Tratamento da madeira de duas espécies florestais por polimerização in situ de monômeros metacrilatos.

Abstract

The aim of this study is to preparation of polymeric composites by in situ polymerisation of methyl methacrylate in the wood of Pinus taeda and Schizolobium parahyba (guarpuruvu), using glycidyl methacrylate (GMA) and methacrylic acid (MAA) as crosslinkers. For this purpose, samples of two wood, previously dried at 90°C were impregnated with vacuum/pressure procedure (30 min of vacuum at 600mmHg and 1h of pressure at 6 atm) and polymerised at 90°C by 10h. The impregnation solutions were based on methyl methacrylate monomer (MMA), with addition of two fractions (2:1 and 3:1) of glycidyl methacrylate (GMA) and methacrylic acid (MAA). The wood treatability was characterised by monomers and polymers retention, conversion rate, permanent volumetric and density swelling, weight percent gain, chemical leaching, and scanning electron microscopic. The wood polymer composites were evaluated in relation to physical properties (water absorption, dimensional stability, dynamic wettability and equilibrium moisture content), mechanical (flexural, hardness and brittleness), thermochemical (ATR-IR spectroscopy, TGA and DSC) and colour (CIELab evaluation, UV-Vis, and specular gloss). According to results it was observed that both are easily treatable woods mainly due to high porosity and low density. Furthermore, we observed good conversion rate of monomers in polymers, and an consequence increased in the conversion was observed with the presence of GMA and MAA. By SEM micrographs it was observed from the addition of crosslinkers (GMA and MAA) polymer material acted as reinforcement interacting with the cell wall, and not just fill in the pores and lumens. All wood composites showed more satisfactory physical and mechanical properties that the wood control, with the insertion of crosslinkers was obtained a subsequent increase in such properties. For the aesthetic properties was observed that after the in situ polymerization treatment, the composites tended to maintain the original colour of the wood, however was change in the brightness, chroma and specular gloss of the samples. On the whole, from the results observed in this study, was concluded that the pine and guapuruvu wood have great potential for the fabrication of new composite wood materials via in situ polymerization treatment, and showed better results when applied to the GMA as crosslinker.