Furfuryl alcohol resin cured with

The industrial value of furfuryl alcohol is a consequence of its low viscosity, high reactivity, and the outstanding chemical, mechanical, and thermal properties of its polymers, corrosion resistance, nonburning, low smoke emission, and exceUent char formation. The reactivity profile of furfuryl alcohol and resins is such that final curing can take place at ambient temperature with strong acids or at elevated temperature with latent acids. Major markets for furfuryl alcohol resins include the production of cores and molds for casting metals, corrosion-resistant fiber-reinforced plastics (FRPs), binders for refractories and corrosion-resistant cements and mortars. 

Fig. 47. 15 MHz 13C MAS NMR spectrum of cured furfuryl alcohol resin a. The spectrum of the same resin obtained with dipolar dephasing (100 ps interrupted decoupling) b (reprinted from Ref.2341 with permission)...

Furfuryl Alcohol Resins. Polymerization and cure, and copolymerization/cure with urea-formaldehyde and phenol-formaldehyde, are generally catalyzed by acids such as p-toluene sulfonic acid and zinc chloride. 

Euran Furan resins are thermosetting polymers derived from furfuryl alcohol and Furfural. The cure must be carefully controlled to avoid the formation of blisters and delaminations. To obtain optimum strength and corrosion resistance, furan composites must undergo a postcure schedule at carefully selected temperatures depending upon the laminate thickness. Equipment made with furan resins exhibits excellent resistance to solvents and combinations of acids and solvents. These resins are not for use in strong oxidizing environments. 

Furfuryl alcohol may also be converted into polymeric materials in the presence of acids and such products have found some commercial use. Typically, furfuryl alcohol is heated at about lOO C with an acid catalyst such as phosphoric acid. The reaction is extremely exothermic and efficient cooling is necessary to prevent premature cross-linking. When the required degree of reaction is reached the system is neutralized and dehydrated under reduced pressure. The product is a dark free-flowing liquid. Often urea and formaldehyde are also included in resin formulations. Final cure of the resin is effected in situ by addition of an acid just prior to application. Weak acids (e.g., phthalic anhydride and phosphoric acid) give mixtures with long pot life which cure at 100—200°C whilst strong acids (e.g., p-toluenesulphonic and sulphuric acids) are effective at room temperature. 

To a resin kettle are added 286 gm of a 70% solids urea-formaldehyde resin (see note below) of the type described in Section 2-1, 80 gm (0.80 mole) furfuryl alcohol, 44 gm wood flour, 1.1 gm triethanolamine, and 2gm tricalcium phosphate. The mixture is stirred (pH approximately 8) and slowly heated to about 90 C over a y-hr period. The temperature is kept at 90°C for about 15 min and then cooled to 30°C over an 80-min period. The product is now ready to be cured with either one of the following catalysts. (Before addition of the catalyst, the adhesive resin is stable for over 3 months at 80°F.)... 

Although molds made with clay or sodium silicate binders are inexpensive, they have low dimensional tolerance and low stability. Phenolic resins used as binders have many good properties such as excellent dimensional stability, fast curing times, and excellent storage of cores and shells. In some applications furfuryl alcohol and urea formaldehyde resins are also used. - ... 

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