R. Rajasekar

Characterization of new cellulose sansevieria ehrenbergii fibers for polymer composites

Natural cellulose fibers were newly identified from the sources of sansevieria ehrenbergii plant. These fibers were extracted using the mechanical decortication process. The hierarchical cell structure of the plant and fibers was analyzed using scanning electron microscope, optical microscope, Fourier transforms infrared, and X-ray diffraction. The density and diameter of the fibers were found to be approximately 0.887 g/cm3 and 10–250 μm, respectively. The various chemical compositions were analyzed and compared with other natural fibers. The thermal stability of the fiber was examined through thermogravimetric analysis/differential thermogravimetric analysis (DTG). The maximum peak temperature was obtained at 333.02 °C in DTG curve. The raw fibers exhibited a tensile strength of 50–585 MPa, an elongation at break of 2.8–21.7%, a Young’s modulus of 2.5–7.5 GPa, and a corrected compliances Young’s modulus of 2.5–7.8 GPa.

Characterization of natural fiber and composites – A review

The natural fiber-reinforced polymer composite materials offered extensive range of properties which are suitable for large number of engineering application. The natural fibers have been abundantly available in the world. It has unique properties compared to synthetic fiber and reduces the plastic usage. This article reports the extraction process of natural fibers, characterization of natural fibers, and preparation of natural fiber-reinforced composites. The mechanical properties such as tensile, flexural, impact, and dynamic properties as well as thermal and machinability properties of the composites with and without chemically treated fibers were reported. The water absorption capability of the composites and its effect on mechanical properties were also reported.

Graphene and modified graphene-based polymer nanocomposites - A review

Graphene has drawn a great attention in the recent research innovations mainly due to its structural geometry, which is composed of one-atom thick planar sheet of hexagonally arrayed sp2 carbon atoms. Development of nanocomposites utilising graphene as the nanofiller offer desired properties to the added polymer matrix. Furthermore, incorporation of functional groups such as hydroxyl, epoxy, carboxyl, etc. on the basal plane of graphene enhances the interaction with the polymer matrices. Better interaction between the nanofiller and the polymer leads to exfoliation of the nanofiller in the matrices, which indeed significantly improves the physical, mechanical, thermal, electrical, electronic properties, etc., of the polymer. The review article explores the recent research findings on the development of polymeric nanocomposites utilising pure and functionalised graphene. The article focuses on the method of synthesis of graphene and functionalised graphene, followed by their characterisation methods and inferences. It also summarises the routes for the preparation of graphene and modified graphene-based polymer nanocomposites. The work highlights the enhancement of properties observed due to the addition of graphene and modified graphene to the polymer matrices. Several surface modifications done on GNS in order to achieve better dispersion of the same in the polymer matrix has been discussed. The review article portrays the recent research reports on graphene and modified graphene-based polymer nanocomposites. Techniques such as cryomilling, latex technology and lyophilisation as applied to polymer nanocomposites have been reviewed. Also, each of the literatures has been reviewed under the synthesis of filler and the preparation of the polymer nanocomposite separately which would serve as a guidance for future research. Literatures in which different carbon nanofillers have been compared to find the optimum filler has also been discussed.

Fabrication and hemocompatibility assessment of novel polyurethane-based bio-nanofibrous dressing loaded with honey and Carica papaya extract for the management of burn injuries

Management of burn injury is an onerous clinical task since it requires continuous monitoring and extensive usage of specialized facilities. Despite rapid improvizations and investments in burn management, >30% of victims hospitalized each year face severe morbidity and mortality. Excessive loss of body fluids, accumulation of exudate, and the development of septic shock are reported to be the main reasons for morbidity in burn victims. To assist burn wound management, a novel polyurethane (PU)-based bio-nanofibrous dressing loaded with honey (HN) and Carica papaya (PA) fruit extract was fabricated using a one-step electrospinning technique. The developed dressing material had a mean fiber diameter of 190±19.93 nm with pore sizes of 4–50 µm to support effective infiltration of nutrients and gas exchange. The successful blending of HN- and PA-based active biomolecules in PU was inferred through changes in surface chemistry. The blend subsequently increased the wettability (14%) and surface energy (24%) of the novel dressing. Ultimately, the presence of hydrophilic biomolecules and high porosity enhanced the water absorption ability of the PU-HN-PA nanofiber samples to 761.67% from 285.13% in PU. Furthermore, the ability of the bio-nanofibrous dressing to support specific protein adsorption (45%), delay thrombus formation, and reduce hemolysis demonstrated its nontoxic and compatible nature with the host tissues. In summary, the excellent physicochemical and hemocompatible properties of the developed PU-HN-PA dressing exhibit its potential in reducing the clinical complications associated with the treatment of burn injuries.

