Polyester Versus Polyethylene

September 5, 2011 by Debra Lynn Dadd

Question from samsam

Hi Debra,You have mentioned that polyethylene plastic provides a good vapor barrier. I am confused. On the internet it says that polyester is the name the textile industry uses for polyethylene or PET. In that case, polyester fiberfill should have the same saftey as polyethylene plastic cover, no? also, does polyethylene not contain phthalates and antimony?

Debra's Answer

Polyethylene is the most widely used plastic. It's primary use is in packaging for plastic bags and films, although we are seeing other uses for it now due to it's safety (Naturepedic, for example, uses polyethylene to make a waterproof layer on their organic cotton crib mattresses, as a replacement for the much more toxic vinyl covering used on most baby mattresses). Polyethylene is also now being used as a vapor barrier to block toxic fumes from mattresses.

The abbreviation for polyethylene is PE.

Polyethylene is classified into different categories. The most commonly used are:

Ultra-high-molecular-weight polyethylene (UHMWPE)

Ultra-low-molecular-weight polyethylene (ULMWPE or PE-WAX)

High-molecular-weight polyethylene (HMWPE)

High-density polyethylene (HDPE -most important)

High-density cross-linked polyethylene (HDXLPE)

Cross-linked polyethylene (PEX or XLPE)

Medium-density polyethylene (MDPE)

Linear low-density polyethylene (LLDPE- most important)

Low-density polyethylene (LDPE- most important)

Very-low-density polyethylene (VLDPE)

Chlorinated polyethylene (CPE)

You will see these on plastic recycling symbols.

UHMWPE is very tough. It is used for things like moving parts on machines, bulletproof vests, and parts for implants used for hip and knee replacements. Nothing we see as consumers.

HDPE is used in products and packaging such as milk jugs, detergent bottles, margarine tubs, garbage containers and water pipes. One third of all plastic toys are manufactured from HDPE (but most are made from the much more toxic polyvinyl chloride).