Treesearch

The incorporation of fibers into polymers is a well-known route for realizing composite materials with improved strength, stiffness, and toughness. Cellulose nanofibrils (CNFs) are a promising reinforcement because of their high aspect ratio, high specific stiffness and specific strength, and transparency and the fact that they are derived from renewable and sustainable sources. Here, we demonstrate the application of CNFs for the reinforcement of continuous polymer fibers (filaments) to achieve a concurrent enhancement of strength, stiffness, and fracture toughness. Poly(methyl methacrylat...

To properly evaluate the reliability of lumber structures, good models for the strength distributions of their components are needed. Modulus of rupture (MOR) distributions of structural lumber grades have often been modeled as two-parameter Weibulls. However, in a series of papers, Verrill and others have established that strength properties of visual and machine stress rated grades of lumber are not distributed as two-parameter Weibulls and that modeling them as two-parameter Weibulls can yield large over- or underestimates of probabilities of breakage. Instead, grades of lumber have...

Vacuum drying is an economical alternative to conventional drying for many species under a variety of environmental and economic conditions. Vacuum drying can reduce drying time and be more energy efficient compared with conventional steam drying. But there are many factors to consider when comparing the two technologies. This report describes the principles and practices of vacuum drying and discusses its advantages and disadvantages. Among other concerns, final moisture content variation and residual stress have been significant issues of concern with vacuum drying. Standard vacuum...

Hazardous fuels such as woody biomass and small-diameter trees accumulate in the forest, contributing to increased risk of wildfires. Two tree species that specifically contribute to this problem in the Midwest and Northeast of the United States are balsam fir and eastern hemlock. If the durability of these two species against fungal decay could be improved, markets for lumber made from these species would increase, contributing to removal of them from the forests. Thermal modification of the wood from these species may improve the fungal durability. In this study, we performed soil-block...

It has been mathematically demonstrated that the distribution of MOR in a graded lumber subpopulation does not have the same theoretical form as the distribution of the mill-run population from which the subpopulation is drawn. However, the distributional form of the graded lumber subpopulation does depend heavily on the distributional form of the full mill-run population, and thus, it is important to characterize the distributions of full mill-run lumber populations. Previous studies presented evidence suggesting that commonly used distributions such as normal, lognormal, and Weibull...

A large family of copulas with gamma components is examined, and interesting submodels are dened and analyzed. Parameter estimation is demonstrated for some of these submodels. A brief discussion of higher-dimensional versions is included

Background: Woody biomass has been considered as a promising feedstock for biofuel production via thermochemical conversion technologies such as fast pyrolysis. Extensive Life Cycle Assessment studies have been completed to evaluate the carbon intensity of woody biomass-derived biofuels via fast pyrolysis. However, most studies assumed that woody biomass such as forest residues is a carbon–neutral feedstock like annual crops, despite a distinctive timeframe it takes to grow woody biomass. Besides, few studies have investigated the impacts of forest dynamics and the temporal effects of...

New approaches for assessing wood durability are needed to help categorize decay resistance as timber utilization shifts towards plantations or native forest regrowth that may be less durable than original native forest resources. This study evaluated attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy combined with principal component analysis (PCA) for distinguishing between groups of Alaska yellow cedar (Cupressus nootkatensis) wood for susceptibility to two decay fungi (Gloeophyllum trabeum and Rhodonia placenta) and the eastern subterranean termite (Reticuli...

Wood is a sustainable structural material, but it cannot be easily shaped while maintaining its mechanical properties. We report a processing strategy that uses cell wall engineering to shape flat sheets of hardwood into versatile three-dimensional (3D) structures. After breaking down wood’s lignin component and closing the vessels and fibers by evaporating water, we partially re-swell the wood in a rapid water-shock process that selectively opens the vessels. This forms a distinct wrinkled cell wall structure that allows the material to be folded and molded into desired shapes. The...

Lignocellulosic biomass is an alternative source of energy that can reduce our dependency on fossil fuels and limit greenhouse gas emissions. Several techno-economic analyses have consistently shown that all the steps in biomass-to-bioproduct processes needs improvement. Simultaneous assessment of genotypes for multiple productivity characteristics and integrating information across production stages has seldom been the focus of research efforts. To address this gap, we first determined the agronomic performance of 10 poplar genotypes. Differences between genotypes in height, diameter at...