Abstract: The invention relates to a process for melt extruding a film layer of a thermoplastic olefin which comprises extruding the film having physical characteristics under process conditions selected by reference to the Draw ratio Dr and the Aspect ratio A such that draw resonance is avoided in which in addition the process conditions are defined by reference to the Deborah number such that the molten polymer is extruded at a Draw ratio of at least 30 in a high elasticity region at a &lgr;c value of characteristic time as defined herein of from 0.001 to 0.6 s, a Deborah number as defined herein in excess of 0.005 and an A value as defined herein lower than 0.8. Narrower ranges of these parameters may be defined for application of the invention to different polymer types.

Abstract: The invention relates to a process for melt extruding a film layer of a thermoplastic olefin which comprises extruding the film having physical characteristics under process conditions selected by reference to the Draw ratio Dr and the Aspect ratio A such that draw resonance is avoided in which in addition the process conditions are defined by reference to the Deborah number such that the molten polymer is extruded at a Draw ratio of at least 30 in a high elasticity region at a &lgr;c value of characteristic time as defined herein of from 0.001 to 0.6 s, a Deborah number as defined herein in excess of 0.005 and an A value as defined herein lower than 0.8. Narrower ranges of these parameters may be defined for application of the invention to different polymer types.

Abstract: It comprises a vaporization chamber containing the material to be vaporized and provided with at least one opening with a given cross-section for maintaining the material to be vaporized in the liquid state within said chamber and for emitting controlled flow molecular beams, a sleeve integral with the vaporization chamber surrounding the opening or openings having a given cross-section, heating means for maintaining the vaporization chamber isothermal and for obtaining an adequate temperature in the sleeve to prevent condensation of the vaporized material in said sleeve and in the opening or openings having a given cross-section.