Modification of fiberboard with an oligomer based on petrochemical and polystyrene waste

Currently, the production of low molecular weight polymers (oligomers) has been mastered on an industrial scale, which have found their application in the production of paints and varnishes, as well as in composite compositions for various purposes. New compositions based on petrochemical waste and polystyrene have been developed and investigated for modifying wood-fiber boards in order to increase their hydrophobic properties and strength indicators. To modify the fiber-wood slabs, an oligomer-based composition prepared from polybutadiene by-products (50% styrene bound content, aluminosilicate catalyst, 160 °C, 24 h) in combination with secondary polystyrene was used. The molecular weight of the prepared oligomeric composition varied from 4000 to 7000, with an increase in the content of secondary polystyrene in the composite from 10 to 40%. The introduction of the oligomeric product into wood slabs was carried out in the form of a toluene solution with the addition of naphthenic siccative. Solvent was removed from impregnated samples of wood-fiber boards and high-temperature treatment of modified boards was carried out at a temperature of 160-165 °C. During high-temperature processing, additional distillation of solvent residues and other low-molecular fractions took place. This ensured the environmental friendliness of the modified plates obtained, and the presence of a siccative ensured the flow of the oligomer structuring processes with the formation of a wood-polymer frame. The oxidative processes occurring in this case provided an increase in the bond between wood fibers and oligomer molecules due to the intermolecular interaction between the polar groups of the woody substance and the modifier. This makes it possible to provide modified plates with increased physical and mechanical properties and significantly reduce their water absorption and swelling.

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