Abstract: The invention concerns a method which consists in first subjecting the polyimide sheet to ionic bombardment, followed by an irradiation in the visible domain and finally a relatively brief chemical etching. Said method enables a thin polyimide sheet comprising pores, of nanometric to micrometric size, having a substantially cylindrical shape and substantially equal diameters to be obtained.

Abstract: The invention concerns a method which consists in first subjecting the polyimide sheet to ionic bombardment, followed by an irradiation in the visible domain and finally a relatively brief chemical etching. Said method enables a thin polyimide sheet comprising pores, of nanometric to micrometric size, having a substantially cylindrical shape and substantially equal diameters to be obtained.

Abstract: The invention relates to a method of creating pores in a polymer material in sheet form or a polymer layer such as a thin film with a thickness equal to around 100 nanometers, previously deposited on a metallic base. The invention further relates to a method of creating pores in a polymer material in sheet form, such as polycarbonate or any other equivalent material, the said method making it possible to obtain porous areas with controllable sizes and shapes, these areas being distributed according to densities and locations which can also be controlled.

Abstract: The invention relates to a method of creating pores in a polymer material in sheet form or a polymer layer such as a thin film with a thickness equal to around 100 nanometers, previously deposited on a metallic base. The invention further relates to a method of creating pores in a polymer material in sheet form, such as polycarbonate or any other equivalent material, the said method making it possible to obtain porous areas with controllable sizes and shapes, these areas being distributed according to densities and locations which can also be controlled.

Abstract: The invention relates to a method for creating pores in a sheet polymer material. The invention more particularly relates to a method for creating nanoscale pores, typically of the order of less than 200 nm, in a polymer material such as sheet polycarbonate or any other equivalent material.

Abstract: The subject of the present invention is a solid material in the form of a microperforated sheet transparent to light of wavelengths in the visible and infrared, characterized in that the mean distance between two immediately neighbouring perforations is at least 5, and preferably 7 .mu.m, and is so over each face of the material. Preferably, the mean angle of inclination of the perforations through the thickness of the material is less than 10.degree., even 5.degree.. In a particular embodiment, the material is a membrane produced from a flexible polymer film with a thickness lying between 0.1 and 100 .mu.m, more generally between 5 and 50 .mu.m, and the perforation diameters lying between 0.01 and 15 .mu.m. The membranes obtained according to the invention are particularly useful as support membranes for viewing in an optical microscope or in infrared spectroscopy. They may also be used as filter membranes or, amongst other applications, as a support for cell culture.

Abstract: The invention relates to a method of producing perforations in a solid material in sheet form, an irradiation device for working the method and the resulting perforated material.

Abstract: The invention concerns a process for crystallizing a polycarbonate polymer which consists in incorporating to said polycarbonate polymer a finely divided nucleating agent and/or a plasticizer for said polycarbonate polymer, and crystallizing the mixture thus obtained at a temperature higher than the vitreous transition temperature.The semi-crystalline polymer material obtained can be reinforced by adding inorganic fibers.