DE102015106348B4 - Process for the production of moldings, the moldings produced thereafter and their use for the production of carbon moldings - Google Patents

Abstract

Process for the production of moldings, in particular fibers or films, based on modified polyolefins or modified polyamides, characterized in that 1.) thermoplastic moldings based on thermoplastic poly-α-olefins, which are based on monomers with a single double bond, or thermoplastic aliphatic polyamides are used as the starting material, 2.) the polyolefins and polyamides of the molded body are crosslinked and 3.) the crosslinked polyolefins and crosslinked polyamides are sulfurized with activated elemental sulfur.

Description

The invention relates to a process for the production of moldings, in particular fibers or films, based on modified polyolefins or modified polyamides, sulfur-containing moldings in the form of fibers or films based on modified polyolefins or modified polyamides, and their use for producing carbon moldings Carbonization and optionally by subsequent graphitization.

Due to their properties (high tensile strength and high modulus with very low density), carbon fibers are the most widely used reinforcing fibers in fiber composite materials made of carbon fiber reinforced plastic (CFRP) for aircraft construction, in automobile construction and for the production of wind turbines, if the properties of other reinforcing fibers, such as that of glass fibers that can no longer meet the requirements, particularly with regard to rigidity. The carbon fibers available on the market are based either on copolymers of polyacrylonitrile (PAN) or so-called “pitch” polymers (PITCH) as precursors, the former being dominant for high-strength fibers and the latter predestined for high-modulus fibers.

The two precursor systems based on PAN or PITCH have so far only been able to compete with metal materials to a limited extent for widespread use in mass production. Therefore, worldwide research is being carried out to find inexpensive, alternative polymer-based precursors. Three polymer classes are advised for this: the wood components cellulose and lignin as well as polyethylene. Due to its carbon content of 44%, cellulose is limited to this value as the maximum carbon yield, with carbon yields of 20 to 25% being typically achieved. Lignin has a carbon content of approx. 60%, of which approx. 45 to 50% can be achieved as a carbon yield. Polyethylene has a carbon content of 85%, with carbon yields of up to 75% being reported in the literature. In terms of economical process management, polyethylene is particularly interesting for carbon fibers.

It is known from the prior art that carbon fibers with a tensile strength of 2.5 GPa and a modulus of 139 GPa can be produced from polyethylene with a very high crystallinity (Horikiri et al., “Process for production of carbon fiber”, US 4,070,446 A. , WO 92/03601 A2 and US 2013/014442 A1 ). According to both documents, polyethylene fibers in the mineral acids, sulfuric acid, oleum or chlorosulfonic acid or mixtures of these, are treated as sulfating agents, the reaction rate increasing in the order of concentrated sulfuric acid <oleum <chlorosulfonic acid. The resulting black fibers are converted to carbon by heating and pyrolysis products in the form of SO ₂ and water are split off.

In general, the prior art uses sulfonation with an SO ₃ species in the form of a gas or as part of a liquid to provide precursor fibers for subsequent carbonization. Known processes use SO ₃ , dissolved in halogenated solvents (WO 2014/011462 A1), sulfonation over strong acids in two steps (WO 2014/011460 A1) or treatment with gaseous SO ₃ (WO 2014/011457 A1).

The above-mentioned methods have the disadvantage that the use of SO _3- containing chemicals for stabilization requires very high-quality materials in order to avoid corrosion. Furthermore, when using technically manageable concentrated sulfuric acid, an acceptable carbon yield is only achieved at concentrations> 98%, so that highly concentrated sulfuric acid must be replenished continuously in the process. In addition, the process must take place under dry nitrogen in order to prevent the supply of air humidity for the same reason. All the methods described for stabilization by wet chemical treatment require a washing process in order to remove the corrosive liquids before further treatment of the precursor fiber.

A particular disadvantage of the prior art is that the treatment with SO _x -containing media limits the temperature to below the melting point of the polyethylene, at least in the first treatment step, in order to prevent the polyethylene from melting. As a result, the active species in the crystalline regions of the polyethylene fibers can only be sulfated very slowly. Therefore, in the prior art, LLDPE is preferably used as the starting polymer, but its lower density has a negative effect on the maximum carbon fiber properties that can be achieved.

In connection with the invention described later, reference should be made to the following prior art: DE 19 58 361 A it is known to pretreat fibers for the production of carbon fibers. This document discloses the fibers in a method for producing carbon fibers pretreatment to permeate it with sulfur by heating the fibers in an atmosphere containing sulfur or sulfur-containing compounds and to subject the pretreated fiber to carbonization or carbonization. These fibers are made of polyacrylonitrile and similar polymers. A comparable state of the art results from the DE 37 83 423 C2 , whereupon acrylic sulfile fibers are produced by heating acrylic fibers. The same applies to the JPH-01306 620 A and the JP 58109625 A , which also only affect the treatment of fibers based on polyacrylonitrile with sulfur. From the US 4,070,446 A a method for crosslinking polyethylene, consequently a polyolefin, is known. Crosslinking takes place by irradiation or by the action of a peroxide compound. The is irrelevant in this regard US 4,080,417 A . A phase based on polyacrylonitrile for crosslinking is then treated with an aminosiloxane at at least 150 ° C. for 0.1 to 3 minutes, so that the fiber obtained contains 20 to 80% by weight of undissolved substance. It is then carbonized. A polyolefin or a polyamide are not crosslinked. It is emphasized that the terms "polyolefin" and "polyamide" are not subject to the term "polyacrylonitrile".

The carbon fibers known from the prior art are not suitable with regard to their production processes and their carbon yield, in terms of price with metallic alloys, such as e.g. Steel, aluminum and magnesium alloys to compete in the area of mechanically loaded components. The known carbon fibers are only used if their superior mechanical properties require such a substitution.

It is therefore the object of the present invention to further develop the method described at the outset in such a way that carbon bodies with improved mechanical characteristics can be produced inexpensively from highly available raw materials. These moldings are said to be particularly suitable for producing advantageous carbon moldings therefrom by carbonization.

This object is achieved according to the invention by a process for the production of moldings, in particular fibers or films, based on modified polyolefins or modified polyamides, which is characterized in that 1.) thermoplastic moldings based on thermoplastic poly-α-olefins which are based on monomers with a single double bond or are used as the starting material for thermoplastic aliphatic polyamides, 2.) the polyolefins and polyamides of the molded body are crosslinked and 3.) the crosslinked polyolefins and crosslinked polyamides are sulfurized with activated elemental sulfur.

