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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
161

A general study of the migration of some contaminants and plasticisers from the packaging materials into food.

January 1995 (has links)
by Wong Siu Kay. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 172-175). / Chapter PARTI : --- Naphthalene contamination in Milk Drinks / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 : --- Methods of determination of Naphthalene in Milk and Packaging Materials --- p.6 / Chapter Chapter 3 : --- Prediction Method I - Simulation --- p.15 / Chapter Chapter 4 : --- Prediction Method II- Mathematical Modelling --- p.24 / Chapter Chapter 5 : --- Atmospheric Effect I - Naphthalene Vapour in Air --- p.31 / Chapter Chapter 6 : --- Atmospheric Effect II- Aromatic Hydrocarbons in Air --- p.44 / Chapter Chapter 7 : --- Naphthalene Contamination In Solid Foods --- p.58 / Chapter Chapter 8 : --- Migration of Naphthalene in other Types of Polymers --- p.69 / Chapter Chapter 9 : --- Further Studies --- p.76 / Reference --- p.31 / Appendix I --- p.88 / Chapter Part II : --- General Study of Plasticisers Migration into Food / Chapter Chapter 1 : --- Introduction --- p.91 / Chapter Chapter 2 : --- Survey of Plasticisers Level in Food Contact Materials --- p.100 / Chapter Chapter 3 : --- Survey of Plasticisers Level in Foodstuff --- p.119 / Chapter Chapter 4 : --- Mathematical Modelling --- p.139 / Chapter Chapter 5 : --- Effect of Microwave Heating --- p.159 / Reference --- p.172 / Appendix II --- p.176
162

An improved method for simulation of vehicle vibration using a journey database and wavelet analysis for the pre-distribution testing of packaging

Griffiths, Katharine Rhiannon January 2013 (has links)
Vehicle vibration is inherently random and non-stationary with a non-Gaussian distribution. In addition, variations in vehicle parameters, product payloads and distribution journeys mean that the characteristics of vibration are not identical for all distribution journeys. Because vehicle vibration and shock are key causes of damage during distribution, their simulation in pre-distribution testing is vital in order to ensure that adequate protection is provided for transported products. The established method set out in the current testing standards utilises a global set of averaged accelerated power spectral density spectra to construct random vibration signals. These signals are stationary with Gaussian distributions and, therefore, do not fully represent actual vehicle vibration, only an average. The aim of the investigation, reported on in this Thesis, was to create an improved test regime for simulating vehicle vibration for pre-distribution testing of packaging. This aim has been achieved through the construction of representative tests and the creation of realistic simulations with statistical significance. A journey database has been created, in which historic road profile data along with a quarter vehicle model have been used to approximate a known vehicle’s vibration on a specific distribution journey. Additionally, a wavelet decomposition method, in which wavelet analysis is used to decompose the approximate vehicle vibration in to a series of Gaussian approximations of varying amplitude and spectral content, has been developed. Along with theoretical work, case studies have been undertaken in order to validate the test regime.
163

Numerical Study of Heat and Mass Transfer Using Phase Change Materials

Mahdavi Nejad, Alireza 20 April 2018 (has links)
Phase Change Materials (PCM) absorb and release heat at preset temperatures. Due to their relatively high values of latent heat, they are capable of storing and releasing large amounts of energy during phase change. When a PCM is in its solid phase, it will absorb heat as the external temperature rises. The temperature of the PCM will mirror the external temperature until the melting point of PCM is reached. At this stage, the PCM will begin to melt with almost no change in its temperature. PCM plays an opposite role when the external temperature drops. It releases the stored energy back while going through phase change from liquid phase to solid phase. The present work is a numerical study towards fundamental understanding of the impact of using PCM on enhancement of heat and mass transfer in several scenarios. A numerical analysis has been carried out to determine the impact of presence of PCM on the insulating characteristics of paper board packaging. Two different cases of a layered PCM and uniformly dispersed PCM within the packaging wall are considered. The numerical results illustrate significant reduction in exchange of heat between the exterior and the interior of the packaging. Specifically, the unique concept of utilizing PCM in drying of paper is proposed and a numerical investigation is performed to determine the corresponding transport characteristics. The results indicate that the PCM acts as a heat source and a heat sink alternatingly throughout the conventional paper drying process, enhancing the drying energy efficiency. This study also included presence of gas-fired infrared emitters in the drying process as well for which the spectral absorption coefficient of PCM was measured and incorporated into the theoretical model. Finally, the impact of the presence of PCM in convective air-drying of moist paper is numerically investigated. The hot air ow is generated by an in-line jet nozzle. The air impinges on the exposed surface of the moist paper while the other side is considered to be perfectly insulated. The results provide the corresponding air flow field as well as air temperature distribution in between the nozzle exit and the surface of the moist paper. The results also reveal the enhancement of drying rates with PCM, fundamentally confirming the role of PCM on enhancing the energy efficiency of convective drying of moist paper.
164

