Organic compound heat stabilizers

Organic compound heat stabilizers include not only primary stabilizers that can be used alone (mainly organic nitrogen compounds), but also polyalcohols and phosphite esters with a high boiling point. Phosphite esters are often used together with metal stabilizers to enhance the weather resistance and transparency of composite materials and improve surface color and luster of products. 

At normal pressures (around atmospheric) and up to about 250°C (approaching the limit of thermal stability for most organic compounds), a volatile substance can be defined as one that can be vaporized by heat between ambient temperature (10 to 30°C) and 200 to 250°C. All other substances are nonvolatile. 

Heat stabilizers protect polymers from the chemical degrading effects of heat or uv irradiation. These additives include a wide variety of chemical substances, ranging from purely organic chemicals to metallic soaps to complex organometaUic compounds. By far the most common polymer requiring the use of heat stabilizers is poly(vinyl chloride) (PVC). However, copolymers of PVC, chlorinated poly(vinyl chloride) (CPVC), poly(vinyhdene chloride) (PVDC), and chlorinated polyethylene (CPE), also benefit from this technology. Without the use of heat stabilizers, PVC could not be the widely used polymer that it is, with worldwide production of nearly 16 million metric tons in 1991 alone (see Vinyl polymers). 

Sulfation is defined as any process of introducing an SO group into an organic compound to produce the characteristic C—OSO configuration. Typically, sulfation of alcohols utilizes chlorosulfuric acid or sulfur trioxide reagents. Unlike the sulfonates, which show remarkable stability even after prolonged heat, sulfated products are unstable toward acid hydrolysis. Hence, alcohol sulfuric esters are immediately neutralized after sulfation in order to preserve a high sulfation yield. 

Because weak CL emission often is produced from the oxidation of many solid organic compounds, the measurement of this light emission may be used as an indicator of changes in materials composition due to oxidation processes, and for evaluating stabilizers intended to prevent or retard these oxidative alterations [6], Some examples of materials than can be characterized by CL emission are the polymers that are degraded by weathering, exposure to heat, or exposure to ionizing radiation, or food components that suffer flavor alterations. In this... 

A variety of materials can be used, and the choice of material will depend on a variety of factors - the amount of heat output required, rate of heat release needed, cost of the materials, stability of the fuel and fuel /oxidizer pair, and amount of gaseous product desired. Fuels can be divided into three main categories. metals, non-metallic elements, and organic compounds. 

There are many organic compounds stabilized by resonance. As a first example we may cite benzene, in which there is resonance between the two Kekule structures. In this case, the resonance energy could be calculated to give good agreement with the experimental data on the heat of formation of the molecule. Perhaps even more remarkable is the compound KC5H5, which is formed when potassium reacts with ryr/opentadiene. 

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