Basically, the above procedure, as can be seen by a person skilled in the art, can also be a mixture of thermoplastic poly-α-olefins, which are based on monomers with a single double bond (hereinafter: “thermoplastic poly-α-olefins), and thermoplastic aliphatic polyamides, if appropriate also Inclusion of additional other thermoplastic materials such as polybutadiene and / or polyisoprene can be used. Thus, various polymers can be added to the starting materials according to the invention in such a proportion, for example polyolefins which are based on monomers with two double bonds, that the desired sulfurized molded articles or the carbon molded articles obtained therefrom still retain the desirable properties, as described in detail below. As a rule, it could be stated that the proportion of polyolefins based on monomers with, for example, two double bonds should be limited to in particular less than 25% by weight. It is preferred to reduce this maximum limit to 15% by weight, in particular to less than 10% by weight. It is particularly preferred if the content of additional material is less than 5% by weight, in particular approximately 0% by weight.

The raw materials according to measure 1.) are not subject to any significant restrictions. The thermoplastic poly-α-olefins and the thermoplastic aliphatic polyamides are first subjected to shaping in order to obtain a shaped body for the purposes of the invention. For example, it can be molded articles in the form of fibers, films and / or also plates and the like. The shaping can be carried out in a customary manner, in particular by melting processes and / or in the case of plate-shaped moldings also by cutting processes or by milling or similar processes.

Processes which are based on a melting process with shaping are particularly favorable, the thermoplastic poly-α-olefins or the thermoplastic aliphatic polyamides being melted and then cooled with shaping. It is advantageous here if fibers are produced from the melt of the thermoplastic poly-α-olefins and the thermoplastic aliphatic polyamides in a customary manner, in particular by extrusion, casting, calendering or blow molding, films and by melt spinning.

A thermoplastic aliphatic polyamide, in particular polyamide 6, 4.6, 6.6, 6.9, 6.10, 6.12, 10.10, 11, 12 with melting points in the range from approximately 180 to 260 ° C. is used as the polyamide. Particularly preferred is the polyamide 6.6, whose high melting point of approximately 260 ° C. effectively prevents the fibers from sintering together when flavored with elemental sulfur.

The polyolefins that come into consideration according to the invention are in particular those which are based on linear α-olefins, in particular those having 1 to 8 carbon atoms. These can be homo- or copolymers. Polyethylene, polypropylene, polyisobutylene and / or polybutylene are preferably used.

It is associated with great advantage if ultra-high molecular weight polyethylene is used as the starting material for the production of the moldings, which has a weight-average molecular weight of> 500,000 g / mol, in particular from 1,000,000 to 10,000,000 g / mol, this being in particular by gel spinning can be converted into fibers. In general, it is preferred that a poly-α-olefin with a weight-average molecular weight of 20,000 to 500,000 g / mol, in particular from 200,000 to 300,000 g / mol, is used. Furthermore, it is preferred if a polyamide with a weight-average molecular weight of 10,000 to 50,000 g / mol, in particular of 15,000 to 30,000 g / mol, is used.

It is also preferred that one or more modifications of PE-LLD, PE-HD, PE-HMW and PE-UHMW, in particular PE-LLD and / or PE-HD, be used as the polyolefin.

It is also advantageous that additives are added to the melted aliphatic poly-α-olefins and / or the melted thermoplastic aliphatic polyamides to control the process with regard to the behavior in the carbonization described later. The melted aliphatic poly-α-olefins and the melted thermoplastic aliphatic polyamides are expediently added to spinning additives during melt spinning, in particular fatty acid amides, waxes and / or ultra-high molecular weight polyethylene.

When producing fibers from thermoplastic aliphatic poly-α-olefins or thermoplastic aliphatic polyamides, it is expedient to use an extruder, in particular a twin-screw extruder. In it, the polyolefins or polyamides are melted or compounded and spun thereon, preferably by extrusion through a spinneret plate with spinning holes with a diameter of 100 to 500 μm, in particular from 200 to 300 μm. It is expedient for the spinning temperature to be set to 200 ° C. to 350 ° C., in particular to 230 ° C. to 320 ° C. It is also advantageous if multifilament yarns are first produced from the polyolefins and polyamides described, in particular as direct rovings or folded rovings. The multifilament yarns can in particular consist of 1000 to 100,000, in particular 12,000 to 64,000, filaments.

• Polyethylenfasern können insbesondere durch Nassspinnen, Gelspinnen, Trockenspinnen und Schmelzspinnen hergestellt werden. Das Gelspinnen ist eine gebräuchliche Technik zur Herstellung von Fasern auf Basis von ultrahochmolekularem Polyethylen. Dafür wird ultrahochmolekulares Polyethylen (PE-UHMW) in einem geeigneten Lösungsmittel gelöst. Durch Ausspinnen einer solchen Lösung bildet sich ein Gelfaden, der durch weitere Behandlung verstreckt und verdichtet wird. Es entstehen hochfeste Fasern mit sehr hoher Kristallinität und Orientierung.

Step 1) to be included in the process according to the invention, after which the thermoplastic poly-α-olefins and / or the thermoplastic aliphatic polyamides are subjected to a shaping, is to be explained in more detail below with reference to preferred embodiments of the invention:

• Polyethylene fibers can be produced in particular by wet spinning, gel spinning, dry spinning and melt spinning. Gel spinning is a common technique for producing fibers based on ultra high molecular weight polyethylene. For this purpose, ultra high molecular weight polyethylene (PE-UHMW) is dissolved in a suitable solvent. By spinning out such a solution, a gel thread is formed, which is stretched and compressed by further treatment. High-strength fibers with very high crystallinity and orientation are created.

Fibers made from thermoplastic aliphatic polyamide fibers are typically produced by melt spinning. The melt-spun fibers made of the polyamides PA6, PA6.6 and PA4.6 are of particular technical importance. There are a large number of other types (PA 6.12, PA11, PA12 etc.) that are also suitable but of minor importance.

According to a preferred embodiment of the present invention, a polyethylene starting fiber is melt spun. One or more of the modifications PE-LLD and / or PE-HD are used as a modification of the polyethylene for melt spinning. The use of PE-LLD and / or PE-HD is particularly preferred, likewise the use of spinning additives, such as low molecular weight waxes and / or fatty acid amides. Melt spinning is preferably carried out using a twin-screw extruder, which can in particular produce mixtures of PE-LLD (component x), PE-HD (component y) and spinning additives (component z) by means of a multi-component metering. Are preferred Mixtures with a proportion of x + y + z = 100% with z in the range from 0 to 5% and x in the range from 0 to 100-yz%, y in the range from 0 to 100-xz%. Mixtures with 1% z z 2 2% and x + y 100 100-zw% are particularly preferred. Particularly suitable as spinning additives z are paraffin oils, paraffin waxes and / or fatty acid amides for lowering the viscosity and / or in particular PE-UHMW, which, with suitable metering, can minimize instabilities in the production of PE fibers in melt spinning.

