This study evaluated, for the first time, the feasibility of using 100% microfibrillated cellulose (MFC) for a barrier coating to preserve the shelf life of bananas. MFC was produced from a commercial bleached kraft hardwood pulp through mechanical milling. Barrier coating was accomplished by dipping bananas into aqueous MFC suspensions. Performance of the barrier coating on the banana peel surface was evaluated from visual observations, weight loss, firmness, and dissolved soluble sugars content of the bananas. The results indicated that coating the banana peel surface with MFC delayed the browning and softening of the banana and the conversion of banana carbohydrates into soluble sugars. Furthermore, the extent of mechanical fibrillation in producing MFC affected MFC suspension wettability of banana peel surface, as well as the effectiveness of banana preservation. Casting-made MFC films were used to understand various factors of MFC barrier coating performance. The extent of MFC fibrillation was found to be more effective than increasing the amount of coating in reducing water vapor permeation for better fruit protection.

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 higher than those from conventional measurements, viscoelastic moduli from nanoindentation and conventional measurements followed the same trends with frequency, which indicated that both types of measurements are sensitive to the same microphysical processes giving rise to the viscoelasticity. Differences in the path dependence of hardness were observed between polymers and attributed to differences in polymer glass transition temperatures. Flow stress versus strain rate data were also calculated from hardness versus indentation strain rate data and compared to literature values. Flow stress versus strain rate obtained from both nanoindentation and conventional uniaxial experiments agreed very closely. Collectively, the comparisons between nanoindentation and conventional measurements over wide timescales further confirmed that viscoelastic and viscoplastic deformations characterized by Berkovich nanoindentation can be related back to conventional measurements and have similar mechanistic interpretations.

To further enhance the performance of wood products, improved tools are needed to study in situ cellular scale phenomena like mechanical deformations and moisture swelling. Micro-X-ray computed tomography (μXCT) using brilliant synchrotron light sources now has the spatial and temporal resolution for real-time visualization of phenomena in three-dimensional cellular structures. However, the tradeoff for speed includes the loss of intensity contrast between different types of materials within the imaged structure, such as cell wall and air in wood. This loss of contrast prevents traditional histogram-based segmentation methods from being used effectively. A new convolutional neural network (CNN) approach was therefore developed to segment fast μXCT images of wood into cell wall and air volumes. The fast μXCT and segmentation were demonstrated in the study of moisture swelling in loblolly pine (Pinus taeda) earlywood and latewood cellular structures conditioned at 0%, 33%, 75%, and 95% relative humidity (RH). The CNN segmentation results had a mean intersection over union (IoU) metric accuracy of 96%. Initial analysis of the swelling in the latewood revealed cell walls swelled about 25% when conditioned from 0% to 95% RH. Additionally, the widths of ray cell lumina in the transverse plane of latewood could be observed to increase at higher RH. The segmentation method presented here will facilitate future quantitative analyses in in situ μXCT studies of wood and other similar cellular materials.

Thermo-hydro-mechanical (THM) processing can improve the intrinsic properties of wood, produce new materials, and give desired form and function to new applications. THM treatments change the mechanical properties of wood and may change its viscoelastic properties as well. Therefore, the objective of this study was to assess the viscoelastic properties of THM-treated wood at several humidity and load levels. To explore these changes, this study applied a THM treatment to beech ( Fagus sylvatica L.) wood with steam (620 kPa) and heat (170 °C), followed by densification and increased temperature (200 °C) in a hot-press, which was then cooled while under pressure. Two initial specimen thicknesses before THM treatment were used to study the difference between density ratios. Specimens were tested in a humidity-controlled dynamic mechanical analyser (DMA) to apply creep stress with different loading levels (20% and 30% of expected modulus of rupture) and relative humidity levels (30%, 50%, and 65% RH). The creep compliance/recovery response was monitored, and dynamic moduli were measured before and after the application of creep stress. The loss modulus measured was highest for specimens tested at 65% RH and lowest in specimens tested at 30% RH, which is a direct result of the viscous response of the material. Increased damping of the specimens was also observed at higher RH, which is typical for wood products due to added moisture in the cell wall acting as a plasticizer to cell wall polymers. Like previous studies, THM treatment lowered the equilibrium moisture content (EMC) of densified wood specimens, which affected their mechanical performance. THM treatment yields higher strength and lower EMC, suggesting that this product could be suitable for structural applications where their service life is in an indoor environment. THM treatment also resulted in decreased creep compliance and recovery compliance as compared to control specimens.

