Nutshell flour

By far the preponderance of the 3400 kt of current worldwide phenolic resin production is in the form of phenol-formaldehyde (PF) reaction products. Phenol and formaldehyde are currently two of the most available monomers on earth. About 6000 kt of phenol and 10,000 kt of formaldehyde (100% basis) were produced in 1998 [55,56]. The organic raw materials for synthesis of phenol and formaldehyde are cumene (derived from benzene and propylene) and methanol, respectively. These materials are, in turn, obtained from petroleum and natural gas at relatively low cost ([57], pp. 10-26 [58], pp. 1-30). Cost is one of the most important advantages of phenolics in most applications. It is critical to the acceptance of phenolics for wood panel manufacture. With the exception of urea-formaldehyde resins, PF resins are the lowest cost thermosetting resins available. In addition to its synthesis from low cost monomers, phenolic resin costs are often further reduced by extension with fillers such as clays, chalk, rags, wood flours, nutshell flours, grain flours, starches, lignins, tannins, and various other low eost materials. Often these fillers and extenders improve the performance of the phenolic for a particular use while reducing cost. 

To incorporate a cellulosic filler, such as a nutshell flour of 200 mesh or finer, in a proportion of about 20 to 40% of phenolic solids. Nonabrasive inorganic fillers may also be satisfactory. 

If paraformaldehyde and fillers, generally wood and nutshell flours, are added, the resin becomes capable of setting in 2 to 3 h and curing in 16 to 24 h at ambient... 

Europe the use of sludge hardeners of type 2 above is fairly common too. When using a powder hardener in adhesives of types 1, 2, and 3, they are mixed before use in a mass/ mass ratio of liquid adhesive resin (50-60% solid content) to powder hardener of 5 1. The powder hardener is generally a mixture of 10 parts paraformaldehyde and 10% fillers. It is comprised of 200-mesh wood flour or a mixture of wood flour and nutshell flour, also 200 mesh. Adhesives of types 4 and 5 have a liquid resin to liquid hardener ratio of 1 1 by mass. This is so because the hardener is also a resin. Adhesives of types 4 and 5 have been used quite extensively in the past in certain markets but have now been superseded by adhesives of type 2 which have several handling advantages. 

Fillers and other additives are used to make molded objects from phenolic resins to reduce shrinkage during cure, improve strength, and provide flow control. Representative materials added are mineral flour, wood flour, nutshell flour, pressed olive stones, lignite, and natural rubber. Crosslinked phenolics containing inorganic or organic fillers are schematically illustrated in Scheme 35. 

Nutshell flour n. Ground peanut or walnut shells, dried by heating or solvent extraction, have been used as low-cost fillers in olyethy-lene. Physical properties are comparable to those of PE filled with wood flour. 

Nutshell flours To 325 mesh Extenders Moisture content is 2%,... 

Glo-Oear, Elexible vinyl sheets, O Sullivan Corp. Gloria, White mineral oil, Witco Corp., Performance Chemicals Group Glniil, Nutshell flour, Agrashell, Inc. 

Organic fillers are of natural origin and abundantly available at low cost. Most of them are fibrous in structure and are composed largely of cellulose, with lesser amounts of lignin and other components. Sources of organic fillers are plentiful and renewable natural (cellulose) and wood flour, flock, nutshell flours, starch, corncobs, and rice hulls. They improve physical, chemical, and electrical properties of compounds. Organic fillers are also used with other types of additives to reduce the cost of the molding compound and to improve processability. 

---