Analysis of plasticisers in food by GC/MS.

January 1996 (has links)
by Wai Yin Karen Fong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves [106]-[110]). / Abstract --- p.2 / Acknowledgments --- p.3 / Dedication --- p.4 / Abbreviations --- p.5 / Table of Contents --- p.7 / Chapter Chapter 1: --- Introduction --- p.11 / Chapter 1.1 --- Overviews of packaging materials --- p.11 / Chapter 1.2 --- Source of contamination --- p.14 / Chapter 1.2.1 --- Contamination from packaging materials --- p.15 / Chapter 1.2.2 --- Contamination of plasticisers from packaging materials and its effect --- p.16 / Chapter 1.3 --- Classification of commercial plasticisers --- p.19 / Chapter 1.3.1 --- Application of plasticisers --- p.20 / Chapter 1.4 --- Analysis of the plasticisers in the food packaging films --- p.22 / Chapter 1.5 --- Analysis of plasticisers in food using isotope dilution technique --- p.22 / Chapter Chapter 2 --- : Instrumentation and Analytical methods --- p.25 / Chapter 2.0 --- Instrumentation --- p.25 / Chapter 2.1 --- Gas chromatography --- p.25 / Chapter 2.2 --- Detector --- p.26 / Chapter 2.2.1 --- Flame ionisation detector --- p.26 / Chapter 2.2.2 --- Mass spectrometer --- p.27 / Chapter 2.2.2.1 --- Ion trap detector --- p.28 / Chapter 2.2.3 --- Ionisation mode --- p.33 / Chapter 2.2.3.1 --- Electron ionisation (EI) --- p.33 / Chapter 2.2.3.2 --- Chemical ionisation (CI) --- p.34 / Chapter 2.4 --- Analytical methods --- p.36 / Chapter 2.3 --- The use of combined GC/MS in the analysis of plasticisers --- p.36 / Chapter 2.3.1 --- Identification by GC/MS --- p.37 / Chapter 2.3.2 --- Qualitative MS --- p.37 / Chapter 2.3.3 --- Quantitative MS --- p.39 / Chapter 2.3.3.1 --- Isotope dilution technique --- p.40 / Chapter Chapter 3: --- Analysis of plasticisers in food packaging materials --- p.41 / Chapter 3.1 --- Introduction --- p.41 / Chapter 3.2 --- Experimental and Instrumental --- p.42 / Chapter 3.2.1 --- Reagents --- p.43 / Chapter 3.2.2 --- Materials --- p.43 / Chapter 3.3 --- Identification of food packaging materials --- p.43 / Chapter 3.3.1 --- Fourier transform infrared spectrometry --- p.44 / Chapter 3.3.2 --- Burning test --- p.45 / Chapter 3.3.3 --- Solvent dissolution method --- p.46 / Chapter 3.4 --- Extraction of plasticisers from the packaging materials --- p.49 / Chapter 3.4.1 --- Chloroform extraction --- p.50 / Chapter 3.4.2 --- Solvent reflux method --- p.50 / Chapter 3.5 --- Results and discussion --- p.51 / Chapter 3.5.1 --- Precision test --- p.51 / Chapter 3.5.2 --- Calibration curve --- p.52 / Chapter 3.5.3 --- Detection limit --- p.54 / Chapter 