Humidity's Effects on Cured Photopolymer Resin Epoxy Tensile Strength

From: Scott Ostrem (
Date: Mon Oct 13 1997 - 21:16:39 EEST

Does anyone have ANY data or experience(s) related to how different humidity
levels affect the tensile strength of Ciba-Geigy's Cibatool SL5180 Photopolymer
resin epoxy after it has cured? How about information related to similar
resin epoxies? 3D Systems was able to provide limited data related to
the tensile modulus versus the humidity environment, but they had no data
relating humidity and the tensile strength of the cured epoxy. A second
question - are there any sealants, paints, etc... that anyone would recommend
applying to the cured part to protect the part from the outside relative
humidity. (The facility we test in has side doors that stay open and allow
outside air in.) Is it true that Thompson's water seal may work? A third
question if anyone knows the answer - what is the bearing strength of the
cured SL5180 epoxy? I ask this question from the standpoint of, "What
kind of torque can be applied to tension fasteners that hold our SLA part

A little background: As a design engineer, I am currently designing a
10 inch inside diameter air flow control valve that we (Boeing Corporation)
plans to build and test in a cold flow propulsion test lab in St. Louis,
Missouri. Using an SLA part instead of a metal part will save a lot of
money, but the unknowns associated with pressurizing a Steriolithography
part in a fairly humid environment have many engineers worried. We plan
to make the valve out of Ciba-Geigy's Cibatool SL5180 due to its published
tensile strength and toughness, and we plan on using a large safety factor.
  What we don't know is how is the documented tensile strength of 6,000
to 6,300 psi affected by various humidity levels and exposure durations?
 Any information would be helpful.

Thank you.

Scott Ostrem
Boeing Corporation
MC S064-1225, Bldg 65, L3
P.O. Box 516
St. Louis, MO 63166-0516
(314) 233-5846
(314) 232-6054 (fax)

This archive was generated by hypermail 2.1.2 : Tue Jun 05 2001 - 22:40:32 EEST