To simulate fuel oil spills occurring during catastrophic floods, short-term absorption of two chemicals, n-hexadecane (representative of semivolatile organic compounds in fuel oil) and water, into southern yellow pine was gravimetrically monitored as a function of time at ambient conditions. Different scenarios were run on the basis of (1) the order of contamination (n-hexadecane followed by water or vice versa) and (2) whether the wood lateral sides were covered with epoxy. The experiments were designed to evaluate fast initial sorption, allowing separate estimation of the end-grain (i.e., total longitudinal) and lateral (i.e., surface longitudinal) liquid penetration. Presaturation of wood with water did not significantly impede the subsequent penetration of n-hexadecane, whereas the presaturation of wood with n-hexadecane led to a significant decrease of the subsequent water uptake. This difference in penetration on the basis of the order of application was explained by the differences in the polarities of the two penetrating liquids and their impacts on the interactions with the wood matrix. Calculated apparent diffusivities for end-grain and lateral penetration were similar at ca. 3 x 10(-7) m(2)/s, indicating that filling of easily accessible near-surface voids does not have a substantial impact on the overall penetration of contaminants into wood. The n-hexadecane distribution profiles based on penetration into wood blocks (obtained by means of gas chromatography) showed that water and n-hexadecane appear to use different (although overlapping) penetration paths owing to the differences in their physical properties.

Contamination of wooden framing structures with semivolatile organic chemicals is a common occurrence from the spillage of chemicals, such as impregnation with fuel oil hydrocarbons during floods. Little information is available to understand the penetration of fuel oil hydrocarbons into wood under ambient conditions. To imitate flood and storage scenarios, the sorption of n-hexadecane (representing fuel oil hydrocarbons) and water by southern yellow pine was studied using gravimetric techniques at ambient temperature and pressure. The sorption curves obtained. had three distinct regions, reflecting three different sorption phases. Lower sorption coefficients were obtained for nonpolar n-hexadecane than for water, leading to n-hexadecane maximum mass uptake values being half those of water. Lower penetration values were obtained for epoxy-coated wood compared with uncoated wood, apparently because of the inaccessibility of diffusion paths along the wood lateral surface and slower air removal from tracheids. Two models were introduced to fit the observed sorption curves into a single algebraic equation, a diffusion (Fickian) model and an empirical (non-Fickian) equation. Effective diffusion coefficients were determined under the Fickian model, resulting in ca. 10(-7) m(2)/s, 10(-8) m(2)/s, and 10(-10) to 10(-11) m(2)/s diffusion rates for sorption in Phases 1, 2, and 3, respectively. The proposed non-Fickian model was based on first order kinetic constants for the second sorption phase and fit the experimental data throughout all three phases. The two models were shown to corroborate each other by demonstrating that the effective surface areas of wood blocks calculated using both models' parameters were consistent with the corresponding expected physical values.

Although it is well known that wood can absorb liquids, the full impact of this phenomenon on resulting adhesive cure and performance is not well understood. In a related soy adhesive study, aspects of this phenomenon were not fully anticipated and resulted in a significant impact on adhesive bond quality. In essence, the wood being bonded acted like chromatography media, filtering relatively smaller molecules from the surrounding adhesive matrix and altering the local composition of the adhesive material. Through the use of soy adhesives containing glycerin, the infiltration of glycerin analogs into wood cell walls has been determined and related with the impact on bondline and wood properties. The impacts of infiltration and chromatographic separation on the cured adhesive are also discussed.

