Grain Deterioration

FIGURE 5.1 Progressive deterioration process of stored cereal grains. 

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Underground storage is considered one of the oldest practices to store a surplus of grains. The method protects the grain from unfavorable environmental conditions and inhibits pests due to the lower oxygen and high carbon dioxide concentration that diminishes both intrinsic and extrinsic grain deterioration (Sauer 1992). 

CHEMICAL AND PHYSICAL CHANGES INCURRED DURING GRAIN DETERIORATION... 

What are the differences between intrinsic and extrinsic grain deterioration ... 

Aeration Common operation performed in grain elevators, consisting of moving air through a bed of stored grain at low airflow rates with the aim of getting rid of the heat and moisture, and therefore lower respiration and extrinsic grain deterioration. 

Extrinsic deterioration Type of grain deterioration due to external factors such as insects, molds, and rodents. 

Dissolution/reprecipitation processes were evaluated for the recycling of poly-epsilon-caprolactam (PA6) and polyhexamethyleneadipamide (PA66). The process involved solution of the polyamide in an appropriate solvent, precipitation by the addition of a non-solvent, and recovery of the polymer by washing and drying. Dimethylsulphoxide was used as the solvent for PA6, and formic acid for PA66, and methylethylketone was used as the non-solvent for both polymers. The recycled polymers were evaluated by determination of molecular weight, crystallinity and grain size. Excellent recoveries were achieved, with no deterioration in the polymer properties. 33 refs. 

In the electrode with CuS alone, which has negligible conductivity, the precipitate ISE with a silicone rubber matrix has better properties than the electrode with a pressed pellet [314], The ISE with a mixture of CuS and Agi S finds broad application [325]. If the membrane is prepared by pressing, the grains of these two compounds combine to form jalpaite, Agi.55C%.4sS [180], This substance is a mixed conductor with transport numbers of Ag, 0.69 Cu(I), 0.30 and electrons, 0.01, at 25 C [175]. The sintered electrode also contains Ag1.2Cuo.8S or Ago.93Cu1.07S. Oxidation of these phases leads to considerable deterioration in the electrode function [180]. Good electrodes... 

Laboratory measurements on stored samples are common, but many precautions must be observed. Samples must be representative of the propellant grain, enclosed in its case-liner insulation envelope. Since diffusion paths and exposed surface area may be germane to aging, these characteristics require duplication in aging samples. There is considerable evidence also that samples stored in sealed containers deteriorate much more rapidly and by different mechanisms than those exposed to the atmosphere. 

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