Development of materials to improve flame resistance of elastic elastomeric fibers is discussed. Two approaches, synthesis of polyether based urethanes and modification of synthesized urethanes with flame ratardant additives, are described. Specific applications of both techniques are presented

Howarth, J. T.

Massucco, A. A.

English

NASA Technical Reports Server

September 1972	 B72-10005 
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NASA TECH BRIEF 
Manned Spacecraft Center	
-4r 
NASA Tech Briefs announce now 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, Springfield, 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. 
Flame Resistant Elastic Elastomeric Fibers 
The problem: 
To improve the flame resistance of the elastic elasto-
meric fibers (flexible urethanes), while maintaining good 
strength, elongation, recovery, and modulus. 
The solution: 
Two approaches were successful: synthesis of poly-
ether based urethanes from halogenated urethane mono-
mers, and modification of synthesized urethanes with 
flame-retardant additives. 
How it's done: 
Flame retardant polyurethane structures were syn-
thesized from brominated polyesters derived from aro-
matic polyols and dibasic acids. The products from this 
process exhibited flame resistance in atmospheric envi-
ronments with oxygen contents ranging from that of air 
to 100 per cent. 
The most promising composition in this category 
consisted of a brominated neopentyl glycol which was 
treated with toluene diisocyanate and used as a con-
ventional diisocyanate in conjunction with hydroxyl-
terminated polyethers or polyesters. The elastomeric 
urethanes thus derived contained about 10 per cent 
bromine by weight. They would not burn in air, had an 
oxygen index of approximately 25 (see note 1), and ex-
hibited tensile strength values of approximately 34x106 
N/rn2 (5000 psi) at 450 per cent elongation. 
Aromatic halide additives have been found to be the 
most efficient flame retardants for urethanes, and the 
most effective of these were the bromide compounds. 
Hexabromobenzene in conjunction with trisbromo-
chloropropyl phosphate (in the ratio 7:3) was an effec-
tive flame retardant additive for flexible urethane. Hexa-
bromobenzene has a high melting point and good ther-
mal stability. Trisbromochloropropyl phosphate provided
some plasticizing effects to the polymer in addition to 
imparting flame resistance. The physical properties of 
the modified polyurethane were directly proportional to 
the additive present. The oxygen index was directly 
proportional to the total halogen in the system. 
Fluorinated elastomer (in combination with hex-
abromobenzene and trisbromochloropropyl phosphate) 
was also found to be an effective additive to other flame 
retardants. The combination resulted in better physical 
properties and flame retardancy at the same halogen con-
tent than hexabromobenzene and trisbromochloropropyl 
phosphate alone. 
Elastomeric fibers prepared from these compositions 
exhibited a greater degree of flame retardancy than 
available in commercial products. However, improve-
ment of the physical properties of these fibers is neces-
sary. The flame resistant fibers have potential industrial, 
commercial, and household applications in the reduc-
tion and prevention of fires and fire hazards. Such fibers 
may be manufactured into drapes, carpeting, bedding, 
and upholstery and may find applicability in the manu-
facture of suits for firemen. 
Notes: 
1. The oxygen index of a material is defined as the per-
centage concentration of oxygen in a mixture of 
oxygen and nitrogen at atmospheric pressure that will 
support sustained combustion of the material. 
2. The following documentation may be obtained from: 
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.95) 
Reference: NASA-CR-115227 (N72-28568). 
Development of a Flameproof Elastic Elasto-
meric Fiber. 
(continued overleaf) 
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.
.
https://ntrs.nasa.gov/search.jsp?R=19720000005 2020-03-17T03:20:52+00:00Z
Patent status: 
Inquiries concerning rights for the commercial use 
of this invention should be addressed to: 
The Patent Counsel 
Manned Spacecraft Center 
Code AM 
Houston, Texas 77058 
Source: John T. Howarth and Arthur A. Massucco of

Arthur D. Little, Inc. 
under contract to
Manned Spacecraft Center
(MSC-1 3923-4) 
I 
B72-10005	 Category 04


Flame resistant elastic elastomeric fibers

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