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LATEST NEWS

16th April 2017
Tommi Borg visits for your meetings at Chinaplas May 16-19, 2017 - Guangzhou, PR China.

24th November 2015
New published paper "Linear viscoelastic model for different flows based on control theory", Appl. Rheol. Read more >>

7th November 2014
RheoPower 4.3 is also available as true 64-bit for heavy computations. Read more >>

20th August 2014
Tommi Borg gives an oral presentation at The International Conference on Polyolefin Characterization (ICPC) September 21-24, 2014 - Valencia, Spain. >>

30th October 2013
New RheoPower 4.2 produce accurate MWD by Multi-Record Analyze. Read more >>

Extrusion Design and Know-How

Warning: The technical description consists of "wheat", but may also have "chaff" information. You will get more information, better and according to our best knowledge by contacting us.

Review

Here you will find processes in the commercial use or have been earlier and we have permission to publish description. Items are shown in decending historical order.

  • Formed HDPE-profile as large U-shape types.
  • Jet Extrusion for oriented extrudates.
  • HS-method for heat shrinkable products directly by extrusion.
  • Pulse Mixer device for effective compounding and mixing.
  • Recycling know-how.

  • For these experiments we had two separate PE-pipe manufacturing plants producing pressure and other pipes with eight extruder lines with output dimensions from 20mm up to 500mm.

    We could test these new systems and inventions at low season described here. No doubt this includes you have to be capable to handle and operate these extruder lines by own hands and myself, if was needed during testing.

    Formed HDPE-profile

    As we know, it is very difficult to form other HDPE-profiles as pipes. Specially large high quality profiles, which also preserve their dimensions. We have succeeded with formed U-shape HDPE extrusion profile, where the dimensions are 400x200x5mm. The markets are the building industry, agriculture and geomenbrances for poisonous materials. Used HMW-PE material is very strong mechanically and chemically. We can provide you with this profile product or extrusion equipment and license. The wrapping of the product has to be avoided during time, which means non-oriented structure on the contrary as in HS-method.

    Jet Extrusion

    In certain extrusion conditions molecules will not only orientate, but also disentangle strongly causing a chain extension in the direction of flow.
    By maintaining this jet orientation in the die during the cooling and stabilizing of the melt flow it is possible to achieve longer molecule relaxation times before the exit of the die. By transiting the structure of polymer flow, the high shear rate melt fractures at die end can be avoided. When the extrudate is quenched to the solid form, the jet orientation state will stay in molecular structure. The manufactured products have new type performance and properties. Jet Extrusion can also be used with annular and flat die.

    Comparison of extrusion methods can be done by multiplying of initial relaxation time and shear rate (~Deborah number). Jet Extrusion is still in laboratory scale extruded.

    BOPE-film

    New generation films are some of the many products, which can be manufactured using the Jet Extrusion method. Not only biaxially oriented PP film (BOPP), but the method is very powerful for manufacturing biaxially oriented HMW-HDPE film (BOPE). The laboratory scale manufactured BOPE film has the following preliminary properties:
  • Tensile strength 200MPa (monoaxially stretched 370MPa and unstretched extrudate 22MPa)
  • Better dead-fold and twisting properties than BOPP (a simplified test for wrap film on candies)
  • Approaching transparency (unusual for HDPE)
  • Tear resistant
  • HS-method; Heat shrinkable products

    We have two new methods to manufacture HS-products directly by extrusion, the older, patented 1987 "Muolon-method" (sold out to USA, EU and Japan) or the new Jet Extrusion method. It is possible to use different ways to do cross-linking, if there is a need for application. For the shrinking property (over 80%) cross-linking is not needed, but good results have been realized with silane peroxides in the material, where the product will cross-link afterwards with the help of moisture in the air or with water.
    HS-products are used widely as a coating against corrosion and moisture in pipelines and electrical applications, but manufacturing principles are also usable and valuable in the shrink packing businesses.

    Pulse Mixer

    Novel new generation method and device for continuous mixing at low heat generation and energy.
    The effective polymer compounder device called the Pulse Mixer device is adapted between the extruder and die without altering output. A single screw extruder turns to a twin screw extruder, and a twin screw extruder respectively to a new extent compounder or reactive mixer. Extruders can be designed for stable, high output, Pulse Mixer takes care of the rest. -Pulse Mixer is not an extruder or a gear pump. The principle is based on repeated momentary high pressure pulses. Unproductive additional high shearing met in distributive and mechanical dispersive mixing, is avoided. The device has been in practice confidential production use for more than a decade, but the true function principle was found recently due to rheological RheoPower and SHPB (Hopkinson Test) software and research. Polymers are capable to conform apparent temporary cylinders between wide teeth of non helical gears. In the strong and rigid planetary roller structure pulses, strong enough, to treat polymer completely during extrusion, can be achieved.

    The calculated capacity of the smallest Pulse Mixer SUN 76 and largest SUN 200 is proved and shown in the technical description. -The capacity level is exceptional high, but the number of pulses has to be kept n in a 2- 5 range to get perfect pulse mixing. The pulses compress the polymer and momentary pressure can increase to more than many hundreds of bars, but the temperature rises less in degrees and thus degradation remains minimal. During compression the risen viscosity makes mixing effective and all different molecules are closer to each other at the higher vibration speed, which makes intimate molecular contact easier. Pulse Mixer is used in the extrusion of film and profiles or for compounding, but can also be used separately to make a laboratory mixer. Especially good results have been achieved in extrusion with HMW-PE, PA- and PP-compounds and in recycling.

    Die design and Modifications of Extruders

    Dies have been drawn up to 630mm diameters for polyolefine plastics. Reconditions and modifications have been carryed for decades extruder screws and tubes.

    Recycling

    The first granted patent was named in 1977 "method and device for granulate plastics waste". We have about 20 years of good and not so good experiences of different procedures of recycling. -"Many things are not written in books or research papers, but if you can do workable products from scrap, then you can do nearly everything from prime and virgin polymers".



















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