The polyethylene in the case of the PE-HD and the PE-LLDPE has in particular an average molecular weight between 20,000 and 500,000 g / mol. An average molecular weight between 200,000 and 300,000 g / mol is particularly preferred. In the case of PE-UHMW as an additive, the polyethylene can have an average molecular weight of 1,000,000 g / mol to 10,000,000 g / mol. An average molecular weight of 4,000,000 g / mol to 5,000,000 g / mol is very particularly preferred.

It is generally advantageous if the fibers used in the context of the invention are stretched on the basis of thermoplastic poly-α-olefin and / or thermoplastic polyamide fibers, in particular to a tensile strength of 20 to 100 cN / tex (according to DIN EN ISO 5079 ) and / or a module from 70 to 500 cN / tex (according to DIN EN ISO 5079). The fibers are advantageously stretched to such an extent that the orientation of the drawn fibers measured by the WAXS analysis is greater than 80%, in particular greater than 90%, and / or the individual filament diameter of the drawn fibers is less than 30 µm, in particular 15 µm .

The stretching is preferably carried out as follows: The stretching is achieved in particular by changing the length of the fibers after the first spinning section within two roll mills with different drive speeds. The stretching is expediently carried out in the running process between two heated rolling mills with different drive speeds. The drawn fibers preferably have a tensile strength of> 20 cN / tex (according to DIN EN ISO 5079) and / or a modulus of> 100 cN / tex (according to DIN EN ISO 5079), particularly preferably a tensile strength of> 40 cN / tex and / or a module of> 200 cN / tex.

According to the invention, the shaped bodies described above are the designated step 2nd .) subjected: The moldings used, in particular films or fibers, are then chemically and / or physically crosslinked. It is preferred here that the chemical crosslinking of the thermoplastic poly-α-olefins with a peroxide compound, in particular with ditertiary butyl peroxide (DTPD) or dicumyl peroxide (DCP), or by grafting vinyl silanes in a reactive extrusion with subsequent crosslinking in a moist environment and the physical crosslinking is carried out by radiation treatment, in particular with UV rays or with electron beams. There are also advantages in that the chemical-physical crosslinking of the thermoplastic aliphatic polyamides is carried out with electron beams with the addition of a crosslinking additive, in particular with crosslinking additives in the form of tetramethylol methane tetraacrylate (A-TMMT), trimethylolpropane triacrylate (A-TMPT), N , N'-m-phenylene dimaleimide (PHDMI), triallyl cyanurate (TAC), triallyl isocyanurate (TAIC) and trimethylolpropane trimethacrylate (TMPTMA), and in particular in combination with a subsequent crosslinking with electron beams. It is expedient for the crosslinking to be carried out during and / or after shaping, in particular during the production of fibers during spinning and / or after spinning. It is advantageous here if the crosslinking is carried out in a treatment chamber with an electron gun under inert gas, in particular in the form of nitrogen.

• Die Vernetzung der schmelzgesponnen Fasern aus Polyethylen kann nach gängigen Verfahren über chemische Methoden und/oder physikalische Methoden erfolgen, um die Fasern unschmelzbar zu machen. Als rein chemische Vernetzer eignen sich Peroxide, dies unterhalb des Schmelzpunktes. Bevorzugt bei einer rein chemischen Vernetzung ist der Einsatz von Vinylsilanen, die nach dem Aufpfropfen auf die Polymerketten des Polyethylens durch die Vinylfunktion durch die Reaktion mit Wassermolekülen mittels der chemischen Bindungsstruktur C-C-Si-O-Si-C-C vernetzen. Die chemisch-physikalische Vernetzung der Fasern gelingt durch Bestrahlung mit UV-Strahlung in Kombination mit UV-sensitiven Vernetzern wie z.B. Benzophenonen, Cyanuraten oder Anthraquinonen.

In the following, step 2.), which is to be carried out according to the invention, is to be explained technologically further, using preferred configurations:

• The melt-spun fibers made of polyethylene can be crosslinked by conventional methods using chemical methods and / or physical methods in order to make the fibers infusible. Peroxides are suitable as purely chemical crosslinkers, this is below the melting point. In the case of purely chemical crosslinking, preference is given to the use of vinylsilanes which, after being grafted onto the polymer chains of polyethylene by the vinyl function, crosslink by reaction with water molecules by means of the chemical bond structure CC-Si-O-Si-CC. The fibers are chemically and physically cross-linked by irradiation with UV radiation in combination with UV-sensitive crosslinkers such as benzophenones, cyanurates or anthraquinones.

Crosslinking by irradiation with high-energy electrons is particularly preferred for the precursor fiber for producing carbon fibers. For this purpose, the fibers are passed through an irradiation unit with an electron accelerator. The fibers are preferably irradiated within an inert gas. The fibers are very particularly preferably heated to between 50 and 80 ° C exposed to the high-energy electrons. In particular, a radiation dose of 100 to 2000 kGy is used, very particularly preferably 400 to 800 kGy. The crosslinked moldings, in particular fibers and films, preferably have a gel content according to ASTM D 2765: 2011 of between 20 and 100%, in particular between 30 and 95% or 70 and 95%. The range from 50 to 70% is also considered to be particularly preferred.

In a particular embodiment of the invention, the crosslinking can be carried out by irradiation with high-energy electrons within the melt spinning process. For this purpose, the polyethylene fibers are crosslinked in the molten state by means of high-energy electrons after leaving the spinnerets. The irradiation takes place by means of an electron source, the exit window of which is installed orthogonally to the fiber direction. The vertical distance between the exit window and the spinnerets is adjustable. The crosslinked fibers are then drawn and / or wound up.
If the invention has been or will be explained in more detail above and below with reference to the use of melt-spun fibers made of polyethylene, then the measures described in connection with this apply equally to fibers based on further poly-α-olefins such as polypropylene, etc. and based on thermoplastic aliphatic polyamides.
In order to achieve the goal set by the invention, the moldings described, obtained in the above manner, must be subjected to the measure 3) mentioned, ie the crosslinked poly-α-olefins, in particular polyethylene, and crosslinked polyamides are activated with elemental sulfur and / or activated elemental sulfur-releasing compounds sulfurized. The sulfurization is preferably carried out with activated sulfur, in particular in the gas phase, at an elevated temperature, in particular a temperature of more than 150 ° C. There are advantages here if the crosslinked poly-α-olefins and the crosslinked polyamides are sulfurized in a protective gas stream, which is heated above the dew point of sulfur, with active sulfur dissolved in the gas phase, which is present therein saturated. An inert gas, in particular nitrogen, is preferably used here as the protective gas. The sulfurization expediently lasts 1/4 to 8 hours, in particular 1 hour to 3 hours. It makes sense to pay attention to the degree of saturation when sulfurizing. The sulfurization of the crosslinked poly-α-olefins or crosslinked polyamides is preferably carried out to a degree of saturation of 20 to 85% by weight, in particular 30 to 60% by weight, the range 40 to 56% by weight being particularly preferred is preferred. The determination was made by elemental analysis.

