. The Bell System technical journal . O MEASURED POINTSSTATIC VALUE OF= POISE ff, 10^ = 10* = 10= ^ 10^ FREQUENCY IN CYCLES PER SECOND 100 X10^. Fig. 13—Shear elasticity for a one per cent solution of polyisobutylene as afunction of frequency for 25°C. MECHANICAL PROPERTIES OF POLYMERS 139 stiffness decreases with increase in temperature for a sinji;le frequencymeasurement. However, when measurements were made at 20, 40, 80and 150 kc it was found that the elasticity was a function of the fre-([uency, which incHcates the presence of more than one relaxation andcomplicates the determinatio
. The Bell System technical journal . O MEASURED POINTSSTATIC VALUE OF= POISE ff, 10^ = 10* = 10= ^ 10^ FREQUENCY IN CYCLES PER SECOND 100 X10^. Fig. 13—Shear elasticity for a one per cent solution of polyisobutylene as afunction of frequency for 25°C. MECHANICAL PROPERTIES OF POLYMERS 139 stiffness decreases with increase in temperature for a sinji;le frequencymeasurement. However, when measurements were made at 20, 40, 80and 150 kc it was found that the elasticity was a function of the fre-([uency, which incHcates the presence of more than one relaxation andcomplicates the determination of the temperature relationships. Fig. 13shows measurements of the shear elasticity over a frequency range kc^ up to 14 megacycles for 25°C. There is a gradual rise up toabout 300 kilocj^les after which there is a sharp break to a stiffness ofabout 90,000 dynes/cm^ for a 1 per cent solution of the 3,930,000 molecu-lar weight polymer in cyclohexane. If one analyzes the freciuency varia-tion of the elasticity he finds that it can be fitted by three relaxationfrequencies, one having a fre(iuency of 230 cycles, one around 66,000cycles
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