3.5.4 --- Recovery --- p.54 / Chapter 3.6 --- Survey of the level of plasticisers in food packaging materials --- p.55 / Chapter 3.7 --- Conclusion --- p.66 / Chapter 4.0 --- Analysis of plasticisers in foods --- p.67 / Chapter 4.1 --- Introduction --- p.67 / Chapter 4.2 --- Experimental and instrument --- p.67 / Chapter 4.2.1 --- Reagents --- p.68 / Chapter 4.2.2 --- Materials --- p.68 / Chapter 4.3 --- Analysis --- p.69 / Chapter 4.3.1 --- selection of stable isotope labelled analogues --- p.69 / Chapter 4.3.2 --- Synthesis of deuterated internal standard --- p.70 / Chapter 4.4 --- Extraction of foods --- p.71 / Chapter 4.4.1 --- Clean up method --- p.73 / Chapter 4.4.2 --- Quantitation --- p.77 / Chapter 4.5 --- Results and discussion --- p.82 / Chapter 4.5.1 --- Precision test --- p.82 / Chapter 4.5.2 --- Calibration curve --- p.84 / Chapter 4.5.3 --- Detection limit --- p.85 / Chapter 4.5.4 --- Survey of the level of plasticisers in food --- p.86 / Chapter 4.6 --- Conclusion --- p.91 / Chapter 5.0 --- Analysis of plasticisers in food by EI and CI method / Chapter 5.1 --- Introduction --- p.93 / Chapter 5.2 --- Experimental and Instrumental --- p.94 / Chapter 5.2.1 --- Reagents --- p.95 / Chapter 5.2.2 --- Materials --- p.95 / Chapter 5.3 --- Extraction of foods --- p.95 / Chapter 5.3.1 --- Clean up method --- p.95 / Chapter 5.4 --- Result and discussion --- p.95 / Chapter 5.4.1 --- Precision test --- p.95 / Chapter 5.4.2 --- Calibration curve --- p.97 / Chapter 5.4.3 --- Detection limit --- p.99 / Chapter 5.4.4 --- Survey of plasticisers in food by EI and CI method --- p.100 / Chapter 5.4.5 --- Paired t-Test --- p.103 / Chapter 5.5 --- Conclusion --- p.104 / Chapter Chapter 6 --- Conclusion --- p.105 / Bibliography --- p.106 / Appendices : / Chapter 1 --- The mass spectrum of DEP --- p.i / Chapter 2 --- The mass spectrum of DIBA --- p.i / Chapter 3 --- The mass spectrum of DIBP --- p.ii / Chapter 4 --- The mass spectrum of DBP --- p.ii / Chapter 5 --- The mass spectrum of DBS --- p.iii / Chapter 6 --- The mass spectrum of ATBC --- p.iii / Chapter 7 --- The mass spectrum of BBP --- p.iv / Chapter 8 --- The mass spectrum of DEHA --- p.iv / Chapter 9 --- The mass spectrum of DPOP --- p.v / Chapter 10 --- The mass spectrum of DEHP --- p.v / Chapter 11 --- The mass spectrum of DCHP --- p.vi / Chapter 12 --- The mass spectrum of DOAZ --- p.vi / Chapter 13 --- The mass spectrum of DOS --- p.vii / Chapter 14 --- Calibration curve of GC/FID --- p.viii / Chapter 15 --- Calibration curve of GC/MS (magnum) --- p.xi / Chapter 16 --- Calibration curve of GC/MS (GCQ) --- p.xiv
165

