Drawing and annealing of fibrous material

The more-than-linear increase of elastic modulus with draw ratio, the gradual disappearance of meridional SAXS maximum, the drastic drop of elastic modulus after annealing and its recovery upon standing at room temperature if the sample was annealed with fixed ends so that it did not shrink, and the shape stability of such polyethylene samples and of superdrawn material (polyethylene, polypropylene, polyoxymethylene) during new annealing can be easily explained by the microfibrillar model of fibrous structure which was developed some years ago on the basis of electron microscopy and x-ray and ir investigation of plastically deformed linear polyethylene and isotatic polypropylene.