Yes / Pre-oriented poly (4-methyl-1-pentene) samples were prepared by the die drawing process. The stress whitening phenomenon induced by cavities in the different die drawn P4M1P samples during the second-stage tensile deformation was investigated at temperatures below and above Tg. At 30 °C and 50 °C, the cavitation process near yield point is influenced by the fraction of unoriented crystalline phase in pre-oriented samples. Cavities originate from the fracture of the crystalline skeleton at small strains were observed in the sample with a high fraction of unoriented crystalline phase. At high deformation temperature, the small strain cavities were suppressed and the cavitation processes in all die drawn samples are due to the failure of the highly oriented fibrillar network caused by the breaking of the load-bearing interfibrillar/microfibrillar tie molecule chains. / The full text will be available at the end of the publisher's embargo: 13th Feb 2025