Polimér: Béda antarrépisi

== Physical properties of polymers ==

Physical properties of polymers include [[degree of polymerization]] and [[molar mass distribution]].

 

=== Branching ===

 

Ethene, however, has no permanent dipole. The attractive forces between polyethylene chains arise from weak [[van der Waals force]]s. Molecules can be thought of as being surrounded by a cloud of negative electrons. As two polymer chains approach, their electron clouds repel one another. This has the effect of lowering the electron density on one side of a polymer chain, creating a slight positive dipole on this side. This charge is enough to actually attract the second polymer chain. Van der Waals forces are quite weak, however, so polyethene melts at low temperatures.

 

=== Polymer characterization ===