Curd syneresis, a critical step in cheesemaking, directly influences the quality of cheese. The syneresis process is empirically controlled in cheese manufacturing plants. A sensor technology for this step would improve process control and enhance cheese quality. A light backscatter sensor with a Large Field of View (LFV) was tested using a central composite design over a broad range of cheese process conditions including milk pH, calcium chloride addition level, milk fat to protein ratio, temperature, and a cutting time factor (β). The research objectives were to determine if the LFV sensor could monitor coagulation and syneresis steps and provide information for predicting pressed curd moisture. Another objective was to optimize cheese yield and quality. The LFV sensor was found to monitor coagulation and syneresis and provide light backscatter information for predicting curd moisture content. A model for relating final curd moisture content with light backscatter response was developed and tested. Models for predicting whey fat losses, pressed curd moisture, and cheese yield were successfully developed (R2>0.75) using the test factors as independent variables. This was the first attempt to develop a technology for controlling pressed curd moisture using a sensor to monitor the syneresis step.

Percent Moisture Content (MC %) of wood is defined to be the weight of the moisture in the wood divided by the weight of the dry wood times 100%. Equilibrium Moisture Content (EMC), moisture content at environmental equilibrium is a very important metric affecting the performance of wood in many applications. For best performance in many applications, the goal is to maintain this value between 6% and 8%. EMC value is a function of the temperature and the relative humidity of the surrounding air of wood. It is very important to maintain this value while processing, storing or finishing the wood. This thesis develops a special purpose sensor and processor system to be implemented as a small hand-held device used to sense, calculate and display the value of EMC of wood depending on surrounding environmental conditions. Wood processing industry personnel would use the hand-held EMC calculating and display device to prevent many potential problems that can show significant affect on the performance of wood. The design of the EMC device requires the use of sensors to obtain the required inputs of temperature and relative humidity. In this thesis various market available sensors are compared and appropriate sensor is chosen for the design. The calculation of EMC requires many arithmetic operations with stringent precision requirements. Various arithmetic algorithms and systems are compared in terms of meeting required arithmetic functionality, precision requirements, and silicon implementation area and gate count, and a suitable choice is made. The resulting processor organization and design is coded in VHDL using the Xilinx ISE 6.2.03i tool set. The design is synthesized, validated via VHDL virtual prototype simulation, and implemented to a Xilinx Spartan2E FPGA for experimental hardware prototype testing and evaluation. It is tested over various ranges of temperature and relative humidity. Comparison of experimentally calculated EMC values with the theoretical values of EMC derived for corresponding temperature and relative humidity points resulted in validation of the EMC processor architecture, functional performance and arithmetic precision requirements.

Gas phase biofilters are used for controlling odors from animal facilities. Some characteristics can affect their performance and moisture content is one very important. A methodology for controlling and measuring moisture content is required to optimize these systems. An experiment was conducted to determine the appropriate placement of a set of soaker hoses 1.2 m in length for water application. It was found that the soaker hose installed in the lower region of the biofilter coupled with appropriate and timely application of water was able to minimize drying of the compost. Thermal conductance proved to be a reliable indicator for measuring the moisture content. Biofilters using the soaker hoses together with the thermal conductance as a media moisture sensor were able to maintain moisture content above 30% w.b. which provided sufficient water for microbial activity and ammonia abatement. A characterization of the ammonia and nitrous oxide concentrations was performed in order to compare the behavior of the gases when water was applied versus no water addition. These analyses revealed that the overall performance was not significantly different between treatments. But a more detailed assessment inside the biofilter media is performed; it is possible to identify different processes taking place.

