Initiation of cavitation upon drawing of pre-oriented polypropylene films has been investigated via in-situ small angle X-ray scattering (SAXS) and wide angle X-ray diffraction (WAXD) techniques. The macroscopic strains for the initiation of the cavitation ε_cav and for the initiation of crystal shear ε_cs have been estimated from in-situ SAXS and WAXD tests respectively. Local crystal shear appears before cavitation upon drawing in machine direction (MD) has been revealed via comparison of ε_cs and ε_cav. The initial size of the cavities in MD is larger than the long period of crystalline lamellae while the size in transverse direction is inversely proportional to the relative fraction of daughter lamellae. Macroscopic critical stresses for the initiation of cavitation σ_cav and for the initiation of crystal shear σ_cs have been estimated as well. The critical stress σ_cav is independent on the crystallinity, whereas σ_cs increases with increasing crystallinity. The mechanism for the initiation of cavitation has been proposed, i.e. the cavitation is initiated by the breakage of crystalline lamellae at the anchor point of the daughter lamellae.

已经通过原位小角度X射线散射（SAXS）和广角X射线衍射（WAXD）技术研究了在拉伸预取向聚丙烯薄膜时产生的气穴现象。对于开始时的宏观菌株的气穴ε _CAV和用于晶体剪切ε起始_CS已经从估计的原位SAXS和WAXD分别测试。气蚀之前后在机器方向上拉伸本地晶体剪切出现（MD）已经经由ε的比较揭示了_CS和ε _CAV。MD中腔体的初始尺寸大于晶体薄片的长周期，而横向尺寸与子代薄片的相对分数成反比。对于空化σ起始宏观临界应力_CAV和用于晶体剪切的引发σ _CS已经被估计为良好。临界应力σ _CAV不依赖于结晶性，而σ _CS随着结晶度的增加。已经提出了引发空化的机制，即，空化是由子代薄片的锚定点处的结晶薄片的破裂引起的。