Calotropis gigantea fibers: A potential reinforcement for polymer matrices

Characterization study of Holoptelea integrifolia tree bark fibres reinforced epoxy composites

This study characterised the composite plate fabricated by epoxy matrix reinforced with alkaline-treated Holoptelea integrifolia tree bark fibre. Tensile and flexural test results clearly show that the mechanical characteristics of pure resin improve in direct proportion to the fibre up to 40%. However, impact test results show that 30% fibre mass ratio composite showed higher mechanical properties. The H. integrifolia fibre composites (HIFC) specimens were also characterised by using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), Energy dispersive X-ray analysis (EDAX) and thermogravimetric analysis-differential scanning calorimetry (TGA-DSC) analysis. FESEM results show that the bonding between fibre and matrix was excellent. EDAX reveals the elemental proportion of HIFC. O-H, C- H, C-O-C, moisture content and aromatic structure are evident by FTIR spectroscopy. Thermal analysis reveals that the composites degrade rapidly when exposed above 210 °C.

Multiresponse Optimization of Mechanical Behaviour of Calotropis gigantea/Nano-Silicon-Based Hybrid Nanocomposites under Cryogenic Environment

The utilization of natural fibre-based biodegradable polymers has expanded in the present circumstances since natural fibres are relatively inexpensive, recyclable, lighter, nonflammable, and harmless. However, hydrophilic nature is the most serious issue. To address this issue, the current study was applied to enhance the material characteristics of hybrid composites strengthened by CGF and nanosilica powder. To accomplish the mentioned goal, RSM calculated and optimized the following processing parameters using the BBD arrangement at various CGF fibre thickness (gsm), weight percent of nanosilica powder (wt. percent), and cryogenic treatment period (min). To prevent hydrophilic nature, the fibres were pretreated for four hours with a 5% alkaline solution. Deterioration models were created to analyze the material characteristics, and the optimal progression variables were determined. Based on the multiresponse surface methodology, the governable process variables for nano-silica- and CGF-based hybrid nanocomposites should be set at 3% silica, 300 gsm of CGF, and 30 minutes of cryogenic treatment. The tension, bending, and impact property correlation coefficient values ( $R^2$ ) are 0.95, 0.94, and 0.95, respectively. The above-mentioned combinations provide better water absorption and mechanical strength.

Effectiveness of Nanosilica on Enhancing the Mechanical and Microstructure Properties of Kenaf/Carbon Fiber-Reinforced Epoxy-Based Nanocomposites

With an ultrasonic frequency of 15 kHz and an 850 W power capacity, the effects of nanosilica particle inclusion on the tensile, flexural, and impact properties of woven fiber-reinforced kenaf/carbon fiber/epoxy hybrid composites were explored experimentally. The nanoparticles were dispersed uniformly in the epoxy using an ultrasonic probe. Test samples were made according to ASTM requirements for three distinct weight compositions of nanosilica particles (1, 1.5, and 2 wt%). The composites were made utilizing the compression moulding process with the following parameters: (i) weight ratio of nanosilica, (ii) length of kenaf fibers, and (iii) number of carbon fiber layers to achieve the objectives above. According to unmodified samples, with a nanosilica concentration of 1.5 wt%, tensile strength improved by 31%, flexural strength increased by 42.36%, and impact strength increased by 22.65%. It was established that the interaction of micro silica particles with epoxy and fiber, which improved interfacial tension, had a substantial impact on mechanical and water retention capabilities. The 1.5 wt% nanosilica inclusion absorbs less moisture than the 1 and 2 wt% silica composites. A scanning electron microscope was used to examine the fractured surface of the tested nanocomposites.

Morphological Structure and Basic Characteristics of Miscanthus floridulus Fibers

Miscanthus floridulus fibers obtained from the seed floss of M. floridulus (a perinneal plant of Gramineae native to Africa and Asia and widely distributed in tropical and subtropical regions) have potential application value in textile and other fields. At present, the biological characteristics and ecological benefits of Miscanthus floridus have been extensively studied by researchers, but there have been no literature on M. floridus fibers. In order to make reasonable use of M. floridus fibers, their morphological structure, physical properties, chemical composition, thermal insulation properties, and surface absorption properties were explored in detail in this study. The results showed that the M. floridus fiber is fine and short and has a hollow structure with a density of 0.67 g cm^-3. Chemical analyses revealed that the main constituents of the fiber are cellulose (66.98%), hemicelluloses (13.86%), lignin (6.97%), pectin (1.99%), and wax (4.38%). The fill power and warmth retention performance of the fiber are similar to those of wool. In particular, the M. floridus fiber surface has hydrophobic and lipophilic properties with a static contact angle of 123.7° for water droplets in equilibrium. Therefore, the M. floridus fiber has a promising application prospect in bulk textile thermal insulation and oil-water separation fields.

