Economic Consequences of Covid-19 Pandemic: An Analysis of Exchange Rate Behaviour

This paper examines the effect of Covid-19 on currency exchange rate behaviour by taking a sample of 37 countries over a period from 4th January 2020 to 30th April 2021. Three variables, such as daily confirmed cases, daily deaths, and the world pandemic uncertainty index (WPUI), are taken as the measure of Covid-19. By applying fixed-effect regression, the study documents that the exchange rate behaves positively to the Covid-19 outbreak, particularly to daily confirmed cases and daily deaths, which implies that the value of other currencies against the US dollar has been depreciated. However, the impact of WPUI is insignificant. On studying the time-varying impact of the pandemic, the study reveals that the Covid-19 has an asymmetric impact on exchange rate over different time frames. Further, it is observed that though daily confirmed cases and daily deaths show a uniform effect, WPUI puts an asymmetric effect on the exchange rate owing to the nature of economies.

Effect of Organo Montmorillonite Nanoclay on Mechanical Properties Thermal Stability and Ablative Rate of Carbon fiber Polybenzoxazine Resin Composites

Organo-Montmorillonite (o-MMT) nanoclay added polybenzoxazine resin (type I composites) were prepared with varying amounts of clay (0, 1, 2, 4 and 6 wt %). Clay dispersion, changes in curing behaviour and thermal stability were assessed in type I composites. Findings from these studies of type I composites were used to understand thermal stability, mechanical, and mass ablation rate behaviour of nanoclay added carbon fiber reinforced polybenzoxazine composites (type II). Interlaminar shear strength and flexural strength of type II composites increase by 25% and 27%, respectively at 2 wt% addition of clay. An oxy-acetylene torch test with a constant heat flux of 125 w/cm2 was used to investigate mass ablation rate of type II composites. The ablation rate has increased as the weight percentage of clay has increased. This is contradicting to type I composites with up to 6 wt% clay and type II composites with up to 4 wt% clay, which have improved thermal stability. The microstructure of the ablated composites was examined using scanning electron microscopy. Increased ablation rates are due to the reaction of charred matrix with nanoclay, which exposes bare fibers to the ablation front, resulting in higher mechanical erosion losses.

Predicting the high strain rate behaviour of particulate composites using time-temperature superposition based modelling

Polymeric particulate composites are widely used in engineering systems where they are subjected to impact loading – at a variety of temperatures – leading to high strain rate deformation. These materials are highly rate and temperature dependent, and this dependence must be well understood for effective design. It is not uncommon for many of these materials to display mechanical responses that range from glassy and brittle to rubbery and hyperelastic [1-3], due to their polymeric constituents. This makes accurate measurements and modelling not only necessary, but challenging. This is made more difficult by experimental artefacts present when traditional tools such as the split Hopkinson pressure (SHPB) or Kolsky bar are used to interrogate the high rate response of low-impedance materials. The transition from isothermal to adiabatic conditions as the rate of deformation increases also has an effect on the mechanical response, which cannot be neglected if the high rate behaviour is to be accurately predicted. In this paper, time-temperature superposition based frameworks that have enabled the high rate behaviour of neoprene rubber [4] and (plasticised) poly(vinyl chloride) [5] to be captured, will be extended to explore the high strain rate behaviour of unfilled natural rubber and several grades of glass microsphere filled natural rubber particulate composites.