Komunikační strategie nové plastové láhve společnosti Coca-Cola. / Concept of communication strategy of The Coca-Cola Company´s new plastic bottle

Němcová, Klára January 2009 (has links)
The thesis relates to theorethical principles of marketing and commercial communications. The application part of the thesis relates to a concept of communication strategy of The Coca-Cola Company's new plastic bottle
166

Characterization of copper diffusion in advanced packaging /

Zhang, Xiaodong. January 2007 (has links)
Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 134-144). Also available in electronic version.
167

Xyloglucan-based polymers and nanocomposites – modification, properties and barrier film applications

Kochumalayil Jose, Joby January 2012 (has links)
Biopolymers from renewable resources are of interest for packaging applications as an alternative to conventional petroleum-based polymers. One of the major application areas for biopolymers is food packaging, where a candidate polymer should meet critical requirements such as mechanical and oxygen barrier performance, also in humid conditions. Starch has long been used in certain packaging applications, either in plasticized state or blended with other polymers. However, native starch has high sensitivity to water and low mechanical and barrier performance. Recently, wood-derived hemicelluloses have been extensively studied as oxygen barrier films, but suffer from low film-forming ability and mechanical performance. In the present study, xyloglucan (XG) from tamarind seed waste is explored as an alternative high-performance biopolymer in packaging applications. The obstacles of polysaccharides in terms of moisture sensitivity and processability are addressed in this thesis. In Paper I, film properties of XG were studied. XG has a cellulose backbone, but unlike cellulose, it is mostly soluble in water forming highly robust films. Moisture sorption isotherms, tensile tests and dynamic mechanical thermal analysis were performed. Enzymatic modification (partial removal of galactose in side chains of XG) was performed to study the effect of galactose on solubility and filmforming characteristics. XG films showed lower moisture sorption than starch. Stiffness and tensile strength were very high of the order of 4 GPa and 70 MPa respectively, with considerable ductility and toughness. The thermomechanical performance was very high with a softening temperature near 260 ºC. In Paper II, several plasticizers were studied in order to facilitate thermal processing of XG films: sorbitol, urea, glycerol and polyethylene oxide. Films of different compositions were prepared and studied for thermomechanical and tensile properties. Highly favorable characteristics were found with XG/sorbitol system. A large drop in glass transition temperature (Tg) of XG of the order of 100 ºC with 20 - 30 wt% sorbitol was observed with an attractive combination of increased toughness. In Paper III, XG was chemically modified and the structure-property relationship of modified XG studied. XG modification was performed using an approach involving periodate oxidation followed by reduction. The oxidation is highly regioselective, where the side chains of XG are mostly affected with the cellulose backbone well-preserved as noticed from MALDI-TOF-MS and carbohydrate analysis. Films were cast from water and characterized by dynamic mechanical thermal analysis, dynamic water vapor sorption, oxygen transmission analysis and tensile tests. Property changes were interpreted from structural changes. The regioselective modification results in new types of cellulose derivatives without the need for harmful solvents. In Paper IV, moisture durability of XG was addressed by dispersing montmorillonite (MTM) platelets in water suspension. Oriented bionanocomposite coatings with strong in-plane orientation of clay platelets were prepared. A continuous water-based processing approach was adopted in view of easy scaling up. The resulting nanocomposites were characterized by FE-SEM, TEM, and XRD. XG adsorption on MTM was measured by quartz crystal microbalance analysis. Mechanical and gas barrier properties were measured, also at high relative humidity. The reinforcement in mechanical properties and effects on barrier properties were remarkable, also in humid conditions. In Paper V, cross-linked XG/MTM composite was prepared with high clay content (ca. 45 vol%) by an industrially scalable “paper-making” method. Instead of using cross-linking molecules, cross-linking sites were created on the XG chain by selective oxidation of side chains. The in-plane orientation of MTM platelets were studied using XRD and FE-SEM. The mechanical properties and barrier performance were evaluated for the resulting 'nacre-mimetic' nanocomposites. The elastic modulus of cross-linked nanocomposites is as high as 30 GPa, one of the stiffest bionanocomposites reported. / <p>QC 20121107</p>
168

Evaluation of Packaging Film Mechanical Integrity Using a Standardized Scratch Test

Hare, Brian 2011 August 1900 (has links)
Polymeric packaging films see widespread use in the food packaging industry, and their mechanical integrity is paramount to maintaining product appearance, freshness, and overall food safety. Current testing methods, such as tensile or puncture tests, do not necessarily correlate well with field damages that are observed to be scratch-like. The standardized linearly increasing load scratch test is investigated as a new means of evaluating the mechanical integrity of packaging films. Mechanical clamp and vacuum fixtures were considered for securing the films to a set of backing materials and tested under various testing rates and film orientation conditions. Film performance was evaluated according to their puncture load. Based on the above study, the vacuum fixture offers the most consistent and meaningful results by providing a more intimate contact between film and backing and minimizing uncontrolled buckling of the film during testing. Additional testing was also carried out on a commercial film to confirm similarity between damage observed in the scratched films and that from the field. The scratch test gives good correlation between field performance and scratch test results on a set of commercial films. The usefulness of the scratch test methodology for packaging film mechanical integrity evaluation is discussed. Scratch-induced damages on multi-layer commercial packaging films are investigated using cross- and longitudinal-sectioning. Scratch test results show clear distinction between the two tested systems on both the inside and outside surfaces. Microscopy was performed to investigate the feasibility of utilizing this methodology as a tool for packaging film structure evaluation by determining the effect each layer has on the resistance of scratch damages. It is shown that the film showing superior scratch test results also shows significantly better stress distribution through its layers during the scratch test, as well as better layer adhesion during severe deformation. The scratch test shows good ability to provide more in-depth film mechanical integrity testing by allowing for layer-by-layer analysis of damages and layer adhesion after testing.
169

