| 1. |
- Idris, Alamin, et al.
(författare)
-
Oxygen Barrier Performance of Poly (Vinyl Alcohol) Coating Films with Different Induced Crystallinity and Model Predictions
- 2021
-
Ingår i: Coatings. - : MDPI AG. - 2079-6412. ; 11, s. 1-12
-
Tidskriftsartikel (refereegranskat)abstract
- The presence of the crystalline regions in poly(vinyl alcohol) coating films acts as barrier clusters forcing the gas molecules to diffuse in a longer pathway in the amorphous region of the polymer, where diffusivity and solubility are promoted in comparison. Evaluating the influence of crystalline regions on the oxygen barrier property of a semi-crystalline polymer is thus essential to prepare better coating films. Poly(vinyl alcohol) coating films with varying induced crystallinity were prepared on a polyethylene terephthalate (PET) substrate by drying at different annealing temperatures for 10 min. The coating films were first delaminated from the PET substrate and then characterized using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD) techniques to determine and confirm the induced percentage of crystallinity. The barrier performance of the coating films, i.e., the oxygen transmission rate (OTR), was measured at room temperature. Results showed a decrease in the OTR values of poly(vinyl alcohol) film with an increase in the degree of crystallinity of the polymer matrix. Tortuosity-based models, i.e., modified Nielsen models, were adopted to predict the barrier property of the semi-crystalline PVOH film with uniform or randomly distributed crystallites. A modified Nielsen model for orderly distributed crystallites with an aspect ratio of 3.4 and for randomly distributed crystallites with an aspect ratio of 10.4 resulted in a good correlation with the experimental observation. For the randomly distributed crystallites, lower absolute average relative errors of 4.66, 4.45, and 5.79% were observed as compared to orderly distributed crystallites when the degree of crystallinity was obtained using FTIR, DSC, and XRD data, respectively.
|
|
| 2. |
- Lestelius, Magnus, 1968-, et al.
(författare)
-
Fiberförstärkta polymerer för 3D-utskrivna laminat, ES3D
- 2022
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Projektet Fiberförstärkta polymerer för 3D-utskrivna laminat (ES3D) var ett samarbete mellan Karlstads universitet och The Wood Region. Syftet var att åstadkomma nya metoder och öka kunskapen kring 3D-utskrivna strukturer med blandningar av termoplaster och sågspån. Genom att öka styrkan i det 3D-utskrivna biobaserade och nedbrytbara materialet kan hållbarhetsmässiga fördelar uppnås. Den enskilda trådens styrka avsågs ökas genom att använda längre spån och rikta dem i utskriftsriktningen. Adhesionen mellan de utskrivna lagren skulle förbättras genom kontrollerad temperatur och s.k. coronabehandling.ES3D har resulterat i en metod för att kunna testa 3D-utskrivna prov i dragprovare för mekanisk karakterisering, som sedankan användas för att jämföra olika materialsammansättningar och tillverkningssätt.Sortering av sågspån, i olika storleksfraktioner, har genomförts med både maskinell rotationssorterare och sållning. Resultatet av den maskinella sorteringen var inte tillräckligt precis för att producera sågspånsfraktioner som kunde användas för ovanstående mål.Ökad adhesion mellan lager med temperaturkontroll eller coronabehandling, har ej kunnat prövas ordentligt, p.g.a. otillräcklig temperaturkontroll, samt att en teknisk lösning för coronabehandling ej fanns.
|
|
| 3. |
- Lidbrand, Isabell, et al.
