Well one of the images is labeled plate mail. but whatever.
Plate mail is more of a style and construction than a material. Plate armors could be made out of chitin, like the exoskeleton of an umber hulk, for instance. Any sufficiently hard and durable material could be made into plate mail.
Of course this doesn't apply here, but modern technology could make plate armor out of a synthetic material like PVC, Kevlar or fiberglass reinforced composites.