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The aim of this study was to develop bio-based adhesives that can be used for various packaging papers. In addition to commercial paper samples, papers produced from harmful plant species in Europe, such as Japanese Knotweed and Canadian Goldenrod, were used. In this research, methods were developed to produce bio-based adhesive solutions in combinations of tannic acid, chitosan, and shellac. The results showed that the viscosity and adhesive strength of the adhesives were best in solutions with added tannic acid and shellac. The tensile strength with adhesives of tannic acid and chitosan was 30% better than with commercial adhesives and 23% for combinations of shellac and chitosan. For paper from Japanese Knotweed and Canadian Goldenrod, the most durable adhesive was pure shellac. Because the surface morphology of the invasive plant papers was more open and had numerous pores compared to the commercial papers, the adhesives penetrated the paper structure and filled the voids. There was less adhesive on the surface and the commercial papers achieved better adhesive properties. As expected, the bio-based adhesives also showed an increase in peel strength and exhibited favorable thermal stability. In summary, these physical properties support the use of bio-based adhesives use in different packaging applications. [ABSTRACT FROM AUTHOR]

Compreg, phenolic resin impregnated veneers cured under high pressure, was developed in the USA during the early 1940s and immediately found use as a replacement for stainless steel in specific niche applications, e.g. pitch propellers and connector plates in the World War II allied air fleet. Similar material is still produced here in Europe under the tradename Panzerholz, which is used in, for example, bulletproof joinery products. This paper presents two materials, similar to compreg, developed within an EU project (Ecobinders). Veneers were impregnated either with furfuryl alcohol (FA) or waterborne furan prepolymer resin with dissolved catalyst and thereafter dried/precured in an oven. The impregnated veneers were glued with FA/lignin adhesive between the plies, and cured in a hot-press under high pressure. The result was in both cases highly densified modified wood products. The products had hardness higher than any known wood species, high dimensional stability and decay resistance. The properties were generally better for the material modified with FA than for the material modified with the prepolymer which, however, had lower weight percentage gains. Kitchen counter-top prototypes were manufactured by laminating medium-density fibreboard with the FA-compregs. The prototypes were tested for surface resistance and the results fulfilled the criteria for the application. [ABSTRACT FROM AUTHOR]

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Fire design models for timber structures usually consider both the loss in cross section attributable to charring and the temperature-dependent reduction of strength and stiffness of the uncharred residual cross section. For bonded timber elements such as glued laminated timber beams, it is assumed that the adhesive in use does not significantly influence the resistance of structural timber beams. To investigate the influence of adhesives in bonded timber elements, a comprehensive research project is currently in progress. The aim of this project is the development of a simplified design model for the fire resistance of bonded structural timber elements, taking into account the behavior of the adhesive at elevated temperature. The paper presents the results of an extensive test series on finger-jointed timber members loaded in tension and exposed to a transient ISO 843 standard fire. The fire tests were performed with different adhesives that fulfill current approval criteria for the use in load-bearing timber components in Europe. Taking into account the different failure modes under observation, the results showed no significant influence of the adhesive on the load-bearing capacity of finger-jointed timber boards. [ABSTRACT FROM AUTHOR]