Organic materials required properties

Water can contribute to the decay and breakdown of some materials not only by its presence but also by its absence most organic materials require some optimum moisture content to preserve their mechanical properties papyrus, skin, parchment, and leather that are too dry, for example, are extremely stiff, brittle, and friable. 

Saline waters, including seawater, contain, besides a variety of inorganic salts, also organic materials and various particles. They differ in composition from site to site, and also change with time as a result of both natural and human causes. Design and operation of desalination plants requires good knowledge of the saline water composition and properties (41,44). 

Antioxidants are used to retard the reaction of organic materials with atmospheric oxygen. Such reaction can cause degradation of the mechanical, aesthetic, and electrical properties of polymers loss of flavor and development of rancidity ia foods and an iacrease ia the viscosity, acidity, and formation of iasolubles ia lubricants. The need for antioxidants depends upon the chemical composition of the substrate and the conditions of exposure. Relatively high concentrations of antioxidants are used to stabilize polymers such as natural mbber and polyunsaturated oils. Saturated polymers have greater oxidative stabiUty and require relatively low concentrations of stabilizers. Specialized antioxidants which have been commercialized meet the needs of the iadustry by extending the useflil Hves of the many substrates produced under anticipated conditions of exposure. The sales of antioxidants ia the United States were approximately 730 million ia 1990 (1,2). 

The automotive industry needs more and more organic material with improved thermomechanical properties up to 200-220°C, but the requirements for the processability and cost make die problem difficult to solve. The development of new... 

The organic materials must evaporate without decomposing during the fabrication process. The typical deposition temperature range is between 150 and 450°C. Factors that contribute to the ultimate temperature used in addition to the physical properties of the material include the vacuum pressure, source to substrate geometry, and required deposition rate. 

The specification requirements for mechanical testing should he performed. Degradation of the physical properties of organic materials is the best indication of chemical, radiation, or thermal degradation. When organic materials are removed from contact with solvents and other chemicals, the physical properties immediately after removal may he quite different than those measured several days later. 

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