Dyneema is a trademark of the Dutch chemical company Royal DSM NV for a synthetic chemical fiber based on polyethylene with ultra-high molecular weight (Ultra-High-Molecular-Weight Polyethylene = UHMWPE or PE-UHMW or high-modulus polyethylene = HMPE). Until 2016, Dyneema was also the trademark of the Japanese group Toyobo Co. Ltd., which, together with DSM, successfully completed the industrial production of UHMWPE fibers by the end of the 1980s. In 2016, the two companies agreed that Toyobo would use a separate brand name. The new brand name for these fibers is IZANAS. Similar high-modulus polyethylene fibers are also marketed by Honeywell under the name Spectra . Fibers made from UHMWPE were also produced under the brand name Certran by Hoechst , later Celanese , but are no longer produced due to a lack of competitiveness.
The Dyneema fiber, which belongs to the HPPE (High Performance Polyethylene) fibers, has tensile strength values of 3 to 4 GPa (3000 to 4000 N / mm²). These very high strength values result from the strong parallel orientation of the PE linear molecules, which is greater than 95%, and a degree of crystallinity of up to 85%.
UHMWPE forms long chains with molecular weights from 2 to 6 million g / mol. The mass is so high that it cannot be measured directly by conventional means, but is derived from its intrinsic viscosity .
The Dyneema fiber is therefore 40% more tensile than aramid fibers (23 cN / dtex), 60% more tensile than HT carbon fibers (20 cN / dtex), comparable to the best commercially available UHT carbon fibers (39 cN / dtex), twice as tensile strength as glass fiber (15 cN / dtex), almost five times more tensile strength than polyamide, polyester and polypropylene fibers (all between 5 cN / dtex and 8 cN / dtex) and up to fifteen times more tensile strength than steel (2 cN / dtex).
There are different types of Dyneema fiber. The fiber types SK60 and SK65 belong to the first generation. These were introduced in the 1980s and have a tensile strength related to the fineness of 32 cN / dtex. The types SK75, SK76 and SK78 belong to the second generation and have been manufactured using a completely new production process since the 1990s. They are 15 to 20% more tensile than those of the first generation and reach between 35 and 40 cN / dtex. There are different titers of the fiber types mentioned, expressed in dtex (mass in grams per 10,000 meters). The fine yarn titers (thin yarns) are between 25 and 220 dtex. They are used for the finest fabrics, sewing threads, fishing lines and kite lines. Medium titers (440 dtex, 880 dtex, 1320 dtex) are used in safety accessories for climbing equipment, helicopter ropes, yacht ropes, fishing nets and are woven into canvas and tarpaulins . The thick yarns with titers of 1500 dtex, 1760 dtex and 2640 dtex are popular in heavy fabrics and ropes for ships, oil platforms and deep-sea installations.
|4 mm||1,400 daN||1.1 kg / 100 m|
|6 mm||3,300 daN||2.8 kg / 100 m|
|8 mm||5,800 daN||5.0 kg / 100 m|
The tear length of Dyneema is almost 400 km. With a density of 0.95 to 0.97 g / cm³, Dyneema is slightly lighter than water and floats. The fiber is very durable and has a high resistance to abrasion, moisture, UV rays and chemicals.
The melting point of Dyneema is between 144 and 152 ° C, the tensile strength and stiffness of Dyneema decrease with increasing temperature. The usability is indicated up to about 80 to 100 ° C. In contrast, the strength increases at temperatures below room temperature, and at −30 ° C the increase in strength is already 30% compared to room temperature. Dyneema can be used down to −150 ° C.
The surface of Dyneema is extremely smooth. The coefficient of friction is 0.05 to 0.08, about 5 times smaller than that of nylon 6. Paint does not adhere well to the smooth surface. Therefore, Dyneema was only available in its natural white color for a long time. Due to increasing demand, DSM developed the Black Dyneema variant, in which black color particles are added to the plastic during production.
The Dyneema fibers are produced by gel extrusion spinning, a special case of solution spinning. There are filaments made from gel-like solutions, the molecules are arranged in parallel. Stretching and thermosetting creates a crystal structure that leads to the high strength of the fiber.
Dyneema is used inter alia for the production of glider launch winch ropes , fishing lines , fishing nets , bow-string , rope robots , helicopters outer load-transport cables, Bergetausystemen, rigging of a sailing boat and slings , ultralight tents / -Tarps and accessories (stuff sack, potcozy etc.) .
