Abstract: A polyamide moulding composition is condensed up in the melt by means of a masterbatch containing a compound having at least two carbonate units and also a polyetheramide in which at least 50% of the end groups are present as amino end groups, whereupon the melt mixture is discharged and solidified to give a moulding composition or a moulding. The product obtained has an increased amino end group content and consequently an improved hydrolysis resistance.

Abstract: In a method for the introduction of an inliner into a pipe or a pipeline, where the external diameter of the inliner is greater than the internal diameter of the pipe or of the pipeline, and where the action of an external force is used to reduce the cross section of the inliner prior to the introduction, the inliner is composed of a polyamide moulding composition which comprises at least 50% by weight of polyamide which is not PA11. The recovery behaviour of said polyamides is similar to that of polyethylene usually used for this purpose.

Abstract: A pipeline laid trenchlessly and/or without a sand bed is produced using a metallic conduit which is encased with an extruded layer of a polyamide moulding material. In this way, the durability of the outer shell required for trenchless laying techniques without a sand bed is ensured.

Abstract: A pipe or hose composed of a polyamide moulding composition whose molecular weight has been increased by condensation, via addition of a compound having at least two carbonate units in a quantitative proportion of from 0.005 to 10% by weight, based on polyamide, where a) a starting polyamide moulding composition was provided, b) a mixture of the starting polyamide moulding composition and of the compound having at least two carbonate units was produced, c) the premix was, if desired, stored and/or transported, and d) the premix was then processed to give the moulding, this step being the first in which the increase of molecular weight by condensation occurred, the moulding being a pipe or hose whose external diameter is at least 25 mm is used as inliner for a pipeline.

Abstract: A pipe includes an outer layer composed of a molding composition which includes at least 40% by weight of a polyamide whose monomer units contain an average of at least 8 carbon atoms, and a layer composed of a polypropylene molding composition. An outer diameter of the pipe is in a range from 6 to 20 mm, a wall thickness of the pipe is in a range from 1.0 to 2.0 mm, and a thickness of the polypropylene layer is from 25 to 75% of the wall thickness. The pipe can be used as an air-brake line that can be produced at low cost, has high bursting strength, and has good low-temperature impact resistance.

Abstract: A pipe, which comprises the following layers: I. an exterior layer composed of a moulding composition which comprises at least 40% by weight of a polyamide whose monomer units contain, on average, at least 8 carbon atoms, III. an intermediate layer composed of a moulding composition which comprises the following components: a) from 70 to 99% by weight of polyamide, selected from PA6, PA66, PA6/66 and mixtures thereof and b) from 1 to 30% by weight of plasticizer, where the moulding composition comprises no impact modifier, and V. an interior layer composed of a moulding composition which comprises at least 40% by weight of a polyamide whose monomer units contain, on average, at least 8 carbon atoms, where a) the exterior diameter of the pipe is in the range from 6 to 20 mm, b) the wall thickness is in the range from 1.0 to 2.

Abstract: A pipe includes an outer layer composed of a molding composition which comprises at least 40% by weight of a polyamide whose monomer units contain an average of at least 8 carbon atoms, and a layer composed of a polypropylene molding composition. An outer diameter of the pipe is in a range from 6 to 20 mm, a wall thickness of the pipe is in a range from 1.0 to 2.0 mm, and a thickness of the polypropylene layer is from 25 to 75% of the wall thickness. The pipe can be used as an air-brake line that can be produced at low cost, has high bursting strength, and has good low-temperature impact resistance.

Abstract: Multilayer composites are obtained from a molding composition which contains the following components: a) 100 parts by weight of polyamide and b) from 0.005 to 10 parts by weight of a compound having at least two carbonate units by coextruding with a molding composition based on a high-melting-point polymer whose crystallite melting point Tm is at least 255° C. and/or whose glass transition temperature Tg is at least 180° C.

Abstract: A flame retardant molding composition contains a) from 43 to 93.5 parts by weight of polyamide, b) from 2 to 12 parts by weight of melamine cyanurate, c) from 1.5 to 15 parts by weight of polyol having at least 3 OH groups per molecule, and d) from 3 to 30 parts by weight of an organophosphorus compound, with the proviso that the parts by weight of components a) to d) give a total of 100. The molding composition has excellent fire properties and, despite the use of the particulate material melamine cyanurate, is flexible.

Abstract: A polyamide molding composition which can be used for production of a printable or printed item contains a) at most 90 parts by weight of a polyamide obtained from a lactam or from an amino carboxylic acid having at least 10 carbon atoms; and b) from 10 to 100 parts by weight of PA1010, wherein a total of components a) and b) is 100 parts by weight.

Abstract: A process for producing moldings with condensing-up of a polyamide molding composition by means of a compound having at least two carbonate units, wherein a) a polyamide molding composition is made available, b) a mixture of the polyamide molding composition and the compound having at least two carbonate units is prepared, c) the mixture is, if appropriate, stored and/or transported and d) the mixture is subsequently processed to produce the molding, with the condensing-up occurring only in this step, and the molding is a hollow body or hollow profile having an external diameter of at least 30 mm and a wall thickness of at least 1 mm, effects a significant increase in the melt stiffness combined with moderate processing presssures, which considerably simplifies the production of these moldings.

Abstract: A process for producing moldings with condensing-up of a polyamide molding composition whose polyamide component contains, as a result of the method of preparation, at least 5 ppm of phosphorus in the form of an acidic compound by means of a compound having at least two carbonate units, wherein a) from 0.001 to 10% by weight, based on the polyamide, of a salt of a weak acid is added to the polyamide molding composition prior to compounding or during compounding, b) a mixture of the finished composition and the compound having at least two carbonate units is prepared, c) the mixture is, if appropriate, stored and/or transported and d) the mixture is subsequently processed to produce the molding, with the condensing-up occurring only in this step, effects a significant increase in the melt stiffness combined with moderate processing presssures, which considerably simplifies, in particular, the production of hollow bodies and hollow profiles having large diameters.

Abstract: A process for condensing polyamides to increase their molecular weight, using a compound having at least two carbonate units comprises using a polyamide which, as a result of its preparation, comprises from 5 to 500 ppm of phosphorus in the form of an acidic compound, and adding, to the polyamide, from 0.001 to 10% by weight of a salt of a weak acid, thus eliminating the inhibiting action of the phosphorus compound.