acrylic polymers, modified nanosilica, DSC diagrams of this composites in Tg are not second order transition whereas are like melting transition, but this effect Becomes more evident with increasing silica particles content.
Physical aging or volume relaxation is a very common phenomenon observed in both organic and inorganic glasses (not only in composites, but also in pure polymers). This is due to the slowed-down motion below the glass transition temperature, which is related to a so-called second order phase transition, where not the volume is discontinuous but its derivative, the thermal expnasion coefficient. If cooled fast the glass cannot attain it quasi-equilbrium specific volume because of kinetic hindrance. If annealed close to the glass temperature the volume will gradually decerease - this is called volume relaxation. It is closely related to the so-called enthalpy relaxation effect.
Hi..
can you pls elaborate 'aging' means, what do exactly observed??
Physical aging or volume relaxation is a very common phenomenon observed in both organic and inorganic glasses (not only in composites, but also in pure polymers). This is due to the slowed-down motion below the glass transition temperature, which is related to a so-called second order phase transition, where not the volume is discontinuous but its derivative, the thermal expnasion coefficient. If cooled fast the glass cannot attain it quasi-equilbrium specific volume because of kinetic hindrance. If annealed close to the glass temperature the volume will gradually decerease - this is called volume relaxation. It is closely related to the so-called enthalpy relaxation effect.
Physical Aging is mainly because of interaction of different forms of available energy in nature.
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