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  1. GrahamBennett

    vulcanisation

    In answer to your question regarding plasticiser content, the answer is yes. As a rule of thumb 2 parts change in plasticiser content = 1 point change in hardness.
  2. GrahamBennett

    rubber analysis

    FTIR and GCMS can be run at the same time so those tests are needed to ID the polymer, I would also order a TGA to ID the quantities of filler and softeners present. The only organic filler likely to be present is carbon black so I would ignore that test and I wouldn't bother trying to ID any...
  3. GrahamBennett

    Rubber to Metal Bonding - Substrate Preparation questions

    Alex is correct. Your response, Max, was highly informative and I learned a lot from it. For that reason, I awarded you a Little Pink Star. www.over50schat.com
  4. GrahamBennett

    banbury mixing

    Thanks Tmoon. Fill factors in the range of 65% or so are normally used for intermeshing rotor machines. If you have the true Banbury style rotors then you should be operating with a fill factor of about 75 - 80% for 2-wing rotors and 80 - 85% for 4-wing rotors. From my experience, your s'...
  5. GrahamBennett

    banbury mixing

    1. Are you talking about the indicated drop temperature or actual bulk material temperature when you mention drop temps? 2. What equipment do you use below the mixer for cooling/sheeting off? 3. I should have asked this before - what make and model is your mixer and what fill factor do you...
  6. GrahamBennett

    banbury mixing

    Ram raise just to vent? 5 seconds or so. Upside down mixing: Master - no ram raises for venting until about 3 mins into mix. Then just 1 or 2 max. Final: I wouldn't vent during a final mix. Single pass: Same as master batch mix. www.over50schat.com
  7. GrahamBennett

    banbury mixing

    You've more or less answered your own question tmoon42. Raising the ram allows you to add other ingredients at different times during the mix cycle as well as allowing volatiles and moisture to escape. Additionally, raising (or floating) the ram reduces the pressure on the mix and, thus...
  8. GrahamBennett

    Natural Rubber Technical Information Sheets

    Done and dusted. www.over50schat.com
  9. GrahamBennett

    Natural Rubber Technical Information Sheets

    Tom, I have a complete set of these. The question is how to email them to you as I think we're not allowed to give each other our email addresses. www.over50schat.com
  10. GrahamBennett

    Butyl rubber as a storage tank liner for high active surfactant?

    Butyl should be fine with most soap (surfactant) solutions but I go along with what btrueblood has said. Test a small piece in a sample of the surfactant, diluted to the usual strength, first to check if the rubber swells. www.over50schat.com
  11. GrahamBennett

    identifying rubber type and lethal ( to the rubber) solvents

    Try standing some of the rubber in normal gasolene for a few hours. If the rubber becomes very soft and sticky, gasolene is your answer, if it doesn't then you need some other solvent. www.over50schat.com
  12. GrahamBennett

    PTFE (Teflon) tape on natural rubber misaligns upon press vulcanization

    2 very good posts there btrueblood. Thanks for responding to Thais' request for clarification. I would have answered exactly the same.[thumbsup2] www.over50schat.com
  13. GrahamBennett

    PTFE (Teflon) tape on natural rubber misaligns upon press vulcanization

    One other important point to remember is that Teflon will not adhere to natural rubber so some form of mechanical bonding is required here also. www.over50schat.com
  14. GrahamBennett

    Chemical migration on vulcanized EPDM products

    Well done, problem solved then. Just remember not to exceed about 0.8phr sulfur in your formulation and not to exceed about 100°C for the batch temperature when the sulfur has been mixed in, otherwise you'll start to get sulfur bloom again. www.over50sforum.com
  15. GrahamBennett

    Chemical migration on vulcanized EPDM products

    Does your formulation contain any insoluble or soluble sulfur? www.over50sforum.com
  16. GrahamBennett

    Cure LUMPs ( Scorch)

    Welcome to the forum Emad. Scorch is usually caused when a rubber compound, that has had the curatives added, reaches too high a temperature and starts to cure. Usually, this occurs either during the final mix stage or immediately afterwards on the equipment below the mixer. It would help if...
  17. GrahamBennett

    [ASK] How to Determine Tensile Modulus at 100% elongation ?

    You can't determine 100% Modulus with the data you have. Ask your supplier's laboratory for the data. www.over50sforum.com
  18. GrahamBennett

    Brown and black marking after post-cure

    We always had problems of discolouration when curing white silicone parts. We solved it by working only under clean room conditions (not easy when the rest of the mixing/curing area is full of carbon black mixes! www.over50sforum.com
  19. GrahamBennett

    Energy return of elastomer

    The rebound occurs when the force is remove. Please remember that not all of the original force will be released by the rubber - this is known as hysteresis. www.over50sforum.com
  20. GrahamBennett

    Best environmentally friendly rubber

    For me there is only one answer to this question and that's natural rubber. To start with, the NR tree from which the latex is gathered sequesters far more carbon dioxide over its lifetime than any other green leafed plant I know of. Then, when the tree is too old to cost effectively produce...

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