Treesearch

Berkovich nanoindentation was used to characterize viscoelastic and viscoplastic deformations in the semicrystalline polymers, poly(ether ether ketone) (PEEK) and low density polyethylene (LDPE). The quasistatic experiments generated viscoelastic moduli over four decades in frequency and hardness over more than four decades of indentation strain rate. These semicrystalline polymer results augment analogous results previously obtained from the amorphous polymers, poly(methyl methacrylate), polycarbonate, and polystyrene. Although nanoindentation viscoelastic moduli were all systematically...

To compare hardness versus strain rate data from different kinds of indentation creep test can be challenging. It is often difficult to determine whether measured differences in material response along different loading paths, such as constant load creep or load relaxation, are real or merely arise as artifacts from the analysis. We argue that the difficulty lies in how indentation strain rate is defined. For traditional definitions of strain rate, such as εh, which measures the rate of penetration, or εA, which measures the growth of indent area, material response might seem path-dependent...

The most commonly used commercial sunscreen agents are aromatic compounds oxybenzone and octinoxate, as they offer a wide range of protection in the UV spectrum. However, oxybenzone has the highest rate of skin irritation, while octinoxate has poor photostability. Oxybenzone is also a genotoxicant and skeletal endocrine disruptor to corals. Appropriate, less toxic and preferentially biorenewable alternatives should be recommended. Lignin, an abundant byproduct of pulp and biorefinery industries, is expected to be an effective replacement for oxybenzone and octinoxate due to its aromatic...

The processes of hemp bast fiber retting, forming, and drying offer the opportunity for value-added products such as natural fiber-reinforced composites. A new process for the retting of raw bast fibers through enzyme-triggered self-cultured bacterial retting was developed in the lab-scale setup. This study focused on comparing the energy consumption and environmental impacts of this bacterial retting process with the thermochemical retting process currently widely used to obtain lignocellulosic fibers for composites. The gate-to-gate life cycle assessment (LCA) models of the two retting...

Previous research found that some organosilicon treatments proved effective in stabilizing waterlogged wood dimensions during drying. The present research aimed to determine the mechanism of wood stabilization by these chemicals to understand their mode of action. The study used chemically (ChP) and biologically degraded (BP) model Scots pine wood treated with Methyltrimethoxysilane (MTMS), (3-Mercaptopropyl) trimethoxysilane (MPTMS), or 1,3-Bis(diethylamino)-3-propoxypropanol)-1,1,3,3-tetramethyldisiloxane (DEAPTMDS). Synchrotron-based X-ray fluorescence microscopy (XFM) was used to...

Adhesion and agglomeration of small sticky particles, i.e., microstickies, not paper and paper machines cause serious problems for recycling mills. Because associations between materials with similar surface energies are strongest, we propose an “adhesives collect stickies” strategy to physically remove microstickies from whitewater systems. We characterized deposits from a commercial paper machine and observed a large amount of acrylate-based materials. Based on this observation, we chose to graft glycidyl methacrylate (GMA) to surfaces of polypropylene (PP) to make it more similar to the...

Buildings play a significant role in the rise of energy consumption and carbon emissions. Building operations are responsible for 28% of the world’s carbon emissions. It is crucial, therefore, to evaluate the environmental impact of various buildings’ operational phase in order to implement sustainable strategies for the mitigation of their energy usage and associated carbon footprint. While numerous studies have been conducted to determine the carbon footprint of conventional building operation phases, there are still a lack of actual data on the operational carbon (OC) emissions of mass...

The effects of the antioxidant, butylated hydroxytoluene (BHT), and the metal chelator, ethylenediaminetetraacetic acid (EDTA) in combination with cedarwood oil (CWO) were investigated for wood preservation against subterranean termites as well as two species of white-rot decay fungi and two species of brown-rot decay fungi. Vacuum pressure impregnation was used to treat wood blocks. Resistance of the treated wood test blocks was evaluated using a no-choice bioassay for termites and a soil bottle assay wood decay fungi. Eight treatments were tested: H2O only; BHT only; EDTA only; BHT with...

This study provided an insight into the projected short-term (<10 years) and long-term (next 10 to 30 years) effects of the ongoing Russian invasion of Ukraine on global forest products trade and associated markets. The assessment was conducted by comparing the projected outcomes from the Global Forest Products Market (GFPM) model for a business-as-usual reference (no invasion) scenario and an alternate scenario representing the current trade sanctions for Russian wood products trade by several major partner countries, and the potential trade disruption in Ukraine due to their military...

Thermally modified woods are a nascent but growing industry in North America, which has seen an increase in both the number of producers as well as annual board footage of material produced. These products are being marketed as a sustainable alternative to tropical hardwoods in areas of non-structural, above ground application. The AWPA P9 committee (non-biocidal wood protection) is responsible for the establishment of Task Groups to consider nonbiocidal wood protection methods and the development of protocols for standardization. Thermally modified wood has been a continual action item on...