Lignin, the glue that keeps fibers together, is a complex three dimensional network polymer which has shown association phenomena in solution. Following the molecular weight of the biopolymer in solution as a function of time allow us to explore their observable de-association phenomena. These measurements were carried out using multiple angle light scattering (MALS) photometry in the static mode. EMAL (Enzymatic Mild Acidolysis Lignin) from hardwood and softwood were isolated and an additional method for the complete dissolution of such biopolymers in THF was further developed. Once the challenge of the measurement procedures were worked out, some rather accurate dn/dC values for lignin solutions were obtained as a function of time. This effort when coupled to additional work using static light scattering measurements (Zimm plots) for the same solutions offered an insight into the self-assembly processes operating within the lignin biopolymer.

Polyampholytes are polymers that have both positively and negatively charged groups in the same chain. In recent years polyampholytes have started to be used in papermaking applications, as well as in sludge treatment processes. Benefits, in the case of papermaking, have included increased dry-strength and faster removal of water. But the molecular mechanisms by which such benefits are achieved have not been fully understood. This thesis project focused on effects related to polyampholyte charge density. A series of polyampholytes with a fixed charge ratio but different charge density was used for the experiments. Analysis methods included pH titrations, streaming current titrations, and adsorption isotherms. From pH titrations the charge density of cationic and anionic groups under different pH were calculated. From streaming current tests the net apparent charge density under different pH was calculated. And from adsorption tests it was found that the highest adsorbed amounts were achieved in certain cases corresponding to the highest content of ionic groups on the polyampholytes. Adsorption depended strongly on pH. Substantial differences were observed when comparing results obtained with polyampholyte samples versus ordinary polyelectrolyte samples with same charge density of cationic or anionic groups.

This study aims at elucidating a variety of salient features that dictate the kinetics and chain length effects governing the formation and antimicrobial activity of sugar esters of fatty acids. To do this, anomerically pure glucose, sucrose and cellobiose sugars were transesterified with the methyl esters of fatty acids of variable chain lengths C4, C8, C12, C18, and C20. The methyl esters of butyric, caprylic, lauric, stearic and arachidic acids were reacted with the above carbohydrates to give the respective penta and octaesters. The kinetics of these transesterification reactions were followed by quantitative 31P NMR after phosphitylation of the labile OH groups with 1,3,2- dioxaphospholanyl chloride. This approach proved to be a facile and quantitative means to follow the specific substitutions occurring at the various OH positions within the sugars as a function of degree of conversion, and incoming chain length. As anticipated, a variety of steric and hydrophobic effects were shown to play a key role in determining the reactivity of these systems. The various sugar esters were then adsorbed onto cellulose disks and their microbial activity was examined. Finally, cellulose esters of butyric acid were synthesized using the acyl chloride process.

The research investigated the interactions between paperboard and the gypsum core during the manufacturing process of gypsum wallboard. The goal of this research was to understand the paper properties that can affect the quality of the adhesive bond under simulated test conditions. The categories of paper properties tested include strength properties, surface properties, and paper additives. This research showed that the current test methods in use did not provide enough sensitive and reproducibility data to gain crucial insight into the paper/core adhesive interaction. A new evaluation method must be secured. However, with the results obtained, it was believed that the three types of failure could be described. First, the adhesive bond may fail resulting in a clean peel during bond quality testing. Second, the paper bond network may fail resulting in complete paper coverage of the gypsum core. Third, a mixed failure of adhesive and paper bond resulted in incomplete and varied paper coverage of the gypsum core.

The research described here provides the technology and theory to quantify surface quality for a variety of wood and wood-based products. This technology provides a means of monitoring trends in surface quality which can be used to discriminate between Agood@ products and Abad@ products (the methods described in this research are not intended to provide ?grading? of individual workpieces) as well as provide information to the machine operator as to the source of poor quality machined surfaces. The analysis can be done either on-line at industrial speeds or off-line as a periodic quality control tool. Although the surface quality can be quantifiably measured, the determination of the best feature from the surface profile (root mean square, peak amplitude, average wavelength, frequency content, Joint Time and Frequency Analysis (JTFA) and Wavelet Analysis results, etc.) for the quantification of surface Adefects@ is highly dependent on the application. This research consisted of three broad areas: (1) determination of an optimal hardware configuration for both laboratory and industrial surface scans of wood products, (2) determination of the optimal set of surface descriptors as well as the development of advanced signal processing techniques such as the wavelet transform to accurately describe the quality of a surface as well as provide information to the machine operator on the cause of the loss of surface quality, and (3) development of a software interface to distill the advanced signal processing techniques into a readily obtainable and readable format for the machine operator as well as provide assistance for process decisions.

In an effort to comprehensively study the wood property variation in juvenile wood, compression wood, and mature wood, and also to provide a rapid and cost-effective assessment tool to screening the wood chemical property variation, several loblolly pines (Pinus tadea), and transmittance near infrared spectroscopy were utilized in this study. The method development results show that a successful screening of wood chemical property variation, such as lignin and á-cellulose contents, could be adapted using stacked wood wafers microtomed from increment cores and combining with transmittance near infrared spectroscopy. The morphological, chemical, and metabolic analyses of juvenile wood and compression wood show that although compression wood and juvenile wood share some properties, they are actually distinct in their chemistry during development and in final wood chemistry and anatomy. The within tree variation analyses also show that juvenile wood from the top of the tree and that from the base of the tree are more different in morphological structures than in chemical structures. A similar pattern was found between juvenile wood and mature wood. The results obtained suggest that the within tree compression wood percentage and the fiber quality differences inherent in juvenile wood appear to have a greater influence on the final wood products.

