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Land use issues have dramatically changed the timber supply outlook for our nation's forest products industry. Since demand for wood products shows no sign of abating, alternative products must be developed. Bamboo is a very promising alternative raw material for the manufacture of structural composite products. It is fast growing, economical, renewable and abundant throughout the world. Bamboo has physical and mechanical properties that are comparable to many commercial timber species, and thus, may easily be processed using existing technology from the wood-based composites industry. Bamboo can be cultivated in the U.S., and thus has the potential to relieve some of the harvesting pressure from our nation's forestlands. However, the use of specific bamboo species for structural composite products will require a thorough investigation of the material as well as its interaction with other components. Thus, the primary objective of this dissertation is to determine the properties of Calcutta bamboo and its interaction with adhesives. The properties investigated were relative density, dimensional stability, equilibrium moisture content, bending strength and stiffness, tensile strength, pH, buffer capacity, wettability and the adhesive penetration. In addition to this, a prototype bamboo parallel strip lumber (BPSL) was manufactured and tested for its physical and mechanical properties. The relationships among the properties of Calcutta bamboo and the prototype bamboo composite were also investigated. As the result of these investigations, it is concluded that Calcutta bamboo is technically a suitable raw material for structural composite products. This result may also be applicable for the utilization of other bamboo species, thus aiding companies in decisions regarding investment in bamboo plantations and manufacturing facilities in the U.S, Malaysia and other parts of the world. The primary benefits from this research may be the development of new products to serve growing markets, and thereby relieving some of the pressure to harvest forestlands. / Ph. D.

The purpose of this research was to determine the effects of cellulose nanocrystals (CNCs), as potential additives, on the properties and performance of phenol–formaldehyde (PF) adhesive resin. The steady-state viscosity of a commercial PF resol resin and three CNC–resin mixtures, containing 1–3 wt % CNCs, based on solids content, was measured with a rheometer as a function of shear rate. The viscosity of the PF resin itself was independent of shear rate. The viscosity–shear rate curves of the CNC–resin mixtures showed two regions, a shear thinning region at lower shear rates and a Newtonian region at higher shear rates. The low-shear-rate viscosity of the resin was greatly increased by the CNCs. The structure of the CNC–resin mixtures under quiescent conditions was analyzed by polarized light microscopy. The mixtures contained CNC aggregates, which could be disrupted by ultrasound treatment. The curing progressions of the resin and CNC–resin mixtures were analyzed by non-isothermal differential scanning calorimetry (DSC). The DSC curves showed two exotherms followed by an endotherm. The energy of activation for the first exotherm was reduced by the CNCs whereas the energy of activation for the second exotherm was not affected by the CNCs. Increasing CNC contents caused higher degrees of reaction conversion during the first curing stage and a greater loss of sample mass, attributed to formaldehyde release during resin cure. For analysis of the mechanical properties during and after cure, sandwich-type test specimens were prepared from southern yellow pine strips and the resin and CNC–resin mixtures. The mechanical properties of the test specimens were measured as a function of time and temperature by dynamic mechanical analysis (DMA). The time to incipient storage modulus increase decreased and the rate of relative storage modulus increase increased with increasing CNC content. The ultimate sample stiffness increased with increasing CNC content for CNC contents between 0 and 2 wt %, which was attributed to mechanical reinforcement of the resin by the CNCs. At a CNC content of 3 wt %, the ultimate sample stiffness was lower than at a CNC content of 2 wt % and the second tan δ maximum occurred earlier in the experiment, indicating an earlier onset of vitrification. The lower ultimate sample stiffness was attributed to premature quenching of the curing reactions through CNC-induced depression of the vitrification point. For analysis of the fracture performance, double cantilever beam test specimens were prepared from southern yellow pine beams and the resin and CNC–resin mixtures, using different hot-pressing times. Fracture energies were measured by mode I cleavage tests. Bondline characteristics were analyzed by light microscopy. At a hot-pressing time of 10 min, the fracture energy decreased with increasing CNC content, whereas it stayed constant for CNC contents between 1 and 3 wt % at a hot-pressing time of 8 min. The bondlines of resin mixtures containing CNCs exhibited voids, whereas those of the pure resin did not. CNCs had both benefitial and detrimental effects on the properties and performace of PF resin. / Master of Science