Wood is used for many applications because of its excellent mechanical properties, relative abundance and as it is a renewable resource. However, its wider utilization as an engineering material is limited because it swells and shrinks upon moisture changes and is susceptible to degradation by microorganisms and/or insects. Chemical modifications of wood have been shown to improve dimensional stability, water repellence and/or durability, thus increasing potential service-life of wood materials. However current treatments are limited because it is difficult to introduce and fix such modifications deep inside the tissue and cell wall. Within the scope of this thesis, novel chemical modification methods of wood cell walls were developed to improve both dimensional stability and water repellence of wood material. These methods were partly inspired by the heartwood formation in living trees, a process, that for some species results in an insertion of hydrophobic chemical substances into the cell walls of already dead wood cells, In the first part of this thesis a chemistry to modify wood cell walls was used, which was inspired by the natural process of heartwood formation. Commercially available hydrophobic flavonoid molecules were effectively inserted in the cell walls of spruce, a softwood species with low natural durability, after a tosylation treatment to obtain “artificial heartwood”. Flavonoid inserted cell walls show a reduced moisture absorption, resulting in better dimensional stability, water repellency and increased hardness. This approach was quite different compared to established modifications which mainly address hydroxyl groups of cell wall polymers with hydrophilic substances. In the second part of the work in-situ styrene polymerization inside the tosylated cell walls was studied. It is known that there is a weak adhesion between hydrophobic polymers and hydrophilic cell wall components. The hydrophobic styrene monomers were inserted into the tosylated wood cell walls for further polymerization to form polystyrene in the cell walls, which increased the dimensional stability of the bulk wood material and reduced water uptake of the cell walls considerably when compared to controls. In the third part of the work, grafting of another hydrophobic and also biodegradable polymer, poly(ɛ-caprolactone) in the wood cell walls by ring opening polymerization of ɛ-caprolactone was studied at mild temperatures. Results indicated that polycaprolactone attached into the cell walls, caused permanent swelling of the cell walls up to 5%. Dimensional stability of the bulk wood material increased 40% and water absorption reduced more than 35%. A fully biodegradable and hydrophobized wood material was obtained with this method which reduces disposal problem of the modified wood materials and has improved properties to extend the material’s service-life. Starting from a bio-inspired approach which showed great promise as an alternative to standard cell wall modifications we showed the possibility of inserting hydrophobic molecules in the cell walls and supported this fact with in-situ styrene and ɛ-caprolactone polymerization into the cell walls. It was shown in this thesis that despite the extensive knowledge and long history of using wood as a material there is still room for novel chemical modifications which could have a high impact on improving wood properties. / Der nachwachsende Rohstoff Holz wird aufgrund seiner guten mechanischen Eigenschaften und der leichten Verfügbarkeit für viele Anwendungszwecke genutzt. Quellen und Schrumpfen bei Feuchtigkeitsänderungen des hygroskopischen Werkstoffs Holz limitieren jedoch die Einsatzmöglichkeiten. Ein weiteres Problem stellt der mitunter leichte Abbau – u.a. bei feuchtem Holz - durch Mikroorganismen und/oder Insekten dar. Durch chemische Modifizierungen können die Dimensionsstabilität, die Hydrophobizität und die Dauerhaftigkeit verbessert und damit die potentielle Lebensdauer des Werkstoffes