Carboxymethylated wood

Kishi, H. and Shiraishi, N. (1986). Wood-phenol adhesives prepared from carboxymethylated wood II. Mokuzai Gakkaishi, 32(7), 520-526. 

Nakano, T. (1993a). Relaxation properties of carboxymethylated wood plus metallic salts in aqueous solution. Holzforschung, 47(3), 202-206. 

Carboxymethylated wood, allylated wood, and hydroxyethylated wood have been liquified in phenol, resorcinol, or their aqueous solutions and formalin after standing or stirring at 170 C for 30-60 min [3]. 

Figure 12 infrared spectra of carboxymethylated wood with various introduced metals. (From Ref. 33.)... 

Figure 13 Relationship between absorbance ratios >1595//) 1505 and the amounts of introduced side chains (Am). O, Carboxymethylated wood , succinylated wood. (From Ref. 33.)...

The amounts of introduced side chains are 1.07 mmol/g for carboxymethylated wood and 2.00 mmohg for succinylated wood. 

Figure 16 shows relationships between the number of introduced side chains and relaxation rigidity (G,) at 900 s for carboxymethylated wood binding various metal ions [341. Wood specimens were prepared from Japanese linden Tilia japonica Smik.). Carboxymethylation and the introduction of metal ions was the same procedure as mentioned in the previous section [32,33]. Stress relaxation measurements were carried out in an aqueous solution at 30°C. The relaxational property of carboxymethylated wood without metal ions is first discussed. For carboxymethylated wood (a broken line in Fig. 16), Gf (900) decreases with an increase in the number of introduced side chain. This rapid decrease appears to be caused by two factors. One is the effect of sodium hydroxide (NaOH). Young s modulus of wood treated with an aqueous solution of NaOH decreases remarkably under wet conditions, especially at concentrations above 10% NaOH [35]. The other factor is the electrostatic repulsion of ionized carboxymethyl groups in carboxymethylated wood, as mentioned in the above section [291. For example, conformation of polypeptide is influenced by the ionization of the side chains, and the structural change of the helix-coil transition has been interpreted as a reversible transformation. Theoretical treatment of the transformation has been reported to explain the mechanism [23-25, 36-43]. The conformation of component molecules in wood, however, cannot change markedly by ionization in comparison with soluble polyelectrolytes in water, because carboxymethylated wood is not dissolved in water. Only space among the main chains is expanded by the electrostatic repulsion due to negatively charged side chains. For these reasons, G (900) of carboxymethylated wood decreases with an increase in the number of introduced side chains.

Figure 16 Relationship between relaxation rigidity at 900 s Gj (900) and content of carboxymethyl group in carboxylated wood (CMW). O, CMW-Na A, CMW-Mg A, CMW-Ca A, CMW-Zn , CMW-Al , CMW-Fe(IlI), carboxymethylated wood without metal ions. (From Ref. 34.)...

We noted that the crosslinking between main chains remains in water for carboxymethylated wood binding AF" or Fe(III). Figure 18 shows the... 

Molecular motion of chemically modified wood is influenced by binding metal ions. One factors is valency, as mentioned previously. In general, however, there is not only valency but also other factors related to mobility [45-47]. Eisenberg reported that the mobility of polymers binding metal ions relates to three factors charge, amount of metal ion, and metal ion radii [48]. The mobility of molecules of carboxymethylated wood, especially that of... 

Figure 19 shows dynamic shear modules (G ) and loss tangent (tan 8) as a functions of temperature for carboxymethylated wood binding various metal ions [49]. The content of carboxymethyl groups in treated wood is about 1.07 mmol/g for each specimen. Dynamic viscoelastic measurements were carried out under vacuum. There are three dispersions in the range below 1(X)°C the P dispersion near 50°C for the carboxymethylcellulose main chain motion in the modified wood, the 7 diversion near 0°C for local mode of wood components related to water, and the 8 dispersion near - 60°C for the side chain... 

Figure 19 Temperature dependence of G and tan 8 for carboxymethylated woods (CMWs) and for CMWs containing metal ions. (From Ref. 49.)...

This equation suggests that the above discussion is reasonable. That is, application of Eisenberg s theory is valid for carboxymethylated wood containing metal ions. Accordingly, the mobility of carboxymethylate cellulose in carboxymethylated wood appears to depend on three factors electric charge, amount, and radius. The relationship is represented by Eq. (8). This result shows that Eisenberg s theory is valid for chemically modified wood containing metal ions. 

Shiraishi, N., and Kishi, N. (1986) Wood-Phenol Adhesives Prepared from Carboxymethylated Wood. I. J. Appl Polym. ScL, 32, 3189-3209. 

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