The use of wheat straw and other agricultural by-product fibers in polymer composite materials offers many economical and environmental benefits. Wheat straw has been recently commercialized as new filler for polypropylene thermoplastic composites in automotive applications. However, to expand its application in the automotive industry and other sectors where highly-engineered materials are needed, a systematic database and reliable composite property models are needed. For this purpose, this research was systematically conducted. A product design approach is used in studying wheat straw polypropylene (WS-PP) composite. A set of thermoplastic composite specifications relevant to several automotive parts was used as a basis for the customer needs which give the direction to the entire product design of thermoplastic composites based on polypropylene and straw. Straw fibers were produced by grinding and sieving (without any other treatment). These fibers were used in the formulation of polypropylene thermoplastic composites to understand the variable that can contribute to minimize production cost, maximize product performance and maximize wheat straw utilization (fraction of renewable material). The variation in chemical composition due to plant variety (parts of the plant, location of harvesting and seasonality), the bonding incompatibility between hydrophobic polypropylene matrix and hydrophilic straw fiber, along with the heterogeneity of fiber size and shape, has made wheat straw polypropylene composite a complex system. This complexity causes the mechanistic approach of composite modeling in the well-established composite theory difficult to be applied, since modeling the contribution of natural fibers to the performance of thermoplastic composites is not as straightforward like in the case of homogenous glass fiber (with same shape, diameter and narrow length distribution). Alternatively, a statistical approach of modeling by using designed experiments was used in this research. The Mixture and Process-Mixture Experimental Design methodologies were applied to develop response surface models that can be used to correlate input properties and formulation of these thermoplastic composites to the final properties of the product. The models obtained can then be inverted to predict the required properties and formulations using fiber (straw), matrix (polypropylene), and additives (coupling agent) as the main components for a specified product performance. The prediction includes the fiber grading (size and aspect ratio) and classification in order to maximize fiber utilization for different needs of composite products. The experiments were designed based on the analysis of the existing data provided by previous research works of wheat straw polypropylene composite system in our laboratory and by experimental data generated during this research. The focus of the analysis was the determination of the factor(s), i.e., the independent variables of the experiments and their acceptable levels. The response variables being measured were chosen based on the required specifications of targeted products. A constrained three-component mixture design of experiment was conducted to develop models for flexural properties of WS-PP composite. The three independent mixture variables in this experiment were the weight proportions of: straw (as fiber), polypropylene (as matrix), and maleic anhydride polypropylene (as coupling agent). Statistical analysis results showed that the obtained models have met standard requirements of response surface models with good predictive capability. One of the important finding of this study was the formulation for optimum coupling agent proportion which gives the best flexural properties of composite. The effect of straw fiber size on composite properties was investigated by using fiber length and aspect ratio as parameters to describe fiber size, instead of the size of sieves used in fiber preparation. Two-stage separation method was applied in the straw fiber preparation process. In this method, width-based separation was followed by length-based separation to obtain fiber fractions with distinct fiber length and aspect ratio. Samples of thermoplastic composites for measurement of physical properties were produced from each fiber factions at two different levels of fiber loading. The samples were compounded by twin-screw extrusion and specimens were prepared by injection molding. The fibers were then extracted from the samples after injection molding (using solvent) and their sizes were measured to investigate the fiber size reduction during the compounding and molding process. A comprehensive analysis was then performed to study the responses of stiffness, impact resistance and specific properties of these composites by including initial fiber sizes, fiber chemical compositions (measured as cellulose, hemi-cellulose and lignin), fiber size reduction during compounding/molding process, and fiber loading as factors. One of the important contributions of this study is fiber grading in terms of their sizes and their respective contributions to the final composite product properties. Based on the previous results, a mixture design of experiment was performed on wheat straw – polypropylene / impact copolymer polypropylene (WS-PP/ICP) composite system. The objective of the experiment was to obtain response surface models that can be used to estimate some important properties required by a set of automotive product specifications. The optimum formulation of coupling agent obtained in the previous study was used to determine the fixed recipe of coupling agent; simplifying the composite system into a three-component mixture, i.e. straw (as fiber) and polypropylene (homopolymer and impact copolymer (polypropylene blend as matrix). Simulation of the models shows the superiority of using a blend of polypropylenes to balance the stiffness and impact strength of the composites and being able to reach three targeted product specifications. A case study was also performed to demonstrate that the models can be used to find optimum formulations to minimize material cost while meeting specifications of all targeted products. Finally, a framework for wheat straw polypropylene product design and development is presented in this thesis. The framework can be used for designing polypropylene-straw thermoplastic composites with various combinations of fiber - polymer matrix - additive systems with different product attributes and specifications suitable for several applications in the automotive industry.

