Furan polymers

IV. The Transformation of Poly(vinylalcohol) into Furan Polymers. .. 85... 

The use of the hydroxyl groups of poly(vinylalcohol) as reactive sites for the preparation of various unconventional polymers is well known and indeed the very synthesis of poly(vinylalcohol) is based on a similar but reverse reaction. This general principle has been applied successfully to the synthesis of some vinyl-type furanic polymers, which cannot be made by classical routes. 

The potential of these transformations has not been fully exploited. The method is certainly valuable both for the purpose of studying the structure of furan polymers which might be of interest but cannot be prepared easily by conventional techniques and for preparing polymers in which a certain proportion of the hydroxyl groups of poly(vinylalcohol) are substituted with a furan moiety which gives the new product some special property. 

The mechanisms of formation of dark resinous materials from these compounds can be studied and subsequently used as models for the understanding of the more complex situations which occur in furan polymers. A brief survey of these topics is given in this chapter. 

All the derivatives examined above owe their instability to the presence of the furan ring similar aldehydes, carbinols, chlorides, etc. bearing aliphatic and aromatic substituents are not prone to resinify. An analogous singularity of behaviour is encountered in furan polymers, as underlined at the beginning of this chapter. In a polymer prepared from a furan derivative three different situations must be considered ... 

The S02process. Sand is mixed with a furane polymer resin (1.2 to 1.4% of sand weight) and an organic peroxide (such as methyl ethyl ketone peroxide at 25 to 60% of resin... 

Uses Solvent for dyes and resins preparation of furfuryl esters furan polymers solvent for textile printing manufacturing wetting agents and resins penetrant flavoring corrosion-resistant sealants and cements viscosity reducer for viscous epoxy resins. 

This polymer suffered thermal degradation only above 400 C, before melting. For molecular weights higher than about 20,000, it showed a lyotropic liquid-crystal behaviour in N-metnypyrrolidone containing LiCl. This is the first reported example of a furanic polymer with mesogenic properties. 

Uses. Solvent refining of lubricating oils, resins, and other organic materials as insecticide, fungicide, germicide an intermediate for tetrahydrofuran, furfural alcohol, phenolic and furan polymers... 

Furans. The last statement is certainly true of furans derived from sugars (142,143), particularly furfural and furfuryl alcohol, which is readily derived from furfural (144)- Dr. McKillip of QO Chemicals discusses furan resin chemistry and furan polymers in Chapter 29. Dr. Stanford and his colleagues at the University of Manchester Institute of Science and Technology discuss the use of a diisocyanate derived from furfural for polyurethane production in Chapter 30. 

Properties Physical properties of atypical asbestos-reinforced furan polymer are d 1.7, tensile strength 5000 psi, flexural strength 7500 psi, impact strength 0.5 ftlb/in. notch, water absorption 0.2%, and coefficient of thermal expansion 3.0-lCf5 in/in/F. 

Use Wetting agent, furan polymers, corrosion-resistant sealants and cements, foundry cores, modified urea-formaldehyde polymers, penetrant, solvent for dyes and resins, flavoring. The polymer is used as a mortar for bonding acid-proof brick and chemical masonry. 

Whereas natural monomers like terpenes and sugars constitute building blocks for a limited number of macromolecular structures, associated with their own peculiar chemical features, the realm of furan polymers bears a qualitatively different connotation in that it resembles the context of petrol refinery, that is, it is open to a whole domain of monomers, whose only specificity is the fact that they all incorporate the furan heterocycle in their structure. This state of affairs stems from the fact that, as in petroleum chemistry, saccharide-based renewable resources are used to produce two first-generation furan derivatives, which constitute the substrates capable of being converted into a vast array of monomers and hence a correspondingly large number of macromolecular structures associated with materials possessing different properties and applications [34]. 

Only some recent contributions to this large field are discussed here, since thorough reviews are available elsewhere. The most interesting studies relate to two very different approaches to furan polymers, namely the synthesis of novel polyesters and the use of the Diels-Alder reaction to prepare thermoreversible materials [37]. 

Furan polymers are based on furfuryl alcohol, which is derived from agricultural residues such as corncobs, rice hulls, oat hulls, or sugar cane bagasse. The furan prepolymer is usually cross-linked with furfuryl alcohol, furfuraldehyde, or formaldehyde to yield thermosetting polymers, highly resistant to most aqueous acidic or basic solutions and strong solvents such as ketones, aromatics, and chlorinated compounds. The important characteristic of furan resins is their ability to be stored for long periods of time (up to 5 years), even at low temperatures. 

The furan polymers are used as binders in mortars and grouts to achieve chemically resistant brick floors (e.g., carbon brick and red shale brick) and linings. In addition to exhibiting superior chemical resistance, these floors have excellent resistance to elevated temperatures and extreme thermal shock [2,6,7],... 

Furan polymer concrete is a corrosion-resistant polymer material. Endurance tests (a year or more) showed high resistance of this material to most industrial chemicals, except oxidants (nitric acid, acetic acid) and some solvents (acetone, benzene, alcohol). 

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