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Arnold M.,University of Applied Sciences Rapperswil | Henne M.,University of Applied Sciences Rapperswil | Bender K.,EMS CHEMIE AG | Drechsler K.,Technical University MunchenInstitute for Carbon Composites
Polymer Composites | Year: 2015

Modifying the impact toughness of carbon fiber-reinforced epoxy composites by introducing thermoplastic inserts in the interlaminar layer is state-of-the-art. This article compares the introduction of thermoplastics in continuous and discontinuous form. Test plate samples were produced using unidirectional noncrimp carbon fabrics with two different aircraft resin systems: HEXFLOW RTM6 (Hexcel) and Cycom 890 RTM (Cytec). In addition, Polyamide 12 (PA12) was laid in the interlaminar layer in the forms of two different laid scrims, as powder or as nonwoven fabric (NWF). The performance of the resulting combinations was assessed by testing the samples in Mode I and II interlaminar fracture toughness (GIc and GIIc), interlaminar shear strength (ILSS), and compression strength after impact (CAI). The results show that in nearly all the tests a fine-mesh laid scrim performs similarly to a NWF with twice the weight per surface area. They show furthermore that the curing dynamics of the resin systems together with the melting characteristics of the thermoplastic during processing have an important effect on the performance of the test samples. Hardening of the resin before the PA12 reaches its melting point hinders the compacting of the thermoplastic. This limits the reduction in the original thickness of the insert, leading to an increase in the sample thickness and, thus, reducing the fiber volume content. Otherwise, the discrete arrangement of the laid scrim has positive effects on the material properties of the composite at elevated temperatures, considerably reducing the falloff in ILSS resulting from the temperature-dependent Young's modulus of PA12. © 2014 Society of Plastics Engineers.

Stolz R.,RWTH Aachen | Vad T.,RWTH Aachen | Seide G.,RWTH Aachen | Gries T.,RWTH Aachen | And 2 more authors.
Tekstilec | Year: 2016

The increase of fibre abrasion properties aims at the lifecycle improvement of technical textiles containing abrasion resistant fibres. Furthermore, the improvement of fibre abrasion properties is – presumably – the key to higher productivity and reduction of energy costs. Especially the fibre composites made of Nylon 6 and two-dimensional particles as organoclays or graphene platelets bear high potentials to achieve increased abrasion properties compared to virgin Nylon 6 fibres. The problems to be solved within this research were the transfer of positive effects known from bulk polymers, the guarantee of stable multifilament spinning and the loss of fibre properties by using additives. The effect of two-dimensional particles was visualised with the analysis of the tribological behaviour and mechanical properties. In order to gain the insight into the relationship among the processing conditions, material composition and resulting material properties, Wide Angle X-ray scattering experiments were performed. © 2016, University of Ljubljana. All rights reserved.

Arnold M.,University of Applied Sciences Rapperswil | Henne M.,University of Applied Sciences Rapperswil | Bender K.,EMS CHEMIE AG | Drechsler K.,TU Munich
Journal of Composite Materials | Year: 2016

Modifying the impact toughness of carbon composite by means of introducing thermoplastic inserts in the interlaminar layer is state of the art. However, these inlayers reduce the electrical conductivity through the thickness of the composite. Because the combination of good electrical conductivity and high fracture toughness is desirable, a detailed investigation was carried out into additive-enhanced polyamide 12 compound. The modification consisted in compounding graphite, graphene and carbon nanotubes with polyamide 12 in various proportions. After it was introduced into the interlaminar layer, the samples' electrical conductivity was measured and their mechanical properties assessed. Afterwards, these results were compared with various inserts made with unmodified polyamide 12. It turned out that the coarse-mesh laid scrim showed only a slight fall in conductivity. Furthermore, it provided promising results regarding the increase of the interlaminar toughness. Thus, the expensive modification of polyamide 12 can be avoided by using discrete laid scrim. © 2015 The Author(s).

This short review introduces EMS-Chemie as a leading producer of high-performance polyamides. The history of polyamides is described as well as their innovative development and modification for customized applications. © Schweizerische Chemische Gesellschaft.

