Polymer crystallinity

We don't normally think of polymers as crystalline. However, they can be highly crystalline depending on structure and processing conditions. Simple linear polymers tend to have high crystallinity, particularly if they are allowed to cool slowly from the melt. Polymers often have portions of their chains that fold up into crystalline sections connected by otherwise amorphous polymer regions. Polymers that are crystalline can even show x-ray diffraction peaks. Density measurements can be a useful tool to determine fraction crystallinity since dense regions will be more dense than amorphous regions. However, this requires know the density of fully crystalline and fully amorphous versions of the polymer.