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  1. gambro

    bubbles in PC

    We had experienced a similar problom a few years back in a section of the mold where the melt flow first passed through a thin-walled section, then a thick-walled section and at last through another thin-walled section. The bubbles formed in thick-walled section. We think the cause is air...
  2. gambro

    Extruding Polymer over Metal Coil

    Try thermoplastic Polyurethane, for example Desmopan from Bayer. They have medical grades with may be irradiated.
  3. gambro

    Supplier for polyurethane viscoelastic system

    Try Morton Polyurethanes. They are a US-base PU system house with affiliates in Europe.
  4. gambro

    SIlicone overmolding

    Try Wacker Silicones. They have some new grades two component Platinum catalyzed silicone rubber for injection molding on the market specially made for overmolding different thermoplastics.
  5. gambro

    Plastic/ Polymer Search

    To my knowledge, PEEK is currently being used for this kind of application. The medical grade type is called PEEK-Optima and manufactured by a Swiss (?) company called Invibio. It's strong, flexible, implant tested and most certainly withstands any type of sterilization and to my knowledge...
  6. gambro

    Non destructive ways to differienciate between Neoprene and EPDM

    Most petroleum-based products (such as hydraulic oil used in injection molding machines) will cause EPDM rubber to swell or dissolve. Chloroprene Rubber (Neoprene) on the other hand is generally resistant to most oils, fats and greases.
  7. gambro

    Polymers in low temp applications

    Filter Media made of expanded PTFE (Trade name Gore-Tex) should do your job very well. Contact Gore for more information.
  8. gambro

    Injection mold piece of Lexan breaks

    Probably what you mean by a "flamed" surface is what is generally called surface splay. There are several causes of splay, all of which may lead to a weakening of the part and possible brittle fracture. Please note that even of you do not see any visible splay, the underlying effects might still...
  9. gambro

    Injection mold piece of Lexan breaks

    I have a few points which might be of some help : 1. Black masterbatch - if you are using a masterbatch with a Polycarbonate carrier, be sure to dry it along with the base material. - if you are using a "universal" Masterbatch with a non-PC carrier, the problem might be due to incompatibility...
  10. gambro

    What is the Glass Transition Temperature, Tg?

    As a short comment : Sometimes blends of two polymers exhibit two glass transition points, one for each of the blend partners.
  11. gambro

    Looking for rect. polycarb tubes

    A big manufacturer of tubes in all shapes and sizes is Ensinger. Look them up at www.ensinger-online.com
  12. gambro

    RF Welding - Materials Selection

    Apart from the RF-weld "standard", which is PVC, themoplastic Polyurethane (TPU) can also give a very good RF weld, although the welding equipment must be modified to accomodate this material. Also, TPU-film is rather expensive. A few years ago, The Dow Chemical Company came out with a new...
  13. gambro

    Clear plastic tube

    One big supplier of ex stock tubes and profiles made of various engineering and high-temperature plastics is a company called Ensinger. Check them out at www.ensinger-online.com. I'm sure they have what you need.
  14. gambro

    Baloon question

    If what you are talking about is a collapsible, high-pressure Balloon Catheder, these are mostly injection molded and either made of PET or PA. For more info see www.advpoly.com I have also seen large, low-pressure Balloon Catheders made of thermoplastic Polyurethane (for example Bayer makes...
  15. gambro

    Using Melt Flow Rate to Determine Change in Molecular Weight

    I would like to point out that, due to the short length of the capillary die used in the standard MFI measurements, the MFI value not only reflects the shear viscosity at a certain shear rate (single-point shear viscosity measurement), but also reflects to a certain degree the so-called normal...
  16. gambro

    PC/ABS molded-in stress quick check

    As I wrote, we use a mixture of 1 volume part "pure" toluene and 3 volume parts "pure" n-propanol. The other two mixtures with methanol we don't use ourselves. I got them out of the technical literature. Sorry, but in the cited literature there is no indication on the purity of these chemicals...
  17. gambro

    ? over wire extrusion.. sparkout problem

    Cleanliness is the top consideration in wire coating. The reason for your sparkouts is most likely due to formation of microvoids resulting from some sort of contamination. One cause could be water. Is the wire completely dry? How high is the air humidity at the extrusion site? Another idea is...
  18. gambro

    Why does my parts made of Polypropylen break?

    Besides patprimmers remark on embrittlement due to low temperatures on application, another cause of embrittlement is improper molding conditions. Assuming that you are using injection molding, PP Homopolymer should be processed at a melt temperature of 220 - 280°C and a die temperature of...
  19. gambro

    Nylon Polyamide 1010

    Try the RTP company (www.rtpcompany.com). If they don't have it, maybe they know where you can get it.
  20. gambro

    How do Plasticizers function?

    I would like to add that although many additives (internal lubricants, mold release agents, processing aids, antistatics, halogenated flame retardants, phosphorous-based flame retardants) exhibit a certain degree of plasticizing effect (lowering of Tg and the Vicat/HDT softening point), this...

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