In Canada, flax (<i>Linum usitatissimum</i> L.) is grown for its seed oil. However, a major disadvantage associated with growing oilseed flax is that the straw is difficult to incorporate into the soil after harvest. Instead, the majority of flax straw is burned in the field, increasing the workload for farmers, as well as creating air pollution. Agronomic concerns are also associated with burning, since it leaves fields vulnerable to wind and water erosion. A small market exists for Canadian flax straw for making high quality paper products and some plastic composites. However, fibre-based and fibre-using industries are growing world wide, and flax straw fibre is becoming an important product. Flax straw fibre concentration varies among cultivars and environments. Consistently high fibre concentrations are essential if the fibre in oilseed flax is to become an important product for Canadian farmers. This study assembled the agronomic information necessary to select for increased straw fibre concentration in the Crop Development Centre (CDC) Flax Breeding Program. Three experiments were conducted to determine: how seeding rate and row spacing effects straw fibre concentration, the effects of seeding date on straw fibre concentration, and how nitrogen fertilizer rates effects straw fibre concentration. Seeding in mid-May at either an 18 or 36 cm row spacing at a seeding rate of 30 or 45 kg/ha resulted in high straw fibre concentration without reducing other important oilseed characteristics such as seed yield, oil content and straw fibre yield. Nitrogen fertilizer did not have an effect on either straw fibre concentration or straw fibre yield.

Densification of biomass is often necessary to combat the negative storage and handling characteristics of these low bulk density materials. A consistent, high-quality densified product is strongly desired, but not always delivered. Within the context of pelleting and briquetting, binding agents are commonly added to comminuted biomass feedstocks to improve the quality of the resulting pellets or briquettes. Many feedstocks naturally possess such binding agents; however, they may not be abundant enough or available in a form or state to significantly contribute to product binding. Also, process parameters (pressure and temperature) and material variables (particle size and moisture content) can be adjusted to improve the quality of the final densified product.<p>Densification of ground biomass materials is still not a science, as much work is still required to fully understand how the chemical composition and physical properties, along with the process variables, impact product quality. Generating densification and compression data, along with physical and mechanical properties of a variety of biomass materials will allow for a deeper understanding of the densification process. This in turn will result in the design of more efficient densification equipment, thus improving the feasibility of using biomass for chemical and energy production.<p>Experiments were carried out wherein process (pressure and temperature) and material (particle size and moisture content) variables were studied for their effect on the densification process (compression and relaxation characteristics) and the physical quality of the resulting products (pellets). Two feedstocks were selected for the investigation; namely, poplar wood and wheat straw, two prominent Canadian biomass resources. Steam explosion pretreatment was also investigated as a potential method of improving the densification characteristics and binding capacity of the two biomass feedstocks.<p> Compression/densification and relaxation testing was conducted in a closed-end cylindrical die at loads of 1000, 2000, 3000, and 4000 N (31.6, 63.2, 94.7, and 126.3 MPa) and die temperatures of 70 and 100°C. The raw poplar and wheat straw were first ground through a hammer mill fitted with 0.8 and 3.2 mm screens, while the particle size of the pretreated poplar and wheat straw was not adjusted. The four feedstocks (2 raw and 2 pretreated) were also conditioned to moisture contents of 9 and 15% wb prior to densification. <p> Previously developed empirical compression models fitted to the data elucidated that along with particle rearrangement and deformation, additional compression mechanisms were present during compression. Also, the compressibility and asymptotic modulus of the biomass grinds were increased by increasing the die temperature and decreasing product moisture content. While particle size did not have a significant effect on the compressibility, reducing it increased the resultant asymptotic modulus value. Steam explosion pretreatment served to decrease the compressibility and asymptotic modulus of the grinds.<p>In terms of physical quality of the resulting product, increasing the applied load naturally increased the initial density of the pellets (immediately after removal from the die). Increasing the die temperature served to increase the initial pellet density, decrease the dimensional (diametral and longitudinal) expansion (after 14 days), and increase the tensile strength of the pellets. Decreasing the raw feedstock particle size allowed for the increase in initial pellet density, decrease in diametral expansion (no effect on longitudinal expansion), and increase in tensile strength of the pellets. Decreasing the moisture content of the feedstocks allowed for higher initial pellet densities, but also an increased dimensional expansion. The pretreated feedstocks generally had higher initial pellet densities than the raw grinds. Also, the pretreated feedstocks shrank in diameter and length, and had higher tensile strengths than the raw feedstocks. The high performance of the pretreated poplar and wheat straw (as compared to their raw counterparts) was attributed to the disruption of the lignocellulosic structure, and removal/hydrolysis of hemicellulose, during the steam pretreatment process which was verified by chemical and Fourier transform infrared analysis. As a result, a higher relative amount of lignin was present. Also, the removal/hydrolysis of hemicellulose would indicate that this lignin was more readily available for binding, thus producing superior pellets.

