Crystalline Polymers

• Polymer chemists use the term crystalline to describe the areas in a polymer where the chains are packed in a regular way.
• Many polymers have a mixture of crystalline (ordered) areas and amorphous (unordered) regions.
• Amorphous regions have more freedom of movement as the chains are further apart.
• Any one polymer chain may be part of an amorphous region and a crystalline region.
• Spaghetti is a good representation of the different areas; when looking at the underside of a clear glass bowl containing spaghetti some regions of the spaghetti are grouped together in a regular layout, while other regions are totally mixed up.
• Polymers with regular chain structures (e.g. isotactic polypropene) and without bulky side groups or extensive chain branching are the most likely to form crystalline regions.
• The percentage of crystallinity in a polymer is important in determining its properties; the more crystalline a polymer is, the stronger and less flexible it becomes.

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