Sintesis Poly (hidroksi) uretan dari Polyol dan Kulit Spruce Terliquifikasi untuk Bahan Impregnasi Kayu
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Date
2013Author
Sitanggang, Vera Juruta br
Wistara, I Nyoman J.
Dannawan, Wayan
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The finding and application of environmentally benign wood preservatives is becoming paramount. Nontoxic and less leachable or degradable chemical have been suggested for exterior application. Polyurethanes synthesized through a green chemical pathway is very promising environmentally friendly wood modification processes. In this study, non-isocyanate route of polyurethane synthesis based on polyol (i.e. xylitol, sorbitol, liquefied spruced bark, glycerol and PG3), alkyl carbonate (i.e. DMC and DEC) and diamine (i.e. HMDA, EDA and DETA) was realized for wood impregnation through in-site polymerization. The structure and mass average molecular weight (Mw) of polyurethanes synthesized and impregnated were then analyzed by using FTIR, NMR and SEC. According to the results, synthesis of polyurethane by two pot method in water brought to cyclic carbonate degradation. The using of DEC in transcarbonatation reaction in two pot method gave similar characters of FTIR spectrum to the use of DMC, however the used of DMC was simpler than that of DEC. The synthesis of polyurethane by one pot method using different diamines confirmed the presences of carbamate function as analyzed by FTIR. However, the visual appearance of polymers produced showed that the use of HMDA as diamine resulted a solid product that was less water-soluble compared to that resulted from the used of EDA and DETA. The distribution of mass average molecular weight (Mw) of polyurethanes synthesized determined by SEC showed that the most satisfying polymer with Mw of 4380 g/mol was prepared without solvent. The reaction in water produced polymers with low Mw (less than 750 g/mol). Polyurethanes synthesized in methanol has higher Mw than that in water. In the same solvent, the use of HMDA resulted in a polymer with higher Mw than that of using EDA. Wood impregnations using one step method using solvent gave unsatisfactory WPG (about 12.59 – 19.71 %) and LC (about 50.36 – 62.80 %). One step impregnation without solvent gave higher WPG (about 78.39 – 87.63 %) and lower LC (19.11 – 21.25 %). However, wood impregnation without solvent is not feasible to be applied industrially. In other hands, five conditions of two step impregnations performed gave WPG of about 14.89 – 30.73 % and LC of about 42.22 – 56.52 %. In the case of two step impregnations without solvent, the first impregnation left inadequate space for the retention of the second step. It corresponds rather to leaching. Moreover, wood impregnation in two step faced a constrain of reaction stoichiometry. Since it is not applicable in charge with wood impregnation using methanol or ethanol as the solvent is more recommended by comparing with impregnation with an aqueous solution. However, it needs improvement on its resistance against leaching when used outdoor.
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