Fibrous poly(1-butene) membranes were prepared from solutions using mixed solvents via electrospinning. The electrospun fibrous poly(1-butene) membranes were stretched at elongations of 8, 16 and 24%, respectively. Scanning electron microscopy and stress-strain analysis showed that the deformation was elastic at an elongation of 8%, while plastic deformation occurred above 16%. The crystalline transformation induced by mechanical stretching was investigated using wide-angle X-ray diffraction. The poly(1-butene) membrane stretched at 24% exhibited decreased diffraction intensity at 2 theta = 11.8 degrees and 18.3 degrees, corresponding to the (200) and (213) crystalline reflections, indicating that crystalline transformation from metastable form II to either stable form I or I' occurred due to mechanical stretching. (C) 2011 Society of Chemical Industry