The temperature during the sulfurization is expediently 150 ° C. to 350 ° C., in particular 200 ° C. to 300 ° C. Maintaining a temperature range of 210 ° C to 280 ° C is particularly preferred.

Step 3.) according to the invention is to be explained in more detail below, using polyethylene as the basis of the fibers, although also applicable to those based on the further polyolefins described and also based on the polyamides described above.

The infusible polyethylene fibers are stabilized by treatment with elemental sulfur in an activated form. In contrast to the SO _x species according to the prior art, the sulfur can advantageously be transported at room temperature without safety measures. The conversion into precursor fibers from highly sulphurized polymers can expediently be carried out in a sulfur-containing liquid or gas phase in the temperature range from 150 to 400 ° C., in particular 150 to 350 ° C. In liquid form, the elemental sulfur can be used as a pure melt of sulfur or, for example, dissolved in acetanilide. The sulfur can be activated in the gas phase or in the liquid phase using purely thermal processes and / or irradiation with microwaves. Elemental sulfur can also be released from sulfur-donating species.

The shaped bodies are particularly preferably treated in a protective gas stream within a reaction space, above the dew point of sulfur, with sulfur dissolved in the gas phase, this in saturated form. The fiber is kept under a defined thread tension. By using separators at the inlets and outlets of the stabilization reaction chamber with a temperature between the melting point and the dew point of the sulfur, the sulfur can be prevented from escaping from the treatment chamber.

The fibers are aromatized by treatment with elemental sulfur. The highly oriented and cross-linked polyethylene polymer chains are simultaneously dehydrated by the action of the sulfur and converted to polymers from the poly (naptha) (thio) -thiophene mixture. Surprisingly, these aromatic layers are very densely packed, as WAXS measurements show. The packing density does not increase further due to subsequent carbonization and is almost as dense as in carbon fibers made of polyacrylonitrile.

The particular value of the moldings obtained according to the invention is that they can be used for the production of carbon moldings, in particular carbon fibers or carbon foils, by carbonization and, if appropriate, subsequent graphitization.

In the context of the present invention, a carbon fiber is understood to mean any carbon-containing and preferably carbon-containing structure which is thin and flexible in relation to its length and which contains at least one monofilament. The term carbon fiber is therefore understood to mean all individual fibers and all carbon fiber bundles or carbon fiber rovings.

• Erfindungsgemäß können die stabilisierten Präkursorfasern bzw. die nach Schritt 3.) entstandenen Präkursorfasern durch Erhitzen in Fasern aus Kohlenstoff carbonisiert werden. Dafür werden die stabilisierten Präkursorfasern unter Schutzgas auf Temperaturen im Bereich von 300°C bis maximal 2000°C erhitzt. Bevorzugt wird auf maximal 1800°C erhitzt, insbesondere maximal 1600°C.

It is preferred that the sulfurized molded body is first oxidatively thermostabilized and then carbonized, it being expedient that oxidative stabilization is carried out up to a final temperature of from 100 ° C. to 400 ° C., in particular from 200 ° C. to 300 ° C. The measure of carbonization of the shaped bodies obtained according to step 3) according to the invention is explained in more detail below on the basis of preferred measures:

• According to the invention, the stabilized precursor fibers or the precursor fibers formed after step 3) can be carbonized by heating in carbon fibers. For this purpose, the stabilized precursor fibers are heated under protective gas to temperatures in the range from 300 ° C to a maximum of 2000 ° C. It is preferably heated to a maximum of 1800 ° C., in particular a maximum of 1600 ° C.

The carbonization is carried out by eliminating elemental sulfur and carbon disulfide, as determined by the determination using a mass spectrometer. The condensation of the polymer precursor according to the invention therefore probably takes place analogously to the condensation reactions of polyacrylonitrile, which generates elemental nitrogen and hydrocyanic acid as condensation products, among other things.

In a subsequent step, the carbonized fiber can be graphitized at a further elevated temperature to a maximum of 3000 ° C., the orientation of the carbon fibers increasing further. The graphitization is subject to the usual conditions known in the art. It is preferably carried out by thermal treatment at about 1500 ° C to 2800 ° C in a protective gas atmosphere. The graphitized fibers have a higher modulus than conventionally carbonized fibers. The graphitization increases the carbon content of the moldings, in particular the fibers, to about 99%.

The carbon fibers obtained, optionally graphitized, preferably have a carbon content of> 98%, in particular> 99%. The carbon fibers preferably have 1,000 to 100,000 monofilaments, particularly preferably 12,000 to 64,000 monofilaments. In particular, the carbon fiber can have 1,000, 3,000, 6,000, 12,000, 24,000, 48,000 or 50,000 individual monofilaments.

The present invention also relates to a sulfur-containing molded article in the form of fibers or films based on modified polyolefins or modified polyamides, the polyolefins and / or polyamides first being crosslinked and then sulfurized and the degree of saturation being in the range from 40 to 56% by weight. lies, obtainable by a process according to at least one of the following claims 1 to 29. This sulfur-containing molded body is advantageous in the form of fibers which are characterized by the following physical values: a tensile strength of 20 to 100 cN / tex (measured according to DIN EN ISO 5079 ) and / or a module from 70 to 500 cN / tex (measured according to DIN EN ISO 5079 ), which are drawn fibers whose orientation measured by the WAXS analysis is greater than 80% and the single filament diameter of the drawn fibers is less than 30 µm.

