Surendran Sankunny

Composite materials are a superior class of material used in almost every field of engineering like construction, military, aerospace, ocean structures, communication, and various other high-performance applications owing to their high specific strength and modulus, increased design flexibility, desirable thermal expansion characteristics good resistance to fatigue and corrosion, and economic efficiency. However, their ply-by-ply nature makes them susceptible to delamination, which originates from the propagation of microcracks in the weak resin-rich layers. Many attempts have been made to address the lack of mechanical properties of this weak interlaminar region. A particularly promising approach involves the incorporation of nanofibers between the reinforcement layers as the composite is laid up. This work involves studying the property improvements in carbon fiber epoxy composite by interleaving electrospun polyacrylonitrile (PAN) nanofibers. Experimental testing involving Tensile, Izod, Charpy and high velocity impact tests showed improved material properties for the PAN nano-interleaved composite. These improvements achieved by nanofiber interleaving shows a greater potential in addressing major concerns for critical application of composite materials in future.

Thermoplastic composites have growing significance due to the rising demand for cost-effective and lightweight materials with high structural endurance and recyclability. The composition of composites is altered to enhance their overall properties. Electrospun Polyacrylonitrile nanofiber interleaving in Carbon fiber thermoplastic composite is investigated in this paper. Material properties are estimated using Tensile, Izod, Charpy, and Ballistic testing. Experimental results suggest that the nanofiber interleaving resulted in a composite with enhanced properties. The study can be further extended in investigating the effect of nanofibrous addition in various composites.

Marine biofouling refers to the undesirable growth and adhesion of marine organisms such as barnacles, macro-algae, microbial slimes etc. on immersed structures. Tropical ocean environment teems with microorganisms, of which some adhere, both to the static ship hull and while en-route to the destination increasing roughness1. A laboratory-scale LIBS technique was used to analyse biofouling samples and its constituent common water-borne algae and bacterial species2. Biofouling composition was determined by collecting samples from marine structures and vessels and analysing them in laboratories. Biofouling characterization tests were also done such as SEM analysis. The Quanta 200 FEG Scanning Electron Microscope (SEM) was used for obtaining the SEM images. The structure of quartz crystal in the biofouling samples was also determined.

In the present study, femtosecond Laser Induced Breakdown Spectroscopy LIBS technique has been used to investigate the growth of biofouling on Fiber Reinforced Plastic (FRP) panels submerged in the Indian Ocean for various stages of growth. The coupons were suspended in the Indian Ocean at a depth of 1m at a distance of 480 m from the shoreline. The panels were recovered from the sea at regular intervals of 5, 10, 15 and 20 days. Growth of fouling panels were monitored and related with contact angle measurements. Elemental characterization conducted with Femtosecond LIBS indicated the presence of the elements Al, Ca, N, Ba, and Na. The study would help in creating a database for marine biofouling.

In the present study, LIBS spectra of biomolecules have been analyzed. The basic biomolecules considered for the analysis were Carbohydrates, Protein and Nucleic acids. It was possible to detect the characteristic emission lines of C, H, N, O, S etc. in the above biomolecules. The samples were prepared for laser ablation as biofilms on glass slides. Interference from substrate was observed in the LIBS spectra of samples. Raman spectra would also be acquired in future studies to obtain molecular information for the biomolecules.