Abstract: Semicrystalline manufactured articles made of syndiotactic poly-p-methylstyrene (s-PpMS) in a crystalline form having a high melting point (225.degree. C.), and processes for the preparation thereof. Processes for preparing semicrystalline manufactured articles (semi-finished products, formed articles, fibers, films, etc.) made of s-PpMS in its different crystalline forms by exposure of amorphous manufactured articles to suitable solvents and by subsequent thermomechanical treatments.

Abstract: This invention relates to composite manufactured articles formed by a set of uniaxially oriented isotatic polypropylene films, having a resistance to delamination of at least 0.4 kg/cm are prepared by heating under pressure a plurality of isotatic polypropylene films superimposed to each other and separated from each other by a non oriented polypropylene films. The oriented films show an orientation of the crystalline phase such as to produce X-ray scattering angles .DELTA..times. equal to or lower than 10.degree.. The non oriented film show an orientation of the crystalline phase such as to produce X-ray scattering angles higher than 20.degree., at a temperature between a temperature equal to or higher than the melting temperature, measured in non restrain conditions, of the non oriented film and a temperature lower than the melting temperature, measured in restrained conditions, of the oriented films.