The compressive stress-strain curves of PMMA in 20 to 160℃ were measured at about 102 to 103/second strain rates by SHPB (Split Hopkinson Pressure Bar) equipment. It was concluded that during the period when the logarithmic strain rate log ε (t)

decreases linearly with time the parameter k which relates the acoustic resistance of one-dimentional wave propagation between PMMA and steel bar equals the constant b which characterizes the viscoelastic proper ties of PMMA

b = E'/η' in accordance with the standard linear mechanical model of visco-elasticity. The variance of k with temperature was regarded as the viscoelastic effect of PMMA.