(författare)
-
Paper Bags vis-à-vis LDPE Bags : Gleanings from Peer-reviewed E-LCA Publications [Torby papierowe a torby foliowe LDPE: wnioski z recenzowanych publikacjina temat oceny cyklu życia (E-LCA)]
- 2023
-
Ingår i: Studia Ecologiae et Bioethicae. - Poland : Scientific Publishing House of the Cardinal Stefan Wyszynski University. - 1733-1218 .- 2719-826X. ; 21:4, s. 63-76
-
Tidskriftsartikel (refereegranskat)abstract
- Fossil-plastics or paper? Or for that matter, bio-plastics and paper? This is a wellentrenched question in academic research, industrial, social and policy-making circles. Asenvironmental life-cycle analyses (or more appropriately, sustainability analyses) show timeand again, no single product or process or mode of operation is a ‘total villain’. There are goodsand bads, and at times, more of the one than the other. This paper, which is based on a coursereport written by the first author at Karlstad University (Sweden), restricts itself to a review ofpublications which have opted to compare paper bags with low density polyethylene (LDPE)plastic bags, on the basis of their environmental impacts. Environmental impact categoriesinclude the global warming potential, energy demand, fossil fuel depletion, water usage,acidification, eutrophication, and a range of toxicities – human, terrestrial, freshwater-aquaticand marine-aquatic. The articles were obtained through Google Scholar, read and reviewed toglean the results presented therein. The ‘What’, ‘How’ and ‘Where’, so to say were studiedcarefully to understand the reasons behind any differences or similarities detected. On the basisof this focused review, even though no new knowledge is being added, the common belief thatthe paper bag is environmentally superior to the LDPE alternative is further consolidated.However, if one focuses on water usage and would assign a high weightage to thatenvironmental impact, LDPE perhaps may score a few ‘brownie points’ over paper. One mustalso not forget that plastics (LDPE in this instance) can be recycled without significantdeterioration in its functional properties. In a circular economy (the bioeconomy part of whichgradually will expand over time), while introducing more and more bio-based products into thetechnosphere by way of trans-materialization is recommended, plastics will still continue toexist – albeit in much smaller amounts – and it would be perfectly fine if the degree of recyclingis augmented significantly. Speaking of a holistic sustainability analysis, the socio-economicaspects of a choice between LDPE and paper bags must also be factored in, and studied. Muchdesired change happens when the top-down meets the bottom-up somewhere midway.
|
|
| 4. |
- Sjöstrand, Björn, 1987-, et al.
(författare)
-
Method for Studying Water Removal and Air Penetration during Through Air Drying of Tissue in Laboratory Scale
- 2023
-
Ingår i: BioResources. - Raleigh : North Carolina State University. - 1930-2126. ; 18:2, s. 3073-3088
-
Tidskriftsartikel (refereegranskat)abstract
- Energy use, together with consumption of raw materials, machine clothing, and wet end chemicals, are some of the most critical aspects in successful tissue making today. This work was aimed at developing a laboratory-scale method of estimating dewatering mechanisms, vacuum efficiency, and energy use of Through Air Drying (TAD) of tissue. When compared to pilot data, the results of the new laboratory method for investigating dewatering during TAD were in the same magnitude, around 24 to 26% dryness after vacuum dewatering, and 27 to 29% dryness after TAD molding. Sheet properties, such as caliper and surface profile, were evaluated and compared to commercial tissue sheets. The results indicate that it will be possible to precisely measure accurate dryness development and penetrated air volume for tissue sheet forming and TAD molding at a laboratory scale. This can contribute to the efforts of implementing a circular forest-based bioeconomy by increasing the fundamental understanding of dewatering of tissue paper materials, which is facilitated by improvements in energy use. The new method developed in this work will make it easier to assess ideas that are difficult to bring to pilot scale or full scale before learning more of the dewatering capabilities. The authors are convinced that improved knowledge of tissue dewatering mechanisms, forming, and material transport during and after TAD dewatering can increase the efficiency of the industrial manufacturing processes.
|
|
| 5. |
|
|
| 6. |
- Wilke, Caroline, 1982-, et al.
(författare)
-
Integrated Forest Biorefinery : A Proposed Pulp Mill of 2040
- 2021
-
Rapport (refereegranskat)abstract
- Negative environmental impact from greenhouse gas emissions and a dwindling oil supply have resulted in an interest in biorefineries based on renewable resources. The objective of a biorefinery is to upgrade the biomass to more valuable products such as biofuels, electricity, materials, and chemicals. Wood biomass is a suitable raw material for a biorefinery since it is abundant, renewable and can be harvested all year round.In the kraft pulping process, only half of the wood biomass is converted into pulp while the remaining part is turned into energy. A conventional kraft pulp mill could be transformed into an integrated forest biorefinery, and thus produce for example biofuels and chemicals in addition to the traditional pulp and paper products, by implementing several new processes that could utilize the byproducts. Utilization of the byproducts for other purposes than energy would obviously affect the energy balance but also the important sodium/sulfur balance.The processes that are discussed in this report have the potential to be included in a BAT pulp mill built in 2040. The processes are black liquor gasification, on-site production of sulfuric acid, production of tall oil diesel, and lignin and hemicellulose extraction. The possibility to produce a cleaner green liquor through a new membrane filter is also discussed.
|
|
