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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.
11

A comparison between the effects of polylactic acid and polystyrene microplastics on Daphnia magna

Puranen Vasilakis, Mikaela January 2017 (has links)
The effects of microplastics on zooplankton are an increasing environmental concern. Both primary microplastics that are produced as constituents of cosmetic products, as well as secondary microplastics that are formed by degradation of larger plastic debris, are ubiquitous in aquatic environments. Today, primary microplastics are being phased out and replaced by plant-derived bioplastics. Whether these new materials have similar effects as oil-based microplastics on animals is currently unknown. Here, we compare the effects of secondary microplastic exposure to Daphnia magna, using polylactic acid (PLA) as a representative for bioplastics and polystyrene (PS) for oil-based plastics. To increase the ecological relevance of our tests, we also provided treatments where the particles were coated with bovine serum albumin (BSA) as a means to simulate the coating of biofilms which readily form on particles under natural conditions. Furthermore, to be able to differentiate the effects of general particles from those specific to microplastics, kaolin clay was used as a control treatments, as well as one treatment containing only algae. The objectives were to test the influence of particles on feeding rates, reproduction and growth. PS caused a higher mortality, decreased feeding rate and reproductive output, while PLA and kaolin did not produce any negative effects. BSA did not have a significant effect on reproduction or growth. However, a decrease in reproduction was observed in the plastic treatments. Degradation of PS into styrene monomers is suggested as a possible explanation for the observed toxicity and effects on life history parameters.
12

Funkcionalizace polyolefinů roubováním / Functionalization of polyolefins by grafting

Paulenka, Igor January 2017 (has links)
The theoretical part of the diploma thesis is focused on the funcionalization of polyolefins in order to accelerate their degradation and to increase their carbon content from renewable resources with focus on hydroxyacids. The experimental part is focused on preparing samples and studying the properties of the polypropylene and polyethylene blends with the polylactide with different contents of the initiator and the maleic anhydride. Samples were evaluated by determining the degree of conversion maleic anhydride, differential scanning calorimetry, infrared spectroscopy, melt flow index and mechanical properties.
13

Produktion av polyhydroxyalkanoater (PHA) av avloppsvatten från massa och pappersindustri : En studie kring bakteriernas förmåga att ackumulera PHA beroende på sammansättning av karboxylsyror / Production of polyhydroxyalkanoates (PHA) from wastewater from pulp and paper industry : A study on the ability of bacteria to accumulate PHA depending on the composition of carboxylic acids

Augustsson, Jimmy, Högfeldt, Jonathan January 2020 (has links)
Since the beginning of the 20th century plastic has been a widely used material, which has resulted in large quantities of plastic being produced in the last century. The plastics of today are mainly produced from fossil raw materials, which gives it a high climate impact. Plastic also has a long service life, which creates problems with handling after the new period when new plastic is produced at a faster rate than plastic debris can be recycled or incinerated. One possible approach is to switch from plastic from fossil sources to bioplastics, which is produced by renewable sources. This means a reduction in the environmental impact as the amount of fossil CO2 emissions from combustion of plastics would decrease. Polyhydroxyalkanoates (PHAs) are created by short volatile fatty acids (VFAs) added to bio sludge from a wastewater treatment plant at a pulp and paper mill where there is a lot of bacteria and microorganisms. Some of the bacteria in the sludge have the ability to accumulate PHA when VFA is added in excess and then be able to use it as an energy and carbon source in cases of starvation. This means that PHA produced in this way can be degraded by bacteria making it biodegradable while having similar properties as oil-based plastics. Production of PHA is currently expensive as it is often necessary to purchase VFA for production. To make it economically sustainable to replace oil-based plastics with PHA, the cost of PHA production must therefore be reduced. This can be done by using mixed bacterial cultures from, for example, industrial wastewater treatment plants and by creating their own composition of VFA through fermentation. At the paper mill at BillerudKorsnäs Gruvön there are several process streams that today are led to the water treatment plant, one of which is from PM6 (Paper Machine 6). By fermenting that stream, VFA can be formed with a composition of acetic acid, propionic acid, and butyric acid. The current may thus be suitable to use as a substrate in PHA production. Another way to produce VFA is to ferment the residual flow from hydrothermal carbonation (HTC) of bio sludge. According to (Samorì et al., 2019), acetic acid, butyric acid and valeric acid are formed, which means that even this stream may be suitable as a substrate for PHA production. The purpose of this thesis is to investigate the effects of the composition of VFA on the production of PHA from forest industrial bio sludge. The study covers two different cases, Case PM6 and Case HTC, where two different types of composition of VFA are added to paper sludge from the paper mill. The experiments were performed in cylindrical tanks on three occasions where the first two experiments had a volume of 30 liters and the last experiment a volume of 10 liters. On the first occasion, the maximum accumulation rate in the growth phase was studied. In the second instance, a high accumulation rate was sought, but also survival after the growth phase. The first two trials were batch trials where the sludge was dosed until saturation was achieved. On the third occasion, the possibility of carrying out PHA production with a continuous sludge exchange was studied. The experiments were analyzed by FTIR which provided information on the absorbance of the sludge which shows how the PHA concentration increased during the course of the experiments. Extractions were then performed to obtain the concentration of PHA that eventually accumulated in the sludge. The results show that biomass from BillerudKorsnäs Gruvön's mills accumulated PHA faster with VFA composition from fermented PM6 effluent compared to VFA composition from fermented HTC condensate. Calculations made with input from the experiments indicate that it is possible to produce a larger amount of PHA per year with Case PM6. The conclusion is therefore that Case PM6 is preferable if as large a PHA production as possible wants to be achieved. Case HTC is instead preferred if reduced PHA production can be tolerated in favor of biocarbon production.
14

