Preetha Balakrishnan

Chitin nanowhisker (ChNW)-functionalized electrospun PVDF membrane for enhanced removal of Indigo carmine

In this study, an active functional adsorbent membrane developed by combining both hydrophilic bio polymer filler such as chitin nanowhiskers (ChNW) which contains two functional groups and a hydrophobic polymer matrix such as polyvinylidene fluoride (PVDF) using electrospinning technique. Here ChNW were successfully extracted by excluding proteins and mineral and well characterized using FTIR, XRD, SEM and TEM. The optimized combination of PVDF/ChNW (15%:1%) membrane was fabricated and well characterized using SEM, water contact angle and FTIR spectroscopy. There was a remarkable difference in contact angle observed for PVDF/ChNW (22.72°) compared to neat PVDF (93.1°) membrane. Ultimately the membrane used for indigo carmine (IC) adsorption and an enhanced removal efficiency (88.9%) and adsorption capacity (72.6mgg-1) were observed compared to neat PVDF. In the future, the overall idea can make leads to various applications such as proteins, virus and hormones adsorption from the contaminated sources.

Facile synthesis of chitin nanocrystals decorated on 3D cellulose aerogels as a new multi-functional material for waste water treatment with enhanced anti-bacterial and anti-oxidant properties

We report the fabrication and application of multi-functional hybrid bio-aerogels based on cellulose nanofibers (CNFs) and chitin nanocrystals (CNCs) developed through an environmentally friendly freeze-drying process. Herein, an organic non-solvent approach such as acid hydrolysis was used to extract CNFs and CNCs from corn husks and shrimp shells respectively followed by characterisation using IR spectroscopy and electron microscopy. The usual wire-like and a rare semi-square morphology was detected for the CNFs and CNCs respectively during electron microscopic analysis. Aerogels with two different quantities of CNCs on the CNFs were prepared (AR1 and AR2) and compared with reference to the neat CNF aerogel (neat AR). Interestingly, for AR2, under an electron microscope, a maple seed like morphology was observed compared to the neat AR and AR1. Their ability in water treatment was determined by conducting adsorption experiments using methylene blue and Rhodamine 6G, and it was found that AR2 had an enhanced removal percentage and adsorption capacity. To address their economic viability, we conducted several rounds of studies and evaluated the reusability of AR2. The antibacterial and antioxidant activities of the aerogels were studied using a disc diffusion method against four bacterial species, including S. aureus, E. coli, S. typhimurium and B. cereus, and the best conditions for the determination of minimal inhibitory concentration were carefully discussed. The prepared material having a higher CNC content (AR2) shows multi-functional behaviour and from further studies it is anticipated that they may be produced on an industrial scale for commercial applications in the future.

Natural fibre and polymer matrix composites and their applications in aerospace engineering

Fibre-reinforced polymer composite materials are fast gaining ground as preferred materials for construction of aircrafts and spacecrafts. In particular, their use as primary structural materials in recent years in several technology demonstrator front-line aerospace projects worldwide has provided confidence that has led to their acceptance as prime materials for aerospace vehicles. Fibre polymer composites alongside aluminium alloys are the most frequently used materials in aircraft structures. The use of composites in civil aircraft, military fighters and helicopters has increased rapidly since the 1990s, and composites are now competing head-to-head with aluminium as the materials of choice in many airframe structures. The use of composites in gas turbine engines for both civil and military aircraft is also growing. The main reasons for using composites are to reduce weight, increase specific stiffness and strength, extend fatigue life and minimize problems with corrosion. Natural fibre composites present several advantages over man-made fibre composites such as low cost, light weight, high specific mechanical properties, nonhazardous nature, eco-friendliness, renewability and so on, and consequently their utilization in various industrial sectors including aerospace engineering is highly promising. This chapter discusses different aspects of natural fibre as well as conventional polymer matrix composites, focussing on aerospace applications.

Polymeric biomaterials: State-of-the-art and new challenges

Abstract The previous two decades have made noteworthy advances in the improvement of biodegradable polymeric materials for biomedical applications. Biodegradable materials as a substitute for creating helpful devices, medicate discharge, and so forth are utilized broadly. Each of these applications requests materials with particular physical, substance, organic, biomechanical, and corruption properties to give proficient treatment. The biomedical area is a specific space of enthusiasm for polymer researchers since it asks for an ever-increasing number of complex structures in their endeavors to satisfy the prerequisites of a large number of various applications. To be sure, in this area, the objectives are gone for abusing mixes with properties that can be considered as under control as far as material designing and properties are concerned. Conversely, the methodologies need to consider complex organic frameworks and procedures that are a long way from being comprehended and along these lines aced, in light of their whole control by nature.

Applications of cellulose nanofibrils in drug delivery

Abstract This chapter describes the recent advances in production of cellulose nanofibrils (CNF), a material with significant barrier, mechanical and colloidal properties, low-density, renewable, and biodegradable character. The above properties make CNF promising for applications in such fields as papermaking, composites, packaging, coatings, biomedicine, and automotive. In this chapter, sources, structural and chemical aspects necessary for understanding the nanofibril extraction process, conventional and novel mechanical disintegration techniques, as well as biological and chemical pre-treatments aimed at facilitating nanofibril isolation, biomedical aspects and drug delivery application of cellulose nanomaterials are summarized. Additionally, the preparation of CNF in various forms, such as suspensions, powders, films or nanopapers, hydrogels and aerogels, and their application in biomedical field is discussed.

Green materials for aerospace industries

Green materials are exciting new range of materials with wide applications. One important application of nanocomposites is their use in engineered structural composites like in aerospace applications. Among the wide variety of structural applications, fiber-reinforced composites for aerospace structures have some of the most demanding physical, chemical, electrical, thermal, and mechanical property requirements. Despite the great advantages of green composite materials, issues still exist. For natural fibers, they are less homogeneous than glass and carbon, tend to absorb moisture, and are less compatible with conventional resin systems. Preprocessing and treatment are thus required to enhance the performance of the composite solution. The development of bioresin is lagging behind the development of natural fibers. Adhesion and interfacial bonding between natural fibers and bioresin need to be addressed.