Phenolic resins overview

This entry will provide an overview of the classical phenol-formaldehyde system. The fundamentals of this system will be described. The current applications of this classical system will be discussed. Resins prepared from structurally modified phenols will be examined and labeled as modified-classical phenol-formaldehyde systems. The effect of these modifications on the mechanical, thermal, and other properties will be examined. Finally, the considerable work on polymers that can be classified as nonclassicaf phenolic resins will be presented and the area of nanocomposites utilizing phenolic resins will be examined. 

This overview of applications for benzene shows that the three most important products from benzene are used in the manufacture of plastics in the form of polystyrene, phenolic resins and polyamide fibers. Other uses for benzene, of lesser importance in terms of quantity but still extremely versatile, are halogen and nitrogen derivatives for the chemistry of dyestuffs, production of plant protection agents and additives for rubber and plastics processing, as well as for the manufacture of pharmaceuticals. 

Fibre-reinforced polymer (FRP) composites are composed of fibres and matrices, which are bonded through the interface to ensure that the composite system as a whole gives satisfactory performance. Part 1 deals with FRP composite matrix materials which provide the foundation for composite materials. Chapter 2 reviews the chemistry of phenolic resins together with their mechanical and thermal properties. Chapter 3 discusses polyester thermoset resins as matrix materials. An overview of the chemistry of vinylester resins, together with their mechanical and chemical properties, as well as their use as a matrix material in the construction industry, is provided in Chapter 4. The final chapter in Part 1 begins with a review of the epoxy resins commonly available on the market, and then focuses on the principal characteristics of epoxy resin composite systems and their practical applications. 

Figure 17 provides an overview of the function of the diazoquinone/novolac materials. The matrix resin is a copolymer of a phenol and formaldehyde. The generic term for this class of polymers is novolac (18) meaning "new lacquer" and describes the purpose for which they were first developed. The chemical industry produces millions of tons of novolac each year where its end use is that of a thermoset resin and adhesive. Novolac is commonly used, for example, as the principle adhesive in the manufacture of plywood. 

There has been little past nationwide activity in the recycle of polyurethanes (PUR) or phenolics even though these resins are among the largest produced. These two resins comprised 9.5% by weight of the resins produced in the U.S. in 1989 (refer to Table 1.2 in Part 1). An overview of some recent work is summariaed here. 

The purpose of this book is to provide, in one volume, an overview of structural adhesives. One chapter will be devoted to each of the major classes of structural adhesives, emphasizing the chemistry of the base resin and the main end uses for the adhesives of that class. The choice of systems is restricted to synthetic resins that are of current industrial interest for structural bonding. Some, such as the phenolics and epoxies, have been used successfully for many years and are of considerable industrial importance. Others, notably the structural acrylics and cyanoacrylates, are generating much interest and will probably become more widely used for industrial applications in the future. The newer polymers, for high-temperature-resistant adhesives, are currently of limited use most activity in these systems is at present still in the research and development stage. The desire for higher-temperature-resistant materials is creating much interest in these polymers and adhesives based on them will undoubtedly become important in the future. 

Figure 9 Overview of the structure and chemistry of two-component DNQ-novolac resists. The polymer resins in these resists are novolacs (which are soluble in both organic solvents used for film casting and aqueous alkaline solutions used for development) that are made by co-condensation of phenols (i.e., typically m- and p-cresol) and formaldehyde. The sensitizer in these resists are substituted DNQs which inhibit the dissolution of novolac and which upon exposure to UV light transform into carboxylic acids that generally increase the dissolution of novolacs in aqueous alkaline solutions.

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