Water-based resol phenol formaldehyde, PF, and organic polymeric methylenebis(phenylisocyanate), pMDI, are the two primary choices for the manufacture of exterior grade wood-based composites. This work addresses simple physical blends of pMDI dispersed in PF as a possible hybrid wood adhesive. Part one of this study examined the morphology of hybrid blends prepared using commercially available PF and pMDI. It was found that the blend components rapidly reacted such that the dispersed pMDI droplets became encased in a polymeric membrane. The phase separation created during liquid/liquid blending appeared to have been preserved in the cured, solid-state. However, substantial interdiffusion and copolymerization between blend components also appeared to have occurred according to measured cure rates, dynamic mechanical analysis, and atomic force microscopy. In the second part of this study a series of PF resins was synthesized employing the so-called "split-cook" method, and by using a range of formaldehyde/phenol and NaOH/phenol mole ratios. These neat PF resins were subjected to the following analyses: 1) steady-state flow viscometry, 2) free formaldehyde titration, 3) non-volatile solids determination, 4) size exclusion chromatography, 5) quantitative solution-state ¹³C nuclear magnetic resonance, NMR, 6) differential scanning calorimetry, 7) parallel-plate oscillatory cure rheology, and 8) dielectric spectroscopy. The neat PF analytical results were unremarkable with one exception; NMR revealed that the formaldehyde/phenol mole ratio in one resin substantially differed from the target mole ratio. The neat PF resins were subsequently used to prepare of series of PF/pMDI blends in a ratio of 75 parts PF solids to 25 parts pMDI solids. The resulting PF/pMDI blends were subjected to the following analyses: 1) differential scanning calorimetry, 2) parallel-plate oscillatory cure rheology, and 3) dielectric spectroscopy. Similar to what was inferred in part one of this study, both differential scanning calorimetry (DSC) and oscillation cure rheology demonstrated that cure of the PF continuous phase was substantially altered and accelerated by pMDI. However within actual wood bondlines, dielectric analysis detected little variation in cure speed between any of the formulations, both hybrid and neat PF. Furthermore, the modulated DSC curing experiments detected some latent reactivity in the hybrid system, both during initial isothermal curing and subsequent thermal scanning. The latent reactivity may suggest that a significant diffusion barrier existed between blend components, preventing complete reaction of hybrid blends even after thermal scanning up to 200 °C. Part three of this work examined the bonded wood mode-I fracture performance of hybrid resins as a function of the resol formaldehyde/phenol ratio and also the alkali content. A moderate increase in unweathered fracture toughness was observed for hybrid formulations relative to neat PF. Following accelerated weathering, the durability of the hybrid blends was promising: weathered hybrid toughness was equivalent to that of weathered neat PF. While the resol F/P ratio and alkali content both influenced hybrid fracture toughness, statistical modeling revealed interaction between these variables that complicated result interpretation: the influence of hybrid alkali content depended heavily on each formulation's specific F/P ratio, and vice versa. / Master of Science

Yes / Among several treatment methods Catalytic Wet Air Oxidation (CWAO) treatment is considered as a useful and powerful method for removing phenol from waste waters. In this work, mathematical model of a trickle bed reactor (TBR) undergoing CWAO of phenol is developed and the best kinetic parameters of the relevant reaction are estimated based on experimental data (from the literature) using parameter estimation technique. The validated model is then utilized for further simulation and optimization of the process. Finally, the TBR is scaled up to predict the behavior of CWAO of phenol in industrial reactors. The optimal operating conditions based on maximum conversion and minimum cost in addition to the optimal distribution of the catalyst bed is considered in scaling up and the optimal ratio of the reactor length to reactor diameter is calculated with taking into account the hydrodynamic factors (radial and axial concentration and temperature distribution).

No / Although ATP-sensitive potassium (K(ATP)) channel openers, e.g., minoxidil and diazoxide, can induce hair growth, their mechanisms require clarification. Improved drugs are needed clinically. but the absence of a good bioassay hampers research. K(ATP) channels from various tissues contain subtypes of the regulatory sulfonylurea receptor, SUR, and pore-forming, K(+) inward rectifier subunits, Kir6.X, giving differing sensitivities to regulators. Therefore, the in vitro effects of established potassium channel openers and inhibitors (tolbutamide and glibenclamide), plus a novel, selective Kir6.2/SUR1 opener, NNC 55-0118, were assessed on deer hair follicle growth in serum-free median without streptomycin. Minoxidil (0.1-100 microM, p<0.001), NNC 55-0118 (1 mM, p<0.01; 0.1, 10, 100 microM, p<0.001), and diazoxide (10 microM, p<0.01) increased growth. Tolbutamide (1 mM) inhibited growth (p<0.001) and abolished the effect of 10 microM minoxidil, diazoxide and NNC 55-0118; glibenclamide (10 microM) had no effect, but prevented stimulation by 10 microM minoxidil. Phenol red stimulated growth (p<0.001), but channel modulator responses remained unaltered. Thus, deer follicles offer a practical, ethically advantageous in vitro bioassay that reflects clinical responses in vivo. The results indicate direct actions of K(ATP) channel modulators within hair follicles via two types of channels, with SUR 1 and SUR 2, probably SUR2B, sulfonylurea receptors.

No / The tetracyclic nucleus of puupehenone, 15-oxopuupehenol and other sesquiterpene¿phenol natural products can be assembled stereoselectively in three steps, the last of these being the 6-endo-trig cyclisation of an alpha-keto radical generated from a substituted 2-(2-cyclohexenyl)ethyl 3-bromo-4-chromanone under metal-free conditions. / EPSRC