maxime Dawoua Kaoutoing Noel Konai Abel Njom Tawe Laynde Danwe Raidandi National Advanced School of Publics Works University of Yaounde1 BP 510 Yaoundé Cameroon Department of Mechanical Petroleum and Gas Engineering National Advanced School of Mines and Petroleum Industries of the University of Maroua PO BOX 08 Kaélé Cameroon Higher Technical Teacher Training College of the University of Douala BP 1872 Douala Cameroon Laboratory of Civil Engineering and Mechanical National Advanced School of Engineering University of Yaoundé 1 BP 8390 Yaoundé Cameroon Laboratory of Materials Architecture and Civil Engineering National Advanced School of Engineering University of Maroua BP 46 Maroua Cameroon

The aim of this work is to improve the high performance of mud bricks. The latter was reinforced with rice straws as stabiliser leading to an improvement of the physico-mechanical properties. Thus, the physical characteristics of the clay such as natural water content, density, atterberg limit, plasticity limit (Wp) and plasticity index (Ip) were determined. Their values are respectively 8.39%, 2025.73 Kg/m3, 47.66%, 29.75% and 17.91%. The clay used is a low plastic organic silt. The normal proctocol provided an optimum dry density (ɣOP) of 1.28 Kg/m3 at an optimum moisture content of 12.42%. The actual density of the straw is 464 Kg/m3, its absorption rate reached 206% in 5 mins and stabilised at 385% at 480 mins of immersion. The maximum bending and compression strengths are respectively 1.52 and 0.164 MPa. The mud brick absorption coefficients obtained are between 4.875 at 0% straw and 20.573% at 3% straw.

关键词： Mud Bricks Physico-Mechanical Characteristics Clay Rice Straw

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Physical-Chemical and Mechanical Characterization of the Bast Fibers of <i>Triumfetta cordifolia</i>A.Rich. from the Equatorial Region of Cameroon

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Journal of Minerals and Materials Characterization and Engineering 2020年第4期8卷 163-176页

作者： Armel Edwige Mewoli César Segovia Fabien Betene Ebanda Atangana Ateba Pierre Marcel Anicet Noah benoit ndiwe Abel Emmanuel Njom Department of Mechanical Engineering ENSET University of Douala Douala Cameroon Laboratory of Mechanics University of Douala Cameroon Douala Cameroon CETELOR University of Lorraine CETELOR/27 rue Philippe SEGUIN Epinal France Laboratory of Mechanics Materials and Modelization National School of AGRO-Industrial Sciences (ENSAI) Physics Application and Engineering Ngaoundere University Ngaoundere Cameroon Laboratory of Mechanics Materials Structures and Integrated Manufacturing National Advanced School of Engineering University of Yaounde 1 Yaounde Cameroon

The project consists in the implementation of a biocomposite based on tannin resin and natural rubber matrices with the bast fibres of Triumfetta cordifolia A.Rich.“Okong” from the equatorial region of Cameroon as reinforcement. A study of this still little known fibre is necessary. This paper evaluates the physico-chemical and mechanical characteristics of the fibers. The fibers are extracted by us. A series of experiments is conducted for this purpose: morphological observation with a scanning electron microscope (SEM);density evaluation with a helium pycnometer;absorption rate evaluation according to the protocol available in the literature, Fourier Transform Infrared Spectrometry (FT-IR), chemical composition evaluation according to ASTM 1972 and ASTM 1977 standards, thermogravimetric analysis (TGA) and tensile tests on fiber bundles according to NF T25-501-3. The results show that the fiber is made up of several elementary fibers with oval cross-sections. A density of 1.477g/cm3 close to that of hemp. These fibers have a water absorption rate of 342.5%, which correlates with the presence of free hydroxyl functional groups obtained from the spectrometry study (FT-IR). Chemical analysis reveals that the fiber is made up of celluloses (44.4%), hemicelluloses (30.8%), lignins (18.9%), pectins (3.3%), waxes (0.5%) and minerals (2.1%). In addition, we learn that the fibers studied dehydrate at 11.49%, showinga notable thermal stability around 235°C with a peak thermal decomposition of cellulose located at 420°C. In terms of mechanical behaviour, the results reveal that the fibers offer a Young’s modulus in traction of 12.4 ± 6.9 GPa, a tensile strength of 526 ± 128 MPa and an elongation at break of 2.25%. The information thus obtained makes it possible to place these fibers in the same fiber group as flax and jute. They could therefore be used for the same types of applications. They also inform us that these fibers can withstand the temperatures of composite shaping by thermocompression.

关键词： Triumfetta cordifolia Fibers Morphology Chemical Analysis Thermal Degradation Mechanical Behavior

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