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Recent content by PrentP

  1. PrentP

    PTFE BEHAVIOUR

    When designing components made of PTFE, the relatively high degree of thermal expansion must be taken into consideration: 20-100 °C: = 16 · 10-5 1/K 20-200 °C: = 23 · 10-5 1/K Recordings of the coefficient of linear expansion reveal two conspicuous transitions: At 19°C there is a conversion...
  2. PrentP

    material selection

    My new fridge/freezer came with a plastic scraper - it looks to be made of ABS. Regards, Peter P
  3. PrentP

    PVC Design Values

    sda97 Have a look at ASTM Standard D1785-03 entitled "Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Pipe, Schedules 40, 80, and 120". There are additional references in this standard. Regards, Peter P
  4. PrentP

    Polypropylene and Printing

    Try Corona Discharge. See http://www.polytechconsultants.com/corona.htm Regards, Peter P
  5. PrentP

    Cadmium in plastic

    Not true Pat - the ban has been lifted. See http://www.millenniumchem.com/Products+and+Services/Products+by+Type/Cadmium+Pigments/r_Whats+New/Cadmium+Pigments+Whats+New_EN.htm Good News for users of Cadmium Pigments Regards, Peter P
  6. PrentP

    Plastics for low temperatures

    Sorry, This should have been in Plastic molds/fabricating engineering. Regards, Peter P
  7. PrentP

    Plastics for low temperatures

    Not true Pat - the ban has been lifted. See http://www.millenniumchem.com/Products+and+Services/Products+by+Type/Cadmium+Pigments/r_Whats+New/Cadmium+Pigments+Whats+New_EN.htm Good News for users of Cadmium Pigments Regards, Peter P
  8. PrentP

    Fracture Toughness

    Nigel, Sorry that should have been plane strain. See http://www.sv.vt.edu/classes/MSE2094_NoteBook/97ClassProj/exper/mcmurtry/www/matt.html#planestr Regards, Peter P
  9. PrentP

    Fracture Toughness

    Nigel, Fracture toughness (or K1C as it is often referred to) is a parameter based on Linear Elastic Fracture Mechanics (LEFM), Which means that your sample must have a linear stress/strain curve up to the point of fracture. This being the case it means that only brittle polymers such as PS or...
  10. PrentP

    Calculation of PSI from PLI in nip

    It's an old book, probably out of print, but it has the best analysis of calendering I have ever found. "Polymer Processing" by James M McKelvey, Published by John Wiley and Sons Inc. 1962. Chapter 9 'Hydrodynamic Analysis of Calenders' - excellent, well worth searching it out. If...
  11. PrentP

    ripple tank fabrication

    You can bond the sheets of acrylic using Tensol Cement. See http://www.mcmordiebros.co.uk/tensol_cement.htm Regards, Peter P
  12. PrentP

    balanced runners

    MEH70US, See my webpage at http://www.polytechconsultants.com/balancing.htm and adapt the analysis for an H shaped cavity system. Regards, Peter P
  13. PrentP

    HDPE chemical storage bottles

    HDPE is very susceptible to Enviromental Stress Cracking (ESC) and is known to embrittle over time. LDPE is less susceptible I would think that the bottles are so cheap that you could afford to replace them, say annually. Regards, Peter P
  14. PrentP

    Heat deflection temperature

    You are looking for something like the Vicat Softening Temperature. See the URLs below http://www.astm.org/cgi-bin/SoftCart.exe/DATABASE.CART/REDLINE_PAGES/D1525.htm?E+mystore http://www.tiniusolsen.com/products/p-hd94.html http://www.ptli.com/testlopedia/tests/Vicat-D1525.asp...
  15. PrentP

    Support Analysis of Thermoplastic Pipe

    What's the polymer? Most are viscoelastic and undergo stress relaxation and creep under load. This is why you will not find design criteria you are looking for and I don't think you will be able to easily compute them. Regards, Peter P
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