erhöht werden. Dabei ist die dauerhafte Modifikation der Zellwand nur äußerst schwer realisierbar. Inspiriert von der Kernholzbildung in lebenden Bäumen, ein zellwandverändernder Prozess, der Jahre nach der Holzbildung erfolgt, wurden im Rahmen dieser Arbeit neue Ansätze zur chemischen Modifizierung der Zellwände entwickelt, um die Dimensionsstabilität und Hydrophobizität zu erhöhen. Der erste Teil der Arbeit ist stark vom Prozess der Kernholzbildung inspiriert, eine abgeleitete Chemie wurde verwendet, um die Zellwände von Fichte, einem Nadelholz von geringer natürlicher Dauerhaftigkeit, zu modifizieren. Kommerziell verfügbare hydrophobe Flavonoide wurden nach einem Tosylierungsschritt erfolgreich in die Zellwand eingebracht, um so „artifizielles Kernholz“ zu erzeugen. Die modifizierten Holzproben zeigten eine verringerte Wasseraufnahme, die zu erhöhter Dimensionsstabilität und Härte führte. Dieser Ansatz unterscheidet sich grundlegend von bereits etablierten Modifikationen, die hauptsächlich hypdrophile Substanzen an die Hydroxylgruppen der Zellwand anlagern. Der zweite Teil der Arbeit beschäftigt sich mit der Polymerisation von Styren in tosylierten Zellwänden. Es ist bekannt, dass es nur eine schwache Adhäsion zwischen den hydrophoben Polymeren und den hydrophilen Zellwandkomponenten gibt. Die hydrophoben Styren-Monomere wurden in die tosylierte Zellwand eingebracht und zu Polystyren polymerisiert. Wie bei der Modifikation mit Flavonoiden konnte eine erhöhte Dimensionsstabilität und reduzierte Wasseraufnahme der Zellwände beobachtet werden. Im dritten Teil der Arbeit wurde das biologisch abbaubare, hydrophobe poly(ɛ-caprolacton) in der Zellwand aufpolymerisiert. Die Ergebnisse deuten darauf hin, dass Polycaprolacton in der Zellwand gebunden ist und zu einer permanenten Quellung führt (bis zu 5 %). Die Dimensionsstabilität nahm um 40 % zu und die Wasseraufnahmerate konnte um mehr als 35 % reduziert werden. Mit dieser Methode kann nicht nur dimensionsstabileres Holz realisiert werden, auch biologische Abbaubarkeit und damit eine einfache Entsorgung sind gewährleistest.

This cumulative dissertation explored the use of the detection of natural background of fast neutrons, the so-called cosmic-ray neutron sensing (CRS) approach to measure field-scale soil moisture in cropped fields. Primary cosmic rays penetrate the top atmosphere and interact with atmospheric particles. Such interaction results on a cascade of high-energy neutrons, which continue traveling through the atmospheric column. Finally, neutrons penetrate the soil surface and a second cascade is produced with the so-called secondary cosmic-ray neutrons (fast neutrons). Partly, fast neutrons are absorbed by hydrogen (soil moisture). Remaining neutrons scatter back to the atmosphere, where its flux is inversely correlated to the soil moisture content, therefore allowing a non-invasive indirect measurement of soil moisture. The CRS methodology is mainly evaluated based on a field study carried out on a farmland in Potsdam (Brandenburg, Germany) along three crop seasons with corn, sunflower and winter rye; a bare soil period; and two winter periods. Also, field monitoring was carried out in the Schaefertal catchment (Harz, Germany) for long-term testing of CRS against ancillary data. In the first experimental site, the CRS method was calibrated and validated using different approaches of soil moisture measurements. In a period with corn, soil moisture measurement at the local scale was performed at near-surface only, and in subsequent periods (sunflower and winter rye) sensors were placed in three depths (5 cm, 20 cm and 40 cm). The direct transfer of CRS calibration parameters between two vegetation periods led to a large overestimation of soil moisture by the CRS. Part of this soil moisture overestimation was attributed to an underestimation of the CRS observation depth during the corn period ( 5-10 cm), which was later recalculated to values between 20-40 cm in other crop periods (sunflower and winter rye). According to results from these monitoring periods with different crops, vegetation played an important role on the CRS measurements. Water contained also in crop biomass, above and below ground, produces important neutron moderation. This effect was accounted for by a simple model for neutron corrections due to vegetation. It followed crop development and reduced overall CRS soil moisture error for periods of sunflower and winter rye. In Potsdam farmland also inversely-estimated soil hydraulic parameters were determined at the field scale, using CRS soil moisture from the sunflower period. A modelling framework coupling HYDRUS-1D and PEST was applied. Subsequently, field-scale soil hydraulic properties were compared against local scale soil properties (modelling and measurements). Successful results were obtained here, despite large difference in support volume. Simple modelling framework emphasizes future research directions with CRS soil moisture to parameterize field scale models. In Schaefertal catchment, CRS measurements were verified using precipitation and evapotranspiration data. At the monthly resolution, CRS soil water storage was well correlated to these two weather variables. Also clearly, water balance could not be closed due to missing information from other compartments such as groundwater, catchment discharge, etc. In the catchment, the snow influence to natural neutrons was also evaluated. As also observed in Potsdam farmland, CRS signal was strongly influenced by snow fall and snow accumulation. A simple strategy to measure snow was presented for Schaefertal case. Concluding remarks of this dissertation showed that (a) the cosmic-ray neutron sensing (CRS) has a strong potential to provide feasible measurement of mean soil moisture at the field scale in cropped fields; (b) CRS soil moisture is strongly influenced by other environmental water pools such as vegetation and snow, therefore these should be considered in analysis; (c) CRS water storage can be used for soil hydrology modelling for determination of soil hydraulic parameters; and (d) CRS approach has strong potential for long term monitoring of soil moisture and for addressing studies of water balance. / In dieser kumulativen Dissertation wird die Detektion des natürlichen Hintergrunds von schnellen Neutronen, das sogenannte “Cosmic-Ray Neutron Sensing” (CRS), zur Messung von Bodenfeuchte auf der Feldskala in landwirtschaftlich genutzten Flächen untersucht. Die kosmische Primärstrahlung durchdringt die oberste Atmosphäre, und interagiert mit atmosphärischen Teilchen. Durch diese Wechselwirkungen entstehen Kaskaden hochenergetischer Teilchen die bis in die Erdoberfläche eindringen, wobei schnelle Neutronen entstehen. Teilweise werden diese durch Wasserstoff (Bodenfeuchte) absorbiert, teilweise zurück in die Atmosphäre gestreut. Dieser Neutronenfluss über dem Boden korreliert invers mit der Bodenfeuchte, was so eine non-invasive und indirekte Bodenfeuchteschätzung ermöglicht. Die CRS-Methode wird vor allem in einer Feldstudie auf einem Ackerland in Potsdam (Brandenburg, Deutschland), einschließlich dreier Phasen mit Anbau von Mais, Sonnenblume und Winterroggen getestet und beurteilt. Darüber hinaus wurde ein Feldmonitoring im Schäfertaleinzugsgebiet (Harz, Deutschland) durchgeführt, um das Potential von Langzeit-CRS-Messungen gegenüber herkömmlich erhobenen bodenhydraulischen Daten abzuschätzen. Im ersten Untersuchungsgebiet wurde die CRS-Methode kalibriert und mittels verschiedener Bodenfeuchtemessansätze validiert. In der Maisanbauphase wurden die Bodenfeuchte-Punktmessungen zunächst nur an der nahen Bodenoberfläche durchgeführt. In den folgendenen Anbauphasen (Sonnenblume und Winterroggen) wurden dann die Sensoren in drei unterschiedlichen Tiefen (5 cm, 20 cm und 40 cm) installiert. Die direkte Übertragung der CRS-Kalibrierparameter zwischen zwei Vegetationsperioden führte zu einer starken Überschätzung der CRS-Bodenfeuchte. Ein Teil