Phenols reference materials

Gel filtration of the hemicellulose was done on a G-50 Sephadex column with water as eluent by the National Food Research Institute of the CSIR. Neutralized samples were applied to the column and fractions (6 mL) collected, of which 1-mL aliquots were assayed by the phenol-sulfuric acid test ( ). Approximate calibration (D.P. versus elution volume on the G-50 column) was done by total carbohydrate and reducing sugar end group analysis (0) using enzymatically debranched starch as reference material. 

For transfer molding, generally pressures of three times the magnitude of those required for compression molding are required. For example, usually a pressure of 9,000 psi (632 kg/cm ) and upward is required for phenolic molding material (the pressure referred to here is that applied to the powder material in the transfer chamber). 

Sulfates of sodium are iadustriaUy important materials commonly sold ia three forms (Table 1). In the period from 1970 to 1981, > 1 million metric tons were consumed aimuaHy ia the United States. Siace then, demand has declined. In 1988 consumption dropped to 890,000 t, and ia 1994 to 610,000 t (1,2). Sodium sulfate is used principally (40%) ia the soap (qv) and detergent iadustries. Pulp and paper manufacturers consume 25%, textiles 19%, glass 5%, and miscellaneous iadustries consume 11% (3). About half of all sodium sulfate produced is a synthetic by-product of rayon, dichromate, phenol (qv), or potash (see Chromium compounds Fibers, regenerated cellulosics Potassium compounds). Sodium sulfate made as a by-product is referred to as synthetic. Sodium sulfate made from mirabilite, thenardite, or naturally occurring brine is called natural sodium sulfate. In 1994, about 300,000 t of sodium sulfate were produced as a by-product another 300,000 t were produced from natural sodium sulfate deposits (4). 

With the advent of these compounds in the 1960s, the hitherto more conventional insulating materials, such as phenol formaldehyde (popularly known as Bakelite) and wood (veneered impregnated) have been almost replaced by them. These compounds offer better electromechanical properties than conventional materials. Below we describe the basic mix and properties of these two basic compounds, for a brief reference. 

Basic materials such as lime or magnesium oxide increase the hardening rate of novolak-hexa compositions and are sometimes referred to as accelerators. They also function as neutralising agents for free phenols and other acidic bodies which cause sticking to, and staining of, moulds and compounding equipment. Such basic substances also act as hardeners for resol-based compositions. 

Thousands of technical papers and many books have been written on the subject of phenolic resins. The polymer is used in hundreds of diverse applications and in very large volumes. It is used worldwide. In fact the term phenolic resin encompasses a wide variety of materials based on a broad range of phenols and co-monomers. In this short article, we cannot expect complete coverage. Our hope is that we can provide an understanding of the fundamental chemistries, uses, and values of these materials as well as enough references to permit the interested reader to begin his own exploration of the topic. 

The alkalis and acids used to catalyze phenolic reactions are highly corrosive and any exposure is a potentially serious health threat. Those handling these materials should be thoroughly familiar with the appropriate Material Safety Data Sheets and emergency procedures. We do not purport to provide any specific health guidance here except to say that one should consult the appropriate references and be properly trained when making phenolic resins. 

In the Colour Index both conventional sulphur dyes and their leuco counterparts are allocated the same Cl constitution number a different number is given to the related solubilised version. Thus, for example, Cl Sulphur Black 1 and Cl Leuco Sulphur Black 1 have the reference Cl 53185 whereas Cl Solubilised Sulphur Black 1 appears under Cl 53186. Because of the complexity of the final products, sulphur dyes are classified according to the chemical structure of the organic starting material that predominates in the manufacturing process. Typical intermediates include aromatic amines, with or without nitro and phenolic groups, and diphenylamine derivatives. 

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