Abstract: A device for expanding heat-shrinkable polymer tubes includes inlet and outlet chambers coaxially and consecutively arranged for immediate contact in the direction of tube advancement. Each chamber is made up of adjoining bushes having threads at the inner surface thereof. The threads of adjacent bushes of each chamber are of the opposite direction. A group of bushes of each chamber having a common thread direction is provided with an independent rotating drive.

Abstract: A method for extrusion of a highly viscous thermosetting or a thermoplastic material comprising extrusion of said material in the presence of substances diminishing external friction of the melt, at a ratio between internal and external friction values of the material melt within the range of from 1.5 to 4.0; the thermosetting material melt viscosity being ranged from 50.times.10.sup.6 to 300.times.10.sup.6 poises, while the thermoplastic material melt index being varied from 0.01 to 0.1 g/10 min.The ratio between internal and external friction values of the material melt is maintained within the above-specified range by way of incorporation, into the starting thermosetting or thermoplastic material, of certain compounds. For thermosetting materials, use is made of, e.g. zinc dialkyldithiophosphate, and for thermoplastic materials barium sulphonate is used as such a compound.

Abstract: The process for producing phenol-formaldehyde oligomers of ortho-specific structure comprises reacting finely-divided crystalline phenol or a mixture of crystalline phenol with crystalline naphthalene, containing from 14 to 58 wt.% of the latter, at a temperature of from 20.degree. to 40.degree. C. with gaseous formaldehyde to give phenolic alcohols. The thus-prepared phenolic alcohols are subjected to polycondensation simultaneously with drying and subsequent heat-treatment of the resulting oligomers of ortho-specific structure.The process according to the present invention makes it possible to intensify the production of phenol-formaldehyde oligomers of ortho-specific structure. Furthermore, owing to the fact that this process makes it possible to eliminate the use of catalysts and high temperatures, it simplifies technology of the production of phenol-formaldehyde oligomers.

Abstract: A process for producing polymeric films from crystallizable polyesters, such as polyethylene terephthalate, comprising extruding a molten polymer onto a receiving surface with subsequent cooling of the polymer on said surface at 20.degree.-80.degree. C. to obtain an amorphous polymeric film. This film is heat-treated at 130.degree.-190.degree. C. to obtain a crystallinity of the film of 5-50%. Then the film is oriented at 130.degree.-250.degree. C., thermally fixed at 170.degree.-250.degree. C. and cooled at 20.degree.-30.degree. C. Polymeric films produced by the above-described method have a high structural homogeneity and elevated physical and mechanical characteristics (ultimate tensile strength up to 4000 kg/cm.sup.2, yield point up to 3500 kg/cm.sup.2).