Figure 4.
Scanning electron microscopy (SEM) images of structure of PUs and PU composites (×100 magnification): (a) 9, (b) 12, (c) 10, (d) 13, (e) 11, (f) 14.
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.