The bullet-resistant protective vests and armor of vehicles, aircraft and ships made of composite from Dyneema are among the thinnest and lightest. Further applications are motorcycle helmets and abrasion-resistant motorcycle jeans with Dyneema fibers.
In cut-resistant protective clothing, large amounts of the fiber are used for gloves and chainsaw pants, chest protection, arm protection and T-shirts. Customers are the forest, metal, glass and meat processing industries with their high demand for comfortable, washable protective clothing.
For leisure and sporting goods, snowboards , shackles and various aids for climbing are made from Dyneema. Dyneema is especially used as a line material in water sports - as there is no horizontal bar and insensitive to salt water - as well as for paragliders and kites and for the winch launch of gliders; partially covered with polyester (PES) to increase the abrasion resistance.
In modern spin fishing the so-called braided is fishing line - 6 to 8 Dyneema monofilaments are intertwined - here to stay. The low stretch enables the detection of bites at great distances and at very great depths. Many fishing methods were previously not possible with a monofilament line made of nylon and its relatively large stretch.
Dyneema ropes also allow tough use in forest technology, where spliceability, breaking load and abrasion resistance play an important role. These ropes are slightly stronger than steel ropes of the same diameter and at the same time are one-seventh of their weight.
In addition, textile chains are made from Dyneema fiber, which can replace steel chains due to their high strength values . The chain links consist of several layers of Dyneema webbing and are sewn together to form a chain. The textile chains are used in load securing and lifting technology . The advantages of textile chains compared to steel chains are their low weight and the associated lower risk of injury.
The first ropes made of Dyneema for the transport of external loads with helicopters were built in Switzerland in 1994 and have been in use at Air Zermatt AG since 1996 as recovery systems with a payload of up to 600 kg. Due to their low mass, these ropes are now replacing the steel ropes previously used in many areas ; in Zermatt, for example, the longest known Dyneema mountain rope with a length of 200 meters was used. Originally it was also assumed that Dyneema ropes could prevent the dreaded rope kickback (English backlash ) due to their very low elongation (0.5 to 2%) , but this was confirmed in 2008 through a series of tests by the professional association for vehicle maintenance in Berlin and the helicopter rope manufacturer AirWork & Heliseilerei GmbH in Immensee / Switzerland refuted. What is certain, however, is that the occurrence of the undesired effect of Pilot Induced Oscillation (PIO) is markedly reduced by static ropes.
In the aviation industry, Dyneema is also used in radomes (radar domes), as it is not only light and extremely impact-resistant, but also the most radar-permeable material known. Composite panels made of Dyneema fiber replace aluminum panels in air cargo containers, so-called air cargo containers or ULD (Unit Load Devices). Other ULDs such as air cargo pallet nets made from Dyneema fiber are up to 50% lighter and help save kerosene and avoid emissions.
The “Dyneema Purity” brand is used in the medical sector. It is a variant for use in the human body.
It is often advised not to knot Dyneema tape slings. The reason for the relatively poor performance of knotted dyneema loops is often referred to as their low melting point, with the indication that knotted dyneema loops heat up so much under stress that they melt (sometimes it is written that they would "burn through"). However, due to the extremely low coefficient of friction of UHMWPE, dyneema nodes heat up only relatively little even under strong dynamic loads. The relatively poor performance of knotted Dyneema tape slings is rather due to their usually small cross-section: they are much more curved in the knots than tape slings made from other materials, which means that the tensions are particularly concentrated. In addition, the low coefficient of friction means that knots roll very easily and can open under load. A sack stitch in a Dyneema sling rolls at around 2 kN. A secure connection of Dyneema material is only possible by splicing or sewing. On the other hand, Dyneema slings have a higher cut resistance than tape slings made of polyamide.
- The Society of Fiber Science and Technology Japan: High-Performance and Specialty Fibers. Springer Japan 2016, ISBN 978-4-431-55202-4 , p. 111.
-  Press release from DSM Dyneema. Retrieved June 27, 2019.
-  Brand name of Toyobo. Retrieved June 27, 2019.
- Anthony R. Bunsell: Handbook of Properties of Textile and Technical Fibers. Elsevisier 2018, ISBN 978-0-08-101272-7 , p. 704.
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- Knotting Dyneema? ( Memento from October 13, 2017 in the Internet Archive )
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- Professional association for vehicle maintenance
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- DSM-Dyneema website with entrance to all special pages
- DSM Dyneema special page on the medical fiber Dyneema Purity
- Technical data on Dyneema (KiTeC) , Dyneema and other materials, especially for kites.
- Dyneema tensile test comparison with steel cable , YouTube