Miljöpåverkan av bioplast från skogsindustriellt avloppsvatten : En jämförande livscykelanalys av polypropen (PP) och polyhydroxyalkanoater (PHA) från Gruvöns massa- och pappersbruk / Environmental impact of bioplastic from forest industrial wastewater : A comparative life cycle assessment of polypropylene (PP) and polyhydroxyalkanoates (PHA) from Gruvöns pulp- and paper mill

Eriksson, Joakim January 2020 (has links)
I den här studien har en beräkningsmodell byggts för hur PHA skulle kunna produceras av substrat i avloppsvatten från Gruvöns bruk. Därefter har en jämförande livscykelanalys utförts där PP-sugrör inom Europa ersätts med PHA-sugrör från bruket. Målet med studien är att utvärdera och jämföra miljöpåverkan för en engångsprodukt av PHA med en engångsprodukt av PP. Syftet är att undersöka ett alternativt material till PP på grund av att fossila resurser är ändliga samt att alternativa material kommer krävas i och med europeiska kommissionens förbud mot engångsplast som träder i kraft 2022. Arbetet utförs också för att bidra med mer forskningsunderlag gällande PHA från restströmmar. Livscykelanalysen utfördes med ISO-standard: 14040 och 14044 som riktlinje för utförande. 1 ton sugrör valdes som funktionell enhet och hela produktens livscykel undersöktes med undantag för användningsfasen. PHA-produktion på bruket beräknades teoretiskt där mass- och energiflöden från modellen sedan användes för miljöbedömning. SimaPro valdes som programvara för LCA-beräkning, miljödata hämtades från databasen Ecoinvent 3 och ELCD där 10 av 18 miljöfaktorer inom metoden ReCiPe midpoint (h) undersöktes kompletterat med kumulativt energibehov (CED).   Resultaten i studien visar en minskning av miljöpåverkan med 99 % om sugrör av PP skulle ersättas med sugrör av PHA från Gruvöns bruk. Samtidigt beräknades CED öka med cirka 50 %. Analyser av resultatet visar att giftighet för ekosystem i sjöar och hav vid materialframställning för PP är de största faktorerna för PP-sugrörets påverkan, motsvarande cirka 85 % av den totala miljöpåverkan. Inkludering av fler produktionsvariationer indikerar också att det finns potential att ytterligare sänka miljöpåverkan från PHA-sugrör samt att få en lägre energianvändning än för PP-sugrör genom att ändra metod för extraktion samt temperatur i fermenteringsprocessen. Resultaten är osäkra på grund av LCA-verktygets osäkerheter, brist på miljödata samt brist på studier. Resultaten kan dock användas för att se trender och potential. Ett exempel är att ingen större skillnad ses mellan engångsprodukter av PP och PHA när enbart klimatpåverkan och energi för produktion undersöks men när hela livscykeln undersöks med fler miljöfaktorer så verkar PP ha klart högre miljöpåverkan än PHA. Slutsatsen som dras är att engångsprodukter av PHA från varma restströmmar har potential att ersätta engångsprodukter av PP på ett för miljön hållbart sätt. Det kan vara en möjlig lösning till att fortsätta producera engångsprodukter som berörs av plastförbudet samt att lätta på en del av problematiken kring utarmning av fossila resurser. Mer studier gällande möjliga användningsområden samt en småskalig pilotanläggning på Gruvöns bruk rekommenderas som vidare steg för att utforska potentialen av PHA från restströmmar. / In this study, a calculation model has been built on how PHA could be produced from forest industrial wastewater at Gruvöns pulp- and paper mill. Subsequently, a comparative life-cycle analysis has been carried out where production of PP-drinking straws in Europe is replaced with PHA-straws from the mill. The objective of the study is to assess and compare the environmental impact of a disposable PHA product with a disposable PP product. The purpose of the study is to examine an alternative material for PP due to the finite nature of fossil resources and the fact that alternative materials will be required when the plastic ban from the European Commission on disposable products comes into force 2022. An additional purpose is to provide more research data on PHA from residual streams. The lifecycle analysis was performed with ISO standard: 14040 and 14044 as a guideline and 1 ton of straw was selected as the functional unit. The entire life cycle was examined with an exception of the usage phase. PHA production at the mill was theoretically calculated and mass and energy flows from the model was then used in the environmental assessment. SimaPro was selected as the software for LCA calculation, environmental data was retrieved from the Ecoinvent 3 database and ELCD database. 10 out of 18 environmental factors within the ReCiPe midpoint (h) method were investigated complemented with cumulative energy demand (CED). The results of the study show a 99 % reduction in environmental impact if drinking straws of PP would be replaced with straws from PHA from Gruvön's mill. At the same time, CED was estimated to increase by about 50 %. Analyses of the results show that the toxicity of material production to marine and freshwater ecosystems is the most influential factor in the impact of PP straws, representing around 85 % of the total environmental impact. Expansion of the calculation model showed that there is potential to further reduce the environmental impact of PHA straws as well as the energy requirements to a level that is lower than that of PP straws by changing method of extraction and fermentation. The results are uncertain due to the uncertainties of the LCA tool, lack of environmental data and lack of studies. However, the results can be used to see trends and potential. One example is that no major difference is seen between disposable PP and PHA products when only climate impact and energy for production are examined, but when the entire life cycle is examined with more environmental factors, PP appears to have a significantly higher environmental impact than PHA. The conclusion drawn in the study is that disposable PHA products from hot residual streams have potential to replace disposable PP products in an environmentally sustainable manner. This may be a possible solution to continue producing disposable products that are affected by the plastic ban and to alleviate some of the problems surrounding depletion of fossil resources. Further studies on possible uses and a small-scale pilot plant at Gruvön's mill are recommended as further steps to explore the potential of PHA from residual streams.
15