der überschätzten Bodenfeuchte wurde der Unterschätzung der CRS-Beobachtungstiefe während der Maisperiode (5-10 cm) zugeschrieben, welche später basierend auf Werten zwischen 20-40 cm in anderen Anbauperioden (Sonnenblume und Winterroggen) neuberechnet wurde. Gemäß der Ergebnisse dieser Beobachtungsperioden mit verschiedenen Feldfrüchten, spielte die Vegetation eine wichtige Rolle für die CRS-Messungen, da das Wasser, das in der über- und unterirdischen Biomasse vorhanden ist, die Neutronen bedeutend abdämpft. Dieser Effekt, sowie der Einfluss des Getreidewachstums und des reduzierten Gesamt-CRS-Bodenfeuchte-Fehlers, wurden in ein einfaches Model zur vegetationsbedingten Neutronenkorrektur berücksichtigt. So wurde ein gekoppelter HYDRUS-1D- und PEST-Ansatz angewendet, um bodenhydraulische Parameter auf dem Feldmassstab während der Sonnenblumen-Phase invers abzuschätzen. Dann wurden die inversen Schätzungen der effektiven bodenhydraulischen Eigenschaften innerhalb des von CRS beobachteten Volumens durch die lokalen Bodeneigenschaften (Modellierung und Messungen) validiert. Abgesehen von Unterschieden auf Grund der Beobachtungstiefe und somit des Volumens, wurden hierbei erfolgreiche Ergebnisse erzielt. Dieser einfache Ansatz unterstreicht das zukünftige Forschungspotential, z.B. um mit Hilfe von Bodenfeuchten aus CRS-Messungen Modelle auf der Feldskala zu parametrisieren. Im Schäfertaleinzugsgebiet wurden die Langzeit-CRS-Messungen mit Nie-derschlags- und Evapotranspirations-Raten abgeglichen. Bei einer monatlichen Auflösung korrelierte die Änderung des CRS-Bodenwasserspeichers mit diesen beiden Wettervariablen. Die Wasserbilanz konnte jedoch auf Grund fehlender Informationen bezüglich Grundwasser, Abfluss des Einzugesgebiets, etc. nicht geschlossen werden. Darüber hinaus wurde, wie auch am Potsdamer Standort, festgestellt, dass das CRS-Signal stark von Schneefall und Schneeakkumulationen beeinflusst wird. Eine einfache Anwendung zur Schneemessung mittels CRS wurde für den Schäfertalfall vorgestellt. Abschließend zeigte sich, dass (a) „Cosmic-Ray Neutron Sensing“ (CRS) ein großes Potential hat, Messungen der mittleren Bodenfeuchte auf der Feldskala im Bereich landwirtschaftlich genutzter Flächen zu realisieren; (b) die CRS-Bodenfeuchte stark durch andere Wasserspeicher, wie Vegetation und Schnee beeinflusst wird, und dies im Rahmen von Analysen berücksichtigt werden sollte; (c) die CRS-Messungen über eine bodenhydraulische Modellierung zur Bestimmung von bodenhydraulischen Paramtern genutzt werden kann; und (d) der CRS-Ansatz ein großes Potential für Langzeit-Bodenfeuchte-Monitoring und für Wasserbilanzstudien hat.

This thesis deals with the experimental description of friction between steel and wood materials, specifically laminated veneer lumber (LVL) and pine wood with two types of annual rings. It studies the influence of a number of different parameters on the coefficient of friction such as contact pressure, moisture content, fiber orientation in relation to the load direction, steel surface roughness, and horizontal load rate. First, the theoretical mechanical and physical properties as well as the coefficient of friction itself are described. This is followed by the description of the test setup including the test method and how the obtained data is exported, handled and processed and how the coefficient of friction is determined. The results study the influence of different parameters and show that the coefficients of friction for the smooth sliding plate tests vary in between 0.1 and 0.3, whereas tests with the rough sliding plate vary around 0.7. Factors influencing the coefficient of friction were found to be the different moisture content under all tested pressures, the different fiber direction under low contact pressure, the contact pressure itself, though under higher pressures the influence was found to be low, and the horizontal load rate under low pressures. The outcomes are further discussed in the discussion chapter.

