Creep of high temperature tape adhesive
high temperature adhesive tape, can by pulling and stretching, shearing, cutting test creep, but what factors will affect the performance of creep?
high temperature creep is a fixed external force (tape ZhongLi, shear force, compression force) The relative deformation sample q change at any time. And stress relaxation, creep in general is a combination of relaxation and viscous flow phenomena. The polymer structure and temperature were the major influencing factors, stress and packing, plasticizer, etc.
1。 Bureau of the structure of the polymer
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who can make big points q interaction force increases, or the chain length ( Motor units) Increase the factors, such as divided the quantity increase, side chain or groups increased, got the higher polarity, crosslinking degree increase, crystallization, etc. , all reduce creep and stress relaxation.
2。 External cause
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high temperature tape creep properties strongly dependent on temperature, especially in the area of the glass transition, many of the polymer in glass transition point ( Tg) Nearby, a maximum in creep rate, below Tg enough, even in a long time, also only minimal creep, Tg in more than a high enough temperature, large secondary there will be long, but general creep rate to decrease.
the behavior of the crystalline polymer is more complicated. They creep temperature dependence is not only strong, and at a given temperature, crystalline polymer sometimes is harder than amorphous polymers and crosslinked polymer asked creep change at any time.
all in all, the temperature increase not only increase the high temperature tape creep rate, and increase the creep variable, also may make the creep types from stop into a steady state, even growth.