Calotropis Gigantea Fiber-A Biogenic Reinforcement Material for Europium Substituted Hydroxyapatite/Poly(3,4-propylenedioxythiophene) Matrix: A Novel Ternary Composite for Biomedical Applications

Novel multifunctional biocomposite materials that mimic the properties of bone are the need of the hour. In view of this, the current work is focused on the fabrication of a snail shells derived europium-substituted hydroxyapatite (Eu-HAP)/poly(3,4-propylenedioxythiophene) (PProDOT)/Calotropis gigantea fiber (CGF) ternary composite on titanium (Ti) for biomedical applications. The structural, morphological, mechanical, electrochemical, and biological properties of the as-developed coatings on Ti were characterized. The obtained results clearly confirmed the formation and properties of the ternary composite (Eu-HAP/PProDOT/CGF). The presence of CGF, an exceptional reinforcement material, in the ternary composite is proven to improve mechanical and biological properties compared to other coatings (i.e., coating without CGF). Also, electrochemical studies revealed better anticorrosion properties of the composite-coated Ti in a simulated body fluid (SBF) solution. Similarly, the presence of Eu-HAP and PProDOT in the composite is clearly evident from the antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) and also by the cell proliferation and cell adhesion by the MTT assay test. Thus, we suggest that the fabricated Eu-HAP/PProDOT/CGF ternary composite with mechanical, corrosion resistance, and biocompatible properties might be an appropriate candidate for biomedical applications.

Design of Alginate-Based Bionanocomposites with Electrical Conductivity for Active Food Packaging

Bionanocomposite materials have been designed as a promising route to enhance biopolymer properties, especially for food packaging application. The present study reports the preparation of bionanocomposite films of alginate with different loadings of pure reduced graphene oxide (rGO) or of mixed zinc oxide-rGO (ZnO-rGO) fillers by solvent casting. Sepiolite is used to make compatible rGO with the hydrophilic matrix. The addition of fillers to alginate matrix maintains the low water solubility promoted by the calcium chloride treatment, and, additionally, they demonstrate a weaker mechanical properties, and a slight increase in water vapor permeability and wettability. Due to the properties of ZnO-rGO, the alginate bionanocomposites show an increase of electrical conductivity with the increase of filler content. While the highest electrical conductivity (0.1 S/m) is achieved by the in-plane measurement, it is in the through-plane measurement the remarkable enhancement of almost 30 times greater than the alginate film. With 50% of ZnO-rGO filler, the bionanocomposites present the highest antioxidant and antibacterial activities. The combination of electrical conductivity with bioactive properties makes these films promising not only to extend food shelf-life but also to allow packaged food sterilization at low temperature.

Characterization and valuable use of Calotropis gigantea seedpods as a biosorbent of methylene blue

In this work, powdered Calotropis gigantea seedpods were characterized and used as biosorbents of methylene blue dye from aqueous solution. FT-IR spectroscopy demonstrated functional groups characteristics of cellulose. Steric exclusion chromatography donated an average molecular weight of 230 kg/mol of the biopolymer. The polymolecularity index value (1.95) proved the good homogeneity of the polysaccharide. Scanning electron microscopy features displayed a homogenous morphology and porous structure. X-ray diffraction patterns showed peaks characteristics of cellulose and non-cellulose compositions. Thermogravimetric analysis/differential thermal analysis displayed exothermal decompositions at 316.9 °C and 456 °C. The maximum biosorption capacity of methylene blue was 88.36 mg/g at pH = 6, time = 60 min, and T = 21 °C. The level was comparable to some other studied agricultural wastes. The adsorption mechanism followed pseudo-second-order and Freundlich models. As it is abundant, available, low-cost, and easily recovered from solution, C. gigantea seedpods could be used as an effective biomaterial for the removal of organic pollutants from contaminated waters. Novelty statement: An abundant, available, and low-cost Calotropis gigantea seedpod was used, for the first time, as an effective biomaterial for the biosorption of organic pollutants. The biosorption level was found to be comparable to some other agricultural wastes studied previously in the literature.

Chemical Constituents and Uses of Calotropis Procera and Calotropis Gigantea – A Review (Part I – The Plants as Material and Energy Resources)

The traditional and current use of Calotropis procera and C. gigantea, two soft-wooded, xerophytic shrubs of the family Apocynaceae, are reviewed against the background of the plants' chemical constituents and their biological properties. The focus is on the usage of the plants for building materials, natural pesticides, animal feed and bioremediative purposes.