ABSTRACT
Rheology is the study of the deformation behaviour of materials when a force is applied to them. Rheology is an active tool used for quality control for raw materials, manufacturing processes, and final products, and it also helps to predict material performance. Rheometers are utilized to measure the effect of fillers on polymer composites. Rheometers are classified into two categories: rotational and capillary types. Natural fibres have some disadvantages like creep (time-dependent deformation), easy absorption of moisture, flammability, thermal expansion, difficulty in application of paint, and so on. Composites made up of PLA and LDPE contain lower amounts of cellulose exhibiting good storage and loss moduli compared to other matrix polymers. An acoustic rheometer employs a piezo-electric crystal. It can easily launch a continuous wave of extensions and contractions into the fluids. Working on a noncontact basis, it relates an oscillating extensional stress. Acoustic rheometers are used to measure the sound speed and attenuation of ultrasound for a set of frequencies in the megahertz range.
