Impregnation of white pine wood with unsaturated polyesters to produce wood-plastic combinations

Two unsaturated polyester resins based on poly(1,2 propylene–maleate–phthalate) (PE1), and poly(oxy–diethylene–maleate–phthalate) (PE2) were used for the impregnation of oven‐dried white pine wood samples in admixture with styrene (S). Curing was affected by the initiator‐heat technique by either using 0.1–0.2% by weight of benzoyl peroxide (Bz2O2), or 1% by weight of methyl ethyl ketone peroxide (MEK). It was found that the use of PE1/S mixture resulted in the formation of wood–plastic combinations (wpc) with higher percent retention and higher percent polymer loadings than those obtained by the impregnation of wood samples with PE2/S imxtures. The use of different swelling solvents including ethanol, acetone or chloroform, did not influence the percent retention or polymer loadings of wpc for either PE1/S or PE2/S mixtures. Physical tests performed on wpc showed that compression, hardness, static bending were generally enhanced, water absorption was decreased, and dimensional change was retarded to different extents for both polyesters used, but no permanent stabilization was attained.