The soy flour as an extender for uf and muf adhesives in birch plywood production

Formaldehyde emission still remains a major disadvantage of widely applied formaldehyde-containing amino resins such as UF (urea-formaldehyde) resin and MUF (melamine-urea-formaldehyde) resin. The compositions of adhesives for plywood manufacturing have to contain a proper extenders in order to adjust their viscosity. Thus, the aim of the study was to investigate the effect of protein-rich soy flour (SF) as the extender for adhesives. The composition of flours and their ability to absorb the formaldehyde were determined. Properties of liquid resins such as gel time, viscosity, pH and solid content were investigated. The possible chemical interaction between the extenders and resins were assessed with the use of FTIR spectroscopy. Plywood panels manufactured using UF and MUF adhesives with the soy flour introduced as the extender in various concentrations were tested in terms of shear strength and formaldehyde release. Studies have shown that soy flour has a favorable composition and formaldehyde-scavenging ability. The addition of SF affected resins properties such as viscosity and gel time but showed no influence on their pH and solid content. FTIR analysis has not explained the chemical interaction between resin and extender. The application of soy flour in the concentration of 15% for UF resin and 10% for MUF resin allowed to produce plywood characterized by improved bonding quality and decreased formaldehyde emission.

Hydrophobic properties of wood traeted with propolis-silane formulations

The study presents results of hydrophobic properties examination of Scots pine wood treated with a propolis extract and two propolis-silane formulations determined by contact angle analysis and water uptake test. From contact angles data the surface free energy and its shares as well as the work of adhesion were calculated and described in this paper. Treatment with the ethanolic extracts of propolis (EEP) and the propolis-silane formulations a water repellent property of treated wood when compared to control wood. Addition of silicon compounds to the propolis extract caused decreased of the water uptake and increased of the contact angle value of treated wood. The most effective hydrophobic effect was obtained using the impregnation with the formulation based on EEP and organosilanes: vinyltrimethoxysilane (VTMOS) and tetraethyl orthosilicate (TEOS).