Abstract: A process for preparing trioxane by trimerization of formaldehyde in aqueous acidic solution and subsequently removing trioxane from a mixture substantially comprising trioxane, water and formaldehyde (crude trioxane product), which comprises a) distilling the crude trioxane product from the trimerization, b) crystallizing the trioxane out and c) removing it from the mother liquor and d) subsequently melting it and e) distilling off further by-products.

Abstract: A process for continuous extraction of polyamide particles in an essentially vertical extraction column using an aqueous extractant comprises using an extraction column that is divided into two zones and performing an extraction with a recirculating 15-40% strength by weight aqueous &egr;-caprolactam solution in the first zone and then with countercurrent water at a from 5 to 40° C. lower temperature in the second zone. The process provides for economical extraction of polyamides with a low level of monomers and oligomers.

Abstract: A method for open-loop and closed-loop control of an electric drive of a vehicle, in particular of a rail vehicle, utilizes a frictional engagement between a wheel and a rail or an underlying surface, to a high degree. A control is carried out which takes into account a gradient of a characteristic frictional engagement line. The system operates with a substitute variable for the gradient, which can be detected by a technical measurement, and a set torque value which is prescribed by the operator being limited in such a way that a travel/braking mode is achieved at an optimum, prescribed operating point of the characteristic frictional engagement line.

Abstract: A process for the continuous production of polyamides from a mixture of at least one lactam and water and, if required, other monomer units and/or conventional additives and fillers under polyamide-forming conditions, where the mixture of the starting materials is heated in liquid phase in a first reaction zone until a conversion of at least 70% is reached, and undergoes adiabatic decompression and further polymerization in another reaction zone, wherein, in the first reaction zone, 0.5-7% by weight of water are employed, the temperature is increased to the range from 220.degree. to 310.degree. C., and polymerization is carried out until a conversion of at least 85% is reached and, in the second reaction zone, after the decompression further polymerization is carried out in the range from 215.degree. to 300.degree. C. without heat input.

Abstract: In a process for producing filler-containing thermoplastic molding compositions by mixing fillers with thermoplastics in the melt,a) the fillers are mixed in a mixing apparatus in the melt with a low molecular weight thermoplastic having a melt viscosity of at most 30 Pas (measured at 20.degree. C. above the melting point of the thermoplastic compound and at a shear gradient of 1,000 s.sup.-1),b) the product thus obtained is removed from the mixing apparatus, cooled and comminuted, andc) the comminuted product is then subjected in the solid phase to a post-condensation.

Abstract: The invention is directed to a headgear with a holding device for a measuring unit, illuminating unit or viewing unit. The headgear has a headband and a frontal band and is mounted on the head of the wearer of the headgear. A base body is mounted on the frontal band and a bracket for holding the unit is attached to said base body by a clamping device. The clamping device is manually actuable between a fixing position wherein the bracket is movably fixed relative to the base body and a releasing position wherein the bracket is released so as to permit movement of the bracket in elevation relative to the base body. A detent device permits the bracket to be rotated relative to the base body while the clamping device is in the fixing position.

Abstract: Linear high molecular weight polyamides containing a regulated level of amino and carboxyl end groups are prepared in a continuous process by reacting polyamides in the melt with polyamide-forming diamines or dicarboxylic acids by continuous mixing for a residence time of .ltoreq.10 minutes, granulating the polyamide, and further condensing the polyamide granules thus obtained in solid phase in the presence of inert gases until the viscosity has reached the desired level.

Abstract: Thermoplastic polyester molding materials essentially contain(A) from 20 to 89% by weight of one or more aliphatic polyesters of an aromatic dicarboxylic acid,(B) from 10 to 79% by weight of one or more aromatic polycarbonates and(C) from 1 to 40% by weight of an elastomer or of a mixture of elastomers consisting ofCA from 5 to 100% by weight of an elastomeric graft polymer composed ofCA1 not less than 50% by weight of a grafting base having a glass transition temperature T.sub.g of less than -20.degree. C.,CA2 from 5 to 20% by weight of a first graft shell consisting of a mixture of a C.sub.1 -C.sub.8 -alkyl ester of acrylic acid and a vinylaromatic in a weight ratio of from 5:95 to 70:30 andCA3 from 10 to 30% by weight of a second graft shell consisting of one or more polymers having a glass transition temperature T.sub.g above 20.degree. C.