Appukuttan Saritha

Bio: Appukuttan Saritha is an academic researcher from Amrita Vishwa Vidyapeetham. The author has contributed to research in topics: Nanocomposite & Materials science. The author has an hindex of 12, co-authored 65 publications receiving 414 citations. Previous affiliations of Appukuttan Saritha include Kakatiya University & Cochin University of Science and Technology.

Fabrication of p-CuO/n-ZnO heterojunction diode via sol-gel spin coating technique

Abstract: We report a facile all-solution approach for the growth of nanostructured p-CuO and n-ZnO thin films. The influence of annealing temperature on the physical properties of CuO and ZnO thin films was examined. XRD and Raman spectra depict the structural and phase purity of solution grown CuO and ZnO films. The electrical as well as the optical properties of thin films were also studied. The average optical transmission of CuO and ZnO thin films in the visible spectral region was found to be above 80 and 95% respectively. Band gap energy variations on annealing temperature were investigated for CuO as well as ZnO films. Surface morphology analyzed by FESEM shows that the films are very smooth. All solution grown p-n heterojunction using p-CuO and n-ZnO films was fabricated in the structure ITO/n-ZnO/p-CuO/Au which showed rectification behavior with a turn on voltage of 2.5 V and an ideality factor of 3.15.

Enhanced visco-elastic and rheological behavior of epoxy composites reinforced with polyimide nanofiber

Abstract: High performance epoxy composites are now a days a must in several industrial applications. In the present work electrospun polyimide (PI) nanofibers with excellent thermal and mechanical properties was used as a reinforcement in epoxy matrix via a simple mechanical mixing followed by thermal curing method. Well defined electrospun nanofibers of aromatic polyimide (PI) were successfully prepared from electrospinning Poly (amic acid) (PAA) and subsequent thermal treatment. The fiber morphology was analyzed using Transmission electron microscopy (TEM) and Atomic force microscopy (AFM). PI/epoxy nanocomposites with different PI loadings were prepared using chopped PI mats. The dynamic mechanical performance of these PI/epoxy composites was investigated to determine the influence of PI fibers in reinforcing the epoxy matrix. The fracture toughness of these composites displayed a note worthy improvement of 20 % at 1 w% loaded samples and the surface of the fractured samples was investigated by Scanning electron microscope. The rheological properties of these systems show a tremendous increase in the storage and loss modulus when compared to neat systems. In addition flow models were employed to model the rheological data and the comparison was made with the experimental data.

The return of a forgotten polymer : Polycaprolactone in the 21st century

Abstract: During the resorbable-polymer-boom of the 1970s and 1980s, polycaprolactone (PCL) was used in the biomaterials field and a number of drug-delivery devices. Its popularity was soon superseded by faster resorbable polymers which had fewer perceived disadvantages associated with long term degradation (up to 3-4 years) and intracellular resorption pathways; consequently, PCL was almost forgotten for most of two decades. Recently, a resurgence of interest has propelled PCL back into the biomaterials-arena. The superior rheological and viscoelastic properties over many of its aliphatic polyester counterparts renders PCL easy to manufacture and manipulate into a large range of implants and devices. Coupled with relatively inexpensive production routes and FDA approval, this provides a promising platform for the production of longer-term degradable implants which may be manipulated physically, chemically and biologically to possess tailorable degradation kinetics to suit a specific anatomical site. This review will discuss the application of PCL as a biomaterial over the last two decades focusing on the advantages which have propagated its return into the spotlight with a particular focus on medical devices, drug delivery and tissue engineering.

Gas Barrier Performance of Graphene/Polymer Nanocomposites

Abstract: Due to its exceptionally outstanding electrical, mechanical and thermal properties, graphene is being explored for a wide array of applications and has attracted enormous academic and industrial interest. Graphene and its derivatives have also been considered as promising nanoscale fillers in gas barrier application of polymer nanocomposites (PNCs). In this review, recent research and development of the utilization of graphene and its derivatives in the fabrication of nanocomposites with different polymer matrices for barrier application are explored. Most synthesis methods of graphene-based PNCs are covered, including solution and melt mixing, in situ polymerization and layer-by-layer process. Graphene layers in polymer matrix are able to produce a tortuous path which works as a barrier structure for gases. A high tortuosity leads to higher barrier properties and lower permeability of PNCs. The influence of the intrinsic properties of these fillers (graphene and its derivatives) and their state of dispersion in polymer matrix on the gas barrier properties of graphene/PNCs are discussed. Analytical modeling aspects of barrier performance of graphene/PNCs are also reviewed in detail. We also discuss and address some of the work on mixed matrix membranes for gas separation.