Anhydride modification

Chemical Modification of Wood (I) Acetic Anhydride Modification... 

Li etal. (2000a, 2001b) smdied the flammability of wood modified with acetic or propionic anhydrides, finding that this parameter, as determined by limiting oxygen index (LOI), was the same as that found for unmodified wood. Samples were also prepared which were impregnated with sodium silicate prior to anhydride modification. The latter treatment resulted in a decrease in flammability, as shown by an increase in the LOI of the wood. 

As noted previously in Chapter 3, the improved dimensional stability of wood as a result of anhydride modification has been found to be a function of WPG only, irrespective of the anhydride used for modification (Stamm and Tarkow, 1947 Hill and Jones, 1996b Li etal., 2000b). This shows that improved dimensional stability arises due to a bulking phenomenon, caused by the volume occupied by the bonded acyl adducts in the cell wall. The dimensional stabilization of wood modified with crotonic anhydride has also been reported ( etin and Ozmen, 2001). Reductions in the EMC have also been attributed to a bulking phenomenon (Papadopoulos and Hill, 2003), and in at least one example of decay protection (Papadopoulos and Hill, 2002). Further research is needed to determine if this is the case for resistance to other decay organisms. Only with the phenomenon of surface wettability does the relationship between a physical property of chemically modified wood and WPG seem to be broken (Hill and Jones, 1996c) (Table 4.1). 

The efficacy of anhydride modification to provide envelope protection to wood was examined using an ENV839 test against G. trabeum or C. versicolor. Wood samples were... 

Four different methods (vapour-phase acetylation using acetic anhydride, acetylation using ketene gas, liquid phase acetylation using acetic anhydride/xylene, or neat acetic anhydride) were used to acetylate pine wood chips to a variety of WPGs for the production of MUF-bonded particleboards (Nilsson etal., 1988). Composite boards were exposed to unsterile soil in fungal cellar tests. Boards made from ketene acetylated chips were not found to be resistant to decay at the maximum WPG level achieved (17 %) with a liquid acetic anhydride modification, no decay was recorded at a WPG level of c. 18 % after 12 months exposure, whereas with a vapour-phase treatment at the same WPG, evidence for decay was found. 

HiU, C.A.S. and HUUer, J. (1998). The kinetics of anhydride modification reactions of wood. Experimental results and theoretical modelling. International Research Group on Wood Preservation, Doc. No. IRGAVP/98-40125. 

Hill, C.A.S. and Jones, D. (1996b). A chemical kinetics study of the propionic anhydride modification of Corsican pine. Determination of activation energies. Journal of Wood Chemistry and Technology, 16(3), 235-247. 

Typical formulations of oil-less toners utilizing COCs are shown in Table 2.5. The compatibility with other resins and the pigment dispersibility can be improved by introducing carboxyl groups into the COC by the fusing air oxidation method, maleic anhydride modification, or acrylic acid modification (53). 

Song HY, Yao JH, Liu JZ et al (2005) Effects of phthalic anhydride modification on horseradish peroxidase stability and structure. Enzyme Microb Technol 36 605-611... 

Cha, J. and White, J. L. 2001. Maleic anhydride modification of polyolefin in an internal mixer and a twin-screw extruder Experiment and kinetic model. Polymer Envineerin and Science 41 1227-1237. 

A patent application by Maruyama et al. [64], teaches that anhydride modification of the butyl rubber improves the exfoliation of amine exchanged clays. This combination produces exfoliated clay-butyl rubber nanocomposites. These nanocomposites have excellent barrier performance. 

Work done by Gong et al. [66] is similar to the work by Maruyama et ah, above. They functionalize butyl rubber with succinic anhydride to improve the compatibility of butyl rubber with an organoclay. Barrier performance of the rubber nanocomposite increases with the amount of succinic anhydride modification. In a companion publication [67], butyl rubber is functionalized by grafting maleic anhydride onto the polymer chain with peroxide. The same organoclay is utilized in this work as well to form the rubber nanocomposite. Barrier performance of the butyl rubber is significantly enhanced. 

Eor pretreatment of sisal fiber chemicals such as alkali (NaOH), permanganate (KMn04), acetylation, peroxide (BPO and DCP), isocyanate treatment, stearic acid, silane, benzoylation [79], maleic anhydride modification, PPG-TDI [34, 60, 61], and cold-plasma treatment are used [76, 118]. 

Reaction of acetic anhydride with (typical wood fiber) OH groups forms an ester bond and acetic acid is formed as a by-product. Reaction without catalyst was conducted at 70°C [33]. It is known that the rate of reaction is promoted by wood-swelling agents such as pyridine that can be used only at laboratory scale. The improved dimensional stability of wood as a result of anhydride modification has been found to be a function of weight percentage gain (WPG) only, regardless of the anhydride used for modification. 

H.P.S. Abdul Khalil, and N.L. Suraya, Anhydride modification of cultivated kenaf bast fibers morphological, spectroscopic and thermal studies. Bioresources 6(2), 1122-1135 (2011). 

The effect of acetic, maleic or snccinic anhydride modifications of wood fibre on the mechanical properties and dimensional stability of differently bonded fibre boards was studied [33]. The binders for the fibreboards used in that work were powdered PF resin of the novolak type, PP and a combination of the two. Significant improvement in the mechanical properties was obtained as a result of the anhydride modifications. Thus, modification of wood fibres with maleic anhydride (MA) resulted in a reduction in the modulus of rupture of the PF and PF/PP-bonded boards, whereas acetylation and modification with succinic anhydride did not cause any significant changes in the modulus of rupture of the boards. The anhydride modifications improved the internal bond strength of the binder type used. Dimensional stability of the fibreboards was observed to increase significantly as result of the modifications [33]. 

Auxiliary agents coupling agents used in con wsites Y-anunojHopyltrimethoxy silane maleic anhydride modification ... 

The electron transport activities, following acetic anhydride modification, and dark pH measurements were performed as described under "Materials and Methods" in Laszlo et al. (1983). 

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