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Thèse Année : 2021

An experimental study of the mechanical properties of jute / polypropylene composites manufactured by the commingled yarn and thermoforming

Etude expérimentale des propriétés mécaniques des composites Fibres de Jute/Polypropylène fabriqués à partir des fils co-torsadés et par la technique de thermoformage

Muhammad Ayub Asghar
  • Fonction : Auteur
  • PersonId : 1258310
  • IdRef : 260491128

Résumé

In the current study the mechanical properties of jute/polypropylene commingled composite made through compression hot press were investigated and compared with non-commingled composites. The effect of instant and gradual loading during thermoforming process was also investigated to check the effect of pressure on the physical and mechanical properties of the composites. To make the commingled composites, the reinforcement used for the fabrication was made with the jute/polypropylene co-twisted yarn. The jute yarn was signed on low flame to remove the protruding fibers, then jute/polypropylene yarn were co-twisted on the simplex frame to make commingled yarn. The UD, 2D and 3D reinforcement was prepared using the commingled yarn. UD and 2D reinforcements were also made with simple jute yarn to develop non-commingled composite to compare with commingled composites. All type of composites were made using compression hot press. For the commingled composites the readymade prepreg made with commingled yarn was used while for non-commingled composites the jute woven fabric and polypropylene matrix sheet were placed alternatively. To evaluate the mechanical performance tensile, flexural, short beam shear and Charpy impact test were conducted as per standard test methods. The microscopic evaluation was also done of tested samples to check the failure pattern in different composites.The results revealed that the commingled composites were dominant over the non-commingled counterparts. The fabrication of composites using commingled yarns technique resulted in impregnation of reinforcement at fiber level, which leads to good adhesion of matrix with fibers, which resulted in improved mechanical properties such as, the tensile strength and the flexural strength of commingled composites as compared to the non-commingled composites. In addition, the Charpy impact energy and Fmax value of commingled composites were also enhanced, which confirms the high quality and better fiber-matrix adhesion in commingled composites as compared to conventional non-commingled ones. It was observed that the fabrication of thermoplastic composites using the commingled technique is a viable solution resulting in the development of high-quality composites with improved matrix distribution around the reinforcement along with enhanced properties. Both UD and 2D commingled composites showed similar kind of behavior as compared to non-commingled composites. The 3D commingled composites were developed for the first time and tested at 0° and 90° orientation. The results showed that the highest mechanical properties at 90° direction due to higher number of reinforcing yarns, whereas in 0° the fewer number of reinforcing yarn result into poor mechanical performance. The cross-section of samples shows that reinforcing yarn are placed in layers which through binding yarn with even fiber-matrix distribution.The results of composites made through instant and gradual loading were evaluated through microstructure study and mechanical performance. The microstructure study was carried out up to fibril level in order to observe the physical effect of instant and gradual loading on the cellulosic structure of jute. The microstructure of fibers of composites made using instant loading showed significant damage as compared to samples which were made with gradual loading. The fibers of composite made using gradual loading had a very healthy fibers with even polygonal boundary. The tensile, flexural, SBS and Charpy impact results showed superior mechanical performance of gradual loaded samples as compared to instant loaded samples.
Cette thèse porte sur une étude expérimentale visant à analyser le couplage entre les proécdés d’élaboration et les propriétés mécanique des bio-composites à base de fibres en jute et du Polypropylène (Jute/PP). Une nouvelle technique a été développée dans le cadre de ce travail. Il s’agit d’un processus basé sur la réalisation des fils co-torsadés Jute/PP qui servent à la fabrication de tissus 2D et 3D. Ainsi, les composites sont fabriqués à l'aide d'une presse à chaud par compression. Cette méthode contribue à améliorer la qualité de fabrication des biocomposites à base de fibres naturelles en minimisant les défauts d’imprégnation. Pour évaluer cet apport, plusieurs essais mécaniques standardisés ont été rélaisés : des essais monotones de traction, de flexion et de cisaillement et des essais dynamiques du type Charpy. Les résultats on été compares à ceux obtenus par une technique alternant un tissu de jute et une feuille de matrice en polypropylene. Tous les résultats montrent que les biocomposités réalisés par la nouvelle technique des fils co-torsadés présentent une tenue mécanique meilleure par rapport à la seconde méthode.En effet, la fabrication de composites utilisant la technique des fils co-torasdés jute/PP entraîne une bonne imprégnation du renfort au niveau des fibres, ce qui conduit à une meilleure adhérence entre la matrice et les fibres. On note que les niveaux de l'énergie d'impact Charpy et de la valeur maxiamle de la charge obtenues pour les biocomposites fabriqués avec des fils co-torsadés sont nettement supérieures et démontrent bien que cette technique améliore notablement la qualité de l’adhrérence Fibres de jute/PP. Aussi, des observations microscopiques ont été effectuées sur des échantillons testés pour vérifier et analyser les modes de dommage pour les différents biocomposites analysés dans cette étude. Cette nouvelle technique de fabrication des biocomposites à base de fibres naturelles a été améliorée en ajustant les paramètres opératoires à savoir la pression et la température.
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Dates et versions

tel-04112766 , version 1 (01-06-2023)

Identifiants

  • HAL Id : tel-04112766 , version 1

Citer

Muhammad Ayub Asghar. An experimental study of the mechanical properties of jute / polypropylene composites manufactured by the commingled yarn and thermoforming. Solid mechanics [physics.class-ph]. Université de Lille, 2021. English. ⟨NNT : 2021LILUN014⟩. ⟨tel-04112766⟩
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