Polyethylene Webbing is also known as Spectra Webbing. It is a very strong material that it can be used in survival because they are so light and able to be bundled into very small areas for carry.
Polyethylene or Spectra Webbing is a very strong webbing like most synthetic materials. They also have a very good shock load. They are very flexible and you can bundle them up into a very small, tight areas to make it easy for use during backpacking or rappelling. They are considered only good in the categories of abrasion resistance, UV and chemical resistance as well. They can be damaged if left out in the sun and you will see them start to fray and weaken if they are exposed to very rough surfaces. They are also considered to be good in the price category.
Many use this in survival because it is so strong and light, but you must be careful using this in rescue and rappelling because it has a slippery surface and the knots can back out. They are most often seen in commercial uses because of the price.