Aging moisture effects

Aging The effect of exposure of plastics to the environment for a length of time. The specific effect and degree depend on the moisture in, and temperature and composition of the environment, in addition to the length of exposure. 

Sugarcane Sower initiation is dependent on day length, temperature, age, moisture, and variety, and can be prevented by chemical applications at, or very close to, the date of floral initiation. The effective chemicals have been of two types (a) photosynthetic inhibitors, such as 3-(p-chlorophenyl)-1,1-dimethylurea (monuron), or (b) leaf-burning, contact chemicals. The very effective bipyridylium herbicides 6,7-dihydrodipyrido[l,2-a 2, r-c]pyrazidinium dibromide (diquat) and 1, l -dimethyl-4,4 -bipyridinium bis (methyl sulfate) (paraquat) combine the two properties, although the... 

Accelerated aging and crystal transformation rates have also been traced to high residual moisture content. Ando et al. studied the effect of moisture content on the crystallization of anhydrous theophylline in tablets [9]. Their results also indicate that anhydrous materials convert to hydrates at high levels of relative humidity. In addition, if hygroscopic materials (e.g., polyethylene glycol 6000) are also contained in the formulation, needle-like crystals form at the tablet surface and significantly reduce the release rate of the theophylline. 

Weathering is clearly a more complicated case than heat ageing alone, because there are temperature effects added to the light and probably other agents such as moisture and ozone as well (see Sections 4.4 and 6.8). Not surprisingly there is no very widely accepted relationship equivalent to Arrhenius. The result is that many workers have developed empirical relations which are usually only shown to be applicable to a narrow range of materials and conditions. 

Where a complex relation between the effect of weathering and time is found, one possibility is that it is due to the interaction of the effects of light and temperature. The property changes measured are the sum of the effects of UV light and temperature (and possibly moisture). If the effect of accelerated heat ageing is not simple this will be reflected in the weathering results. 

Weathering/Aging - the combined effect of cyclic exposure to varying moisture, temperature and sun exposure, or specific cyclic application conditions such as under the hood grease, oil and temperature variations. 

A Relationship between net photosynthesis, foliage age, and foliage retention B Effect ofplant moisture stress on net photosynthesis C Relationship between mineral uptake and net photosynthesis D Relationship between net photosynthesis and carbohydrate storage E Relationship between water uptake and mineral nutrition F Relationship between carbohydrate storage and bark characteristics G Relationship between carbohydrate storage and wood H Relationship between carbohydrate storage and cone production... 

The effect of ozone injury on herbaceous plant reproduction has been mentioned earlier in this chapter and in Chapter 11. Seed production by annuals is influenced mainly by the envirorunental conditions of the current year, but perennial woody plants—particularly conifers—are erratic seed-producers. Intrinsic factors affecting cone production include age and vigor seasonal temperature and soil moisture are important environmental factors. ... 

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