preprints.org > chemistry and materials science > analytical chemistry > doi: 10.20944/preprints202307.1725.v1

Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Version 1 : Received: 25 July 2023 / Approved: 25 July 2023 / Online: 26 July 2023 (03:25:06 CEST)

This publication investigates the potential application of bark extractives as a biopolyol and extracted bark residues as a filler for producing polyurethane materials. The aim is to enhance the properties of polymeric composites while reducing the environmental impact associated with the complex utilization of bark.The comprehensive study of compositions of extractives isolated from black alder (Alnus glutinosa) and Baltic pine (Pinus silvestris) barks was performed using microwave-assisted water extraction. The yield of the extracts obtained under different extraction conditions, as well as the total phenolic and monomeric carbohydrate content in the extractives, were studied. Furthermore, UHPLC-HRMS analysis was conducted to study the detailed composition of the bark extracts.The total content of hydroxyl groups and the relative portion of aliphatic and phenolic groups in the isolated extracts were determined depending on the extraction regimes and bark origination. The dominant compounds in black alder bark extracts isolated at 70-90⁰C were identified as diarylheptanoids and their derivatives bearing sugar units, with oregonin being the main compound. Pine bark extracts isolated at the same temperature were found to be rich in oligomeric proanthocyanidins. Extracts from both black alder and pine barks obtained at different times of isothermal heating between 130-150°C were rich in carbohydrates and showed an increased proportion of aliphatic OH groups.The study also focused on the composition of residual biomass. It was indicated by Py-GC/MS/FID and wet chemistry methods that residues of both black alder and pine bark are enriched with lignin in comparison with initial barks. Therefore, it can be proposed that extracted bark residues introduced into polyurethane compositions will act as a charcoal formation promoter, thus increasing the flame resistance of materials.Overall, the study provides valuable insights into the chemical composition of bark extractives and extracted bark residues for their potential application as biopolyol and fillers of polyurethane materials, contributing to a more sustainable approach in polymer composite production.

Extraction; Bark residues; Polyurethane; Analytical pyrolysis

Chemistry and Materials Science, Analytical Chemistry

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