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Plastic is Plastic Right? Are there any differences?

Posted by The Plastic Sheeting Gurus! on Mon, May 23, 2016 @ 03:44

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In the world of engineered plastic sheeting there are a variety of terms that are used freely in conversation and in the written word. Terms such as "low density polyethylene" or "Polyolefin vs Polyethylene". Below is a brief explanation of commonly used terms.

Low Density versus High Density- what's the difference?

HDPE.png  ldpe.jpg

 Question:  What is the difference between low density and high density polyethylene?

Answer: The biggest difference is how closely the molecules bond to each other in the structure of the product.  High density has a lot more molecules in the same amount of space.  This causes high density to have different qualities when compared to low density.  For instance, High density of the same thickness will be stronger, more puncture resistant, more tear resistant, tougher, stiffer, more chemical resistant, than a low density polyethylene made from the same grade of polyethylene. Low density polyethylene is a softer material, more pliable, more conforming.  These are general types of polyethylene.  Within each type there are varying quality levels, additives, and much more science to vary the products from their natural states to give them the qualities needed for the applications.

 There are many reasons why one might be used in a given application, compared to using the other.  Call866.597.9298 if you would like a further explanation. 

Plastic Classifications

Question:  What are all the classifications of plastic?

Answer:  Polyethylene is classified into several different categories based mostly on its density and branching.

  • Ultra high molecular weight polyethylene(UHMWPE)
  • Ultra low molecular weight polyethylene(ULMWPE or PE-WAX)
  • High molecular weight polyethylene(HMWPE)
  • High density polyethylene(HDPE)
  • High density cross-linked polyethylene(HDXLPE)
  • Cross-linked polyethylene(PEX or XLPE)
  • Medium density polyethylene(MDPE)
  • Linear low density polyethylene(LLDPE)
  • Low density polyethylene(LDPE)
  • Very low density polyethylene(VLDPE)

Polyolefin and Polyethylene- What's the difference

  1. What is the difference between Polyolefin and Polyethylene?
  2. Polyolefin is a material that is made of only carbon and hydrogen atoms. When the Polyolefin molecule is bonded in a more complex manner, then you have a variety of materials made from the polyolefin material.Polyolefin materials such as polyethylene, polypropylene and polybutene have more complex olefin branches than simple polyolefin. 

For example, Polybutene is a liquid polymer used in sealants, synthetic rubber and lubricants.  Polyethylene is used to make products like shrink wrap, and a variety of plastic sheeting products.  Polypropylene is a hard resin used in carpeting, food packaging and electronics. Don't be confused if a plastic sheeting product is referred to as a "polyolefin". Saying it is a polyolefin does not imply it is a superior plastic. After all, now you know that plastic sheeting is made up of Polyolefin.

How do you measure a mil?

Question:  How do you measure a mil?

Answer:  For plastic sheeting, the industry uses an instrument called a micrometer.

How thick is a mil and what is it?

Question:  How thick is a mil and what is it?

Answer:  A mil is a unit of length equal to one thousandth (10-3) of an inch (0.0254 millimeter). It is used in the plastic sheeting world to define the thickness of the film.    

1 mil    = 0.001 in

1 mil    = 0.0254 mm

1 mil    = 25.40μ (microns)

Another way to look at it is, 20 mils = .508 mm which is thinner than the thickness of a dime (10 cents) which is rougly 1.24461mm.

GRI- what does it stand for?

Question:  What does GRI stand for regarding 12 mil polyethylene sheeting or various vapor barriers/retarders?  The Geosynthetic Research Institute.

For example you might see, GRI=GM22 standard specification which is a test method that specifies the required properties and testing frequencies for scrim reinforced polyethylene geomembranes that are used in an exposed (out doors) application. It establishes minimum physical, mechanical and durability properties that must be met.  The GRI GM22 cover scrim reinforced poly geomembranes in thicknesses of 0.50 mm (20 mil), and 0.20mm (8 mil). This spec represents manufacturing quality control (MCQ).

For more information please visit the GRI's website.