Experienced truckers are well aware that extreme cold weather and truck tarps do not necessarily play well together. The colder the temperature, the more brittle tarp fabrics become. Tarps tend to tear or break with just the slightest amount of pressure in extremely frigid conditions. But why does this happen?
To someone not familiar with the science, it may seem strange that a poly or vinyl tarp can hold up very well in hot summer weather but then become fragile in the dead of winter. But knowing the science suddenly clears things up.
The Nature of Plastics
Vinyl, polyethylene, and polypropylene are all plastic polymers that can be used for multiple applications. Some finished materials are engineered to be extremely rigid while others are a lot more flexible. The flexible plastic polymers owe their flexibility to something MIT calls ductility. What is ductility? It is the ability of the molecules in a polymer to stretch.
Plastic polymers consist of chains of molecules bound together to form a particular substance. If it helps, think of a standard chain-link made of rubber rather than steel. The rubber link can be stretched fairly easily while a steel link cannot. The molecule chains of plastic polymers are similar to a rubber chain-link except on a molecular scale.
The thing to understand about plastic polymers is that the molecule chains only remain flexible in warm temperatures. The colder it gets, the less flexible the chains become. It is possible, under extremely cold conditions, for molecule chains to be frozen in place. When this occurs, a vinyl or poly material becomes extremely fragile. But even if the chains do not freeze, vinyl and poly materials do get more brittle as the temperature falls.
Wind Adds to the Problem
Cold temperatures automatically reduce the flexibility of vinyl and poly tarps by reducing the ductility of plastic polymer chains. When you throw in the wind caused by a truck driving down the highway, conditions deteriorate even further. It’s a matter of the wind displacing surface heat.
Although wind chill does not apply to non-biological materials, the wind chill principal is similar to what happens with truck tarps when exposed to cold. The wind displaces any surface heat a vinyl or poly tarp may hold, thus causing a further reduction in temperature. Any heat that might be absorbed by sunshine will also be displaced by the wind.
As you can see, combining already cold temperatures with the wind of highway travel exposes vinyl and poly tarps to the kinds of conditions that would significantly reduce ductility. The more drastic the combination of cold and wind, the less flexible a tarp is.
Tarp Maintenance in Winter
Now that you know the science behind brittle truck tarps, the obvious thing to do is to take extra good care of your tarps during the winter months. We highly recommend being more careful when applying tarps in cold and windy conditions so as to avoid tears and rips. Make sure to use edge and corner protectors. The right combination of cold and wind could cause a sharp edge to rip right through a cold tarp.
Tarping loads indoors would be ideal as the temperatures will be warmer and it is easy to apply the tarp by oneself. If that’s not possible, it’s always a good idea to enlist any available help to get tarps on and secured as quickly and safely as possible. Also avoid standing on top of a load after a tarp has been applied because cold tarps can be slippery.
So now that
1. MIT – http://engineering.mit.edu/ask/why-do-plastics-get-brittle-when-they-get-cold