• Die Lösung der Erfindung basiert auf der überraschenden Erkenntnis, dass vorvernetzte Formkörper auf Basis von thermoplastischen Poly-α-Olefinen, die auf Monomere mit einer einzigen Doppelbindung zurückgehen, und/oder thermoplastischen Polyamiden, wie vorstehend im Einzelnen dargestellt, in Fasern oder Folien unter Erhalt der Ursprungsform durch die Einwirkung von elementarem Schwefel unter erhöhter

In summary and technologically, the invention, which is based on a number of surprising findings, can be represented as follows:

• The solution of the invention is based on the surprising finding that pre-crosslinked molded articles based on thermoplastic poly-α-olefins, which are based on monomers with a single double bond, and / or thermoplastic polyamides, as shown in detail above, are obtained in fibers or films the original form due to the action of elemental sulfur under increased

Exposure to temperature can be converted into precursor polymers of the class poly (naptha) - (thio) thiophene. It is far more surprising that these polymers with high carbon yield while maintaining the Original form can be converted into fibers made mainly of carbon. It was also very surprising to discover that the effects of elemental sulfur on pre-crosslinked polyamides can be used to produce molded articles and in particular fibers from predominantly carbon. Elemental sulfur as an agent is readily available from desulfurization processes, easy to store and has no special hazard labeling. The sulfur is only activated in the process of stabilizing the moldings described, in particular of precursor fibers. It is therefore preferable to all SO _x -containing agents.

The basic chemical reaction was on uncrosslinked polyethylene in a melt of polyethylene in elemental Sulfur from Trovimov et al. (Russian Chemical Bulletin, Vol. 49, No. 5. May. (2000) 863-869 / A. Trofimov, Sulfur Reports, 2003, Vol. 24, NO. 3, pp. 283-305) . The hydrogen of the polyethylene is removed by sulfur and one sulfur atom per carbon atom is bonded to the carbon chain via a double bond. The hydrogen is removed as hydrogen disulfide. The resulting compound is ultimately converted into a mixture of the polymers poly (naptha) (thio) thiophene as an insoluble and infusible powder by means of several condensation steps with elimination of elemental sulfur. The present invention applies this response to cross-linked polyethylene. As a result, moldings made of crosslinked polyethylene and / or polyamides can be converted from the polymer mixture poly (naptha) (thio) thiophene into a molded body, in particular films and fibers, without changing the basic geometry. According to the invention, any pre-crosslinked molded articles based on polyolefin and / or polyamides can therefore be converted to a stable shape by treatment with elemental sulfur.

If preferred embodiments of the invention or the knowledge obtained in connection with the invention are described with reference to polyethylene, then it is readily apparent that these statements also apply correspondingly to the other designated thermoplastic poly-α-olefins and thermoplastic aliphatic polyamides.

• 1 Die nach Trovimov et al., „Sulfur Reports“, 2003, Vol. 24, No. 3, S. 283-305 , ablaufenden chemischen Reaktionen bei der Umwandlung von Polyethylen in die Präkursorpolymere der Klasse Poly-(naptha)(thio)thiophen,
• 2 Ramanspektren, die die Umwandlung des Polyethylens in das aromatisierte Polyolefin und in die Kohlenstoffphase belegen,
• 3 die Intensitätsverteilung der Ramanbande bei 1420 cm^-1 einer Präkursorfaser aus aromatisiertem Polyolefin im Anschliff über den Querschnitt, die die homogene Stabilisierung von Polyethylen zeigt,
• 4 TGA-Signale der Konvertierung von Fasern aus aromatisiertem Polyolefin in Carbonfasern,
• 5 WAXS-Messungen der stabilisierten und carbonisierten Fasern aus LLD-PE im Vergleich zur einer polyacrylnitrilbasierten Carbonfaser, und
• 6 gemessene Ramanverschiebung der sulphurierten Präkursorfasern im Vergleich zur simulierten Ramanverschiebung der Verbindung Polynaphtathiophen.

The following explains the further explanation of the invention 1 to 6 . In detail, these figures relate to the following:

• 1 According to Trovimov et al., "Sulfur Reports", 2003, Vol. 24, No. 3, pp. 283-305 chemical reactions occurring during the conversion of polyethylene into the precursor polymers of the class poly (naptha) (thio) thiophene,
• 2nd Raman spectra, which show the conversion of the polyethylene into the flavored polyolefin and into the carbon phase,
• 3rd the intensity distribution of the Raman band at 1420 cm ^{-1 of} a precursor fiber made of flavored polyolefin in the bevel across the cross section, which shows the homogeneous stabilization of polyethylene,
• 4th TGA signals from the conversion of fibers from flavored polyolefin to carbon fibers,
• 5 WAXS measurements of the stabilized and carbonized fibers made of LLD-PE compared to a polyacrylonitrile-based carbon fiber, and
• 6 measured Raman shift of the sulfurized precursor fibers in comparison to the simulated Raman shift of the compound polynaphtathiophene.

The 1 refers to chemical reactions in the conversion of polyethylene into the precursor polymers of the class poly (naptha) (thio) thiophene. The insertion of elemental sulfur removes the hydrogen as H ₂ S from the polymer in gaseous form. Reaction with additional sulfur produces polythiophenes, polythiothiophenes and polynaphthathiophenes.

The 2nd shows the conversion of the polyethylene (top curve) by treatment with sulfur into flavored polyolefin (middle curve) using Raman spectra, which were obtained with a Raman microscope on fiber samples at an excitation frequency of 532 nm. After thermal treatment at elevated temperature, the bottom curve is obtained, which shows typical bands of an almost pure carbon compound.

3rd demonstrates the homogeneity by treatment with sulfur compared to the prior art by means of a line profile of the intensity of the Raman signal over the filament cross section of a precursor fiber made of sulfur-treated polyethylene. When stabilizing highly crystalline, large-diameter polyethylene fibers, the entire filament cross-section becomes completely homogeneous Conversion achieved. According to the prior art for carbon fibers made of polyethylene, such results can only be achieved with less dense polyethylene types, preferably from PE-LLD.

4th demonstrates the stabilizability of both PE-LLD and PE-HD by treatment with activated elemental sulfur by measuring the mass decreases. Only cross-linked polyethylene (PE-X) without further treatment cannot be carbonized.

5 shows wide-angle measurements of the X-ray diffraction of sulfur-stabilized precursor fibers made of polyethylene and the carbon fibers made from them. The peak at 2 theta = 24.8 ° shows that the stabilization according to the invention produces a very densely packed aromatic structure from the polymer class poly (naptha) (thio) thiophene. Surprisingly, the layer plane spacing in the precursor fiber is identical to the carbonized fiber produced therefrom and is similar to a commercial carbon fiber based on polyacrylonitrile.

6 shows the measured Raman shift of the precursor fibers from sulfurized polyethylene in comparison to a simulated Raman shift of the compound polynaphtathiophene. The simulation was carried out by a quantum mechanical calculation of the polarizability of a model molecule made of polynaphthathiophene with seven monomer units based on the semi-empirical method ZINDO / S with the program ORCA (Mulliken Center / University of Bonn). The very good reproduction of the peaks in the region of the Raman shift of 1300-1600 cm ^-1 could not be achieved with any other model connection. The precursor fiber is, with some probability, predominantly polynaphtathiophene.

