If you would like to help with the overall layout of this website, please discuss in the UpCycleIt layout page.

From UpCycleIt

Polyethylene (IUPAC name polyethene) is a thermoplastic commodity heavily used in consumer products. Over 60 million tons of the material are produced worldwide every year.

[edit] Description

Polyethylene is a polymer consisting of long chains of the monomer ethylene (IUPAC name ethene). The recommended scientific name 'polyethene' is systematically derived from the scientific name of the monomer.[1][2] In certain circumstances it is useful to use a structure–based nomenclature. In such cases IUPAC recommends poly(methylene).[2] The difference is due to the 'opening up' of the monomer's double bond upon polymerisation.

In the polymer industry the name is sometimes shortened to PE, in a manner similar to that by which other polymers like polypropylene and polystyrene are shortened to PP and PS, respectively. In the United Kingdom the polymer is commonly called polythene, although this is not recognised scientifically.

The ethene molecule (known almost universally by its common name ethylene), C2H4 is CH2=CH2.

Polyethylene is created through polymerization of ethene. It can be produced through radical polymerization, anionic addition polymerization, ion coordination polymerization or cationic addition polymerization. This is because ethene does not have any substituent groups that influence the stability of the propagation head of the polymer. Each of these methods results in a different type of polyethylene.

[edit] High density polyethylene

HDPE is defined by a density of greater or equal to 0.941 g/cm3. HDPE has a low degree of branching and thus stronger intermolecular forces and tensile strength. HDPE can be produced by chromium/silica catalysts, Ziegler-Natta catalysts or metallocene catalysts. The lack of branching is ensured by an appropriate choice of catalyst (e.g. chromium catalysts or Ziegler-Natta catalysts) and reaction conditions. HDPE is used in products and packaging such as milk jugs, detergent bottles, margarine tubs, garbage containers, water pipes, and plastic shopping bags.

See below for upcycling techniques.

[edit] Low density polyethylene

Low-density polyethylene (LDPE) is a thermoplastic made from oil. It is unreactive at room temperatures, except by strong oxidizing agents, and some solvents cause swelling. It can withstand temperatures of 80 °C continuously and 95 °C for a short time. Made in translucent or opaque variations, it is quite flexible, and tough to the degree of being almost unbreakable. LDPE is defined by a density range of 0.910 - 0.940 g/cm3. LDPE has a high degree of short and long chain branching, which means that the chains do not pack into the crystal structure as well. It has therefore less strong intermolecular forces as the instantaneous-dipole induced-dipole attraction is less. This results in a lower tensile strength and increased ductility. LDPE is created by free radical polymerization. The high degree of branches with long chains gives molten LDPE unique and desirable flow properties. LDPE is used for both rigid containers and plastic film applications such as plastic bags and film wrap.

See below for upcycling techniques.

[edit] Upcycling HDPE/LDPE

HDPE and LDPE can be easily upcycled due to their ability to bind to itself at a high temperature. This means that plastic shopping bags from stores can be easily bound together to form a thicker and much stronger sheet of plastic that is still easily cuttable and sewable.

[edit] Binding HDPE/LDPE

This process involves layering thin plastic bags so that they are at least 8 layers thick and heating them to a high temperature. To do this, follow these steps:

• One

Cut the plastic into a square sheet and either layer multiple bags atop each other or fold one bag several times until it is eight layers thick, making sure any ink printed on the bag is facing towards the center of the layers.

• Two

Sandwich the layered plastic between two sheets of parchment paper.

• Three

Heat an iron to a temperature setting between rayon and polyester. Press the iron onto the parchment paper and iron the plastic layers as though you are ironing a shirt. Be sure to iron all of the plastic and pay special attention to the edges. Remove the iron and wait a few seconds for the plastic to cool.

The plastic should now be one solid sheet. If there is any peeling or any indication that not all of the plastic is bound together then simply repeat the process. Expect the plastic to shrink by 50%

You now have a plastic sheet that can be made into a number of different products such as reusable shopping bags, waterproof laptop sleeves, or messenger bags. It can be used pretty similarly to cloth, an upcycled waterproof cloth!

Here's a link to Make: Magazine's well documented guide to making a messenger bag using this material.

[edit] External Links

Make: Magazine's guide to making a messenger bag using upcycled plastic bags