24-10-2012, 11:07 AM
Vectran Fiber Time-Dependent Behavior and Additional Static Loading Properties
ABSTRACT
Vectran HS appears from literature and testing to date to be an ideal upgrade from Kevlar braided cords for many
long-term, static-loading applications such as tie-downs on solar arrays. Vectran is a liquid crystalline polymer and exhibits
excellent tensile properties. The material has been touted as a zero creep product. Testing discussed in this report does not
support this statement, though the creep is on the order of four times slower than with similar Kevlar 49 products. Previous
work with Kevlar and new analysis of Vectran testing has led to a simple predictive model for Vectran at ambient conditions.
The mean coefficient of thermal expansion (negative in this case) is similar to Kevlar 49, but is not linear. A positive transition
in the curve occurs near 100 C. Out-gassing tests show that the material performs well within parameters for most space flight
applications. Vectran also offers increased abrasion resistance, minimal moisture regain, and similar UV degradation. The
effects of material construction appear to have a dramatic effect in stress relaxation for braided Vectran. To achieve the
improved relaxation rate, upgrades must also examine alternate construction or preconditioning methods. This report
recommends Vectran HS as a greatly improved replacement material for applications where time-dependent relaxation is a
major factor.