The method according to the invention makes it possible to produce economically advantageously stabilized precursors for molded carbon bodies, in particular carbon fibers.

• Die mit im Überschuss an elementarem Schwefel sulphurierten modifizierten Formkörper sind wirtschaftlich und in vorteilhafter Weise herstellbar und zeichnen sich insbesondere dadurch aus, dass aus einem sulphurierten thermoplastischem Polymer in einer einzigen Hochtemperaturbehandlung beliebig komplexe Formkörper aus verdichtetem turbostratischem Kohlenstoff oder Graphit mit sehr hohen Kohlenstoffausbeuten hergestellt werden können. So kann eine Formgebung des Formkörpers aus einem thermoplastischen Poly-α-Olefin oder thermoplastischem aliphatischen Polyamid auch durch Spritzgießen, 3D-Druck, Fräsen oder analoge Verfahren erfolgen. Die sulphurierten modifizierten Formkörper zeichnen sich zudem durch eine hohe mechanische Festigkeit und nicht-sprödes Verhalten aus, insbesondere in Form von Fasern und Folien, so dass sie vor der Carbonisierung leicht in weiteren formgebenden Prozessen verarbeitet werden können. Hier ist insbesondere auch die Herstellung textiler Strukturen zu nennen. Für die Herstellung von Carbonfasern ist die hohe mechanische Festigkeit von Vorteil, da die Fadenführung bei der Stabilisierung und Carbonisierung nicht auf niedrige Festigkeiten ausgelegt werden muss, wie das bei Pech-basierten Carbonfasern der Fall ist, sondern es können Fadenführungskonzepte aus dem Bereich der Polyacrylnitril-basierten Carbonfaser verwendet werden.

The other particular advantages associated with the present invention can be illustrated as follows:

• The shaped bodies which have been sulfurized in excess of elemental sulfur can be produced economically and advantageously and are particularly distinguished by the fact that shaped bodies of any desired complexity can be produced from compressed, turbostratic carbon or graphite with very high carbon yields from a sulfurized thermoplastic polymer in a single high-temperature treatment . For example, the molded body can be shaped from a thermoplastic poly-α-olefin or thermoplastic aliphatic polyamide by injection molding, 3D printing, milling or similar processes. The sulfurized modified molded articles are also characterized by high mechanical strength and non-brittle behavior, in particular in the form of fibers and foils, so that they can easily be processed in other shaping processes before carbonization. The production of textile structures is particularly worth mentioning here. The high mechanical strength is advantageous for the production of carbon fibers, since the thread guide during stabilization and carbonization does not have to be designed for low strengths, as is the case with pitch-based carbon fibers, but thread guide concepts from the area of polyacrylonitrile based carbon fiber can be used.

The following examples serve to further explain the invention:

Example 1 (melt spinning / drawing)

A PE-HD with an average molecular weight of approx. 300,000 g / mol is spun at 320 ° C on a single-screw extruder with a downstream spinning unit. The spinneret diameter is 300 µm. The winding speed is 300 m / min. The wound fiber is stretched to a maximum length by stretching on a heating rail, so that no filament breaks can be seen. The tensile strength of the drawn polyethylene filament yarn is 13.4 cN / tex (measured according to DIN EN ISO 5079 ), the module 91.5 cN / tex (measured according to DIN EN ISO 5079 ).

Example 2 (melt spinning)

A PE-LLD with an average molecular weight of approx. 240,000 g / mol is spun on a single-screw extruder with a downstream spinning unit at 320 ° C. The spinneret diameter is 200 µm. The winding speed is 200 m / min. The tensile strength of the polyethylene filament yarn is 5.9 cN / tex (measured according to DIN EN ISO 5079 ), the module 14.5 cN / tex (measured according to DIN EN ISO 5079 ).

Example 3 (stretching)

The polyethylene filament yarn from Example 1 is post-drawn on a drawing device with heating to 80 ° C. by the drawing ratio 3.5. The tensile strength of the polyethylene filament yarn is 42 cN / tex (measured according to DIN EN ISO 5079 ), the module 240 cN / tex (measured according to DIN EN ISO 5079 ).

Example 4 (stretching)

The polyethylene filament yarn from Example 2 is post-drawn on a drawing device with heating to 80 ° C. by the drawing ratio 4.7. The tensile strength of the polyethylene filament yarn is 28 cN / tex (measured according to DIN EN ISO 5079 ), the module 85 cN / tex (measured according to DIN EN ISO 5079 ).

Example 5 (crosslinking)

The drawn polyethylene filament yarn from Example 3 is fixed in a on a textile conveyor belt of an electron irradiation system and continuously irradiated with a dose of 300 kGy. The tensile strength of the cross-linked polyethylene filament yarn is 27 cN / tex (measured according to DIN EN ISO 5079 ).

Example 6 (networking)

The drawn polyethylene filament yarn from Example 4 is fixed in a on a textile conveyor belt of an electron irradiation system and continuously irradiated with a dose of 300 kGy. The tensile strength of the cross-linked polyethylene filament yarn is 24 cN / tex (measured according to DIN EN ISO 5079 ).

Example 7 (Sulfurizing)

The crosslinked polyethylene filament yarn from Example 5 is fixed in a glass bulb on a metal frame and treated in liquid sulfur under inert gas at a temperature of 255 ° C. for 3 hours. During the treatment, hydrogen sulfide is released. The sulfur content determined by elemental analysis is 51% by weight. The fibers obtained have a metallic sheen.

Example 8 (Sulfurizing)

The crosslinked polyethylene filament yarn from Example 6 is fixed in a glass bulb on a metal frame and treated in liquid sulfur under an inert gas at a temperature of 255 ° C. for 3 hours. During the treatment, hydrogen sulfide is released. The sulfur content determined by elemental analysis is 56% by weight. The fibers obtained have a metallic sheen.

Example 9 (Carbonizing)

The sulfurized polyethylene filament yarn from Example 7 is placed in a graphite crucible and heated and carbonized at 10 K / min to a maximum of 1800 ° C. under inert gas in a chamber furnace. The average carbon fiber diameter is 13 µm. The orientation determined by WAXS analysis is 66%. The carbon content determined from an elemental analysis was 98.7%.

Example 10 (Carbonization)

The sulfurized polyethylene filament yarn from Example 8 is placed in a graphite crucible and heated and carbonized at 10 K / min to a maximum of 1800 ° C. under inert gas in a chamber furnace. The average carbon fiber diameter is 16 µm. The orientation determined by WAXS analysis is 65%. The carbon content determined from an elementary analysis is 98.7%, the average tensile strength of the carbon fiber 0.7 GPa (measured according to DIN EN ISO 5079 ), the maximum values of a single filament 1.11 GPa. The average module is 81 GPa (measured according to DIN EN ISO 5079 ), the maximum value of a single filament 135 GPa.

