The crystallization and orientation of natural rubber under uniaxial drawing were investigated by the electron microscope. From electron microscope and electron diffraction pattern it is revealed that the structure of the fibre from natural rubber is similar to that of the polyethylene fibre. Its basic structural element is also micro-fibril

highly aligned in the draw direction and the microfibril is formed by the folded chain blocks

aligned perpendicular to the draw direction. Thus it seems to be reasonable that the structural model of polyethylene microfibril could be considered as a general model for crystalline fibres of such linear polymers.