Back in the pre-internet days, this is the book that we all used to look up materials and find property data sheets. The Plastics Materials Digest: International Plastics Selector.
I have been looking for one of these old books on Ebay for a couple of years now and I finally came across this near perfect copy dated 1988 which happens to be my first year in the industry.
Polyethylene was first discovered by accident in a laboratory in 1898. This is a running theme throughout the history of the plastics industry. It was not until 35 years later that the first commercially viable polyethylene was synthesized in 1933 by Imperial Chemical Industries (ICI). The long gap between the initial discovery of a polymer and the commercialization is also a recurring theme in the history of the plastics industry.
Polyethylene is the most commonly used plastic globally. According to Wikipedia, annual production is around 80 million metric tons or 176 billion pounds. It is used in many applications such as film that is used for everything from moisture barrier to grocery bags. It is also used for things like pick-up truck bed liners and tanks of all kinds. In recent years, polyethylene has been used for increasingly demanding applications like automotive fuel tanks, potable water pipe, artificial hip joints and even fiber for bulletproof vests.
Polyethylene’s use in these increasingly demanding applications has been made possible by innovations from the material manufacturers. Unlike TPO, these innovations have not happened at compounders but during the reaction of the polymer. These innovations have brought a dizzying array of new polyethylene materials to the market. A quick look at Matweb shows that there are currently 5534 different grades of polyethylene. I want to break down some of the different types that are now available.
I was sick as could be last week so I did not make any posts. I will resume the normal schedule today.
*Updated with additional information on 8/30/2016
Acetal, also known as poyoxymethylene (POM), is a very commonly used thermoplastic material that we are all familiar with. Everyone in the industry has a story of the time when someone ran some acetal at too high a temperature and had it degrade filling the plant with formaldehyde. However, not everyone is aware that there are actually two different versions of acetal on the market, copolymers and homopolymers.
I see a lot more copolymer being used than homopolymer at injection molders which puzzles me. This might be because the homopolymers tend to come at a premium price. Sometimes, however, you get what you pay for. A brief history of acetal might explain why homopolymer is more expensive and also why you should consider using it
In specifying materials for certain applications, we might need to know what kind of heat resistance that the material has. This is a vague concept at best. What do we mean by heat resistance? Can the heat resistance of a material be altered with additives or fillers?
Let’s delve into a few of these issues and I will show you where to find the best indication of heat resistance of plastic materials as well as give you some guidelines that you can use for picking materials.