THE EFFECTS OF ABRASION THE EFFECTS OF ABRASION ON A FABRIC S RESISTANCE TO PERMEATION AND PENETRATION
Fabric abrasion can seriously undermine the protective effi ciency of a fabric. For example, fabrics that rely on thin coatings (please see Annexe 3) or have an inherently weak physical structure can quickly and easily lose their resistance to penetration under operating conditions. This loss of protection is particularly dangerous because in many cases the damage is not readily apparent or is not discovered until after an exposure occurrence. The susceptibility of some fabrics to a severe deterioration in penetration resistance following abrasion can be seen in the following hydrostatic pressure test. Hydrohead is an indicator for liquid barrier performance. It determines the resistance of a fabric to water penetration under slight pressure.
Prior to the abrasion test Microporous Film offers the best resistance to liquid pressure. But after just 10 cycles of abrasion, its performance takes a spectacular dive, while SMS is less affected but starts from a much lower performance level, and Tyvek® continues to protect. After abrasion, Tyvek® penetration performance is the highest.
200
180
160
140
120
100
80
60
40
20
0
120 112
180
16
81 80
Hydrostatic Head remains >1m after 10 cycles
H ei
gh t o
f w at
er c
ol um
n on
fa br
ic (c
m )
Tyvek® MPF SMS
Based on mean value N=144 specimens tested. Source: Independent Institute.
Before abrasion After abrasion
THE EFFECTS OF ABRASION ON A FABRIC S RESISTANCE TO PERMEATION
The illustrations illustrate how the homogenous structure of a fabric such as Tyvek®, where the barrier properties are a function of the inherently tough material itself rather than a thin coating or layer, offer much superior and more reliable permeation resistance under under working conditions and over prolonged wear times compared to similar laminated products.
500
450
400
350
300
250
200
150
100
50
0
480
270
Tyvek®
31 0
Proshield® 30 (MPF 1)
6 0
MPF 2
0 0
Proshield® 10 SMS
N or
m al
iz ed
b re
ak th
ro ug
h tim
e at
a p
er m
ea tio
n ra
te o
f 1 .0
μ g/
cm ²/m
in in
m in
ut es
Source: Independent Institute.
Before abrasion After abrasion
ANNEXE 4: FABRIC TESTING
Figure 6. Liquid barrier performance. Hydrostatic Head: EN 20811. Before and after 10 cycles of abrasion (EN 530 - Method 2).
Figure 7. Permeation resistance to sulfuric acid 18%.
Annexe 462