Polyethylene or PE is a polymer obtained by polymerization of ethylene. It is a colorless, odorless, waxy solid that is the most common plastic material.

It has the advantage of being resistant to oxidation, temperature variations, easy to transform and to handle. Polyethylene can be dyed in the mass and can be smooth or rough.

Polyethylene (PE) is used for example in the manufacture of bags, films, bottles, cans, fuel tanks for automobiles…

The chemical analysis and physical characterization of polyethylene is an essential step for the control of its transformation and the prediction of possible failures. It allows to :

• Determine the chemical composition of a polyethylene
• Carry out a physico-chemical and thermal characterization of the polyethylene material: density, molecular weight, thermal analysis, calorimetric analysis of polyethylene…
• To identify the nature of a polyethylene and its additives
• Determine its mineral load (chalk, talc…)
• Characterize a failure (adhesion defect, delamination, inclusion…) present on the polyethylene
• To check the conformity of the finished product based on Polyethylene

Polyethylene is a member of the important family of polyolefin resins. It is the most widely used plastic in the world, being made into products ranging from clear food wrap and shopping bags to detergent bottles and automobile fuel tanks. It can also be slit or spun into synthetic fibres or modified to take on the elastic properties of a rubber.

Major polyethylene compounds

Low-density polyethylene

LDPE is prepared from gaseous ethylene under very high. These processes yield a polymer structure with both long and short branches. Because the branches prevent the polyethylene molecules from packing closely together in hard, stiff, crystalline arrangements, LDPE is a very flexible material. Its melting point is approximately 110 °C (230 °F). Principal uses are in packaging film, trash and grocery bags, agricultural mulch, wire and cable insulation, squeeze bottles, toys, and housewares. The plastic recycling code of LDPE is.

Ultrahigh-molecular-weight polyethylene

Linear polyethylene can be produced in ultrahigh-molecular-weight versions, with molecular weights of 3,000,000 to 6,000,000 atomic units, as opposed to 500,000 atomic units for HDPE. These polymers can be spun into fibres and then drawn, or stretched, into a highly crystalline state, resulting in high stiffness and a tensile strength many times that of steel. Yarns made from these fibres are woven into bulletproof vests.

Linear low-density polyethylene

LLDPE is structurally similar to LDPE. It is made by copolymerizing ethylene with 1-butene and smaller amounts of 1-hexene and 1-octene, using Ziegler-Natta or metallocene catalysts. The resultant structure has a linear backbone, but it has short, uniform branches that, like the longer branches of LDPE, prevent the polymer chains from packing closely together. Overall, LLDPE has similar properties to LDPE and competes for the same markets. The main advantages of LLDPE are that the polymerization conditions are less energy-intensive and that the polymer’s properties may be altered by varying the type and amount of its chemical ingredients. The plastic recycling code of LLDPE is.

High-density polyethylene

HDPE is manufactured at low temperatures and pressures, using Ziegler-Natta and metallocene catalysts or activated chromium oxide (known as a Phillips catalyst). Products include blow-molded bottles for milk and household cleaners; blow-extruded grocery bags, construction film, and agricultural mulch; and Ainjection-molded pails, caps, appliance housings, and toys. The plastic recycling code number of HDPE is