A study was conducted on an annual cropped field near Lanigan, Saskatchewan over two years (2005-2006, 2006-2007) to evaluate the effects of three extensive winter feeding systems (bale grazing (BG), swath grazing (SG) and straw-chaff grazing (ST-CH)) and one intensive winter feeding system (drylot (DL)) on cow performance, soil nutrients, crop yield and system cost of production.<p> Differences in BW (P<0.05) were observed during the 2005-2006 study period with the greatest difference occurring with cows in the SG feeding system. Cows grazing swaths (SG) had a BW loss of 8.0 kg over the 78 d trial period, however these cows consumed 15% less DM and 13% less TDN than cows bale grazing, grazing crop residue or fed in drylot pens. Differences in BW change (P<0.05) were also observed during Yr 2 between the cows fed drylot and cows grazing barley straw-chaff, 32.9 and 6.5 kg, respectively. This difference in body weight change (BW∆) and lower TDN consumption may be attributed to inaccessibility of the straw-chaff feed in the field, due to inclement weather and would suggest a lengthy acclimation period for extensive field grazing systems.<p> The effects of extensive winter feeding system on soil nutrients and soil structure were determined the following spring after winter grazing. NO3-N levels at the low slope position in the 0-15 cm depth were 53% higher on the BG sites than the ST-CH sites. This may be attributed to the larger concentration of feed, thus feed nutrients, in the BG feeding system. Phosphorus levels on the BG wintering sites were 34% higher than levels in the SG or ST-CH sites. Crop biomass measured on the BG sites was consistent with soil nutrients captured, resulting in a 15% increase in biomass compared to ST-CH and SG sites. Soil nutrient and crop biomass distribution was consistent among winter grazing sites with the ST-CH sites having the most uniform distribution of nutrients and crop biomass, and the BG sites having the least.

In this work, 80% lime-treated rice straw and 20% lime-treated chicken manure were used as substrates in rotary fermentors. Countercurrent fermentation was performed at various volatile solid loading rates (VSLR) and liquid residence times (LRT). The highest acid productivity of 1.69 g/(L·d) was at a total acid concentration of 32.4 g/L. The highest conversion and yield were 0.692 g VS digested/g VS fed and 0.29 g total acids/g VS fed, respectively. The continuum particle distribution model (CPDM) was used to predict product concentrations at various VSLR and LRT. CPDM predicted the experimental total acid concentration and conversion at an average error of 6.41% and 6.55%, respectively. A fixed-bed fermentation system was designed to perform pretreatment and fermentation in the same unit. High product concentrations (~48 g/L) as well as high conversions (0.741 g VS digested/g VS fed, F4, Train B) were obtained from the same fermentor. CPDM was extended to predict product concentrations in the fixed-bed fermentation system. The model gave a good estimate of the product concentrations and retention time. After biomass fermentation, the residue can be combusted to generate heat. For pretreatment purposes, the use of ash can replace lime. A study was performed using ash as a potential pretreatment agent. Ash from raw poplar wood was effective in pretreating poplar wood; however, ash from bagasse fermentation residues was not useful in pretreating bagasse. Previous modeling studies indicate that a conversion of 95% could be achieved with bagasse using countercurrent fermentation. Because lignin constitutes 13% of the dry weight of bagasse, this means lignin would have to be digested to obtain a conversion of 95%. Experiments on the fermentation of enzymatically liberated lignin from both poplar wood and bagasse do not show that solubilized lignin was fermented to organic acids by using a mixed culture of marine microorganisms. Two buffer systems (ammonium bicarbonate and calcium carbonate) were used to compare product concentrations of carboxylic acid fermentations using office paper and chicken manure. It has been demonstrated that the total product concentration using ammonium bicarbonate is almost double the product concentration using calcium carbonate.