Bender K.,Ems Chemie AG | Schach C.,Ems Chemie AG | Rosa S.,Ems Chemie AG
Melliand International | Year: 2013

Nexylon FR is an intrinsic flame-retardant polyamide fiber (FR-PA66), which is rated as hardly combustible (B1, 4102-1) and has a LOI of 28. The FR additive is wash resistant and free of halogens and toxic compounds. The additive does not influence the textile properties of the PA fiber; rather the abrasion resistance of the fiber is improved via a special polymer recipe. Flammability tests of fiber blends between Nexylon FR and other treated or inherent flame-retardant fibers are shown as well as corresponding abrasion resistance tests.

Ems Chemie Ag | Date: 2011-08-12

The invention relates to thermoplastic polyamide moulding compositions containing: (A) at least 20% by wt. polyamide and/or at least one copolymer containing at least 20% by wt. polyamide structural units; (B) 0.01% by wt. to 2% by wt., relative to the polyamide portion and/or the portion of polyamide structural units, of the composition of a copper-containing stabiliser; and (C) 0.01% by wt. to 3% by wt., relative to the polyamide portion and/or the portion of polyamide structural units of the composition, of at least one organic compound containing metal complexing groups, so that the copper ions are present in complexed form through binding to the metal-complexing groups. These moulding compositions may be used as coating material for coolant lines.

The invention describes a new synthetic fiber material of polyhydroxyether, as well as a melt-spinning method for its production. The new material can be used, in particular, for stabilization of the reinforcement fibers of high-performance fiber composite materials before they are embedded in the matrix material. During this usage, the polyhydroxyether fiber material dissolves at a temperature above its glass transition temperature entirely in the matrix material, so that the reinforcement fibers can be arranged largely free of kinking. In addition, it forms cross-links with the matrix material to form a homogeneous matrix and thus does not constitute a disruptive third phase in the composite material. The compatibility of the matrix and reinforcement fiber is also improved. It was possible to improve the bending strength of test slabs by 12% as compared to that of reference slabs with polyester filament.

Filled polyamide molding materials, in particular polyamide molding materials with medium filler content, are producible from a polyamide blend and for example by compounding with chopped or endless fibers on two-screw extruders, and have a combination of reduced water absorption and good mechanical properties, which results in very good dimensional stability and reduced variation of the electrical properties of the produced molded part, such as an antenna housings of stationary or mobile communication devices. These thermoplastic polyamide molding materials are suitable for manufacturing molded parts and other semi-finished or finished parts, for example by extrusion, injection molding, pressing, direct process or direct compounding, respectively, wherein the compounded polyamide molding material is directly processed by injection molding or other shaping methods.

The present invention relates to reinforced polyamide molding materials with high notch impact strengths, comprising low viscous polyamides and flat glass fibers as a reinforcing medium, characterized in a polyamide matrix, comprising the following components: (A) 0 to 60 wt.-% of at least one aliphatic, partly crystalline polyamide with a solution viscosity, measured in m-cresol (0.5 wt-%), of _(rel )less than 1.9, (B) 0 to 60 wt.-% of at least one amorphous or microcrystalline polyamide based on aliphatic, cycloaliphatic or aromatic diamines, dicarboxylic acids, lactams and/or aminocarboxylic acids, preferably with 6 to 36 carbon atoms, or a mixture of such homopolyamides and/or copolyamides, wherein the components (A) and (B) fulfill the condition: (A)+(B)=20 to 60 wt.-% and that, in the case of a mixture of components (A) and (B), at least 50 weight parts aliphatic blocks (A) are present in the mixture, and a filler component, comprising: (C) 40 to 80 wt.-% flat glass fibers with elongated shape, and the glass fibers have a non-circular cross-sectional area and a size ratio of the main cross-sectional axis to the secondary cross-sectional axis of between 2 to 5, particularly between 3 and 4, and (D) 0 to 40 wt.-% particle like or layer like fillers, with the prerequisite that carbon fibers are excluded, wherein the polyamide molding materials optionally comprise up to 5 wt.-% of further usual additives and auxiliary agents (E), and wherein the weight of the components (A) to (E) sums up to 100%.

Moulded articles having reduced surface carbonization and longer retention of the mechanical properties and methods of producing same are presented. In an embodiment, the moulded article comprises polyamides with nanofillers, which can be produced by means of injection moulding or extrusion, in particular by extrusion blow moulding, coextrusion blow moulding or sequential blow moulding with and without 3D hose manipulation. For example, the polyamide moulding materials for the production of moulded articles have reduced surface carbonization in the moulded articles in subsequent long-term use at elevated temperatures.

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