Lignin filler

Current research indicates that there is a growing interest in natural fibers. Natural fibers Ifom jute were tested in thermosetting and thermoplastic resins. Lignin fillers were used in phenol-formaldehyde, SBR, SBS, and S1S ° and with good results. The opportunities for applications of natural fibers in industrial products have been the subject of recent reviews. Cellulose whiskers with a high reinforcing value were obtained from wheat straw. " Wood fibers were found applicable to such diverse materials as polypropylene... 

Lignin fillers decreased the cure rate of phenol-formaldehyde resin. Here, the filler acts as a diluent and does not have the ability to affect the reaction kinetics by interaction with the polymer. Glass fibers also decreased the rate of cure of a phenolic resin in another study. 

Peng and Riedl (1994) investigated the chemorheology of phenol formaldehyde resins filled with unmodified and methylolated lignin fillers. They found that both fillers reduced the reaction rate and that the chemorheology profile of filled systems is better represented by the WLF model than by the Arrenhius model. 

Current research indicates that there is a growing interest in natural fibers. Natural fibers from jute were tested in thermosetting and thermoplastic resins. Lignin fillers were used in phenol-formaldehyde, SBR, SBS, and SIS and... 

Treatments such as mercerization/acetylation of fibers will result in an increase in the dynamic mechanical properties of composites, which was observed by Martins and Mattoso [40]. The stabilizing effect of lignin filler on NR was examined by Kosikova et al. [41], using DMA. Addition of hgnin improved the dynamic mechanical properties of NR vulcanizates. In another study. Da Costa et al. [27] found that addition of RHA to NR causes a shift in Tg values of filled mbber vulcanizates toward higher temperatures, showing the presence of cross-Unks,... 

Kosikova, B., Osvald, A., and Krajcovicova, J. (2007) Role of lignin filler in stabilization of natural mbber-based composites. J. ApjA. Polym. Sci., 103, 1226-1231. 

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. 

Other spherical fillers include carbon black. This has several roles particularly in combination with elastomers, e.g., black pigment, anti-oxidant and UV stabiliser, reinforcing filler, and an electrical conductor when used at 60% concentration. Wood flour is particularly effective in phenol/formaldehyde and melamine or urea/formaldehyde thermoset resins because the phenolic lignin component in the wood reacts with the methylol groups (-CH2OH) in the growing polymer. 

Carbon black pigments, 19 409-410 Carbon blacks, 10 713 11 316-317 as graphite filler materials, 12 724 production of, 19 385 Carbon—carbon bond cleavage, in lignin, 15 6... 

Lignosulfonates have recently been tried as a filler for rubber but are slightly less efficient than carbon black, the cheap conventional filler with which it must compete. However, it is conceivable that lignin could increase the stability of rubber to ozone, the natural reagent which causes vulcanized rubber to "perish. ... 

Fillers are relatively inert materials that usually add bulk but when well chosen, they can enhance physical and chemical properties. Many natural and synthetic materials are used as fillers today. These include polysaccharides (cellulosics), lignin, carbon-based materials, glass, and other inorganic materials. 

Back (10) has indicated that superior board performance is achieved with covalent bonding of the adhesive to the wood. A binder, then, must have at least the minimum number of reactive sites per molecule. If there is one or fewer such sites, then the lignin should behave as a filler, which may or may not be chemically bound to the resin. In the case of two reactive sites, a linear macromolecule is possible, or the lignin may be considered to behave as an extender for a resin. When three or more sites are available, crosslinking can occur and the lignin could then become a full partner in the crosslinked binder. One may project how the lignin could behave, once the reactive sites on the lignin molecule have been mapped. For this chapter, the interactive sites will be alcohols and benzyl alcohols, to simulate the reaction of PF resins with the carbohydrates in the wood. 

The gluability of the lignin-epoxy resin adhesives was found to be improved by the addition of calcium carbonate (50% by weight) to the liquid resin. This must be attributed to the nature of the weak alkali in calcium carbonate as a cure accelerator, and to the reinforcement effect of fillers. Since wood surfaces are acidic, the addition of alkaline fillers effectively alters the pH of the glue line. 

