Question

In addition to LDPE and HDPE, polyethylene is manufactured as MDPE and LLDPE. Use the Internet to find out about these and other types of polyethylene. How do their properties differ? Explain

Answer 1

there are many kinds of polyethylene among them important are  

LDPE (Low-density Polyethylene): 1. Density is 0.910-.940 g/cm³

2. It has high degree of long-chain branches

3) LDPE has lower tensile strength compare with LLDPE as it does not pack into the crystal structure due to high degree of long chain branches as well. It has, therefore, less strong intermolecular forces as the instantaneous-dipole induced-dipole attraction is less.

4) it is made by free radical polymerization

5) used for rigid containers and plastic films

HDPE (High-density Polyethylene)

1.Density is 0.941 g/cm3

2 it has low degree of branches

3.HDPE has higher tensile strength in which mostly linear molecules pack together well, so intermolecular forces are stronger than in highly branched polymers.

4. manufactured by chromium/ silica, Ziegler Natta Catalysts ...

5. used in product and packaging such as detergent bottles, Milk jugs, and water pipes......

MDPE (Medium density polyethylene)

1) Density is 0.926-.940 g/ cm3

2) can be produced by chromium/silica catalysts, Ziegler-Natta catalysts, or metallocene catalysts

3)it is good to shock resistant

4) used in gas pipes, shrinks, carrier bags.......

LLDPE (linear low-density polyethylene)

1) Density is 0.915-0.925 g/cm3

2)it is a linear polymer with short branches

3)it is higher in tensile strength when compare with LDPE

4) can be produced by  copolymerization of ethylene with short-chain alpha-olefins

5)used in product and packaging particularly bags and sheets cable covering, toys, lids, buckets etc....