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  1. 1399

    HDPE chemical storage bottles

    ESC may be defined as the accelaeration of stress cracking by contact with a fluid, without chemical degradation. Tehe mechanism is purely phisycqal. The interactions between the fluid , the stress, and the polymer include local yielding, fluid absortion, plasticisation, craze intiation, crack...
  2. 1399

    UV effects on polyurethane

    Compare to other diene elastomers , Polyurethanes show good weathering properties. However the show slight embritlement under sun after years of exposure. It depends on weather conditions (ozone, oxigen sun) and PU type:Polyether based slightly more resistant than polyester based
  3. 1399

    High pressure hose failure (polyester tube)

    What you have probably is related to polyester hidrolysis. This may cause hardening and material embritlement Polyesters are not hidrolytically stable and suffer degradation via hidrolisis which is promoted by acids(H2S) This is common in polymers such as: Polyesters, Nylons, Acetals...
  4. 1399

    SHORE HARDNESS

    Hardness may be defined as the resistance to indentation under conditions that do not puncture the rubber.Different instruments designed to measure hardness do not usually agree well with each other. The spring -loaded pocket durometer is the most common instrument to measure hardness...
  5. 1399

    UV Protection of Polypropylene Coating

    Hi, You may try some some tapes made of low insaturated butyl elastomers.A brand called Denso Butyl 20 tape is available http://www.densona.com
  6. 1399

    Thermally and Electrically Conductive Rubber

    Hi, There are new technologies that can make rubber conductive using carbon nanotubes. They are comercially available Ex. magnetorestrictive materials. regards, 1399
  7. 1399

    Simple introduction on QC

    Well.....check Internetand take a basic course on QC....then teach your fellows. Ask to more "experienced" fellows in that developing country,I am sure you will find them.
  8. 1399

    Water tight seal using elastic property of gasket material

    Hi, I am not sure if I understand the question correctly. Apologyse if I mistaken. Dimension of unstretched gasket will depend on how long you want to stretch it. knowing the stretching ratio consider rubbers are incompresible in bulk (constant volume), a reasonably asumption in most cases...
  9. 1399

    Blooming in NR

    Hi, In addition to Mr berti and pronate comments I would add that when blooming come from sulfur the process is as follows: there two kind of sulfur, ordinary orthorombic an insoluble Ordinary sulfur is cristalline and soluble in rubber. It dissolve during the hot mixing process. On cooling...
  10. 1399

    O-ring Pipe Crawler Wheel

    In case of polyurethane you should bear in mind what the "wet" conditions are. If the medium is water Polyurethane undergoes hidrolysis easily. In that case you may use a Ether Type polyurethane rather than an ester type Polyurethane (most common)
  11. 1399

    SN curve for Natural Rubber

    Problem with with S-N curves is since cracks initiate from some flaws in the sample, large scatter is found in fatigue lives of specimens without a defined precrack. Therefore these tests are very tedious, time consuming and information obtained is specific to the specimen used which may not be...
  12. 1399

    Bush contraction

    try the equation for torsional stiffness of a tube form elastomeric bearing:(taken form design of components, P.Sheridan) Ktor= T/ang= pixGxL/(1/(DixDi)-1(DoxDo) pi= constant= 3,14 Ktor= torsional stiffness G=Rubber shear modulus L= Bearing Length Di=bearing inner Diameter Do=Bearing outer...
  13. 1399

    replaceing rubber by polyuratin

    Since there chlorine presence Im not very sure if a polyurethane coating is the best solution. If you do not other choices try using a ether type PU minimize hidrolysis regards Oscar Salazar
  14. 1399

    Smell of nitrile

    If the smell comes from sulfur you may chek if blooming is ocurring. (unreacted sulfur migrating to surface). You may try using non soluble amorphous sulfur and add it in a master batch at the end of mixing to reduce its heat history. You may try a combination of sulfur and acelerators sas...

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