Wood pulp industry by-product valorization for acrylate synthesis and bio-based polymer development via Michael addition reaction

Abstract

It is crucial to adapt the processing of forest bio-resources into biochemicals and bio-based advanced materials in order to transform the current economic climate into a greener economy. Tall oil, as a by-product of the Kraft process of wood pulp manufacture, is a promising resource for the extraction of various value-added products. Tall oil fatty acids-based multifunctional Michael acceptor acrylates were developed. The suitability of developed acrylates for polymerization with tall oil fatty acids-based Michael donor acetoacetates to form a highly cross-linked polymer material via the Michael addition was investigated. With this novel strategy, valuable chemicals and innovative polymer materials can be produced from tall oil in an entirely new way, making a significant contribution to the development of a forest-based bioeconomy. Two different tall oil-based acrylates were successfully synthesized and characterized. Synthesized acrylates were successfully used in the synthesis of bio-based thermoset polymers. Obtained polymers had a wide variety of mechanical and thermal properties (glass transition temperature from –12.1 to 29.6 °C by dynamic mechanical analysis, Young's modulus from 15 to 1 760 MPa, and stress at break from 0.9 to 16.1 MPa). Gel permeation chromatography, Fourier-transform infrared (FT-IR) spectroscopy, matrix-assisted laser desorption/ionization-time of flight mass spectrometry, and nuclear magnetic resonance were used to analyse the chemical structure of synthesized acrylates. In addition, various titration methods and rheology tests were applied to characterize acrylates. The chemical composition and thermal and mechanical properties of the developed polymers were studied by using FT-IR, solid-state nuclear magnetic resonance, thermal gravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and universal strength testing apparatus.