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...
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...
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
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