Produktdesign för ett ekologiskt hållbart sportfiske / Product design for ecologically sustainable sport fishing

Carlsson, Axel January 2023 (has links)
Fiske förekommer runt om i hela världen, men det utförs av många olika anledningar. Det kan vara ett yrke, en hobby eller ett sätt att få mat på bordet. Men oavsett syftet kan beten gå sönder, fastna eller lossna. I Norden tappar vi uppskattningsvis 28 miljoner beten varje år. Att beten lossnar är inte något som alla kan påverka eller undvika. Något som däremot går att ändra är vilka beten vi faktiskt använder oss av och vilka material de består av. Det finns en mängd olika fiskeutövare som skulle kunna dra nytta av ny forskning inom området och det är på tiden att vi anammar ett mer hållbart sportfiske. Studien undersöker hur ett ekologiskt hållbart fiskedrag i form av en jigg kan framtas genom en materialcentrerad designprocess. Med hjälp av materialdriven design och användarcentrerad design undersöks möjligheterna att ersätta syntetiska plaster med bioplaster, i ett mjukt plastbete. Designmetoder användes för att granska och bekräfta problemet med förlorade fiskedrag. Marknadsanalyser, deltagande observationer och intervjuer utfördes med verksamma inom sport- och hobbyfiske. Metoderna gav en bredare uppfattning av problemet och vilka förbättringsmöjligheter som fanns. Olika prototyper skissades och framtogs genom bioplaster. För att säkerställa att produkten lever upp till användarnas krav, genomgick prototyperna olika tester, samt utvärderas. Studien ger ett kunskapsbidrag om vilka material som fungerar och vilka som inte fungerar vid tillverkning av mjuka plastdrag. Den visar dessutom hur massproducerade formar skulle kunna uppmana hobbyfiskare att tillverka sina egna drag. Det framgår också hur man från grunden kan framställa egna fiskedrag genom ett DIY-projekt. Studien resulterar även i två bionedbrytbara produkter. En produkt för abborrefiske och en för gäddfiske. / Fishing occurs throughout the entire planet, but it occurs for different reasons. It could be a profession, a hobby or a livelihood. Regardless, the bait can break, get stuck or get loose. In the North we lose around 28 million baits every year. The fact that lures is not something that everyone can influence or avoid. However, something that can be changed, is which lures we use and which materials they are made of. There are a variety of anglers who could benefit from new research in this field, and it is about time we embrace a more sustainable sport fishing. This study examines how an ecologically sustainable fishing lure in the shape of a jig, can be produced through a material centered design process. With material driven design and user centered design, this study investigates the possibilities of replacing synthetic plastics with bioplastics in a soft plastic bait. Several design methods were used to research and confirm the problem of lost fishing lures. Market analyses, participant observations and interviews were done with people active in sport- and hobby fishing. These methods gave a broader perception of the problem and which opportunities there are. Different prototypes were sketched and then made by bioplastics. The prototypes were evaluated through different tests, to ensure that the products will live up to the requirements presented by the users. This study provides knowledge about which materials work, and which do not when manufacturing soft plastic features. It also shows how mass-produced molds could encourage hobby anglers to make their own lures. It’s also shown how you can make your own fishing lures from scratch, through a DIY project. The study also results in two biodegradable products. One product for perch fishing and one for pike fishing.
16