A study was conducted in 2004 and 2005 to determine the effect of liquid hog manure fertilization on greenhouse gas emissions from the surface of a grassland pasture in south-eastern Manitoba. The objectives of this research were to determine the effects of manure application, itstiming and soil moisture on greenhouse gas emissions from pasture soil, cattle dung and urine patches. Nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) emissions were determined from grassland soil surface, and from cattle dung and artificial urine patches. Liquid hog manure treatments were no manure (Control); 153 kg ha-1 of available-nitrogen (N) (two year average) in spring (Spring); and 149 kg ha-1 as half-rate applications in fall and spring (Split). Four field experiments were conducted on grassland plots. The static-vented chamber technique was used to estimate gas emission rates. Two of the experiments focused on the effects of manure application timing and soil moisture on greenhouse gas emissions from the grassland soil surface. The other two experiments focused on the effects of manure application and soil moisture on greenhouse gas emissions from cattle dung and artificial urine patches. Fresh cattle dung was collected from steers grazing adjacent pastures receiving the same three manure treatments. Artificial cattle urine treatments were generated by converting blood urea concentrations of the steers into urine-N concentrations. Manure application increased (P≤0.01) cumulative N2O emissions from the grassland soil surface with Control, Split and Spring treatments averaging 7, 43 and 120 mg N2O-N m-2, respectively. Of the two manure treatments, the Spring treatment emitted higher (P≤0.10) N2O emissions than the Split treatment. Soil moisture was a major factor influencing the quantity and type of greenhouse gas emissions, with saturated areas emitting CH4 during warm periods, whereas drier areas emitted N2O. Nitrous oxide emissions from these dry areas were higher in manure-treated plots. Spring application increased root density by 45% in the top 5 cm of soil compared to the Control. An increase in soil organic carbon with root density may offset any increase in greenhouse gas emissions caused by manure treatment. Cattle dung from Split and Spring treatments had higher cumulative N2O emissions (30 and 82 mg N2O-N m-2, respectively) compared to dung from Control pastures (6 mg N2O-N m-2) over two study years. Dung from the Spring treatment emitted more N2O (P≤0.01) than the other two treatments. All cattle dung patches emitted CH4 after deposition though unaffected by manure treatment. Artificial urine having highest N concentration had greater (P≤0.05) cumulative N2O emissions (690 mg N2O-N m-2) than urine with the lowest N concentration (170 mg N2O-N m-2). Drier soil locations emitted more N2O from cattle dung and artificial urine patches than wetter areas. This study demonstrated that Split application of liquid hog manure to grassland emitted less N2O than a complete application in spring. Moisture greatly affected the location of N2O and CH4 emissions. Drier areas emitted more N2O than wetter ones. Particularly, the findings indicate a need to assess grassland on periodically saturated soils as sources rather than sinks for CH4. Application of manure increased greenhouse gas emissions from cattle dung and urine patches with urine potentially having the greatest impact because of their higher emissions of N2O. An increase in root growth seems to offset greenhouse gas emissions from manure application.

For two fire seasons in Nordegg, Alberta, a system of in-stand weather stations were arranged along a north and south aligned valley and combined with collection of destructive fine fuel moisture content data in order to quantify variations due to differences in slope and aspect. South-facing sites were found to be slightly warmer (1.5°C), less humid (5%) and received on average 20% more solar radiation than the north-facing sites during the peak burning period of the day. Based on these weather observations a difference of 1 or 2 % moisture content between north and south sites was predicted using existing theoretical relationships. A corresponding difference in observed moisture content was not identified, due to the low transmittance recorded at the in-stand sites (<10% of open solar radiation measurements), variation amongst destructive samples and logistical limits on the number of replicates collected.

For two fire seasons in Nordegg, Alberta, a system of in-stand weather stations were arranged along a north and south aligned valley and combined with collection of destructive fine fuel moisture content data in order to quantify variations due to differences in slope and aspect. South-facing sites were found to be slightly warmer (1.5°C), less humid (5%) and received on average 20% more solar radiation than the north-facing sites during the peak burning period of the day. Based on these weather observations a difference of 1 or 2 % moisture content between north and south sites was predicted using existing theoretical relationships. A corresponding difference in observed moisture content was not identified, due to the low transmittance recorded at the in-stand sites (<10% of open solar radiation measurements), variation amongst destructive samples and logistical limits on the number of replicates collected.

