RESUMO
The Cameroon has two bamboo species indigenous to Africa (the alpine bamboo, Yushina alpina and the savannah bamboo, Oxytenanthera abyssinica), and one largely exotic species, Bambusa vulgaris. However, little on their physical characteristics and strength for the composites materials applications is known for these two indigenous bamboos species in Cameroon. Therefore, in this study, emphasis was laid on the alpine bamboo Y. alpina, to evaluate its potential for biocomposites applications. Y. alpina with ages ranging from 1 to 3 years, 4-5 years, and 7 years were characterized. The mechanical and physical properties of these three age ranges were compared. In the first place, the surface texture of the fibers was examined by scanning electron microscopy. Afterwards, chemical treatment was performed on the fibers with 1 % NaOH. In addition, the chemical bonds of the molecules (functional groups) were identified by Fourier transform infrared spectra (FTIR) and the thermal properties of the fibers were examined with a thermogravimetric analyzer. Furthermore, the fibers density was assessed using the Rilem protocol and a tensile testing machine was used to determine the mechanical properties of the treated fibers with 1 % of NaOH. Finally, a dynamic mechanical analysis of 7-year-old Y. alpina fibers was carry out. The results indicate that the Young's modulus of treated fibers with ages ranging from 1 to 3 years, 4-5 years, and 7 years were around 18 GPa, 10 GPa, and 14 GPa, respectively. In summary, this study underlines two primary points: (1) providing a platform for researchers to better understand the influence of age on the physical and mechanical properties of indigenous bamboo Y. alpina; and (2) providing a platform to validate suitable designs of biocomposites materials with Y. alpina.
RESUMO
This study focuses on the use of tomato (Solanum lycopersicum L.) by-product biomass from industrial plants as reinforcement for designing a range of new degradable and biobased thermoplastic materials. As a novel technique, this fully circular approach enables a promising up-cycling of tomato wastes. After an in-depth morphological study of the degree of reinforcement through SEM and dynamic analysis, mechanical characterization was carried out. Our mechanical results demonstrate that this circular approach is of interest for composite applications. Despite their moderate aspect ratio values (between 1.5 and 2), the tomato by-product-reinforced materials can mechanically compete with existing formulations; PBS-Tomato fiber, for example, exhibits mechanical performance very close to that of PP-flax, especially regarding strength (+11%) and elongation at break (+6%). According to the matrix and particle morphology, a large range of products-biobased and/or degradable, depending on the targeted application-can be designed from tomato cultivation by-products.
RESUMO
Fibre bundles are groups of elementary fibres glued together thanks to the middle lamella, and are the main fraction in plant fibre composites. In this study, relationship between the mechanical properties of flax fibre bundles, chemical composition and cellulose structure were investigated. To do so, a sequential biopolymer extraction was implemented. Fibre bundles were first depectinated by oxalate extraction, and then the hemicelluloses were extracted by LiCl/dimethyl sulfoxide (DMSO) and KOH. The oxalate extract consisted of homogalacturonans and type I rhamnogalacturonans, while the LiCl extract was composed mainly of glucomannans and the KOH extract of xyloglucans. The KOH stage resulted in the appearance of cellulose II in flax bundles. The extraction of pectin and hemicelluloses led to the disappearance of the middle lamella concomitant with a decrease in the tensile Young's modulus and maximum strength. Finally, the fibre bundle composition, ultrastructure and mechanical properties are discussed together in view of the thin middle lamella.