Physical and mechanical properties of polyurethane thermoset matrices reinforced with green coconut fibres

Abstract

<jats:p> Currently, the use of composites to replace parts made only with plastics has been gradually employed. The advantages of these composites are low cost, high availability of raw materials and good physical and mechanical properties. Thus, this work aimed at producing and characterizing composites produced with coconut fibre reinforced polyurethane matrices. The coconut fibres were studied as to their chemical constituents, aspect ratio, bulk density, pH, tensile properties, and surface SEM images. The composites were prepared using the hand lay-up process and four different concentrations of coconut fibre were evaluated: 30, 40, 50, and 60%. The composites were assessed as for water absorption after 20 days of immersion, bulk density, impact IZOD, tensile tests, and visualize the matrix-reinforcement interface using SEM. The electron micrographs showed a great deal of impurities on the surface of coconut fibres, such as greases, waxes, and gums, due to the high amount of extraction material (19.78%), which damages the adherence of the polymer onto the coconut fibre and, as observed, cause detachment between the reinforcement and the matrix. The tensile strength of the composites tended to increase as greater amounts of coconut fibres were added to the matrix. The averages were around 6.51 to 6.72 MPa for composites with 30 and 60% fibres, respectively. Therefore, coconut fibres can be considered as an alternative to synthetic fibres commonly used in composites, and they can be used at a ratio of 60% without prejudicing the properties of the composites, making them lighter and cheaper. </jats:p>

Structural and mechanical characterization of polyurethane-CaCO3 composites synthesized at high calcium carbonate loading: An experimental and theoretical study

“…However, as PU polymers lack certain essential characteristics related to tensile strength and stiffness, new composites have been studied. 10,[22][23][24][25][26][27] These advances in PU research present two main strategies for improving compounds. 28 One involves the modification of the polyether or polyester, and the diisocyanate, while the other entails the introduction of components into the PU composition, where calcium carbonate (CaCO 3 ), [22][23][24] metal oxides (Al 2 O 3 , Fe 2 O 3 , FeO 4 , ZnO, SiO 2 and TiO 2 ), clays, and aluminosilicates are the most representative options.…”

Influence of temperature on the creep behaviour by macroindentation of Cocos nucifera shells and Canarium schweinfurthii cores (bio-shellnut wastes in Cameroon)

“…The field of use of biomaterials is large, including construction industry [1,4,5,[8][9][10], thermal, sound and electrical insulated components [1,[4][5][6][11][12][13][14][15], but also as parts for wear resistance [1] or those exhibiting improved impact strength [1,3,6,11,12,16,17]. Many other applications related to biocomposites have also be found in the automotive field [1,5,11].…”

“…When these natural materials are in the form of fibres, surface preparation [1,6,7,9,12,14,34,36] and/or physical or chemical pre-treatments [8-10, 16, 17, 34] are needed in order to achieve the best interface with the matrix and/or an improvement within the strength of the fibres.…”

“…In addition, the dynamic behaviour in connection with dedicated applications is sometimes studied with composites, especially when impact strength is sought [1,6,11,16,17]. The way fibres or aggregates have to be prepared prior to their incorporation into composites is also well known from many years, including their surface preparation to achieve a good interface with the matrix [1,7,12,14,33,36].…”

“…Characterization by indentation allows several parameters to be determined at the same time: hardness, Young's modulus, and creep [6,7,11,12]. However, as reported by Flores-Johnson et al [3], who determine the hardness of acrocomia mexicana fruit shell, such a technique is seldom used for biomaterials characterization.…”