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The tensile strength of fibers extracted by retting from Acacia Caesia bark was measured and their fracture morphology was examined, with the idea to propose their potential use as the reinforcement in polymer composites. Four categories of fibers were investigated, namely untreated and treated with a concentration of 5, 10 and 15% sodium hydroxide (NaOH) for 24 hours at ambient temperature. The increase of alkali concentration resulted in a gradual reduction of hemicellulose, wax, and moisture, which on the other side increased the fiber density. Single fiber tensile tests were performed according to ASTM D3822 standard. The fracture surfaces of the fibers were observed using an optical microscope and scanning electron microscope (SEM). The tensile tests revealed that the 10% NaOH treatment sample showed the highest performance, namely an average tensile strength of 16.2 (±5.63) N with an ultimate elongation of 4.6 (± 1.0)%. SEM evidenced the different possible morphologies of Acacia Caesia bark fiber fractures, including sliding and tearing, splitting and torsion of fibrils.

Snake grass fiber was used as a supporting material in an epoxy matrix. The goal was to develop a lightweight structural material. To enhance the interfacial bonding between the snake grass (Sansevieria ehrenbergii) fiber and polymer matrices, the fiber underwent chemical treatment with NaOH. Samples were prepared with both neat and treated fibers mixed with epoxy at various volume percentages. The mechanical properties of snake grass fiber exhibited improvement with increasing fiber length and fixation, reaching optimal values at 20 mm length and 20% v/v fixation. Dynamic mechanical analysis (DMA) demonstrated superior energy absorption by the composite up to 140 °C, irrespective of repetition. Thermogravimetric analysis (TGA) indicated rapid degradation of untreated fiber with a residue level of 0.2%, while the snake grass composite (25% v/v) exhibited stable residue content at 11%. Microscopic evaluation using a scanning electron microscope provided insights into the morphology of the fiber surface. [ABSTRACT FROM AUTHOR]

The introduction of natural fibers as a filler in a natural rubber (NR) matrix can be of relevance for their eco-friendly and sustainable nature as the substitute for carbon-based fillers. In this work, short Phormium tenax fibers were introduced in random orientation into a NR matrix in different lengths (6, 10, and 14 mm) and various amounts (10, 20, and 30%, taking 100 as the NR weight). The composite was fabricated using a two-roll mill according to American Society for Testing and Materials (ASTM) D3184-11 standard. Several properties were determined, namely tensile and tear characteristics, hardness, and abrasion resistance. The results suggest that the shortest fiber length used, 6 mm, offered the best combination between loss of mechanical (tensile and tear) properties and hardness and the most acceptable resistance to abrasion, with the properties increasing with the amount of fibers present in NR. As a consequence, it is indicated that a higher amount of fibers could be possibly introduced, especially to achieve harder composites, though this would require a more controlled mixing process not excessively reducing tensile elongation at break.

The stem bark of Acacia caesia, or Senegalia caesia, richly available in the Western Ghats of Tamilnadu and Kerala, India, does potentially offer a ligno-cellulosic fiber, which was characterized in this work, studying its chemical composition, morphology, and thermal degradation. The as-received fibers, which were extracted as technical fibers with diameters ranging between 100 and 150 µm, had a density of 1200 kg/m3. Their composition included 37% cellulose, 20% hemicellulose and 18% lignin, not very dissimilar, among other fibers, from alfa esparto and particularly coir. Their thermal degradation onset was at 308°C, which suggested a potential in composite application with traditional oil-based matrices and possibly also in the long run on bio-based ones. However, their high roughness and easy splitting of the fibers suggested that possible use as the filler for composites would require fiber treatment, namely, to remove undesired loose parts, hence regularizing their geometry. This would also serve to reduce the likeliness of longitudinal splitting, which is a widely recognized occurrence during stripping of bark fibers. [ABSTRACT FROM AUTHOR]

Availability of additive manufacturing has influenced the scientific community to improve on production and versatility of the components created with several associated technologies. Adding multiple substances through superimposing levels is considered as a part of three‐dimensional (3D) printing innovations to produce required products. These technologies are experiencing an increase in development nowadays. It requires frequently adding substance and has capacity to fabricate extremely complex geometrical shapes. However, the fundamental issues with this advancement include alteration of capacity to create special products with usefulness and properties at an economically viable price. In this study, significant procedural parameters: layer designs/ patterns (hexagonal, rectangular and triangular) and infill densities (30%, 40%, and 50%) were considered to investigate into their effects on mechanical behaviors off fused deposition modeling or 3D‐printed onyx‐carbon fiber reinforced composite specimens, using a high‐end 3D printing machine. Mechanical (tensile and impact) properties of the printed specimens were conclusively analyzed. From the results obtained, it was observed that better qualities were achieved with an increased infill density, and rectangular‐shaped design exhibited an optimum or maximum tensile strength and energy absorption rate, when compared with other counterparts. The measurable relapse conditions were viably evolved to anticipate the real mechanical qualities with an accuracy of 96.4%. In comparison with other patterns, this was more closely predicted in the rectangular design, using regression models. The modeled linear regression helps to define the association of two dependent variables linked with properties of the dissimilar composite material natures. The models can further predict response of the quantities before and also guide practical applications. [ABSTRACT FROM AUTHOR]