Effects of heat radiation to textiles

[Martti]

The Finnish Defence Forces along with VTT Technical Research Centre of Finland conducted a series of experiments in 1983 to find out the maximum amount of heat radiation that some textiles and clothing items can be subjected to without completely destroying them. I find the information they gathered rather interesting to our purposes as often one has to spend considerable amount of time near a fire during winter time.

I'm not going to reproduce the original 52 page research paper here but I'll try to find the most interesting textiles and items and reproduce the findings. If you thing I'm missing something, please post your question here on this thread. The materials were tested under 5, 10, 20 and some also under 40 and 60 kW/m² of heat radiation. The first rating corresponds roughly to 100 - 200°C depending the distance from the source, the second one to 200 - 300°C and the last ones from 300 to 1200°C. The average solar radiation to the surface of Earth is around 1 kW/m² and 4 kW/m² is enough to cause second-degree burns to the skin within 30 seconds of exposure.

Some of the tested fabrics were:

1) 370 g/m² 100 % CO sateen with camouflage pattern. Obtains a brown tint at 20 kW/m².
2) 370 g/m² 70 % CO/30 % PE with camouflage pattern. A brown tint at 10 kW/m².
3) 550 g/m² 85 % WO/15 % PA brushed twill. A brown tint at 10 kW/m². Charring and shrinking at 20 and 40 kW/m².
4) 100 % WO sweater. A brown tint at 10 kW/m². Charring at 20 and 40 kW/m².
5) 100 % PE pile lining. Shrinked at 10 kW/m². Burnt through at 20 kW/m².
6) 100 % PE wadding. Shrinked at 10 kW/m². Melted at 20 kW/m².
7) Tanned leather boot. Shrinking at 5 and 10 kW/m². Shrinking and tearing at 20 kW/m². Broke down at 40 kW/m².
8) Vulcanized natural rubber boot. Some surface damage at 10 kW/m². Charring at 20 kW/m².
9) 330 g/m² 100 % AR. Hardens at 20 kW/m². Shrinking, charring and tears at 60 kW/m². The only one capable of withstanding 60 kW/² for some time.

When comparing fabrics of same thickness, wool ranks the best after aramid and polyester is the worst. However a thick and dense cotton fabric can be better than a thin wool one as we can see in the case of the wool sweater. Rubber is considered better than leather. In previous Finnish tests a 100 % wool fabric of similar weight than the blend fabric in this test was found to withstand the effects of napalm for some time.

 

[udamiano]

very informative, A similar test was done on the UV and severe cold degradation of materials in arctic conditions again in the early 80s with many man-made material suffering under prolong UV exposure, which is why many of the expedition type tents especially the extreme types still being made from materials like ventile. while many nylon based materials simply began to degrade and become brittle at temperatures around the -50 range.
If I can find the original research link, ill post it up

Thanks for the post Martti

 

[Hoodoo]

very informative, A similar test was done on the UV and severe cold degradation of materials in arctic conditions again in the early 80s with many man-made material suffering under prolong UV exposure, which is why many of the expedition type tents especially the extreme types still being made from materials like ventile. while many nylon based materials simply began to degrade and become brittle at temperatures around the -50 range.
If I can find the original research link, ill post it up

Thanks for the post Martti

I spent the summer back around 2000 living in a nylon tent pitched in an open meadow and by the end of the summer you could easily shred the nylon in your hands. However I had a screen house pitched at the same site that had a polyester ceiling and it held up well, which is why many good tents today have a polyester fly. Prolonged exposure to UV is pretty rough on nylon tents.

 

[udamiano]

yes, nylon takes a beating from UV. When i used to go into the Arctic north, we always used cotton canvas, or similar with heaters, the covers for the vehicles were made from heavy grade nylon and within a week would fall to bits, same with the storage boxes we used, they would turn brittle and just crumble; in the end we started using wooden crates and canvas covers.

 

[Martti]

I think nylon 6,6 is superior to "regular nylon" in the case of ultraviolet resistance.

 

[udamiano]

A lot of the extreme nylon tents have silver added to the weave to stabilise the UV problem. and have 40D outers and 40D inners, thus the reason for the very high cost.
Still much prefer the ventile ones though

 

[rg598]

That is very interesting. Thank you for posting it. I expected much more of a difference. From what you posted it seems that most materials suffer damage at about the same point (10-20 kw/m^2). From all the talking we have done of wool being fire resistant, I expected it to outperform the other materials by quite a bit. Do you have the source of the survey? It would be great to look at the details.

 

[Martti]

From all the talking we have done of wool being fire resistant, I expected it to outperform the other materials by quite a bit.

The materials were tested only for their resistance against heat radiation and not for conductivity by other means. If you throw cotton and wool fabrics into fire, the first ones will probably caught fire much faster than these tests would indicate. I think I have exact numbers also for the previous napalm test somewhere.

Do you have the source of the survey? It would be great to look at the details.

The name of the study is Säteilyn vaikutus Puolustusvoimissa käytettyihin vaatetusmateriaaleihin by Scientific Advisory Board for Defence (MATINE) and VTT Technical Research Centre of Finland. The only copy I have found thus far is at a folder at the Finnish National Archive.

 

[rg598]

That's great. Thank you.