抄録
High polymers have generally larger internal loss than metals. Therefore we can damp undesirable vibrations of some machines or tools by using them as structural materials in place of metals. But unfortunately high material damping often seems incompatible with high stiffness or small temperature coefficients of stiffness or damping itself.
It is the aim of this paper to study experimentally such interrelations between internal loss and stiffness for many practical polymers.
The temperature dependence of complex dynamic Young's moduli of twelve thermoplastic resins and three thermosetting resins, of which the latter the dynamic viscoelastic properties have hitherto been but scantily reported, has been measured of dozens of cps and in the temperature range of -30∼+100°C.
It has been shown that the loss tangents of these polymers are approximately proportional to the temperature coefficients of storage moduli.
The proportion factor K(T) for amorphous polymers in the glass transition region depends roughly on activation energy of relaxation time and absolute temperature.
A method of calculating approximate values of activation energy from measurement of K(T) at a fixed frequency has been studied about an example of NBS polyisobuthylene measured by Ferry et al.
Experimental results on the explicit relations between the storage modulus and the loss tangent are given for many polymers and commented on briefly from the standpoint of structural damping.
