The effect of adhesive concentration and strand moisture on adhesive penetration pattern in core and middle layers of Oriented Strand Board (OSB)

Abstract
Background and objectives: One of the requirements of adhesive joints formation is penetration into the wooden substrate. This phenomenon is influenced by multiple factors such as resin viscosity and wooden substrate moisture. There are many studies which had been done on adhesive penetration in wood veneers and two strands. In this study, adhesive penetration pattern due to strand moisture and resin concentration in a particulate wood-based composite; OSB, was investigated. For this purpose, micro photographs of cross section of the produced boards were prepared and parameters of the adhesive penetration pattern were evaluated and compared between treatments.
Materials and methods: for this research, oriented strand boards were made with poplar strand and phenol formaldehyde resin. The variables consisted of strand moisture content with three levels; 2%, 6% and 10% and resin concentration with 45%, 50% and 55% levels. After preparation microscopy samples, micro photographs of core layer and middle layer were taken. FFN and FVN as penetration pattern parameters were measured. In order to determine significant effects, one way ANOVA was used. For grouping the mean amounts, Tukey test was applied.
Results: the effects of strand moisture content, resin concentration and position in the board thickness on penetration parameters were significant. Higher strand moisture content increased the penetration especially in fibers. Application of lower resin concentration improved the penetration. The penetration of resin was higher in middle layer that was near to hot platen of press.
Conclusion: As mentioned in previous studies, the existence of moisture in strand prevents increasing of resin viscosity and causes more penetration. In other words, the more dryness in wooden substrate, the more increasing in resin viscosity and could limit the resin penetration. Generally the parameter take from fiber counting showed more organized changes with compare to FVN parameter that was taken from vessel counting due to strand moisture and resin concentration effects. Also it was determined that, the penetration pattern in core and middle layers of board are different.
Background and objectives: One of the requirements of adhesive joints formation is penetration into the wooden substrate. This phenomenon is influenced by multiple factors such as resin viscosity and wooden substrate moisture. There are many studies which had been done on adhesive penetration in wood veneers and two strands. In this study, adhesive penetration pattern due to strand moisture and resin concentration in a particulate wood-based composite; OSB, was investigated. For this purpose, micro photographs of cross section of the produced boards were prepared and parameters of the adhesive penetration pattern were evaluated and compared between treatments.
Materials and methods: for this research, oriented strand boards were made with poplar strand and phenol formaldehyde resin. The variables consisted of strand moisture content with three levels; 2%, 6% and 10% and resin concentration with 45%, 50% and 55% levels. After preparation microscopy samples, micro photographs of core layer and middle layer were taken. FFN and FVN as penetration pattern parameters were measured. In order to determine significant effects, one way ANOVA was used. For grouping the mean amounts, Tukey test was applied.