Thermochemical and hygroscopicity properties of pinewood treated by in situ copolymerisation with methacrylate monomers

• The wood from pine fast-growing plantation was used to prepared high performance wood–polymer composites.
• The wood was treated with various methacrylic monomers that were successively cross-linked in situ.
• The treatment modified the hydrophilic untreated pinewood into hydrophobic composites.
• No chemical decomposition of wood was observed during the in situ polymerisation.
• Surface wettability decreased after treatments.

This study aims to evaluate the hygroscopicity and thermochemical properties of pine wood/polymer composites prepared by in situ polymerisation of methyl methacrylate (MMA) using glycidyl methacrylate (GMA) and methacrylic acid (MAA) as cross-linkers. The pine wood samples were impregnated in a vacuum/pressure system and polymerised in an oven at 90 °C for 10 h, using benzoyl peroxide at 1.5 wt.% as catalyst. The composite was characterised through dynamic wettability, water uptake and dimensional stability tests, ATR-IR spectroscopy, TGA, and DSC. ATR-IR spectra show an increase of the peaks at 1746, 1460, and 1145 cm−1 corresponding to the chemical structures of the polymers into the pores and capillaries of treated wood. The TGA and DSC analysis pointed out a chemical interaction between the copolymer and the wood cell wall in composites with GMA and MAA. The composites prepared with MMA presented improvements for the hygroscopicity and dimensional stability properties by 50%. However, the addition of GMA and MAA resulted in the best increases for hydrophobicity and dimensional stability of the samples, ∼65–78%.