| 1. |
- Carlsson, Gunilla, 1962-, et al.
(author)
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Characterization of Micro Fibrillated Cellulose using fluorescence microscopy : Evaluation of pretreatments of Micro Fibrillated Cellulose using fluorescence microscopy
- 2011
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Conference paper (peer-reviewed)abstract
- The paper making process is well known but the underlying mechanisms are not fully understood. Paper builds up from cellulose fibers and many additives are needed in the process. The interactions between components in the furnish are important. Pulp fibers have a wide size distribution and the finest particle fraction is called fines. The fines used in this study are Micro Fibrillated Cellulose (MFC) from bleached craft pulp. A model system containing fibers and latex was used together with fluorescence microscopy and image analysis. By studying the motion of a labeled latex particle more can be understood about the internal structure of the system. The system consists of: A water suspension of MFC. At the concentrations used the fines are interacting with each other, forming a gel like structure. Negatively charged labeled latex particles (probes), with radius 0,1 µm. Two types of electrolytes (NaCl and CaCl2). The electrolytes were used for altering the electrical double layer of the charged surfaces in the system. Different pretreatments of the MFC has been investigated and evaluated using the movements of the probe in the network of fibers.
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| 2. |
- Govindarajan, Venkatesh, 1972-, et al.
(author)
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An economic-environmental analysis of selected barrier coating materials used in packaging food products : A Swedish case study
- 2018
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In: Environment, Development and Sustainability. - Dordrecht : Springer. - 1387-585X .- 1573-2975. ; 20:4, s. 1483-1497
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Journal article (peer-reviewed)abstract
- The purpose of a barrier coating in food packaging is primarily to increase the shelf life of the foodstuff contained within the packaging, preserve its colour, odour, taste and quality, and thereby reduce food wastage (both at retail outlets and households). While most publications hitherto have compared packaging and barrier-coating materials on the basis of their environmental impacts alone, this paper adopts a more holistic approach by factoring in the economic aspect as well. Four barrier material alternatives—starch, polyethylene, EVOH + kaolin and latex + kaolin are analysed. Two well-defined end-of-life handling scenarios, relevant to Sweden, are: one in which everything except starch is recycled, with starch being composted, and the other in which everything is incinerated. Among the several environmental impact categories which can be analysed, this paper considers only global warming. Two approaches are tested to combine the economic and environmental aspects—normalisation, weighting and aggregating on the one hand, and using the carbon tax to internalise the externality caused by GHG emissions on the other. For the set of weighting factors obtained thanks to a survey conducted by the authors (40.6% for environmental and 59.4% for economic), starch emerges as the most sustainable alternative, followed by polyethylene for both the end-of-life handling scenarios. This tallies with the result obtained by using the carbon tax for internalisation of the externality. The case study, methodology and results presented in this paper, will hopefully be a springboard for more detailed studies of this nature, under the umbrella of sustainability.
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| 3. |
- Lestelius, Magnus, 1968-, et al.
(author)
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Oxygen permeabilityand economic-environmental impact studies of some polyvinyl alcohol dispersionbarrier coatings for packaging applications
- 2017
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Conference paper (other academic/artistic)abstract
- Purposes of employing barrier coatings in packaging, and in particular food packaging, can be to increase the shelf life, preserve colour, odour, and taste, and to protect from a harmful environment in general. Barrier coatings can thus help to reduce food waste along the value chain until end use. Including both materials choice for packaging and the possible fates of the used package, even further steps to provide greater knowledge for decisions on choices of packaging solutions. To that end, we have conducted several experimental and transport modeling studies on oxygen barrier coatings performance. The coating system of choice has been dispersion coatings of poly vinyl alcohol (PVOH), with additions of kaolin. Physical and chemical features of the coatings were characterized to obtain information on polymer crystallinity, free volume and filler orientation as these characteristics are influential to the oxygen mass transport performance. In turn, the oxygen mass transport was also measured, both in steady state and dynamically. In so doing, we obtained information useful for developing a general model to describe the oxygen permeability taking into account the physical and chemical features, described above, of the coating layer. Attempts on describing the interdependence and impact, for instance between crystalline and amorphous polymer regions and moisture, was added to the model. The model showed agreement to experimental data for PVOH-kaolin coating in this particular case. However, the basic permeability model has been applied to many different polymers.To further explore the potential of these types of coating, which are technically possible to produce in paperboard production, an economic-environmental impact comparison to other existing material solutions was made. Four barrier material alternatives – starch, polyethylene, ethyl vinyl alcohol (chosen as an alternative for PVOH, where data was difficult to obtain) and kaolin, and latex and kaolin, were analyzed with respect to cost and global warming potential. Weighting and comparing cost to environmental aspect, weighting factors based on interviews with experts in the packaging value chain, starch emerges as the most sustainable alternative. However, previous coating and mass transport studies also shows how these renewable materials require some further technical development to be competitive.The mass transport model can serve as a tool for customizing barrier coatings and to predict the barrier performance, as permeability is obtained and thus shelf-life estimation is possible. The overall concept, the combination of assessment of structural performance and the environmental studies, can be employed to find sustainable food packaging solutions.
