rheology2 Flashcards
what is glass transition range
intermediate temperature range where polymer is neither glass or polymer
viscoelasticity what is it
it the property of material that exhibit both viscous and elastic characteristics when under shear stress/ deformation. they resist shear force and shear linearity while a stress is applied
what is the charecteristic of elastic material
strain instaneously and when strectched and as quickly when stress is removed return back to original shapeq
what occurs to viscoelastic material
dissipate some of stress in viscous flow and store rest which is recovered once stress is removed
polymers how do they repsonse
time-dependent resp non-recovery of strain on removal of stress non-linearity of resp direct dependence fractures
linear and non-linear viscoelasticity
linear is when the fn is separable both in creep and stress and time abnormalitites while in non- it is usually when changes to property occur through deformation
what is effect of heat on viscoelastic material
low temp- brittle or glass like high temp- flexible and rubber like
behaviour of elastic solids
follow hookes law which states that stress directly proportional to strain and independent of rate of strain
behaviour of liquids
obeys newtons law which demonstrates that rate of shear is directly proportional to stress
when these properties are not followed
viscoelastic then
how to tell from graph if something is more elastic or viscous
complete but slow recovery elasticity but some viscosity
in complete recovery indicate viscosity with some elasticity
kevin or voight model
purely viscous damper and purely elastic spring connected in parallel the stress applied is same thus we use the differentiation in
