ポリアクリロニトリルでしょう
poriakurironitorirudeshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of ポリアクリロニトリル

1. Polyacrylonitrile, probably.; It will likely be polyacrylonitrile.

Polite
Presumptive
Conjecture
Chemistry