Fig. 8.
Optical micrographs of cross-sectioned rigid polyurethane foams (×4 magnification): a B1 (100:0), b HF1 (70:30), c HF2 (60:40) and d HF3 (50:50)
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.