Rheometry of novel shear thickening fluid and its application for improving the impact energy absorption of p-aramid fabric

Abstract

The present work deals with synthesis and rheological characterisation of chemically modified polyethylene glycol (PEG) based novel shear thickening fluids (STFs) and their application to enhance impact resistance performance of p-aramid fabrics. The carrier fluid, i.e., PEG 200 was modified with citric acid and then modified PEG (M-PEG) was characterised by FTIR and NMR analysis which confirmed formation of ester link by reaction between PEG and citric acid. Mass distribution of M-PEG, analysed by MALDI-TOF, showed that either one or two PEG molecules reacted with one molecule of citric acid. A comparative thorough rheological analysis of M-STF and virgin STF showed significant increase in thickening behaviour in M-STF. The peak viscosity of M-STF increased 76 times while the critical shear rate decreased from 95.4 to 0.212 s−1. Evidently, the chemical modification of PEG results in higher molar mass and higher number of hydrophilic functional groups, exhibiting better media-particle interaction by abundant H-bonding. Further, this media-particle interaction was studied by dynamic rheological analysis. As a consequence of enhanced dilatancy, impact resistance performance of M-STF treated para-aramid fabric improved by 30% with respect to that of virgin STF treated fabrics.