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Polypropylene- Is it different from Polyethylene?

Posted by Nana Hinsley on Sun, May 01, 2016 @ 01:01

How is Polypropylene different from Polyethylene? Well.....

polyprop structure resized 600Poluethylene structure resized 600

Polypropylene, also know as polypropene is a form of plastic just as polyethylene is. What separates polypropylene from polyethylene for starters is the fact that polypropylene can be molded in essence becoming pliable above a certain temperature. When it cools it will return to its solid state. Polypropylene can be used not only as a structural plastic, but it can be used as a fiber. It also has a high melting point, which differentiates it from polyethylene. One area where polyethylene has over polypropylene is that polyethylene is more stable. Polypropylene has the advantage that it can take repeated motions such as being a hinge.  A hinge made out of polypropylene can be opened and closed many many times, and hold up just fine. This is known as having "good resistance to fatigue". MORE

Polypropylene can be combined with other materials, as can polyethylene. Rubber for example can be added, to make it more pliable.  One of the exciting additives that is added to polypropylene are minerals. These minerals allow a polypropylene sheet to become a synthetic paper.  synthetic paper is essentially plastic paper.  It can be easily printed on. It can be folded, hot stamped, die cut, sewn and more.  Best of all it is environmentally friendly! All of a sudden polypropylene is transformed into a slew of products. Synthetic paper made from polypropylene is used to make banners, membership cards, maps, menus, phone cards, signs, tags, floor graphics, counter mats, and booklets. The list goes on from here!  What is outstanding about synthetic paper is that is is durable, tear and water resistant!(Products made from polypropylene)

Polyethylene has more demand however than polypropylene. Polypropylene is used extensively in the automotive industry as well as the packaging industry. 70% of the polypropylene  uses is for packaging needs for the food industry. It can be made into bottles, food containers, food crates and pallets.

Polypropylene is used to make house wears, appliances and toys. It is also used to make make carpeting and upholstery. The polypropylene is heated and made into fibers. There are so many uses for both polypropylene and polyethylene.

Polyethylene is inert, translucent and creates a lower static charge than polypropylene. That makes polyethylene a candidate to be a sleeve to house collectible documents.  It is "inert" and cannot product mold or mildew.  It is also translucent in nature so it allows less light through it than polypropylene.  It has a lower static charge than polypropylene so it attracts less dust and dirt.  Polyethylene costs more than polpropylene because it has a higher purity (100% virgin).

Here is a list of some of the differences between polyethylene and polypropylene: 

  • Polyethylene and Polypropylene are very similar as far as physical properties.
  • However, Polyethylene can be produced optically clear where polypropylene can only be made translucent like a milk jug.
  • Polyethylene does have physical properties that allow it to stand up better in cold temperatures, particularly when using it as signs.
  • Polyethylene is a good electrical insulator. It offers good tracking resistance, however, it becomes easily electrostatically charged (which can be reduced by additions of graphite, carbon black or antistatic agents).
  • Polypropylenes are light in weight. They have a high resistance to cracking, acids, organic solvents and electrolytes. They also have high melting point and good dielectric properties and are non-toxic.
  •  Monomer of polyethylene is ethylene and monomer of polypropylene is propylene.
  • Polyethylene has a lower melting point compared to the higher melting point of polypropylene. (this may be a good test for you)
  • Polypropylene is not as sturdy as polyethylene.
  • Polypropylene is stiffer and resistant to chemicals and organic solvents compared to polyethylene.
  • Polypropylene is pure, non-stretching and generally more rigid than polyethylene.

Tags: polyethylene, polypropylene

The History of Polyethylene

Posted by Nana Hinsley on Fri, Feb 13, 2015 @ 10:19

On March 27, 1933, two organic chemists working for the Imperial Chemical Industries Research Laboratory were testing various chemicals. To  R.O Gibson and E.W. Fawcett's surprise the white, waxy substance they were testing would become a revolutionary substance that would change the world. Polyethylene was born!

 polethylene resin for plastic sheeting

The researchers set off a reaction between ethylene and benzaldehyde, in an autoclave. It seems their testing container sprang a leak and all of the pressure escaped. There was the white, waxy substance that greatly resembled plastic. Upon carefully repeating and analyzing the experiment, the scientists discovered that the loss of pressure was only partly due to a leak; the major reason was the polymerization process that had occurred leaving behind polyethylene. The first patents for polythene were registered in 1936 by Imperial Chemical Industries.  A year later the first practical use for the material, as a film, was discovered. In 1953 Karl Ziegler of the Kaiser Wilhelm Institute and Erhard Holzkamp invented HDPE (High Density Polyethylene). From there, two years later, in 1955, HDPE was produced as pipe.  Ziegler was awarded the 1963 Nobel Prize for Chemistry.

Did you know that polyethylene played a key supporting role during World War II? It was first  used as an underwater cable coating and then as a critical insulating material for  vital military applications as radar insulation. This is because it was so light and thin that it made placing radar onto airplanes possible thus vastly reducing the weigh. The substance was a highly guarded secret.

After the war, polyethylene became a tremendous hit with consumers It became the first plastic in the United States to sell more than a billion pounds a year. It is currently the largest volume plastic in the world.

 Today, Polyethylene has the advantages of excellent moisture-vapor, chemical, and electrical resistance. It is widely used for making containers, wire cable insulation, pipe, linings, coatings, and engineered films. It is used to power transmission, consumer goods, packaging, electronics household good and more. Its principal disadvantage is poor mechanical strength, unless it has a little help from scrim reinforcement! Developments in technology continues to improve its functionality making it the most efficient use of natural resources petroleum and natural gas. We applaud these scientists for creating polyethylene that is used in a variety of plastic sheeting products today.

Polyethylene is the largest volume polymer produced globally, with over 90 million metric tons per year!


Tags: plastic sheeting, polyethylene, film, history of polyethylene