Volvo Logistics Corporation Returnable Packaging System : a model for analysing cost savings when switching packaging system

Beselin Hallberg, Jacob, Uhrbom, Per January 2008 (has links)
This thesis is a study for analysing costs affected by packaging in a producing industry. The purpose is to develop a model that will calculate and present possible cost savings for the customer by using Volvo Logistics Corporations, VLC’s, returnable packaging instead of other packaging solutions. The thesis is based on qualitative data gained from both theoretical and empirical studies. The methodology for gaining information has been to study theoretical sources such as course literature and articles, as well as through interviews and consolidation with staff at Volvo Logistics Corporations office in Gothenburg. The model is constructed in Microsoft Excel and consists of six different sheets. The first sheet is a front page that summarises the costs calculated in the other sheets and presents the possible cost savings. After the front page there are three sheets with calculations for the costs in different scenarios, Today’s Situation, VLC Packaging Solution (Pre implementation) and VLC Packaging Solution (Post implementation). The first sheet, Today’s Situation, presents the result of the model that will calculate the customers’ current costs that are associated with packaging. The different costs presented in the model are costs for unloading, repacking, today’s cost for an internal packaging solution, quality related costs, one-way packaging costs and the costs for other packaging solutions. The next sheet, VLC Packaging Solution (Pre), presents an estimation of the cost for thecustomer when using VLC’s returnable packaging system. The estimation will serve as an investment tool, for calculating possible cost savings compared to the present situation. The different costs that will be discussed are handling costs, quality related costs, distribution cost, transaction cost, and investment cost. The third and final calculation sheet, VLC Packaging Solution (Post), presents the actual costs for the customer after the implementation. When the costs have been calculated they will be used to evaluate the actual cost savings for the customer. The last two sheets are a data sheet, which consists of data needed for the calculations in the previous sheets, and an instruction sheet where there are instructions to the different calculations in the model. The conclusion shows that the objective to create a model for calculating the costs for different packaging systems and present possible cost savings is fulfilled.
170

Moisture and Interfacial Adhesion in Microelectronic Assemblies

Ferguson, Timothy Patrick 21 June 2004 (has links)
In this research, a systematic and multi-disciplinary study was conducted to understand the fundamental science of moisture-induced degradation of interfacial adhesion. The research is comprised of both experimental and modeling components of analysis and consists of four primary components. First, the moisture transport behavior within underfill adhesives is experimentally characterized and incorporated into a finite element model to depict the moisture ingress and interfacial moisture concentration for each respective level of moisture preconditioning. Second, the effect of moisture on the variation of the underfill elastic modulus is demonstrated and the physical mechanisms for the change identified. Third, the aggregate effect of moisture on the interfacial fracture toughness of underfill to both copper and FR-4 board substrates is determined. This includes the primary effect of moisture being physically present at the interface and the secondary effect of moisture changing the elastic modulus of the adhesive when absorbed. Last, the recovery of both the elastic modulus and interfacial fracture toughness from moisture preconditioning is assessed with reversible and irreversible components identified. Using adsorption theory in conjunction with fracture mechanics, an analytical model is developed that predicts the loss in interfacial fracture toughness as a function of moisture content. The model incorporates key parameters relevant to the problem of moisture in epoxy joints identified from the experimental portion of this research, including the interfacial hydrophobicity, epoxy nanopore density, saturation concentration, and density of water. This research results in a comprehensive understanding of the primary mechanisms responsible for the interfacial degradation due to the presence of moisture. The experimental results obtained through this research provide definitive data for the electronics industry to use in their product design, failure analysis, and reliability modeling. The predictive model developed in this research provides a useful tool for developing new adhesives, innovative surface treatment methods, and effective protection methodologies for enhancing interfacial adhesion.

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