Description
Polypropylene (PP) in their natural state (without additives) are inherently unstable and degrade when exposed to oxygen. The polymers change color to yellow-brown and begin to flake away until the material becomes useless.
When PP degrades, chain scission takes place. The physical properties of the polymer deteriorate and its average molecular weight (chain length) decreases, melt flow rate increases and a powdery surface eventually forms. Polymer degradation is a natural phenomenon that cannot be totally stopped.
Instead, resin producers seek to stabilize the color and physical properties of their polymers for a reasonable life span, which varies depending on the end-use requirements.
Polypropylene can be processed by virtually all thermoplastic-processing methods. Most typically PP products are manufactured by:
- Extrusion Blow Molding,
- Injection Molding, and
- General Purpose Extrusion
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