Resins Infusible

In addition to the above possible mechanisms the possibility of reaction at w-positions should not be excluded. For example, it has been shown by Koebner that o- and p-cresols, ostensibly difunctional, can, under certain conditions, react with formaldehyde to give insoluble and infusible resins. Furthermore, Megson has shown that 2,4,6-trimethylphenol, in which the two ortho- and the one para-positions are blocked, can condense with formaldehyde under strongly acidic conditions. It is of interest to note that Redfam produced an infusible resin from 3,4,5,-trimethylphenol under alkaline conditions. Here the two m- and the p-positions were blocked and this experimental observation provides supplementary evidence that additional functionalities are developed during reaction, for example in the formation of quinone methides. 

Reactant for /-butyl phenolic resins. Magnesium oxide reacts in solution with /-butyl phenolic resin to produce an infusible resinate (Fig. 36) which provides improved heat resistance. The resinate has no melting point and decomposes above 200°C. Although oxides of calcium, lead and lithium can also be used, they are not as efficient as magnesium oxide and also tend to separate from solution. Where clear adhesive solutions are required epoxide resins, zinc-calcium resinates or zinc carbonate can be used. 

The high heat resistance produced by adding phenolic resins to solvent-borne CR adhesives is due to the formation of the infusible resinate, which reduces the thermoplasticity of the adhesive and provides good bond strength up to 80°C (Table 11). The resinate also increases the adhesive bond strength development by accelerating solvent release. 4 phr of magnesium oxide for 40 phr of phenolic resin are sufficient to produce a room temperature reaction. A small amount of water (1-2 phr) is necessary as a catalyst for the reaction. Furthermore, the solvent... 

Final reaction stage of various thermosetting resins. In this stage material is insoluble and infusible. Resin in fully cured thermosetting... 

Some interesting resins have been obtained from the dianhydrides through their acrylic or methacrylic esters. Thus, 2,5-dimethacrylyl-l,4 3,6-dianhydro-mannitol (XIX) was formed by treating dianhydro-mannitol with methacrylyl chloride in the presence of sodium hydroxide. The product, a crystalline compound, polymerized extremely rapidly to a colorless, transparent, infusible resin. The corresponding sorbitol derivative, however, was an oil which polymerized to a softer resin. On the other hand, 2,5-diacrylyl-l,4 3,6-dianhydro-sorbitol (XX) was a crystalline compound, which polymerized to a hard, infusible, glass-like resin. 

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. 

A procedure based on condensation with phenol and paraform (used as formaldehyde source) was developed to convert spent UNEX solvent (CCD, PEG-400, Ph2-CMPO, and FS-13) into a solid infusible resin for disposal. The resulting material is insoluble in aqueous alkali and acidic solutions and organic solvents. Incorporation of FS-13 in the cross-linked polymer was confirmed by physicochemical methods. Resistance of the cured resin to high temperatures was proven by thermogravimetry... 

Attempts to make adhesive formulations by direct reaction of formaldehyde or its equivalent resulted in products that were excessively viscous, and the working time was too short for commercial application (57). It was concluded that formaldehyde, although readily reactive with the tannin molecule, provided much too short linkages to connect the bulky tannin molecules. This problem was circumvented by the preparation of a polymethylolphenol reagent that, when put in solution with the bark extract, formed a combination that was stable for several weeks at room temperature. When heated, the polymethylolphenol and bark extract reacted rapidly to form an infusible resin. Commercial trials were made to produce exterior-grade Douglas-fir plywood. Widespread use of the extracts for this purpose, however, was inhibited by a drop in the price of phenol below what the bark extracts could be manufactured for. (The best extract for adhesive purposes was an ammonia extract of hemlock bark converted to a sodium derivative prior to spray drying, a more costly extraction procedure than simple sodium hydroxide extraction of bark.)... 

Use A cross-linking agent with polymerization characteristics. Product is a hard, clear, infusable resin. Uses include inks, adhesives, textile products, polyesters, and photoresists. 

Large spars are fabricated. An 86 ft unstayed carbon fiber mast built by Composites Engineering for Ocean Planet, a yacht built by Schooner Creek Boat Works for an American owner, utilizes an infusion resin and hardener specialty formulated by MAS Epoxies. 

Linseed oil presented another interesting opportunity for the production of bioplastics. The highly polyunsaturated nature of the oil allowed for a large number of reactive sites to be introduced onto the material for subsequent polymerization. As has previously been mentioned, this increased reactivity has been shown to limit the physical properties of the materials and as such there has been little commercial interest in taking these materials further. Epoxida-tion, acrylation and maleinization of linseed oil before polymerization produced a heavily crosslinked polymer [59]. A formulation for potential in infusion resins was developed with a mixture of epoxidized linseed oil and phthalic anhydride with the curing catalysed by 2-methylimidazole [60]. 

Crystalline thermoplastic polymers made from two or more different monomers, usually ethylene and propylene. A family of polymers based on the combination of trimellitic anhydride with aromatic diamines. In the uncured form (ortho-amic acid), the polymers are soluble in polar organic solvents. The imide linkage is formed by heating, producing an infusible resin with thermal stability up to 290 °C. These resins are used for laminates, prepregs, and electrical components. 

Vacuum infusion (resin infusion under flexible tooling, RIFT)... 

X, Y, and Z directions. Orthogonally woven structures offer superior mechanical properties and corrosion resistance after infusing resin into a composite. The panel, as shown in Figure 9.25, has 61 layers of warp, 62 layers of fill, and Z fibers. The typical fiber volume of the panel is around 55%, and X, Y, and Z fiber volume fractions are around 40%, 40%, and 20%, respectively. The typical Z fiber volume fraction can vary from 3% to 33%, depending on the performance requirements of the end use. 

D noncrimp fabric Resin film infusion resin transfer molding 0.30 0.55... 

Possible structure for bakelite (infusible resin) Fig. 136. Some three-dimensional networks. 

The toluene solution of the chlorosilanes is hydrolyzed, and the aqueous hydrochloric acid is separated, washed, and then heated in the presence of a mild condensation catalyst to adjust the resin to the proper viscosity and cure time. Fillers can be added prior to the removal of the solvent and isolation of the final resin. A resin can also be prepared from phenyl-trichlorosilane alone to give a tough, infusible resin that can be cast from solvents to give a clear film [74, 75]. 

Epoxies have historically been the major adhesive family used for the structural bonding of metals and composites in the aerospace, industrial and automotive industries. They are characterised by curing to hard infusible resins that bond to a wide range of metals and have excellent resistance to heat and the environment. Epoxies have been used since the 1940s and have an excellent track record of successful structural bonding. Two-component and heat-cured one-component versions are available and literally thousands of formulations have been developed over the years for specific applications. 

Infusible resins in which the component molecules are made up of a three-dimensional netw ork consisting of cross-linked molecules. 

Infusible Resins. The cross-linked resins n bich ai infusible and insoluble in organic solvents may be regarded as the products of polymethylol-phenols x -hioh can condense vuth other phenolic nuclei in three dimensions to form cross-Hnked macro-molecules. Thex are most readily prepared from phenols in xx hich the three actix-e, 2, 4 and 6, ring positions are unsubstituted. Alkali catalysts favor their formation and a formaldehx de-to-phenol molar ratio of greater than one is desirable. Granger points out that, when acid catalysts are employed, considerable excess formaldehyde is required and much of it does not react and is wasted. Satisfactory results are obtained by acid condensation of polymethylolphenols produced under alkaline conditions. 

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