The performance of some polymeric materials is profoundly affected by long-term exposure to moisture during service. This poses problems for high precision and/or load bearing components in engineering applications where moisture-induced changes in mechanical properties and dimensional stability could compromise the reliability of the device or structure. In addition to external factors such as moisture, the material properties are also evolving due to inherent structural relaxation within the polymeric material through a process known as physical aging. Based on the current knowledge of both mechanisms, they have opposite effects on material properties. The common approach to studying the effects of moisture is to expose the polymeric material to combined moisture and heat, also referred to as hygrothermal conditions. The application of heat not only increases the rate of moisture diffusion but also accelerates physical aging processes which would otherwise be very slow. In spite of this coupled response, nearly all hygrothermal studies ignore physical aging in their investigations due to the complexity of the coupled problem. The goal of this work is to develop a numerical model for simulating the interactive effects of moisture diffusion and physical aging in a glassy polymer. The intent is to develop a capability that would also allow one to model these effects under various mechanical loading and heat transfer conditions. The study has chosen to model the response of polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS), which is a glassy polymer blend that has very similar behaviour to polycarbonate. In this study, a comprehensive approach which considers four physical mechanisms – structural mechanics, moisture diffusion, heat conduction, and physical aging – has been applied. The most current analytical models in the literature usually attempt to model two or three coupled physical phenomena. To develop the four coupled phenomena model, the current work has undertaken an extensive scope of work involving experimental characterization and finite element modeling. In the experimental part of this work, seven sets of different tests were conducted to characterize the behaviour of PC/ABS exposed to moisture diffusion and accelerated physical aging. These experiments provided a comparative study between the effects of physical aging and moisture diffusion on the material’s behaviour; and at the same time, provided data for the numerical modeling. The dual glass transition temperatures (Tg) of the material were determined using two techniques: dynamic mechanical analysis (DMA) and thermo-mechanical analysis (TMA). The DMA tests provided data for studying the effects of hygrothermal aging on the Tg’s of the material and were also useful for mechanical tests such as creep and stress relaxation performed using the DMA. The Tg’s obtained using the TMA were also required for physical aging experiments using the dilatometry mode of TMA. Structural relaxation of the blend was studied by aging the material at 80 °C for 7 aging times in the TMA. These experiments gave an insight into the volume relaxation behaviour of the blend at a constant temperature. Specific heat capacity of the PC/ABS blend was also measured using another thermal analysis technique; i.e., differential scanning calorimeter (DSC), before and after test specimens were exposed to hygrothermal aging for 168 hours. The interactive effects of physical aging and moisture diffusion on the moisture uptake of the material were studied using gravimetric experiments performed at 5 different hygrothermal conditions. The experimental results were used to determine the coefficient of diffusion as well as the equilibrium moisture uptake of the samples. Furthermore, the effects of both moisture diffusion and physical aging on the mechanical behaviour of the polymer blend were investigated using stress relaxation tests. The comparison of the results of the tests performed on un-aged specimens with those of thermally and hygrothermally aged samples showed how physical aging effects competed with moisture diffusion. Also, the coefficient of hygroscopic expansion of the PC/ABS blend was determined using a so-called TMA/TGA technique. The numerical modeling of the four-coupled physics was achieved using the governing equations in the form of partial differential equations. Modeling was performed using the commercial finite element software package, COMSOL Multiphysics®. First, the uncoupled physical mechanisms of structural mechanics, moisture diffusion, and heat conduction were modeled separately to investigate the validity of the PDEs for each individual phenomenon. The modeling of the coupled physics was undertaken in two parts. The three coupled physics of structural mechanics, moisture diffusion, and heat conduction was first simulated for a gas pipe having a linear elastic behaviour. The comparison of the results with similar analysis available in the literature showed the capability of the developed model for the analysis of the triple coupled mechanisms. The second part modeled the four coupled phenomena by incorporating the experimentally determined coupling coefficients. In the developed numerical model, the material behaviour was considered to be linear viscoelastic, which complicated the model further but provided more realistic results for the behaviour of the polymer blend. Moreover, an approximation method was proposed for estimating the coupling coefficients that exist between different coupled physics in this study. It was also suggested that the anomalous moisture diffusion in the material can be modeled using a time varying boundary condition. Finally, the model was successfully verified and demonstrated using test case studies with thin thermoplastic plates. The proposed four-coupled physics model was able to predict with good accuracy the deflection of thin thermoplastic plates under bending for a set of hygorthermal test condition.