The blue-end of the spectrum of plastics : A step toward understanding the role of blue biopolymers in phasing out fossil plastics / Den blå delen av plastspektrumet : Ett steg mot att förstå blåa biopolymerers roll i utfasningen av fossila plaster

Rudberg, Alice January 2021 (has links)
For more than a century, plastics have become an increasingly important part of the human society. Thanks to the durability and the many varieties of plastic it has a wide range of applications, but unfortunately the traditional plastic made from fossil oil has its drawbacks. Neither the fact that fossil oil is used, nor that these plastics won’t degrade in nature, are in any way sustainable for the environment in the long run. But out of the shadow of these problems, new technologies for the manufacturing of bioplastics are born. This thesis aims towards mapping out properties of different plastics, fossil based as well as bio-based, and investigating the possibilities to manufacture plastic material from algae, so called blue plastics. Additionally, the thesis shed light on terms related to plastic production and bioplastics.  The result shows that there are multiple approaches to the manufacturing of blue plastics; several divergent polymers (e.g. starch, protein and alginate) can be extracted from algae for the production of plastic material, and there is a large number of algae strains and methods to use. Blue plastics are still not produced in large scale, and therefore suffer from high production costs, which makes it challenging to replace traditional plastics. Another obstacle is bad durability and mechanical properties of some algae-based materials. But the blue side of the spectrum of plastics is still a young field of study and new innovations are yet to be discovered. / I över ett sekel har plast blivit en allt viktigare del i det mänskliga samhället. Tack vare sin tålighet och mångsidighet har plast en mängd olika användningsområden, men tyvärr har den traditionella plasten även sina nackdelar. Varken det faktum att fossil olja används, eller det faktum att dessa plaster inte bryts ned i naturen, kan anses hållbart i längden. Men ur skuggan av dessa problem träder nya tekniker fram, som möjliggör tillverkning av bioplaster. Detta projekt syftar till att kartlägga egenskaperna hos olika plaster, fossilbaserade såväl som biobaserade, samt möjligheterna att tillverka plast med alger som råvara. Dessutom läggs fokus på att förklara vissa termer relaterade till plaster, bioplaster och dess livscykel.  Resultatet visar att det finns ett flertal tillvägagångssätt för tillverkningen av algbaserade plaster. Flera olika polymerer (t.ex. stärkelse, protein och alginat) kan extraheras från alger för vidare produktion av plastmaterial, och dessutom finns ett stort antal olika algarter och tillverkningsmetoder som kan användas. Idag produceras algplaster ännu inte i stor skala, något som innebär att produktionskostnaderna fortfarande är höga och att det således är svårt att konkurrera ekonomiskt med traditionella plaster. Ett annat hinder för algbaserade plaster är i vissa fall låg resistans och sämre mekaniska egenskaper jämfört med traditionella plaster. Men den algbaserade delen av plastspektrumet är fortfarande ung och outforskad, fortfarande finns nya upptäckter och möjligheter som väntar på att bli funna.
17

Bacteria - based self - healing mortar with bio - plastic healing agents : Comparative analysis on quantification and characterization of self-healing by various experimental techniques