Example 11 (Carbonization / Graphitization)

The carbonized and previously sulfurized polyethylene filament yarn from Example 7 is placed in a graphite crucible and heated under inert gas in a chamber furnace at 10 K / min to a maximum of 2000 ° C. and graphitized. The orientation determined by WAXS analysis is 70%. The average tensile strength of the carbon fiber is 0.83 GPa and the average modulus 97 GPa (measured according to DIN EN ISO 5079).

Example 12 (Carbonization)

The sulfurized polyethylene filament yarn from Example 7 is placed in a graphite crucible and treated in air at an increasing temperature of 0.25 K / min from room temperature to 250 ° C. The resulting fiber is heated under inert gas in a chamber furnace at an increasing temperature of 10 K / min to a maximum of 1400 ° C. and carbonized. The carbon yield during carbonization based on the sulfurized polyethylene filament yarn increases by 28%.

Example 13 (Carbonization)

A fiber made of PA6.6 is crosslinked with a dose of 600 kGy in an electron irradiation system. A black fiber is obtained by treatment in molten sulfur for 2 h at 255 ° C. The fiber is heated and carbonized under inert gas at a heating rate of 10 K / min to a maximum of 1400 ° C. The remaining mass of the fiber is 35.5%.

Example 14 (Cross-linking / Sutration)

A film of LDPE is crosslinked by irradiation with electrons at a dose of 300 kGy and sulfurized in liquid elemental sulfur for 3 hours at 250 ° C under inert gas. The resulting film has a gold-metallic sheen.

Finally, the invention is to be explained in greater detail on the basis of various characteristic data of the carbon fibers obtained according to the invention. These are recorded in the following tables.

The mechanical characteristics of individual exemplary carbon fiber monofilaments made of PE-HD by treatment with sulfur and subsequent carbonization, at 1400 ° C, are shown in Table 1. Table 1 Filament Ø Diameter [µm] Tensile strength [GPa] Module [GPa] 1 16.6 1.11 109.3 2nd 16.6 0.39 63.3 3rd 17.9 0.64 114.6 4th 17.9 0.70 135.8 5 21.1 0.63 82.4 6 13.8 0.43 55.5 7 13.8 0.86 78.5 8th 13.8 0.56 93.7 9 17.9 0.94 88.3 10th 17.9 0.49 61.4 11 17.6 0.53 60.1 12th 17.6 0.56 54.4 13 15.6 1.05 105.9 14 13.9 0.52 55.3 15 13.9 0.43 66.7 16 13.2 0.73 77.6 17th 13.4 1.03 83.8 18th 13.4 0.99 79.2 O 15.9 0.70 81.4

Note: The tensile strength [GPa] and the modulus (Young Modulus) [GPa] have been reduced DIN EN ISO 5079 determines what also applies to the following tables.

The mechanical characteristics of individual exemplary carbon fiber monofilaments made from PE-HD by treatment with sulfur and subsequent carbonization at 2000 ° C are shown in Table 2: Table 2 Filament Ø Diameter [µm] Tensile strength [GPa] Module [GPa] Elongation at break [%] 1 15.4 0.69 74.5 1.0 2nd 15.7 0.92 82.1 1.2 3rd 15.9 0.79 90.4 0.9 4th 16.0 0.93 90.6 1.1 5 16.0 0.63 104.7 0.7 6 16.4 0.69 100.1 0.8 7 16.4 0.83 113.0 0.8 8th 17.4 1.08 89.2 1.2 9 18.2 0.94 126.9 0.8 O 16.4 0.83 96.8 0.9

The maximum values of the mechanical characteristic values tensile strength and modulus for a carbonization temperature below 2000 ° C correspond to the state of the art (WO2014011462 / WO2014011460) both in terms of tensile strength and on the modulus, as shown in Table 3: Table 3 Mechanical characteristic Carbonization temperature [° C] Tensile strength [GPa] Module [GPa] invention 1400 0.70 81 invention 2000 0.83 97 WO 2014/011462 A1 1150 1.06 73 WO 2014/011460 A1 1800 0.61 54 WO 2014/011460 A1 2000 0.70 93 WO 2014/011460 A1 2200 1.14 193 Adv. Mater. (2012), 24, 2386-2389 1200 1.10 103.4

The following Table 4 shows the good to very good orientation levels in the melt-spun, sulfur-stabilized and then produced carbon fibers. The melt-spun polyethylene fibers generally achieve an orientation of> 90 °. Due to the stabilization, a certain degree of orientation is naturally lost as a result of binding rearrangements as part of the bond rearrangement. The resulting carbon fibers generally have an orientation of 60 to 73%. Table 4 designation Orientation (%) PE-LLD melt-spun 94 PE-LLD stabilized 61 PE-LLD carbonized up to 1800 ° C 65 PE-LLD carbonized up to 2000 ° C 66 PE-HD melt-spun 96 PE-HD stabilized 72 PE-HD carbonized up to 1800 ° C 66 PE-HD carbonized up to 2000 ° C 70 PE-HD graphitized at 2200 ° C 73

The following Table 5 shows evaluations of wide-angle measurements of the X-ray diffraction of sulfur-stabilized precursor fibers made of polyethylene of the PE-HD and PE-LLD type and the carbon fibers produced therefrom at various maximum carbonization temperatures. Table 5 Precursor / carbonization temperature [° C] Peak max. [2 theta] d ₀₀₂ [nm] Orientation (%) PE-HD / 1600 24.7 0.360 65 PE-HD / 1800 24.7 0.360 66 PE-HD / 2000 25.4 0.350 70 PE-HD / 2200 25.8 0.345 73 LLD-PE / 1400 23.1 0.385 59 LLD-PE / 1800 24.7 0.360 65 LLD-PE / 2000 25.2 0.353 66 LLD-PE / 2200 25.4 0.350 68

Claims (35)

