2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
Figure 2: Skin Model tests on ballistic protective compounds: Relative humidity rh inside the
microclimate after a simulated vaporous sweat impulse as a function of time t.
Figure 3: Skin Model tests on ballistic protective compounds: Buffering capacity against
liquid sweat impulses Kf.
However, it should be mentioned that superabsorbent polymers also have some disadvantages
when used in a ballistic protective vest. They add extra weight, although this a maximal of
9%, they slightly increase thermal insulation, and SAPs may lead to a more pronounced postexercise
chill, because after getting wet, they hold the moisture for a long time and dry
slowly. Last but not least, SAP-compounds are stiffer than a cotton jersey.
DISCUSSION
Via adding superabsorbent polymers (SAPs), the moisture management properties of a
ballistic proof vest can be significantly improved in three ways: (1) The water vapour
absorbency is enhanced. (2) After a vaporous sweat impulse, the microclimate below the vest
stays dryer. (3) More liquid sweat is removed from the skin surface. Results obtained by the
Skin Model were validated by wearer trials with human test subjects. However, the
disadvantages of SAPs in ballistic proof vests are a slightly increased weight and thermal
insulation, a poorer post-exercise chill behaviour, and greater clothing stiffness.
206
rh / %
K f
90
80
70
60
50
40
30
20
1.0
0.9
0.8
0.7
E/5+CO
E/5+200Kb
E/5+400Kb
0 30 60 90 120
t / min
E/5+CO E/5+200Kb E/5+400Kb
sample