Wood polymer composites with thermally modified wood | Koksnes polimēru kompozīti ar termiski modificētu koksni

Inglés. With the expansion of industrial wood thermal modification, the resources of utilisable modified wood residues available for the production of higher value added products increase. Aim of the work: Study of the thermally modified wood utilisation feasibility for wood-polymer composites. Wood polymer composites (WPC) are considered to be eco-friendly products, because at least 50 mass% of the composite contain natural fibres; as a binder (matrix) for WPC recycled thermoplastics can be used; WPC are recyclable. The use of thermally modified (TM) wood in wood polymer composites is promising due to the availability of TM wood residues, since the TM industrial production volume has a stable annual growth. Utilisation possibilities of birch and pine wood, modified at various thermo-hydro treatment (THT) regimes, for manufacturing wood polymer composites, in which polypropylene (PP) is used as the matrix, were investigated. The composition of unmodified (UM) and THT wood particles fractions, L/D ratio and chemical composition were determined. The effect of the THT regime on the WPC properties (melt flow index, bending properties, impact resistance, biological durability, water absorption and surface properties) was studied, and the optimal wood modification regimes were found. The effect of the wood particle size on the WPC properties was analysed; it is found that the particle size, unlike the case of unmodified wood, has little effect on the properties of composites with THT wood. The WPC properties’ improvement possibilities, changing the composition, were studied. The WPC fracture mechanism in the impact strength tests was studied by SEM.

Letón. Paplašinoties rūpnieciskai koksnes termiskai modifikācijai, pieaug utilizējamu modificētas koksnes atlikumu resursi, kas pieejami augstākas pievienotās vērtības produktu ražošanai. Izpētītas pie dažādiem hidrotermiskās modifikācijas (HTM) režīmiem modificētas bērza un priedes koksnes atlikumu izmantošanas iespējas koksnes polimēra kompozītu (KPK) izgatavošanā, kuros kā matrica izmantots polipropilēns (PP). Noteikts koksnes skaidu frakciju sastāvs, garuma/diametra (L/D) attiecība un ķīmiskais sastāvs. Pētīta HTM režīma ietekme uz KPK īpašībām (kausējuma tecētspēju, lieces īpašībām, triecienizturību, bioloģisko izturību, ūdens absorbciju un virsmas īpašībām) un atrasti optimālie koksnes modificēšanas režīmi. Analizēta koksnes daļiņu izmēra ietekme uz KPK īpašībām un atrasts, ka daļiņu izmērs, atšķirībā no nemodificētas koksnes, maz ietekmē īpašības kompozītiem ar HTM koksni. Izpētītas KPK īpašību uzlabošanas iespējas, izmainot sastāvu. Ar SEM pētīts KPK sagraušanas mehānisms.