Note: The Xenoy grade 2730U, which did relatively poorly in this particular set of tests reported below, has been selected for the SCIGN radome on the basis of its superior viscosity characteristics. It is more feasible to make the dome by injection molding using this grade of Xenoy than it would be using the significantly more viscous Xenoy grades we tested, or either of the Lexan grades we tested. We had earlier ruled Geloy out from further consideration because we recognized it to be the most viscous of all the plastics we tested. (KWH 4/20/98)

We can't claim much here, but we have tried to simulate what sort of
damage might be inflicted on the candidate plastics, and there are
differences though perhaps not as much as I would have expected.
The Xenoy, once brutalized, shows the results of the effort.  The
Lexan is really resistant to deformation.

[plastic.samp.tst]                                               3/17/98

 PLASTIC SAMPLE TESTING

3/13/98:  Simple pull and pry testing in two locations, in 0.125" samples
provided by Ken Hudnut in February 1998.

Test #1:____________________

Drilled clearance holes for #10 screws near corner (1/2") and then
countersunk for flat-head screws. A 90 degree countersink was used, which is
not the correct angle for flat-head screws, and the operation left chatter
marks. In addition, the depth wasn't well controlled.  With sample screwed
to aluminum test fixture we tried to pull screw through sample by pulling
up on opposite corner.

Sample Lexan 143 -- couldn't pull screw through sample. Only damage was
small mark in counter sink from screw edge.

Lexan HF1130 -- same as sample #1.

Xenoy 2230EU -- screwed through easily.  Plastic stayed deformed (bent).

Xenoy 2730EU -- screw pulled through easily. The hole ripped and the
plastic deformed.

Xenoy 1731 -- screw pulled through easily without leaving as much
deformation as in #3 and #4.

Test #2:____________________

Drilled #10 clearance hole and countersunk with proper angle 82 degree
countersink till screw head was just flush. Tried to pull apart and then
tried to pry plastic off test fixture with large screwdriver.

Sample

Lexan 143 -- couldn't pull screw through. It did leave mark in
countersink. (This was true on all second tests.) Not much permanent
deformation.

Lexan HF1130 -- same as #1.

Xenoy 2230EU -- couldn't pull or pry screw through sample. Less
deformation then #4 and more than #5.

Xenoy 2730EU -- couldn't pull or pry screw screw through sample. This
sample deformed the most of all tested samples.

Xenoy 1731 -- couldn't pull or pry screw through sample. This deformed
the least of the Xenoy samples.

For reference and comparison to other reports:

Samples Used for Testing:

Number	Type	Grade	
------	-----	------	
1. 	Lexan	143 	
2. 	Lexan	HF1130	
3. 	Xenoy	2230EU	
4. 	Xenoy	2730EU	
5. 	Xenoy	1731	
6. 	Geloy	XP2003	
7. 	Geloy	XP2003	

These reports are preliminary and have not been reviewed for conformity with U. S. Geological Survey editorial standards. Any use of trade, product, or firm names is for descriptive use only and does not imply endorsement by the U. S. Government.

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