Resole plastic

These thermoplastic resoles and novolacs are mixed with lubricants, pigments and additives, such as wood flour. The molding compound is converted to an infusible resin by heating it under pressure in a mold. A typical sequence of chemical reactions associated with the formation of this complex, three-dimensional polymer is shown in Figure 15.4. Typical properties of phenolic plastics are shown in Table 15.4. 

In recent years there has been activity generally in the production of safe plastic foams and in this connection certain flame retardant phenolic resin foams formulated from resols containing phenolic resin oligomers involving CNSL have been found to be free of harmful gases on combustion (ref. 254). 

Resols are of limited use as sole binders on account of their brittleness they are generally used in combination with plasticizing co-resins. 

Combinations with Epoxy Resins. When resols are cross-linked with epoxy resins, the latter serve as plasticizing components. The hydroxymethyl groups of the resols are assumed to react with the hydroxyl groups of the epoxy resins to produce flexible coatings. 

Combinations with Poly (Vinyl Butyrals). Poly(vinyl butyral) resins with a high acetal content are used, like epoxy resins, to plasticize resols. The weight ratio of resols to poly(vinyl butyral) is generally between 95 5 and 70 30. The employed application methods and curing conditions are similar to those used in the resol-epoxy resin systems. The resistance of such paint films to organic solvents, amines. 

Electrical Insulation Paints. Resols combined with poly(vinyl butyral), oil-free polyester resins, or poly(vinyl formal), as plasticizing components are used for this special application. The presence of small amounts of free phenols can increase the reactivity of these systems. These paints are used to coat wires, sheet metal for transformers and dynamos, as well as to impregnate electric motor windings. The paints are cross-linked at 100-300°C. 

Pi-Pi interactions and the strong shielding zone between highly polar and nonpolar groups in the novolacs and resols formed produce a plastic, which seems to exhibit low permeability, even to small molecules. 

Phenolic resin foam is an interesting material for the cellular insulation industry because of its high temperature resistance, fire resistance, and very low smoke generation [16]. The aqueous resole is crosslinked in the presence of a surfactant and a low boiling liquid, that volatizes during the increase ofviscosity or plasticity of the mixture. The surfectant is necessary to develop a uniform fine cellular foam stracture [1,6], Carbonization of phenolic foams yields carbon foams with an excellent thermal resistance, that are applied as high temperature insulation materials for the production of filters for corrosive agents and catalyst supports [1]. 

The phenolic resins are condensation products of phenol and formaldehyde [144-146, 148]. These materials were among the earliest commercial synthetic plastics. Two different methods [144-146] are used to prepare them. In the first one, the condensations are base catalyzed, while in the second one, they are acid-catalyzed. The products formed with basic catalysts are called resols and with acidic ones novolacs. Phenolic resins are used widely in coatings and laminates. The pure resins are too friable for use as structural materials by themselves. They become useful plastics, however, when filled with various fillers. 

Oscillatory shear rheology of EPDM plasticized with resol was used to determine an equilibrium shear modulus Ge), relaxation in compression and strain recovery. Ge was analysed with consideration of crosslink density and permanent entanglements, including evaluation of plasticizer and soluble polymer fraction. Relaxation data were modelled with the empirical Chasset-Thirion equation and it was proposed that longer relaxation times were associated with chains pendant from the network. Relaxation times increased with crosslink density. When the crosslink density was low and pendant chains were longer and more numerous, relaxation times were increased and elastic recovery diminished. ... 

Water-based dispersions or emulsions such as polyvinyl acetate, acrylics, polyvinyl chloride and polyvinyl alcohol with plasticizers and tackifiers. In addition, this range can include urea formaldehyde and phenolic adhesives, resins, natural adhesives produced from starch, dextrin, casein, animal glues (see Polyvinyl alcohol in adhesives, Phenolic adhesives single-stage resoles. Phenolic adhesives two-stage novolacs. Animal glues and technical gelatins) and rubber latex (see Emulsion and dispersion adhesives). Solvent-free 100% solids such as polyurethane. Hot melt adhesives include Ethylene-vinyl acetate copolymers, polyolefins, polyamides, polyesters with tackifiers and waxes. More recent additions include cross-linkable systems. 

Arpino, P.J. Dilettato, D. Nguyen, K. Bruchet, A. Investigation of antioxidants and UV stabilizers from plastics. Part I Comparison of HPLC and SFC pieUminaty SFC/ MS study. J. High-Resol. Chromatogr. 1990,13, 5-12. 

Whereas celluloid was the first plastic material obtained by chemical modification of cellulose, the phenol-formaldehyde (PF) resin was the first commercially successful synthetic plastic. This phenolic plastic was discovered by L.Fi. Baekeland in Belgium in 1907, and Bakelite was produced industrially in 1910. Baekeland used the term resole to describe PF resins made with an alkaline catalyst, and those made with an acidic catalyst were called novolac. The ability of formaldehyde to transform some products in resinous materials was observed by Butlerov (1859) and Bayer (1872) [3]. 

A modified phenolic resole resin with improved plasticity and toughness, and recommended for applications in the chemical environment. 

The use of straight resol and novolak resins derived from phenol in surface coatings is very limited, mainly because of the brittleness of the films. Further, vegetable oils cannot be used as plasticizers since they are incompatible with the resins. However, there are a number of ways in which oil-solubility can be achieved and large quantities of phenolic resins suitable for surface coatings are produced by such methods as the following ... 

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