Furfural, resins

Besides, furfural polymerizes in the presence of an acid catalyst with phenol, urea, and acetone. In this regard, the phenol-furfural and urea-furfural resins are important [221-223], Furfural reacts usually as does all a-substituted aldehydes in this regard, with phenol it condenses in the presence of either alkali or acid to form synthetic resins in a reaction that is very similar to that of phenol with formaldehyde or acetaldehyde [223], 

However, the most important furan resins are those produced with 2-furfuryl alcohol, for example, the 2-furfuryl alcohol-formaldehyde-based resins, which are normally synthesized by a condensation reaction catalyzed by acidic sites and promoted by heat [224] or the poly(furfuryl alcohol) thermosetting resin that is usually synthesized by the cationic condensation of its monomer 2-furfuryl alcohol, which polymerizes exothermically in the presence of a catalyst such as acid and iodine in methylene chloride, producing black, amorphous, and branched and/or cross-linked structures [225], 

FIGURE 2.46 Poly(glycidyl methacrylate-ethyleneglycol dimethacrylate) copolymer. 

---

The presence of stable free radicals in the final polycondensate is supported by the observation that traces of (11) have a strong inhibiting effect on the thermal polymerization of a number of vinyl monomers. Radical polymerization was inhibited to a larger extent by a furfural resin than by typical polymerization inhibitors (34). Thermal degradative methods have been used to study the stmcture of furfural resinifted to an insoluble and infusible state, leading to proposed stmctural features (35). 

Examples include acetaldehyde, CH CHO paraldehyde, (CH CHO) glyoxal, OCH—CHO and furfural. The reaction is usually kept on the acid side to minimize aldol formation. Furfural resins, however, are prepared with alkaline catalysts because furfural self-condenses under acid conditions to form a gel. 

Resistance to chemical attack is generally improved by resin impregnation, which protects the underlying wood and reduces movement of Hquid into the wood. Resistance to acids can be obtained by impregnating with phenoHc resin and to alkaHes by impregnating with furfural resin (see Phenolic RESINs). 

Furfural is a colourless liquid which darkens in air and has a boiling point of 161.7°C at atmospheric pressure. Its principal uses are as a selective solvent used in such operations as the purification of wood resin and in the extraction of butadiene from other refinery gases. It is also used in the manufacture of phenol-furfural resins and as a raw material for the nylons. The material will resinify in the presence of acids but the product has little commercial value. 

Phenol-furfural resins find limited application in the moulding of thick parts such as television cabinets, storage battery cases, etc. 

PHENOL-FURFURAL RESIN, A phenolic resin that has a somewhat sharper transition than phenol-formaldehyde from the soft, thermoplastic stage to the cured, infusible state and can be fabricated by injection molding since it has little tendency to harden before curing conditions are reached. 

Other Papers.—Various iron species prepared by the vacuum pyrrolysis of acetyl-ferrocene-furfural resins at 400°C have been studied by Mossbauer spectroscopy. These consist of an amorphous glass-like carbon matrix containing free iron atoms, Fe+ ions, iron clusters, superparamagnetic iron, and ferromagnetic iron.333 The effect of pressure of up to 50kbar on the absorption spectra of five iron(m), two iron(n) and one mixed valence compound has been studied. In six of the compounds, but not in basic ferric acetate or soluble Prussian Blue, the observed pressure-induced bands were assigned to d-d transitions of converted iron(n) for the ferric compounds and to spin-forbidden d-d bands for the ferrous compounds. The charge-transfer band from iron(n) to iron(m) in soluble Prussian Blue showed a blue shift at pressures up to 7.2 kbar.334... 

Petroleum-derived bitumens are also used as extenders in epoxy formulations. High-boiling-point petroleum distillates can serve as low-cost extenders, but a compatibilizer such as an alkylphenol must be present in the mix to achieve compatibility between the resin and the extender. Furfural resins can also be used with epoxies, to reduce cost and to obtain increased resistance to acids. 

Furfural 69, which can be manufactured from hardwood waste, is used for the manufacturing of a furfural-acetone monomer <2000MI15>. This monomer is then used to obtain furfural resins which are suitable as binders for the production of particleboards. In a further application, these furan resins of low toxicity have been used as adhesives in the manufacture of plywood <1999MI24>. The use of such resins is recommended as it leads to products with advantageous economic and ecological indicators. The result is plywood with good physiomechanical properties when the Monomer furfuryl alcohol (FA) was used as the adhesive. 

Furfural-salicylic acid and furfural-P-naphthalenesulfonic acid resins possess thermal stabilityexceeding that of KU-1 (sulfonated phenol-formaldehyde resin) and approaching that of KU-2 (sulfonated SDVB copolymer). The heat resistance of toluenesulfonic acid-furfural resin is quite similar to that of KU-2 resin. The improved thermal stability of furfural-based cation-exchange resins is attributed to the presence of heterocyclic and aromatic rings in these resins. 

Ethers. The polycondensation of diphenyl ether and furfural (1 1.5mole ratio) in presence of sulfuric acid yields a resin which has been sulfonated by sulfuric acid at 50 °C for 10 h to give a cation-exchange resin The swelling and the exchange capacity of the product increase with the amount of sulfuric acid present during the polycondensation and are higher for a resin obtained by polycondensation in carbon tetrachloride than the one prepared in absence of solvent. The thermal stability of sulfonated diphenyl ether-furfural resin is more than that of KU-1 and comparable to that of KU-2. The sulfonic acid resin derived from the copolymer obtained by the polymerization of diphenyl ether and furfural at a mole ratio of 1 2 in carbon tetrachloride has optimum adsorption and catalytic activity... 

Epoxy resins form alloys with a number of other resins such as polysulphides, polyurethanes, fluorocarbons, silicones, furfural resins and acrylic resins. 

In perfect analogy to the formation of phenol/formaldehyde resins, phenol reacts with furfural to form phenol/furfural resins. In phenol, due to its hydroxyl group, the hydrogen atoms in ortho and para positions are highly reactive. Consequently, phenol reacts with furfural to form phenol fiirfurylol ... 

The phenol/furfural resins have a greater hydrocarbon solvent tolerance than phenol/formaldehyde resins. This is an advantage in the preparation of resin solutions used for the impregnation of paper or cloth for laminating. 

The phenol/furfural resins yield products of greatly reduced brittleness. 

Alcohol resins, polyvinyl Alkyd resins Allyl resins Butadiene copolymers, containing less than 50 percent butadione Carbohydrate plastics Casein plastics Cellulose nitrate resins Cellulose propionate (plastics) Coal tar resins Condensation plastics Coumarone-iodene resins Cresol resins Cresol-furfural resins Dicyandiamine resins Diisocyanate resins Elastomers, nonvulcanizable (plastics)... 

Petroleum polymer resins Phenol-furfural resins Phenolic resins Phenoxy resins Phthalic alkyd resins Phthalic anhydride resins Polyacrylonitrile resins Polyamide resins Polycarbonate resins Polyesters Polyethylene resins Polyhexamothylemediamine adipamide resins Polyisobutylenes Polymerization plastics, except fibers... 

The phosphorylation of phenol-furfural condensate l03) affords a cation-exchange resin with improved thermal and chemical resistance. The heat treatment104> of phosphonic add resins from furfural resins, phenol-resorcinol-formaldehyde resin, and polystyrene at 100-180 °C for 10-48 h shows that the furfural-based phosphonic acid resins possess higher thermal stability than those from the other two polymers. 

---