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ARTICLE

Effect of Phenolation, Lignin-Type and Degree of Substitution on the Properties of Lignin-Modified Phenol-Formaldehyde Impregnation Resins: Molecular Weight Distribution, Wetting Behavior, Rheological Properties and Thermal Curing Profiles

by Marion Thébault, Larysa Kutuzova, Sandra Jury, Iris Eicher, Edith-Martha Zikulnig-Rusch, Andreas Kandelbauer

1 Kompetenzzentrum Holz (Wood K Plus), Linz, A-4040, Austria
2 Reutlingen University, Lehr-und Forschungszentrum Process Analysis & Technology, School of Applied Chemistry, Reutlingen, D-72762, Germany

* Corresponding Author: Andreas Kandelbauer. Email:

(This article belongs to the Special Issue: Renewable and Biosourced Adhesives)

Journal of Renewable Materials 2020, 8(6), 603-630. https://doi.org/10.32604/jrm.2020.09616

Received 03 February 2020; Accepted 25 March 2020; Issue published 12 May 2020

Abstract

Here, the effects of substituting portions of fossil-based phenol in phenol formaldehyde resin by renewable lignin from two different sources are investigated using a factorial screening experimental design. Among the resins consumed by the wood-based industry, phenolics are one of the most important types used for impregnation, coating or gluing purposes. They are prepared by condensing phenol with formaldehyde (PF). One major use of PF is as matrix polymer for decorative laminates in exterior cladding and wet-room applications. Important requirements for such PFs are favorable flow properties (low viscosity), rapid curing behavior (high reactivity) and sufficient self-adhesion capacity (high residual curing potential). Partially substituting phenol in PF with bio-based phenolic co-reagents like lignin modifies the physicochemical properties of the resulting resin. In this study, phenol-formaldehyde formulations were synthesized where either 30% or 50% (in weight) of the phenol monomer were substituted by either sodium lignosulfonate or Kraft lignin. The effect of modifying the lignin material by phenolation before incorporation into the resin synthesis was also investigated. The resins so obtained were characterized by Fourier Transform Infra-Red (FTIR) spectroscopy, Size Exclusion Chromatography (SEC), Differential Scanning Calorimetry (DSC), rheology, and measurements of contact angle and surface tension using the Wilhelmy plate method and drop shape analysis.

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