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  1. RichGeoffroy

    Crosslinked Polyethylene

    In a recent e-mail inquiry, a reader asked: In my experience, neither will occur. First, the melting point is a function of crystalline packing --- the more uniform the packing, the higher the crystalline melting point of polyethylene. Melting point is not a function of molecular weight...
  2. RichGeoffroy

    Top 10 Consulting Pitfalls

    Here is a GREAT article that I found at monster.com. I hope you appreciate it as much as I have. Rich Geoffroy Polymer Services Group
  3. RichGeoffroy

    Starting Out

    In a recent e-mail, a subscriber posed the following question: There is no magic wand that will make your life easy in regard to establishing your initial business plan. Your potential competitors are probably your best source of information on costs --- if you think one is willing to share...
  4. RichGeoffroy

    The Ethics of Consulting

    I take no credit for this article. I stumbled across it on Monster.com, and it was too appropriate to this forum to not pass this on. Rich Geoffroy Polymer Services Group POLYSERV@aol.com
  5. RichGeoffroy

    PVC Fabrication

    First of all, the process will not make an epoxy, but it will make a PVC solvent cement. Secondly, why go through all that work when you can purchase it at any hardware store. The joint, however, will not be as strong as the PVC sheet itself. It will very likely break at the bond if you...
  6. RichGeoffroy

    The Key to Success is Marketing

    The thing about consulting (at least from my experience) is that you never know where your next job is going to come from. Actual selling is difficult unless you can identify those prospects that actually need your services right now. If they don’t have a problem, they don’t want to hear from...
  7. RichGeoffroy

    What are Copolymers?

    Polymers (“poly” = many; “mer” = unit) are long-chain molecules that consist of “many units”, i.e., repeating sections of monomers --- like links in a chain --- e.g., polyethylene would consist of many ethylene (-CH2-CH2-) units. These monomers can be added one to another to create longer and...
  8. RichGeoffroy

    How Long will this Part Last?

    There is no test that can answer the question, “How long will this part last?”, because there are too many factors that can affect the service life of a product. However, there are tests that can yield important long-term information which can help ensure satisfactory long-term service of a...
  9. RichGeoffroy

    Do you have Standard Terms of Agreement?

    Any agreement, whether it’s written or verbal, can be considered a legally-binding contract. A lot of business is carried out over a handshake and verbal understanding of what each party is supposed to do. Generally, this understanding may be somewhat formalized by a letter confirming what you...
  10. RichGeoffroy

    What are Tie Molecules?

    Crystalline polymers, such as polyethylene and polypropylene, exist as composites of regularly-ordered, closely-packed, hard, crystalline segments in a matrix of unordered, rubbery, amorphous polymer. Chemically, the two phases of polymer are indistinguishable from each other, yet they form...
  11. RichGeoffroy

    How Do Plastic Parts Fail?

    Plastics parts fail simply by pulling them apart --- they always fail as a result of tension. Whether the part is in flexure, torsion, shear, or even compression, failure always is the result of tensile effects on the polymer molecules --- they are simply being pulled apart as a result of the...
  12. RichGeoffroy

    Do you require a Retainer?

    It depends on your relationship with your client. There are situations were requesting a retainer may not fit into the relationship because there is a lot of trust and respect between you and the client. However, there are other situations where you may have reason to question the motives or...
  13. RichGeoffroy

    What's the difference between Crystalline and Amorphous States?

    The nature of crystalline and amorphous polymer states is often misconstrued and misused. The term amorphous means to have no defined shape, or an easily altered shape, like a liquid or a rubber. Crystalline, on the other hand, insinuates that there is a regular, defined pattern to the...
  14. RichGeoffroy

    What's the best way to Invoice?

    What's the best way to invoice --- up front and in full, if you think you can get away with it. One guy I knew used to invoice the client 50% as soon as the project came in, but he was able to get away with it. Generally your client will want to be billed after everything is completed --- that...
  15. RichGeoffroy

    Are Test Standardized --- or Not?

    Real differences can exist when comparing most “data sheet” properties of different materials. Standardized tests work fine for establishing comparative values for the same material, but can be very misleading when comparing different materials --- mainly because the “standardized” tests for...
  16. RichGeoffroy

    You are What You Do --- Not What You Know

    One of the most frustrating things in consulting is getting your clients to understand what services you can provide. Don’t take for granted that they know what you can do --- because they absolutely don’t know. Each client or prospective client has a very myopic view of your technical...
  17. RichGeoffroy

    The Fallacy of Tensile Strength

    One of the most-often-specified properties for polymers, and indeed for most materials, is tensile strength. It is used in comparisons of materials to determine which material is the “strongest” --- i.e., which material is most likely to succeed in an application. Unfortunately, many times a...
  18. RichGeoffroy

    Budget for Success

    Before you even consider starting your own engineering practice, you have to have some idea of how much it’s going to cost for you to run the business --- never mind trying to make a profit. One of the first things you have to do is to prepare a budget. A budget is nothing more than a...
  19. RichGeoffroy

    How do Plasticizers function?

    A polymer is similar to a plateful of uncut spaghetti. The points at which the spaghetti strands contact each other are “sticky”, similar to the attractive forces between molecules. Because of their long lengths, many of the molecules are entangled, among themselves and with other molecules...
  20. RichGeoffroy

    Using Melt Flow Rate to Determine Change in Molecular Weight

    If there is one key property for polymers, it is molecular weight --- actually it’s the presence of the very-high-molecular weight fraction. It’s these very long molecules which give the polymer its high elongation, toughness, impact strength, long-term creep resistance and resistance to stress...

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