INFLUENCE OF ACID-BASE ENVIRONMENTS ON ELASTIC-STRENGTH CHARACTERISTICS OF WOOD-POLYMER COMPOSITES

A study was conducted of the influence of acid-base media on the elastic-strength characteristics of wood-polymer composites. High-pressure polyethylene grade 15303-003 produced by Kazanorgsintez PJSC was selected as the object of study, and wood flour (from coniferous wood) was pre-dried and crushed in a rotary knife mill PM 120 as a filler. As a component ensuring the thermodynamic compatibility of the mixture of polyethylenes and filler, Sevilen grade 12206-007 produced by Neftekhimsevilen OJSC, functionalized by the alcoholysis method, was introduced into the composite. Samples of composites containing wood flour from 10 to 30% were examined. The study of composites for water absorption was carried out in accordance with GOST 56652-2015. It has been established that as the exposure time of composites in distilled water increases, water absorption increases. Composites are saturated with water after the first twenty days. The study of the influence of acid-base media was carried out in accordance with GOST 12020-2018. The effect of 5% solutions of HCl and KOH on the change in mass of composites was studied. It has been established that as the filler content increases, the mass of the composites increases after exposure to HCl and NaOH solutions. The increase in mass persists even after drying the composites for 24 hours in air. As the filler content increases, the tensile strength and elastic modulus increase, and the tensile elongation decreases. This trend persists both for the original composites and for the composites that have undergone chemical treatment. At the same time, the elastic-strength characteristics of the original composites are slightly higher in comparison with composites exposed in 5% solutions of HCl and NaOH, which is apparently due to the hydrolysis of the main components of wood. This leads to partial rupture of polymer bonds in cellulose and lignin macromolecules. It has also been established that acidic and basic environments do not have a significant effect on the elastic-strength characteristics of wood-polymer composites when filled with wood flour up to 30%.