Polyurethane adhesive mixed to various proportions with milled glass fibers match the thermal characteristics of 2014-T6 aluminum at cryogenic temperatures

Helf, J. C.

Hill, W. L.

Matsuoka, T.

English

NASA Technical Reports Server

July 1972	 B72-10346 
.
	
NASA TECH BRIEF 
Marshall Space Flight Center 
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. 
Adhesive for Aluminum Withstands Cryogenic Temperatures 
The problem: 
The existing adhesives that are used for bonding parts 
to aluminum alloys at room temperatures are prone to 
failures at cryogenic temperatures. The reason for such 
failures has been a large difference in coefficients of 
contraction between the metal and the adhesive in 
cryogenic temperature ranges. 
The solution: 
Tests on a polyurethane adhesive which is mixed to 
various proportions with milled glass fibers have shown 
that it can match the thermal characteristics of 2014-T6 
aluminum at cryogenic temperatures. 
How it's done: 
Monostrairi specimens were fabricated which con-
sisted of a polyurethane adhesive system, 1% by weight 
of silane, and different experimental percentage quan-
tities of milled glass (length 1/32 inch or 0.79 mm) 
fibers. The quantity of milled fibers was varied from 15 
to 65% to determine their effect on the physical 
characteristics of the polyurethane adhesive. Samples 
were made of the 68.58-cm (27-inch) adhesive composite 
and were cured at room temperature for at least seven 
days prior to the tests. The samples were then tested 
down to 125K (-3000F) for coefficient of contraction 
(L/L, where L is the length of the sample), the tensile 
modulus (E), the ultimate tensile strength, and the per-
centage of elongation at failure. 
Results of these tests showed that, with 15% glass 
fibers, the coefficient of contraction from room temper-
ature to 125K was approximately 0.0072; with 65% 
glass fibers, however, the contraction was approximately 
0.0033. The tensile modulus at 125K varied from 7.38 x
10 9 to 11.73 x 10 9 N/rn2 (1.07 x 106 to 1.70x 106 psi) 
for 15 and 65% fiber content, respectively. The ultimate 
tensile stress at 125K varied from 75.90 x 106 to 10.01 
X 107 N/m 2
 (11000 to 14500 psi) and showed a 
slight increase toward the 65% fiber content. Percentage 
of elongation of the samples before the breakage 
varied from 1.22 to 0.72% with a slight decrease for 
larger proportion of fiber contents. 
Additional tests of the metal-to-metal lap shear 
strength performed on the polyurethane containing 30, 
50, and 65% of glass fibers were conducted at room 
temperature and 125K. Results revealed that the sample 
shear strength was 41.4 x 106 N/m2 (6000 psi) through-
out at 125K, which exceeded the 27.6 x 106 N/rn2 
(4000 psi) requirement. 
Shear strengths on all samples at room temperature 
exceeded the 6.9 x 106 N/rn2 (1000 psi) by 12 to 50%. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Code A&TS-TU 
Huntsville, Alabama 35812 
Reference: B72-10346 
Patent status: 
No patent action is contemplated by NASA. 
Source: W. L. Hill, T. Matsuoka, and J. C. Helf of

North American Rockwell Corp.

under contract to

Marshal} Space Flight Center

(MFS- 16848) 
/
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.
https://ntrs.nasa.gov/search.jsp?R=19720000345 2020-03-17T03:30:17+00:00Z


Adhesive for aluminum withstands cryogenic temperatures

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