Roy, Rahul January 2020 (has links)
Crack formation in concrete structures due to various load and non-load factors leading to degradation of service life is very common. Repair and maintenance operations are, therefore, necessary to prevent cracks propagating and reducing the service life of the structures. Accessibility to affected areas can, however, be difficult and the reconstruction and maintenance of concrete buildings are expensive in labor and capital. Autonomous healing by encapsulated bacteria-based self-healing agents is a possible solution. In this study, a novel bacteria-based healing agent was investigated in order to test the self-healing efficiency of the specimens in comparison to the commonly used healing agents made of lactic acid derivatives. (PLA). The novel integrated healing agent is a non-toxic, biodegradable dissolved inorganic carbon substrate derived from wastewater that has been used as an encapsulation material for spores of cohnii bacteria in the Bacillus gene family and for nutrients made up of yeast extract. This dissolved inorganic carbon substrate is a bioplastic made by the bacteria in wastewater known as alkanoate derivatives (AKD). To assess the effect of these healing agents on the mortar characteristics, quantification and characterization of the self-healing were conducted. The quantification of the self-healing efficiency was performed by various experimental techniques such as light microscopy, water permeability, chloride ion permeability, and thermogravimetric analysis whereas the material characterization was investigated by x-ray diffraction and environmental scanning electron microscope. Moreover, a statistical analysis was performed to study the correlation of self-healing efficiency between various experimental techniques. The incorporated dosages of healing agents adopted were 2.6% and 5% by weight of cement. Complete immersion in water was considered to be the condition of treatment of the specimen for healing at two separate periods of 28 and 56 days. The crack widths investigated were in the range of 0.04 to 0.8 mm. The quantification and characterization tests indicated that bacterial containing mortar series especially PLA and AKD at 5% dosage displayed a higher self-healing performance and an indication of precipitated calcium carbonate in the crack mouth. However, the results from the chloride migration test didn’t show any influence by the self-healing healing agents. Furthermore, the statistical analysis identified a major impact of the internal crack geometry on the difference in self-healing ratios, also in the cases where effective crack width is equal. / Sprickbildning i betongkonstruktioner p.g.a. olika laster och lastoberoende faktorer som leder till förkortning av livslängden är mycket vanligt förekommande. Reparation och underhåll är därför nödvändiga för att förhindra att sprickorna propagerar och reduceras konstruktionernas livslängd. Möjligheterna att komma åt de skadade partierna kan dock vara svåra och reparationerna är vanligen både arbetsintensiva och kostsamma. Självläkning med ingjutna bakteriebaserade, självläkande tillsatser är en möjlig lösning på problemet. I denna studie undersöktes en ny bakteriebaserat självläkande tillsats för att prova den självläkande förmågan i jämförelse med vanligt förekommande självläkande tillsatser av mjölksyrederivat (PLA). Den nya integrerade självläkande tillsatsen är en giftfri, biologiskt nedbrytningsbar, oorganisk kolsubstratslösning utvunnen ur avloppsvatten, en tillsats som har använts som ett inkapslingsmaterial för sporer från cohnii-bakterier från bacillussläktet och från näringsämnen framställda ur jästextrakt. Denna kolsubstratslösning är en bioplast framställd ur avloppsvatten och känd som alkanoatderivat (AKD). För att bestämma effekten av dessa självläkande tillsatser på cement bruks egenskaper genomfördes kvantifiering och karakterisering av självläkningen. Kvantifieringen av självläkningens effektivitet utfördes genom olika experimentella metoder såsom ljusmikroskopi, vattengenomsläpplighet, kloridjonstransport och termogravimetriska analyser medan materialkarakteriseringen utfördes med röntgendiffraktion och svepelektronmikroskop (ESEM). Vidare genomfördes en statistisk analys för att undersöka korrelationen mellan olika experimentella metoder. De doser av självläkande tillsatser som användes var 2,6 och 5 % av cementvikten. Fullständig nedsänkning i vatten ansågs vara den lämpligaste lagringen för självläkning under två olika tidsperioder på 28 respektive 56 dygn. De sprickbredder som studerades låg i intervallet 0.04 till 0.8 mm. Försöken kring kvantifiering och karakterisering indikerade att bruken innehållande bakterier, i synnerhet 5 % PLA och AKD, utvecklade en högre form av självläkande beteende och en förekomst av kalciumkarbonat i sprickspetsen. Resultaten från försöken kring kloridtransport visade emellertid inga tecken på någon effekt från de självläkande tillsatserna. Vidare identifierades i den statistiska analysen att inre sprickbildning har stor betydelse för självläkningseffekten även i fall där den effektiva sprickbredden är lika stor.

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