Stiff blue plastic sheet?

[Andrew TinsleyParticipant @andrewtinsley63637]

I have a Mirror dinghy, for the grandchildren to sail. Its cover is made of blue plastic material of some sort. When new it was quite supple. Now it is as stiff as a board! I understand well enough that ultra violet is responsible for degrading many plastics. The thing that puzzles me is that most similar looking plastics go brittle and split quite easily. This cover is simply very stiff and shows no sign of splitting or disintegration.

Anyone any ideas as to what the material is? Apart from being somewhat awkward to refit, it seems to be fine for keeping water out. Pity I can’t find a process to soften it a little!!

Andrew.

[Robert Atkinson 2Participant @robertatkinson2]

Probably loss of plasticiser rather than UV damage.
May well be PVC. That is easy to identify by burning a tiny sample. See this guide from The Welding Institute:

https://www.twi-global.com/technical-knowledge/faqs/faq-how-using-simple-manual-tests-can-i-identify-an-unknown-plastic-material

Robert.

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