Prymnesium parvum Carter, a haptophyte species capable of forming harmful algal blooms (HABs), has been identified in fresh and brackish water habitats worldwide. In Texas, P. parvum blooms have diminished local community revenues from losses to tourism, fishing, and hatchery production. In this thesis, P. parvum dynamics were studied using in-situ microcosm experiments at Lake Possum Kingdom, Texas during three seasons (fall, winter, spring) in 2004-2005. Specifically, nutrient additions were used to test the hypothesis that increased nutrient levels would not enhance P. parvum's ability to invade phytoplankton communities. In addition to full nutrient additions to levels of f/2 media, other treatments included nutrient additions deficient in either nitrogen (N) or phosphorus (P). Additionally, barley straw extract was tested as a growth inhibitor to prevent P. parvum blooms. Furthermore, P. parvum initial population density was examined to test the hypothesis that increased initial populations could promote an increase in P. parvum population densities. Findings indicated that P. parvum populations in Lake Possum Kingdom would not likely gain a selective advantage over other species when inorganic nutrients (nitrogen and phosphorus) were not limiting. P. parvum did, however, gain an advantage during both N- and P-limited conditions as indicated by toxicity, cell concentrations, and bulk phytoplankton community shifts. Furthermore, P. parvum blooms in Lake Possum Kingdom would likely not be inhibited by barley straw extract application. Initial population densities affected the final population density, but only when initial populations were low. A method to quickly and accurately detect the presence of P. parvum is needed due to P. parvum's potential to cause toxic and lethal blooms. This thesis tested whether P. parvum photopigments are conservative regardless of growth conditions and could be used to quantify the relative abundance of P. parvum in mixed community samples. If biomarker pigments are conservative, then an optimized version of CHEMTAX could be employed as an alternative diagnostic tool to microscopy for enumeration of P. parvum. However, P. parvum pigments in the Texas strain were not conservative throughout the growth cycle and therefore may not be a reliable indicator of cell abundance.

Pre-treatment of wheat straw(lignocellulosic) biomass is a crucial step as it has direct impact on the subsequent yield of enzymatic saccharification and alcohol fermentation processes in the production of biofuel. Twin screw extrusion is a highly feasible pretreatment method and has been received great interest in the recent year pre-treatment studies. Twin screw extrusion is a continuous process, where the biomass feedstock can be subjected to a combination of simultaneous physical, thermal and chemical treatments. Steam explosion is a batch process and is the most commonly used method for lignocellulosic pre-treatment. In the initial stage of this study, the yield of glucose obtained from enzymatic saccharification for both methods (extrusion and steam explosion) were compared to identify the most effective pre-treatment approach. Effectiveness of the conventional steam explosion pre-treatment was used as benchmark for the directions of development of effective extrusion fractionation for wheat straw. In subsequent study, the impact of physical operating parameters (moisture, barrel temperature, compaction, screw speed and size reduction before extrusion) over twin screw extrusion with and without NaOH were studied. Low temperature (50°C) and increased moisture extrusion were preferred extrusion conditions. Yield of glucose can be improved by addition of NaOH (0.04g / g straw) and barrel temperature profile optimisation. Post extrusion washing was recommended. Findings from FTIR and TGA help to understand the chemical and structural changes took place in the pre-treatment and can be correlated with the glucose yield at the end of enzymatic hydrolysis. Characterisation analysis was extended to FT-NIR, morphology, crystallinity and specific surface area analysis to analyse the structural changes of lignocellulose biomass in extrusion pre-treatment and correlation with glucose yield. Chemometric analysis was used to statistically process large amounts of spectral data. The PCA scores plots showed good cluster segregation of the samples and were thus able to distinguish the effects of different pre-treatment conditions. The PLS regression models for both FTIR and FT-NIR showed good statistical regression and predictive ability correlated to the glucose yield. For the lignin ultilisation study, crude lignin was recovered from black liquor and fractionated with solvents. Lignin and the fractions were characterised with solvent solubility, SEC, UV, FTIR, 1H and 13C NMR and evaluated for the antioxidant activity with AAI ranged from 0.3 to 2.4. Reason for the low performance was proposed and experiment was extended to the intended application performance screening. Lignin application study was further extended to assess the feasibility of using lignin as an antioxidant in carboxylated acrilonitrile-butadiene rubber, XNBR glove. Evaluation involved physical observation, mechanical properties and thermal analysis – DSC-OIT after incorporation of lignin into XNBR glove. Lignin antioxidant performance was compared with current chemical antioxidant in used in industry. A part from antioxidant behaviour, lignin was also found can enhance the softness of XNBR film after accelerated heat aging.

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