Showing papers by "Pijush Ghosh published in 2016"
TL;DR: In this article, the authors studied the interface response of PMMA thin film (150nm) on a softer epoxy substrate and a stiffer glass substrate of increasing interfacial strength applying nanoindentation (NI) and nanoscratching.
39 citations
TL;DR: Improvement in mechanical properties due to combination of particle reinforcement and cross-linking agent with chitosan is investigated and it is observed that nanoparticle reinforcement provided necessary mechanical properties such as ductility and modulus.
Abstract: Chitosan (CS) is a biomaterial that offers many sophisticated and innovative applications in the biomedical field owing to its excellent characteristics of biodegradability, biocompatibility and non-toxicity. However, very low mechanical properties of chitosan polymer impose restriction on its further development. Cross-linking and nanoparticle reinforcement are the two possible methods to improve the mechanical properties of chitosan films. In this research, these two methods are adopted individually by using tripolyphosphate as cross-linker and nano-hydroxyapatite as particle reinforcement. The nanomechanical characterizations under static loading conditions are performed on these modified chitosan films. It is observed that nanoparticle reinforcement provided necessary mechanical properties such as ductility and modulus. The mechanisms involved in improvement of mechanical properties due to particle reinforcement are studied by molecular dynamics (MD). Further, improvement in mechanical properties due to combination of particle reinforcement and cross-linking agent with chitosan is investigated. The stress relaxation behavior for all these types of films is characterized under dynamic loading conditions using dynamic mechanical analysis (nanoDMA) experiment. A viscoelastic solid like response is observed for all types of film with modulus relaxing by 3-6% of its initial value. A suitable generalized Maxwell model is fitted with the obtained viscoelastic response of these films. The response to nano-scratch behavior is also studied for particle reinforced composite films.
29 citations
TL;DR: Molecular dynamics simulation is applied to perform uniaxial tension and pull out tests to understand the mechanism contributing towards the enhanced mechanical properties of hydrogels and reveals that the formation of hydrogen bonds and electrostatic interactions is responsible for the variations in different systems.
23 citations
TL;DR: This work reports that cross-linking is an efficient means of modifying a single layer biopolymer film for a controlled and predictable pathway of folding and demonstrates the potential application of the controlled folding of the cross-linked film as a sensor and as a soft crane.
Abstract: Water responsive biopolymers are gaining enormous attention in the different areas of research and applications related to self-folding. In this work, we report that cross-linking is an efficient means of modifying a single layer biopolymer film for a controlled and predictable pathway of folding. The initiation of the folding of a film is caused by the diffusion of water molecules along the film thickness. However, this folding is observed to take place in an unpredictable and random fashion with a pristine biopolymer film and a nano-particle reinforced film. The mechanical properties and the diffusion characteristics of the film are strongly interrelated and affect the overall folding behavior. The underlying mechanism behind this relation is appropriately substantiated by an in depth molecular dynamic study. The detailed characterization of the folding shape and material behavior is performed applying suitable experimental techniques. The potential application of the controlled folding of the cross-linked film as a sensor and as a soft crane is demonstrated in this report.
18 citations