White patches on clear parts

[walkingcube]

Hi folks,

I'm making some thin-walled containers via stretch blow moulding out of clear PEBA and Nylon 12. On some runs, some of the parts have silvery-white patches on them, especially around bends and edges (ex: where the side wall meets the bottom).

Any ideas on what might be the cause?


Thanks a lot!

 

[SteveMartin]

Some clear plastics will turn opaque (usually white) under stress. Maybe the molding stresses in these areas are too high. I would expect the patches to be on all runs if this were the case though, but I don't have another thought.