Fire-resistant and nonsmoking foam can be prepared in desirable density range of 24 to 50 kg/cu m by controlled thermal crosslinking of polybenzimidazole prepolymer. Reproducible foams of specific density can be produced by controlling volative content and melting temperature of prepolymer

Deland, C.

Kourtides, D.

Milligan, R.

Parker, J. A.

English

NASA Technical Reports Server

r	 - April 1975	 B75-10056 
•	 NASA TECH BRIEF 
Ames Research Center
 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, SpringtieJd, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Low-Density Polybenzimidazole Foams for Thermal
Insulation and Fire Protection 
I.
The thermophysical properties of polybenzimid-
azole foams make them particularly useful as a ma-
terial for construction of wall structures, especially 
interior walls in aircraft. However, as prepared by the 
usual processes, the foams are not of the desirable 
light weight, i.e., their density falls in the range of 
400 to 800 kg/M3. Carbon or silica microballoons 
have been incorporated in the foams during manu-
facture to reduce weight, but a density lower than 
160 kg/M3 has not been achieved. 
A fire-resistant and nonsmoking foam can be pre-
pared in the desirable density range of 24 to 50 
kg/M3 by controlled thermal crosslinking of poly-
benzimidazole prepolymer which has been prepared 
by the reaction of diphenyl isophthalate with 3,3',4,4'-
tetraaminobiphenyl monomer containing 95.0 to 
97.6% theoretical orthodiainino groups. During the 
thermal crosslinking of the prepolymer, particularly 
in the temperature range of 4570 to 550°K, volatile 
substances released during polymerization (phenol 
and water) cause foaming. Reproducible foams of a 
specific density can be produced by controlling the 
volatile content and the melting temperature of the 
prepolymer. 
The polymer is heated to the maximum cure 
temperature of 740°-800°K in order to obtain the 
optimum thermophysical properties; the final product 
has good cell quality, resilience, and low friability. 
The foam may be reinforced by blending certain
fibers with the prepolymer; the fiber additives in-
crease the density of the foam, but may reduce the 
effective thermal conductivity by reducing the cell 
size. 
Notes: 
Requests for additional information may be di-
rected to: 
Technology Utilization Officer 
Ames Research Center 
Moffett Field, California 94035 
Reference: TSP 75-10056 
Patent status: 
This invention is owned by NASA, and a patent 
application has been filed. Inquiries concerning non-
exclusive or exclusive license for its commercial de-
velopment should be addressed to: 
NASA Patent Counsel 
Mail Code 200-1 IA 
Ames Research Center 
Moffett Field, California 94035 
Source: Demetrius A. Kourtides and John A. Parker 
Ames Research Center

with Chadwick Delano and Robert Milligan of

Whittaker Corporation
under contract to

Ames Research Center
(ARC-10823) 
Category 04 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
S
https://ntrs.nasa.gov/search.jsp?R=19750000056 2020-03-19T20:05:28+00:00Z


Low-density polybenzimidazole foams for thermal insulation and fire protection

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server