聚四氟乙烯动态特性的实验研究

 在10~55 GPa的高压范围用化爆装置、采用阻抗匹配法测得了聚四氟乙烯（初始密度ρ₀=2.19 g/cm³）的冲击波速度D和波后粒子速度u之关系为：D=2.10+1.62u（mm/μs）。在0.2~3 GPa的低压范围用气炮装置、采用电磁速度计测量了材料内加、卸载过程的拉格朗日粒子速度波形，获得的冲击加载D-u关系为：D=1.24+3.72u-1.94u²（mm/μs）。实测卸载曲线和加载冲击绝热线接近一致，残余应变似乎不存在或者说很小；弹性区段很不明显，聚四氟乙烯本质上呈现出塑性性质。

EXPERIMENTAL STUDIES ON THE DYNAMIC BEHAVIOUR OF POLYTETRAFLUOROETHYLENE (PTFE)

The shock adiabat of PTFE (with the initial density 2.19 g/cm³) has been measured with the impedance matching method at high pressures. LY-12 Al was used as a standard material (the initial density is 2.794 g/cm³, and the linear relation between the shock velocity D and the particle velocity u is D=5.47+1.28u (mm/μs).). In the experiments, the plane shock waves were produced by means of the contact explosion technique or the flyer impact technique, and the shock velocity D was measured by the high-speed scanning photography combined with the flash-gap technique. Is the pressure range from 10 to 55 GPa, the obtained linear relation between D and u of PTFE is D=2.10+1.62u (mm/μs). At lower pressures (0.2~3 GPa), the experiments were conducted on a gas-gun with the symmetric impact principle, the impact velocities were measured by a laser system the Lagrange particle velocity profiles for loading and unloading processes and the shock velocity in the specimen were measured with the electro-magnetic velocity gages. For the shock loading process, the obtained D-u relation and the shock adiabat are respectively. D=1.24+3.72u-1.94u² (mm/μs) and σ=2.10ε+44.5ε²+123.2ε³ where σ is the axial stress behind the shock front for one-dimensional strain, and ε is the corresponding bulk strain. The obtained unloading paths are almost in agreement with the shock adiabat. The residual strains seem to be either inexistent or very small. The elastic behavior almost does not occur; i. e. PTFE presents plastic behavior essentially.