Process for the production of moldings, in particular fibers or films, based on modified polyolefins or modified polyamides, characterized in that 1.) thermoplastic moldings based on thermoplastic poly-α-olefins which are based on monomers with a single double bond, or thermoplastic aliphatic polyamides are used as the starting material, 2.) the polyolefins and polyamides of the molded body are crosslinked and 3.) the crosslinked polyolefins and crosslinked polyamides are sulfurized with activated elemental sulfur. Procedure according to Claim 1 , characterized in that in step 1.) thermoplastic polyolefins or thermoplastic polyamides are melted and cooled with shaping. Procedure according to one of the Claim 2 , characterized in that foils are produced from the melt of the thermoplastic polyolefins and the thermoplastic polyamides by extrusion, casting, calendering or blow molding and fibers by melt spinning. Procedure according to one of the Claims 1 to 3rd , characterized in that polyethylene, polypropylene, polyisobutylene and / or polybutylene is used as the poly-α-olefin and polyamide 6, 4, 6, 6, 6, 6, 6, 12, 10, 10, 11 or 12 is used as the polyamide. Procedure according to Claim 3 or 4th , characterized in that ultra high molecular weight polyethylene with a weight average molecular weight of> 500,000 g / mol is used, this being converted into fibers in particular by gel spinning. Procedure according to Claim 5 , characterized in that an ultra-high molecular weight polyethylene with a weight-average molecular weight of 1,000,000 to 10,000,000 g / mol is used. (Original revelation Claim 15 ) Procedure according to one of the Claims 1 to 4th , characterized in that a thermoplastic polyolefin of a weight-average molecular weight of 20,000 to 500,000 g / mol or a thermoplastic polyamide of a weight-average molecular weight of 10,000 to 50,000 g / mol is used. Procedure according to one of the Claims 1 to 7 , characterized in that one or more modifications PE-LLD, PE-HD, PE-HMW and PE-UHMW are used as the thermoplastic polyolefin. Procedure according to at least one of the Claims 2 to 8th , characterized in that additives are added to the melted polyolefins or the melted polyamides for process control with regard to the behavior of the modified carbon body in a subsequent carbonization. Procedure according to Claim 9 , characterized in that spinning additives are added to the melted polyolefins or the melted polyamides during melt spinning. Procedure according to Claim 10 , characterized in that spinning additives are added in the form of fatty acid amides, waxes and / or ultra high molecular weight polyethylene. Method according to at least one of the preceding claims, characterized in that the thermoplastic polyolefins or the thermoplastic polyamides are melted or compounded in the production of fibers in an extruder and are then spun by extrusion through a spinneret plate with spinning holes with a diameter of 100 to 500 µm. Procedure according to at least one of the Claims 3 to 12th , characterized in that the spinning temperature is set to 200 ° C to 350 ° C. Procedure according to at least one of the Claims 1 to 13 , characterized in that in step 1.) multifilament yarns based on thermoplastic polyolefins or thermoplastic polyamides are used as direct rovings or folded rovings. Procedure according to at least one of the Claims 3 to 14 , characterized in that the polyolefin or the polyamide fibers are stretched to a tensile strength of 20 to 100 cN / tex (according to DIN EN ISO 5079) and / or to a modulus of 70 to 500 cN / tex (according to DIN EN ISO 5079) . Procedure according to Claim 15 , characterized in that the fibers are stretched to such an extent that the orientation of the stretched fibers measured by the WAXS analysis is greater than 80% and / or the individual filament diameter of the stretched fibers is less than 30 µm. Procedure according to at least one of the Claims 1 to 16 , characterized in that the polyolefins and the polyamides of the moldings formed therefrom are chemically and / or physically crosslinked. Procedure according to Claim 17 , characterized in that the molded body is chemically and / or physically crosslinked up to a gel content according to ASTM D 2765: 2011 between about 20 and 100%. (Original revelation Claim 16 ) Procedure according to Claim 17 or 18th , characterized in that the chemical crosslinking of the polyolefins with a peroxide compound, in particular with ditertiary butyl peroxide (DTPD) or dicumyl peroxide (DCP), or by grafting vinyl silanes in a reactive extrusion with subsequent crosslinking in a moist environment and the physical crosslinking is carried out by radiation treatment . Procedure according to one of the Claims 18 or 19th , characterized in that the chemical-physical crosslinking of the polyamides with electron beams with the addition of a crosslinking additive in the form of tetramethylol methane tetraacrylate (A-TMMT), trimethylolpropane triacrylate (A-TMPT), N, N'-m-phenyoldimaleimide (PHDMI), triallyl cyanurate ( TAC), triallyl isocyanurate (TAIC) and / or trimethylolpropane trimethacrylate (TMPTMA) is carried out. Method according to at least one of the preceding claims, characterized in that the crosslinking in the production of fibers is carried out during spinning and / or after spinning. Procedure according to at least one of the Claims 1 to 21 , characterized in that the crosslinking is carried out in a treatment chamber with an electron gun under inert gas. Method according to at least one of the preceding claims, characterized in that the moldings based on crosslinked polyolefins or crosslinked polyamides are sulfurized. Procedure according to Claim 23 , characterized in that the sulfurization with activated sulfur is carried out in a gas phase at elevated temperature. Method according to at least one of the preceding claims, characterized in that the crosslinked polyolefins or the crosslinked polyamides are sulfurized in a protective gas stream which is heated above the dew point of sulfur with active sulfur dissolved in the gas phase and which is saturated therein. Procedure according to Claim 25 , characterized in that an inert gas, in particular nitrogen, is used as the protective gas. Method according to at least one of the preceding claims, characterized in that sulfurization is carried out for a period of ¼ h to 8 h. Method according to at least one of the preceding claims, characterized in that the crosslinked polyolefins or the crosslinked polyamides are sulfurized to a degree of saturation of 20 to 85 wt .-%. Procedure according to at least one of the Claims 1 to 28 , characterized in that sulfurization is carried out at a temperature of 150 ° C to 350 ° C. Use of the sulfurized moldings obtained by the process according to at least one of the preceding claims for the production of carbon moldings by carbonization and, if appropriate, by subsequent graphitization. Use after Claim 30 , characterized in that the carbon molded bodies are carbon fibers or carbon foils. Use after Claim 30 or 31 , characterized in that the sulfurized molded body is oxidatively thermostabilized and then carbonized. Use after Claim 32 , characterized in that up to a final temperature of 100 ° C to 400 ° C, in particular from 200 ° C to 300 ° C, is oxidatively thermostabilized. Sulfur-containing moldings in the form of fibers or films based on modified polyolefins or modified polyamides, the polyolefins and / or polyamides first being crosslinked and then sulfurized and the degree of saturation being in the range from 40 to 56% by weight, obtainable by a process according to at least one of the Claims 1 to 29 . Sulfur-containing molded body after Claim 34 in the form of fibers, which are characterized by the following physical values: a tensile strength of 20 to 100 cN / tex (measured according to DIN EN ISO 5079) and / or a module of 70 to 500 cN / tex (measured according to DIN EN ISO 5079) , which are drawn fibers whose orientation measured by the WAXS analysis is greater than 80% and the single filament diameter of the drawn fibers is less than 30 µm.

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