Thermal Properties

Vectran™ HT shows robust performance in a broad spectrum of responses to thermal loading.These responses aresummarized below and in Table 3:

• Good LOI (equivalent to aramids) and low smoke generation

• Low thermal shrinkage (hot air,boiling water and laundry)

• No dripping in vertical flammability tests

• Good strength retention after hot air and radiant energy exposures

• Low,negative coefficient of thermal expansion

• Excellent property retention in a broad temperature range

• No measurable volatile condensable mass (VCM) and 0.3% maximum weight loss
(TML or TWL) in testingfor aerospace applications
(see also “Offgassing/Outgassing”)

Mechanical property retention during or after thermal exposure is a key concern in many applications. Mostcommonly, high temperatures are encountered during a downstream processing step, such as coating orlaminating. Care must be taken to minimize line tensions or other mechanical loads during the hightemperature step. Figure 3, which describes Vectran’s tensile strength at temperature,should be used as areference in selecting process conditions. For high temperature processing at low mechanical load, Figure 4 shows that Vectran™ will have excellent strength after processing, in fact, superior to aramids.

For end uses that call for longterm or cyclic thermal exposure, Vectran™ can also offer increased productlifetimes. Figure 5 illustrates that Vectran™has little to no strength loss in cyclic exposures to 120°C. Vectran’sresistance to cyclic thermal loads is confirmed at higher temperatures in Figure 6, which also illustrates Vectran’s superiority to aramids in this respect. Note that the aramid in Figure 6 suffered 30% strength lossin roughly a dozen 8-hr cycles, or 4 days of exposure (in total). Similar trends are observed when Vectran™ isheld at 250°C continuously (Figure 7) and after 120°C steam exposure (Figure 8).

Vectran™ fiber's performance at low temperature was evaluated by ILC Dover during the design of the airbagsystem for the 1997 Mars Pathfinder mission.ILC reported that Vectran™ actually increased in strength in testsat -62°C,leading to its selection for the airbag fabric and external assembly tendons (Development andEvaluation of the Mars Pathfinder Inflatable Airbag System, D.Cadogen et al, ILC Dover,Inc., 49th International Astronautical Congress,1998.) This distinguishing characteristic of Vectran™ is shown in Figure 9.

Vectran™ has a low,negative coefficient of thermal expansion (Table 5). This is particularly beneficial fordimensional control of composites. Thermal conductivity properties are given in Table 6.