Self-bonding properties

One year later, Burrows published results from a comprehensive series of experiments using 100% Douglas-fir bark as furnish for particleboard (35). No binder was used he relied upon the "self-bonding" properties of Douglas-fir bark. Variables included bark particle size, mat moisture content, pressing pressure, and use of various overlays. Additional boards were made from ponderosa pine, western hemlock, and white fir barks. A pilot-plant-size run was made using results gathered from the study. 

Because of its strong self-bonding properties, an isolated molecule of water can be found only in steam (Fig. 3.4a). Such a molecule is roughly triangular with an O—H distance of 0.96 A and a H—O—H angle of 105°. The two protons and two lone-pairs of electrons occupy tetrahedrally disposed, hybridized orbitals. 

Neste patented an industrial route to a cellulose carbamate pulp (90) which was stable enough to be shipped into rayon plants for dissolution as if it were xanthate. The carbamate solution could be spun into sulfuric acid or sodium carbonate solutions, to give fibers which when completely regenerated had similar properties to viscose rayon. When incompletely regenerated they were sufficientiy self-bonding for use in papermaking. The process was said to be cheaper than the viscose route and to have a lower environmental impact (91). It has not been commercialized, so no confirmation of its potential is yet available. 

The self-extinguishing properties of the resin are due to the high chlorine content of the acid (54.8%). The double bond of the acid is unreactive and it is... 

Kiguchi, M. and Yamamoto, K. (1992). Chemical modification of wood snrfaces by esterification III. Some properties of self-bonded benzylated particleboard. Mokuzai Gakkaishi, 38(2), 150-158. 

Forrest, C.W., Kennedy, P. and Shennan, J.V. (1972) The fabrication and properties of self-bonded silicon carbide bodies, in Special Ceramics 5, The British Ceramic Research Association, Stoke-on Trent, UK. 

Therefore, silanol species can be a driving force of the resulting organization in the hybrid material. More interestingly, silanols are now used as reactive supramolecular functions, that is to say as a synthetic tool allowing the association of molecular units and their further transformation, see below. On the other hand, these self-assembling properties do not appear to be clearly predictable, especially because in the Sol-Gel process other H-bonding species (mainly alcohol, water and sometimes solvent) are present and can disturb the silanol self-association. 

The thermoplasticization of wood can be subdivided into two categories (Fig. 8) (1) the total thermoplasticization of wood meals to produce products that can be used as wood based adhesives or as moulded substitutes for synthetic plastics [21-23] and (2) partial thermoplasticization of wood. The development of hot-melted and self-bonded wood materials and methods of improving the surface properties of natural wood by partial thermoplasticization of wood are reviewed below. 

Some Properties of Hot-Melted and Self-Bonded Boards... 

Since the bonding strength of benzylated wood surfaces was similar to that achieved using commercial hot-melt adhesives, the development of self-bonded wood materials using surface benzylated particles was possible [32]. Suzuki and Iwakiri [33] reported that self-bonded fiberboard produced from benzylated asplund-processed fibers had high thermoplasticity, dimensional stability, and water resistance. Morita and Sakata also produced hot-melt cyanoethylated fiberboards, but they showed poor water resistance [34]. Both benzylated and cyanoethylated fiberboards lacked many of the inherent good properties of solid wood because they did not retain the cellular construction of wood. 

Hot-melted and self-bonded boards show curve moldability during secondary processing, and some of the properties of the boards may be altered by modifying the shape of the wood particles or by changing the reaction conditions. Such boards show the properties of both wood and plastics. Thus a... 

Of all of the elements of the Periodic Table, only neighboring carbon and boron share the properties of self-bonding (catenation) and the support of electron-delocalized structures based upon these catenated frameworks. Carbon catenation, of course, leads to the immense field of organic chemistry. Boron catenation provides the nido-, arachno-, and /i p/io-boranes, which may be considered as the borane equivalents of aliphatic hydrocarbons, and the discrete families of c/oso-borane derivatives which bear a for nal resemblance to the aromatic hydrocarbons, heterocycles, and metallocenes. Aside from these analogies, boron and carbon chemistries are also important to each other through their extravagant ability to mix m ways not available to other element-pairs. Thus, the conflux of boron and carbon chemistries effectively provides an element-pair for exploitation in a variety of novel ways. 

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