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| 4. |
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| 5. |
- Nyflött, Åsa, 1986-, et al.
(author)
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Influence of kaolin addition on the dynamics of oxygen mass transport in polyvinyl alcohol dispersion coatings
- 2015
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In: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 30:3, s. 385-392
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Journal article (peer-reviewed)abstract
- The permeability of dispersion barriers produced from polyvinyl alcohol (PVOH) and kaolin clay blends coated onto polymeric supports has been studied by employing two different measurement methods: the oxygen transmission rate (OTR) and the ambient oxygen ingress rate (AOIR). Coatings with different thicknesses and kaolin contents were studied. Structural information of the dispersion-barrier coatings was obtained by Fourier transform infrared spectroscopy (FTIR) spectroscopy and scanning electron microscopy (SEM). These results showed that the kaolin content influences both the orientation of the kaolin and the degree of crystallinity of the PVOH coating. Increased kaolin content increased the alignment of the kaolin platelets to the basal plane of the coating. Higher kaolin content was accompanied by higher degree of crystallinity of the PVOH. The barrier thickness proved to be less important in the early stages of the mass transport process, whereas it had a significant influence on the steady-state permeability. The results from this study demonstrate the need for better understanding of how permeability is influenced by (chemical and physical) structure.
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| 9. |
- Nyflött, Åsa, 1986-
(author)
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Structural Studies and Modelling of Oxygen Transport in Barrier Materials for Food Packaging
- 2014
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Licentiate thesis (other academic/artistic)abstract
- The requirements of food packages are to ensure food safety and quality, to minimize spoilage, and to provide an easy way to store and handle food. To meet these demands for fibre-based food packages, barrier coatings are generally used to regulate the amount of gases entering a package, as some gases are detrimental to food quality. Oxygen, for example, initiates lipid oxidation in fatty foods. Bakery products may also be sensitive to oxygen.This thesis focused on mass transport of oxygen in order to gain deeper knowledge in the performance of barrier coatings and to develop means to optimize the performance of barrier coatings. This experimental study along with computer modelling characterized the structure of barrier materials with respect to the mass transport process.This project was performed as part of the multidisciplinary industrial graduate school VIPP (www.kau.se/en/vipp) - Values Created in Fibre Based Processes and Products – at Karlstad University, with the financial support from the Knowledge Foundation, Sweden, and Stora Enso.
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| 10. |
- Nyflött, Åsa, 1986-
(author)
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Structure-Performance Relations of Oxygen Barriers for Food Packaging
- 2017
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Doctoral thesis (other academic/artistic)abstract
- Food packaging should ensure the safety and quality of food, minimize spoilage and provide an easy way of storing and handling it. Barrier coatings are generally used to meet the demands placed on fibre-based food packages, as these have the ability to regulate the amount of gases that can enter them. Some gases are detrimental to food quality: oxygen, for example, initiates lipid oxidation in fatty foods. Using both experimental data and computer modelling, this thesis explains some aspects of how the structure of barrier coatings influences the mass transport of oxygen with the aim of obtaining essential knowledge that can be used to optimize the performance of barriers.Barrier coatings are produced from polyvinyl alcohol and kaolin blends that are coated onto a polymeric support. The chemical and physical structures of these barriers were characterized according to their influence on permeability in various climates. At a low concentration of kaolin, the crystallinity of polyvinyl alcohol decreased; in the thinner films, the kaolin particles were orientated in the basal plane of the barrier coating. The experimental results indicated a complex interplay between the polymer and the filler with respect to permeability.A computer model for permeability incorporating theories for the filled polymeric layer to include the polymer crystallinity, addition of filler, filler aspect ratio and surrounding moisture was developed. The model shows that mass transport was affected by the aspect ratio of the clay in combination with the clay concentration, as well as the polymer crystallinity. The combined model agreed with the experiments, showing that it is possible to combine different theories into one model that can be used to predict the mass transport.Four barrier coatings: polyethylene, ethylene vinyl alcohol + kaolin, latex + kaolin and starch were evaluated using the parameters of greenhouse gas emissions and product costs. After the production of the barrier material, the coating process and the end-of-life handling scenarios were analysed, it emerged that starch had the lowest environmental impact and latex + kaolin had the highest.
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