Natural High-Molecular-Weight Organic Substances

12 NATURAL HIGH-MOLECULAR-WEIGHT ORGANIC SUBSTANCES 

Natural organic colloids have variable composition, and the surface properties of various specimens of nominally the same material can vary substantially. The PZCs/IEPs of natural high-molecular-weight organic substances are presented in Tables 3.2124-3.2147. 

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Natural high-molecular-weight organic compounds. These include humic substances and natural organic matter, asphaltene, and cellulose. 

The term plastic comes from the Greek word to form. It identifies many different plastic materials. Polymers, the basic ingredients used in practically all plastics, can be defined as high molecular weight organic compounds, synthetic or natural substance... 

The materials being reviewed in this book, as in the industry, are identified by different terms such as polymer, plastic, resin, elastomer, reinforced plastic (RP), and composite unreinforced or reinforced plastic. They are somewhat synonymous. Polymers, the basic ingredients in plastics, can be defined as high molecular weight organic chemical compounds, synthetic or natural substances consisting of molecules. Practically all of these polymers are compounded with other products (additives, fillers, reinforcements, etc.) to provide many different properties and/or processing capabilities. Thus plastics is the correct technical term to use except in very few applications where only the polymer is used to fabricate products. 

These are semisolid or solid substances formed in nature from crude oils after the volatile components have evaporated and the remainder has undergone oxidation and polymerization. They are also referred to as bitumens, waxes, and pitch. These materials are believed to consist of mixtures of complex organic molecules of high molecular weight. As with crude oils, which contain thousands of different chemical compounds, an exact chemical analysis for identification and composition is impractical to perform on the solid deposits of petroleum. 

The term microbial toxin is usually reserved by microbiologists for toxic substances produced by microorganisms that are of high molecular weight and have antigenic properties toxic compounds produced by bacteria that do not fit these criteria are referred to simply as poisons. Many of the former are proteins or mucoproteins and may have a variety of enzymatic properties. They include some of the most toxic substances known, such as tetanus toxin, botulinus toxin, and diphtheria toxin. Bacterial toxins may be extremely toxic to mammals and may affect a variety of organ systems, including the nervous system and the cardiovascular system. A detailed account of their chemical nature and mode of action is beyond the scope of this volume. 

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