Weathering surface sensitivity

Vinyls Vinyl chloride co-polymer resins were developed in the USA in the late 1930s. They have better weather and slightly more chemical resistance than chlorinated rubber paints. They are generally resistant to crude oil but application is more critical. For example, they are particularly sensitive to moisture present on a surface during painting and this can lead to adhesion failure. They are also more prone to solvent entrapment than chlorinated rubber paints. 

As more sensitive analytical methods for pesticides are developed, greater care must be taken to avoid sample contamination and misidentification of residues. For example, in pesticide leaching or field dissipation studies, small amounts of surface soil coming in contact with soil core or soil pore water samples taken from further below the ground surface can sometimes lead to wildly inaccurate analytical results. This is probably the cause of isolated, high-level detections of pesticides in the lower part of the vadose zone or in groundwater in samples taken soon after application when other data (weather, soil permeability determinations and other pesticide or tracer analytical results) imply that such results are highly improbable. 

Persistence is the net result of many interacting factors, but chemical properties of the pesticide can play a dominant role. Volatility, solubility, stability to ultraviolet irradiation, tendency to adsorb onto or dissolve into tissue surfaces, ease of hydrolysis, sensitivity to humidity, potentiality to polymerize with or without ultraviolet irradiation, possible isomerization or other molecular rearrangement are all important chemical properties which play a significant role in persistence. Weather conditions such as wind, rain, amount and intensity of light, air temperature, and humidity play important roles. Rainfall is usually con-... 

Weathering reactions are caused by the interaction of water and air with the near surface of compounds contained in the crust of the Earth. Such reactions are slow, and the rates are sensitive to water flow and/or to the rate of mineral surface reactions. Surface runoff interacts minimally, but infiltrating and percolating water has an intense interaction. 

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