Weather Damage

Fig. 1. Time profile of the observed weathering damage over the past 200 years...

Alkane hydrocarbons are often used as fuels to provide heat and, sometimes, light. The smudge pots shown on the left produce heat that helps prevent cold-weather damage to citrus crops. The gas lantern gives off light, and the gas-log fireplace provides both heat and light. 

A nonconcentrating solar heat collector consists of a transparent cover, an absorber, tubes or ducts for the heat transport fluid, and an insulated case that limits the thermal losses to the environment. The collector cover serves several important functions it permits the passage of the solar radiation, prevents loss of heat, and protects the absorber from mechanical and weathering damage. The cover is selected for the highest transmittance of solar radiation and the lowest transmittance of the infi ared reradiated from the absorber. Polymeric materials have a low absorptivity for solar radiation and the absorptance can be decreased, compared to glass, by using thinner sheets or films. 

The ravelling test, carried out in accordance to ASTM D 7196 (2012), is useful for classifying the curing and formulation of cold asphalt samples through ravel testing of compacted specimens. This performance test should be used to rank the mix conditions and approximate curing time for return to traffic and resistance to weather damage. 

From the point of weathering damage the most important of the internal chromophores absorbing in the near ultraviolet are those containing oxygen (C=0, OOH), since they are most likely to be formed in polymers degraded in the atmosphere. 

Well matured, practically free from weather-damaged kernels... 

The number of vessels suffering weather damage is comparatively low as seen in the graph in Figure 2.5. Small vessels are particularly vulnerable to these accidents, especially when they go out further away from the coastline for their fishing operation (due to the reduced fishing opportunities in British waters). These small vessels will be working far offshore where they cannot withstand the severe weather and wave conditions that can occur unexpectedly. Heavy... 

Recently, market forces have combined to reduce the supply and increase the cost of linear sidechain dialkyl phthalate plasticizers. Diisodecyl phthalate (DIDP) is, in many ways, an attractive alternative to these linear plasticizers but questions remain about its effects on weathering properties of flexible PVC. This paper looks at the effects of using DIDP or blends of DIDP with linear phthalate in flexible PVC exposed to outdoor weathering. Degradation mechanisms and additive packages to limit weathering damage are also discussed. 

The QUV from Q-Lab Corporation is a fluorescent UV weathering tester based on the precept that, for durable materials, short-wave UV causes most weathering damage. 

The fluorescent UV weathering tester, on the other hand, does not attempt to reproduce sunlight, just the damaging effects of sunlight that occur from 300 nm - 400 nm. It is based on the concept that, for durable materials exposed outdoors, short-wave UV causes the most weathering damage (Figure 1). 

Most weathering damage is caused by three factors light, high temperature, and moisture. Any one of these factors may cause deterioration. Together, they often work synergistically to cause more damage than any one factor alone. 

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