Mechanical properties and water absorption of snake grass longitudinal fiber reinforced isophthalic polyester composites

Natural fiber reinforced composites have replaced the existing conventional materials due to its light weight and enhanced load-bearing capabilities. In the present work, the newly identified snake grass (Sansevieria ehrenbergii) fiber-reinforced isophthalic polyester composites are prepared by simple hand lay-up method with different fiber weight fractions. The mechanical properties like tensile strength, flexural strength and modulus are analyzed for the longitudinal and transverse direction according to the prescribed standards. The obtained tensile strength and modulus are compared with the theoretically predicted values. The impact strength and energy absorption of the composites are analyzed and compared with control. The water uptake of pure and fiber incorporated resin under varying time period and climatic conditions are examined. The experimental results proves that the composites containing high fiber weight content contribute to remarkable increase in mechanical properties and water absorption capabilities compared to control.

Investigation of chemically treated longitudinally oriented snake grass fiber-reinforced isophthallic polyester composites

Snake grass fibers are subjected to various chemical surface modifications such as alkali, benzoyl peroxide, benzoyl chloride, potassium permanganate and stearic acid. These fibers are utilized to fabricate the longitudinal oriented fiber-reinforced composites at 40% weight fraction of fiber. The mechanical properties of treated fiber composites are found to be higher than those of raw ones. Potassium permanganate treated fiber composites has optimum mechanical properties than other chemicals treated snake grass fibers composites. The scanning electron microscopic images of the tensile and impact fractured composites containing treated and untreated fibers have been examined. The fiber pull-out from the specimen has been found low for the treated fibers compared to untreated fiber composites. The kinetics of water absorption of the composites studied at various time intervals and temperature reveals that the treated fiber-reinforced composites has less water uptake compared to untreated one.

Investigation of chemically treated randomly oriented sansevieria ehrenbergii fiber reinforced isophthallic polyester composites

Surface treatment of sansevieria ehrenbergii fibers were carried out using various chemicals like alkali, benzoyl peroxide, benzoyl chloride, permanganate and stearic acid in order to improve the interfacial bonding between the fiber and matrix. Polyester composites were prepared using raw and surface-treated fibers. Morphology and physico-mechanical properties of the prepared composites are analyzed and compared with pure resin. Fourier transform infra-red spectroscopic analysis examined for the chemically treated fibers affirm the removal of moisture, hemicellulose, lignin and wax content. Scanning electron microscopic images prove the formation of rough surface on the fiber after chemical treatment due to the removal of lignocellulose content. The physico-mechanical properties of the treated fiber reinforced polyester composites are enhanced due to good physical interaction between the fiber and polymer matrix. The chemically treated fiber shows lower water absorption compared to untreated fiber composites.

Mechanical Properties and Water Absorption of Short Snake Grass Fiber Reinforced Isophthallic Polyester Composites

Natural fiber composite replaces the conventional and synthetic materials in many fields especially in light weight applications. The randomly oriented short snake grass fiber reinforced isophthallic polyester composites are prepared by hand lay-up technique and finally compression molded. The various length and weight fraction of fiber are used in composite fabrication. The mechanical properties and water absorption under various climatic conditions are examined according to the prescribed standard. SEM image revealing the fiber pullout and breakage of the tensile and impact fractured composite specimens has been analysed and compared with control through scanning electron microscope. The result shows that the mechanical properties increase with increase in fiber length and weight fraction of the composites. The rate of water absorption increases with increase in temperature and time. Obtained experimental tensile strength of the composite is compared with various theoretical models such as Series, Hirsch’s, Halpin-Tsai, Modified Halpin-Tsai and Modified Bowyer & Brader’s and the obtained inferences are discussed.

A Review on Biodegradable Polymeric Materials Striving Towards the Attainment of Green Environment

Polymers are a chain of repeating monomers that can be either non-biodegradable or biodegradable with technical properties for a wide range of applications. The present scenario drives industries to develop new and eco-friendly materials to replace non-biodegradable materials to attain a clean and green environment. Significant research work has been carried out on the development of biocomposites based on biodegradable polymers and natural fibers. The review article addresses the wide range of biodegradable composites that are capable of undergoing degradation by various routes. Our main emphasis has been on the preparation and characterization of biocomposites, using various biodegradable polymers and natural fibers for wide applications like biomedical, packaging, aerospace, agriculture etc. It is clear that blending of reinforcing fibers and fillers with biodegradable polymers significantly enhanced the physical, chemical, biological, mechanical, thermal and biodegradation properties of the base matrix.

Acoustic emission testing of surface roughness and wear caused by grinding of ceramic materials

Abstract The current manufacturing trend mainly involves automation precisely to offer better productivity and improved quality. In this context, on-line monitoring of tools becomes essential. Acoustic emission is the most recognized technique used for condition monitoring of machine tools. Grinding is a material removal and surface generation process employed to shape and finish components made of metals and other materials. The research work deals with machining of CUMITUFF WR-90 alumina ceramics by employing two different grinding wheels made of aluminum oxide and silicon carbide under varying depth of cut. Surface roughness of the machined component and wear of both grinding wheels were analyzed using acoustic emission technique. For a constant depth, the quality of machining has been improved for the material grinded using silicon carbide wheel, which is inferred from low surface roughness value compared to material grinded using aluminum oxide wheel.