Chemical “upcycling,” or converting plastics into higher-value products, to the left. Materials that repair damage and restore themselves to the right. Straight ahead: fibers that can be woven into fabrics and used as microphones or loudspeakers. Such was the varied innovation that crowded MIT’s Morss Hall on Polymer Day 2023. Sixty-four teams from schools throughout the Northeast and beyond presented research ahead of a poster contest — the most since the event started in 2013. “We were almost running out of space in Morss Hall,” says Eric Lee, a graduate…