Structure-property relationships of cellulose-based materials including paper, micro- and nano-fiber composites are often strongly influenced by environmental variables. The interaction of polymeric and crystalline structure in cellulose bio-based materials is of high technological importance. Therefore, understanding the underlying mechanism of environmental/material interactions is crucial for engineering products from bio-based materials. This study was undertaken in an effort to develop a technique for the assessment of dimensional stability of cellulose microfibrils as a function of different relative humidity. Analysis of atomic force microscopy images showed that the local dimensional properties of cellulose microfibrils are highly responsive to variable relative humidity, and their hygro-expansive behavior depends on the relative humidity history, and their method of preparation. The results obtained suggested that dimensional and hygro-expansive behaviors of cellulose microfibrils are related to their ultra-structural arrangements and their origin, either directly or indirectly. These findings, hopefully, will prompt an open discussion regarding the dynamic interactions between cellulose and water molecules at a nano-scale.

Low temperature pyrolysis offers a feasible option for wood waste management and the recovery of a variety of useful chemicals. The effect of Chromated Copper Arsenate (CCA) wood preservatives on the yield and composition of various pyrolysis products was investigated in the present research. A novel quantitative 31P NMR methodology has been developed to quantify levoglucosan and levoglucosenone from the pyrolysate of CCA-treated and untreated wood. The CCA treatment on wood had a significant effect on the amount of main carbohydrate derived degradation products of tar. In particular, a higher yield of levoglucosan can be obtained compared to that from untreated wood. Phosphoric acid has proven to be an efficient catalyst to favor levoglucosenone formation. The pyrolysis of CCA-treated wood in the presence of phosphoric acid gave rise to high yields of levoglucosenone, which demonstrated the potential for a new pathway in the rational use of CCA-treated wood waste. Pretreated wood with metal compounds has demonstrated that K2Cr2O7 and CuSO4 salts promote the formation of levoglucosan. The CrO3 treatment was found to favor the formation of levoglucosenone. A kinetic study of the pyrolysis of CCA-treated wood by thermogravimetric analysis has shown that CCA components have a significant influence on the thermal decomposition behavior of CCA-treated wood, which accelerate the weight loss of wood and the oxidation of the char.

<p>Over the years, hydrogen peroxide has been used to improve the brightness of pulp at the end of a bleaching sequence. However, the degree of delignification achieved by a hydrogen peroxide stage is usually modest. That is because in alkaline condition the hydroperoxy anion reacts with chromophores in pulp as a nucleophile that does not oxidize residual lignin to a significant extent. In order to enhance the reactivity of hydrogen peroxide as an oxidant, a binuclear manganese complex Mn(IV)2-Me4DTNE was added. As a result, the degree of delignification was significantly improved, while at the same time, the strength properties of the pulp were better preserved compared traditional in hydrogen peroxide delignification. In order to better understand the mechanism of this delignification process, lignin model compound oxidation and kinetics of pulp delignification were studied. In addition, residual lignin was isolated from the pulp before and after delignification and then characterized by GPC, FTIR, and 1H-13C 2D NMR. Shown by the model compound study, hydrogen peroxide is able to oxidize 1-(3,4-dimethoxyphenyl)ethanol, E-diphenylethene, and 1-(3,4-dimethoxyphenyl)-1-propene to a considerable extent when catalyzed by Mn(IV)2-Me4DTNE, indicating that the reactivity of hydrogen peroxide as an oxidant is significantly improved. Indeed, as shown by the kinetic study of pulp delignification, the degree of delignification as well as the rate of delignification were greatly improved when the catalyst was applied. In addition, the catalyzed delignification process benefits from the concerted reaction mechanism that regulates the formation of hydroxyl radicals responsible for the severe damage to the fibers. As a result, the strength properties were well preserved. Shown by the characterization of residual lignin before and after the delignification, residual lignin was oxidized to a good extent which accounts for the significant degree of delignification. The process simulation of this catalyzed delignification process by WinGEMS4.0 showed that this process was profitable if the cost of the catalyst was kept below $330/kg.<P>

<p>The purpose of this research was to study the effect of pretreatment on the extractive content and bleachability of extended delignified kraft pulps. The studies were carried out on both southern hardwood and southern softwood species. It was found that the extractives affected the bleachability of pulps by reaction and blocking mechanisms. For hardwood pulps, the reaction of extractives with bleaching chemicals was more significant. For softwood, the blocking effect of extractives was more pronounced. During the batch extended delignification process, the extractives were accumulated and precipitated on the pulps due to the black liquor recycling. The amount of precipitates was determined by the pretreatment conditions. It was possible to lower the extractive content of both the softwood and hardwood pulps by introducing a gas-off process in the pretreatment stage of a batch extended delignification process. The removal efficiency of extractives was affected by the gas-off process and the extractive distribution. The amount of extractives that was removed by the gas-off process was affected by the pretreatment operational conditions and the volatility of the extractives. The distribution of the extractives in the digester was also affected by the operational conditions. For the softwood, the natural extractives were comparatively volatile. It was possible to perform the gas-off under a high temperature and a high pH of the system. For the hardwood, the natural extractives were not volatile. High temperature and high pH were the ideal gas-off conditions. Apart from the extractive content, the fiber morphology also affected the bleachability of kraft pulps. For the softwood, the earlywood was easier to cook than the latewood. With the same kappa number, the final brightness of the earlywood pulp was at least 2% ISO higher than the latewood pulp because of the thinner fiber wall and faster leaching rate. <P>