The study of deposition of wood extractives and model compound colloids onto chromium and cellulose surfaces using quartz crystal microbalance with dissipation (QCM-D)
Quartz crystal microbalance with dissipation monitoring (QCM-D) was used to investigate the fundamental interactions between wood extractives and surfaces used in papermaking. Experiments were carried out at 25. °C and 50. °C on a microcrystalline cellulose-coated surface (a surrogate for paper) and a chromium surface (a surrogate for metal surfaces in paper machines and printing presses) using colloids prepared from wood extractives and model compounds of the components in wood extractives. Differences in adsorption behaviour were observed between the two surfaces as a function of temperature. On both surfaces, triolein and abietic acid were found to deposit to a greater extent than wood extractives, mixed model compounds and oleic acid. At 25. °C the colloids were found to have two phases of adsorption onto cellulose surfaces, an initial rapid adsorption phase followed by a slower phase, compared to a single adsorption phase onto chromium. At 50. °C, only a single adsorption phase was observed on both surfaces. Abietic acid and oleic acid were found to desorb readily from both the cellulose and chromium substrates, while triolein remained strongly adsorbed. However significantly more abietic acid remained on the chromium surface at 25. °C compared to any other tested material, providing a possible explanation for the observed high rates of resin acid deposition onto metal surfaces during papermaking and printing. At 25. °C and 50. °C, less wood extractives and mixed model compound colloids were deposited onto cellulose than onto chromium, which may also explain the high rates of deposition on the metal surface. Stabilisation of the colloids due to interactions between different components within the colloid results in lower deposition of wood extractives and mixed model compound colloids compared to individual component colloids.