We studied the high temperature performance of soy meal processed to different protein concentrations (flour, concentrate, and isolate), as well as formulated soy-based adhesives, and commercial nonsoy adhesives for comparison. No thermal transitions were seen in phenol-resorcinol-formaldehyde (PRF) or soy-phenol-formaldehyde (SoyPF) or in as-received soy flour adhesive during differential scanning calorimetry scans heating at 10 degrees C/min between 35 and 235 degrees C. Heat flow rates decreased in the order soy flour (as received)>SoyPF>PRF>emulsion polymer isocyanate (EPI). In thermogravimetric analysis (TGA) scans from 110 to 300 degrees C at 2 degrees C/min, total weight loss decreased in the order soy flour (as-received)>SoyPF>PRF>casein>maple>EPI. For bio-based materials, the total weight loss (TGA) decreased in the order soy flour (as-received) > concentrate, casein>isolate. Dynamic mechanical analysis from 35 to 235 degrees C at 5 degrees C/min of two veneers bonded by cured adhesive showed 30-40% decline in storage modulus for maple compared to 45-55% for the adhesive made from soy flour in water (Soy Flour) and 70-80% for a commercial poly(vinyl acetate) modified for heat resistance. DMA on glass fiber mats showed thermal softening temperatures increasing in the order Soy Flour<casein<isolate<concentrate. We suggest that the low molecular weight carbohydrates plasticize the flour product. When soy-based adhesives were tested in real bondlines in DMA and creep tests in shear, they showed less decrease in storage modulus than the glass fiber-supported specimens. This suggests that interaction with the wood substrate improved the heat resistance property of the adhesive. Average hot shear strengths (ASTM D7247) were 4.6 and 3.1MPa for SoyPF and Soy Flour compared to 4.7 and 0.8MPa for PRF and EPI and 4.7 for solid maple. As a whole, these data suggest that despite indications of heat sensitivity when tested neat, soy-based adhesives are likely to pass the heat resistance criterion required for structural adhesives.

Internal steam pressure produced during the hot-pressing cycle in particleboard production is critical to the newly developed bond strength that will determine the overall performance of particleboard. The difference between the accumulation of internal steam pressure for small panels made in the laboratory and that of large commercial-sized panels makes it difficult to transfer knowledge gained from the laboratory to the commercial plant. The objective of this research project is 2-fold: first to investigate the effect of panel size on the initial development and subsequent dissipation of internal steam pressure during the hot-pressing cycle; and second, to learn how to improve of small laboratory presses to better mimic conditions experienced in the large press used in the manufacturing plant. In this study, changes in the panel size from 56 by 56 cm to 86 by 86) cm resulted in changes in the maximum steam pressure of up to 3.5-fold. A collar made from a steel rod was used, which prevented steam from escaping and helped to build higher internal steam pressure in smaller panels. Finally, the effects of a "burp" (briefly opening the press during the press cycle) or use of a forming screen were also studied in relation to internal steam pressure.

An algorithm is developed for describing ideal membrane cascades for fractionation of binary and pseudo-binary mixtures. It is shown that solvent management plays a key role in determining both purification and yield. Development of efficient diafilters is needed if membrane cascades are to achieve their full potential in competing with both chromatography and simulated moving bed operations in downstream processing of proteins. Such a replacement will also be important for fractionation of higher titers and larger substrates, such as plasmids, viruses, and even whole cells.

Abstract Fibers from treetop residues of lodgepole pine (Pinus contorta) and recycled old corrugated containers were used to fabricate wet-formed fiberboard panels over a range of densities from 300 to 1100 kg m-3, a thickness range from 1.3 to 4.8 mm, and phenolic resin contents from 0% to 4.5%. The panels were then tested after conditioning in 50% and 90% relative humidity (RH) environments. Density, thickness, equilibrium moisture content, bending modulus of elasticity (MOE), and modulus of rupture (MOR) were measured for each panel. Panel apparent-density increased with thickness, but this may be due to surface effects rather than true density values. The equilibrium moisture content approximately doubled for the panels in the 90% RH environment, compared to 50% RH. At 50% and 90% RH conditions, equilibrium moisture contents decreased significantly when only 0.5% resin was added and remained essentially the same with increasing resin levels. In this study, both MOE and MOR increased with approximately the square of density. MOE increased, whereas MOR showed no clear effects as thickness and resin amount increased. This research is part of a larger program for developing an understanding of panel properties for engineered three-dimensional fiberboard products.

Suggestions are made for the practical implementation of membrane cascades using diafiltration for the fractionation of solute pairs. Experiments are described that demonstrate the desirability of replacing solvent during the course of each diafiltration, and a parallel modeling development suggests an attractive means for accomplishing this replacement. A batch process is described to achieve such separations by simple assemblies of existing equipment, and suggestions are made for designing continuous processors. Such cascades are attractive for a wide variety of solutes including native proteins, as well as commodity chemicals, and they can be applied to the resolution of enantiomers through simple modifications already described in the public literature. The same techniques can be applied to multicomponent systems using the concept of key components as has long been done in distillation. The low inherent capital costs and high throughput rates of such membrane cascades strongly suggest that they should compete successfully against a significant number of presently used chromatographic processes, and their simplicity should make then formidable competitors to simulated moving beds as well.