Thermoforming Polypropylene: Syntactic Foam vs. Solid Polymer

We’ve had a lot of discussions over the years with plastics processors about thermoforming polypropylene (PP) cups. PP is susceptible to scratching, especially with deep draw parts such as drink cups. While syntactic foam has become the preferred plug assist material, the high glass content can cause issues with scratching. Therefore, solid engineered thermoplastics such as polyetheretherketone (PEEK) and polyetherimide (PEI) are sometimes used as plug assists to minimize scratching in transparent PP parts. As we know, several other variables are at play in thermoforming and in the case of PP, sheet temperature can never be overlooked.  Just a few degrees can be the difference between a beautiful, high-clarity part and an imperfect one with scratches.

Digging into the archives, we published a paper showing the results of tests comparing our HYTAC materials with solid polymers. We’re making it available again here via a republished blogpost in case you missed it a few years back.

As always, we’d love to hear your thoughts. Do you have challenges with PP? What steps have you taken to improve the process?