Retarded Elasticity for Crosslinked Polymers. There is always an instantaneous strain in response to a step change in stress·At temperatures significantly below T., the solid is essentially elastic.Attemperatures significantlyaboveT.,the solid is very compliant: For a range of temperatures near T., the solid shows a slow transient response.The deformation is reversible, although this may take a very long timeComplianceJRubberyregimeT>>TgUnloadingTransitionregimeJ (T)GlassyregimeT<<TYTimet6
• There is always an instantaneous strain in response to a step change in stress. • At temperatures significantly below Tg , the solid is essentially elastic. • At temperatures significantly above Tg , the solid is very compliant. • For a range of temperatures near Tg , the solid shows a slow transient response. • The deformation is reversible, although this may take a very long time. Retarded Elasticity for Crosslinked Polymers 6
Steady-state Creep for uncrosslinked polymers: There is always an instantaneous strain in response to a step changein stress, exactly as in crosslinked polymers: At temperatures well below T., the solid is essentially elastic andhas a very low compliance, comparable with J.. At temperatures above T., the solid is very compliant. For mostpractical ranges of loading, the compliance will increase more orless linearly with time. The slope of compliance is stronglytemperature dependentComplianceJ个·Above the glass transitiontemperature T。, the deformationis irreversible.Unloading10Timet7
• There is always an instantaneous strain in response to a step change in stress, exactly as in crosslinked polymers. • At temperatures well below Tg , the solid is essentially elastic and has a very low compliance, comparable with Jg . • At temperatures above Tg , the solid is very compliant. For most practical ranges of loading, the compliance will increase more or less linearly with time. The slope of compliance is strongly temperature dependent. Steady-state Creep for uncrosslinked polymers 7 • Above the glass transition temperature Tg , the deformation is irreversible