Wood forms one of the world s most important chemical raw materials. It is the primary source of cellulose for the pulp and paper and cellulose industries. These industries are well up in the group of 10 major industries of the United Slates. For paper, rayon, films, lacquers, explosives and plastics, which comprise the greatest chemical uses of wood, it is the cellulose component (plus certain amounts of hemicellulose) of wood that is of value. The lignin forms a major industrial waste as a by-product of the paper and cellulose industries. Its major use is in its heat value in the recovery of alkaline pulping chemicals. A variety of minor uses for lignin have been developed, such as for the manufacture of vanillin, adhesives, plastics, oil-well drilling compounds and fillers for rubber. 

The filler is usually "furafil," (a ligno-cellulose by-product of furfural production of Quaker Oats Company), Douglas fir or alder bark, wood particleboard sander dust and/or attapulgite clay. A sulfite paper mill lignin is also used as a filler in the Northwest. Between 50,000 and 60,000 tons of filler were used in phenolic glue mixes per year. 

Sulfonated lignin is predominately used as a stabiliser in drilling muds and emulsions. However it has a wide range of other potential, though relatively low value, applications, including use as a dispersant in paints, clay, porcelain, dyes, pesticides and industrial cleaning agents. It is also used as a binder and filler in... 

Organic Extenders. Organic extenders are primarily of two types (1) fillers derived from organic materials and (2) low-cost, naturally occurring or synthetic resins. Of the first type, wood flour, shell flour, and other cellulosic fillers are the most common. They also provide a margin of mechanical property reinforcement because of their relatively high aspect ratio. Of the resinous types these are petroleum-based derivatives as well as soluble lignin and scrap synthetic resins. 

Chemical Characteristics of Paper Documents. From the earliest times up to the present day, the substances used as vehicles for writing have been numerous. Ancient paper documents were basically made from rags of cotton and linters cellulose is the major chemical constituent (I). Modern papers, however, are made of wood fibers, which usually are composed of cellulose, hemicelluloses, and lignin (I). In addition, for most of the modern papers, fillers, sizing agents, and other additives are used to improve paper properties (I). 

Typical fillers wood flour, glass fiber, carbon fiber, mica, wollastonite, mineral wool, talc, magnesium hydroxide, graphite, molybdenum sulfide, carbon black, cashew shell particles, alumina, chromium oxide, brass and copper powder, iron particles, steel fiber, ceramic powder, rubber particles, aramid, wollastonite, cellulosic fiber, lignin... 

Methods of filler pretreatment lignin treated by methylolation decreases the rate of cure of phenolic adhesives " carbon fiber was anodicaUy oxidized and subjected to various treatments with coupling agents to improve interfacial interaction with phenolic resins and oxidative stability of carbon fibers titanate coupling of oxidized fibers resulted in improved adhesion to matrix and enhanced thermal stability of fibers ... 

Typical fillers barium sulfate, calcium carbonate, carbon black, calcium sulfate whiskers, diatomaceous earth, glass fiber, glass spheres, hollow silicates, kaolin, mica, talc, wollastonite, silica, magnesium hydroxide, hydrotalcite, red mud, ground tire rubber, ferromagnetic powder, nickel fibers, wood flour, zirconium silicate, starch, soot, marble, aluminum, lignin, sand... 

Table VI also shows the relationship between the amount of hydrocarbon in the form of percent Ct and the relative fuse grade. The number of samples in Table VI is reduced from previous tables since many of the papers, because of their properties, were unable to withstand the abrasive fuse grade testing. For example, the sample with high levels of filler separated rather easily and pulled fibers from the surface, invalidating the test procedure. Even without these samples, however, a clear relationship between the amount of hydrocarbon on the surface, either in the form of rosin and rosin salts or lignin, is clearly related to the adhesion of the toner polymers to the paper surface. A least square fit of these data has a (relatively low) correlation coefficient of 0.85, and a slope of -0.8. Although the relationship may not be a linear one, it is clearly reasonable to presume that higher quantities of hydrocarbon on the surface of paper do prevent adequate adhesion of toner. This result corresponds with the previous work done by Borch(16) and also with results presented elsewhere in this symposium volume.

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