Drying rate during industrial coating application is important to understand because drying a coated paper requires energy. If an unnecessary high amount of energy is used to dry paper, a fast evaporation rate can be achieved which can result in defects of the coated surface.   In this bachelor’s thesis, temperature profile during industrial coating application was studied. An industrial pilot trial on a coating machine was implemented at UMV coatings at Säffle, Sweden. Two boards with grammages of 210 and 350 gsm were used, where cardboard 210 gsm was precoated on the backside with two different precoatings. Where the two precoating differed in latex content and type of Hydrocarb. Board 350 gsm was not precoated. Temperatures between 65 to 85 oC were achieved in the drying section, depending on which substrate that was used.  Laboratory tests were also performed to investigate the relationship between surface temperature and dry content of a substrate during drying. As the temperature and time increased, did also the surface temperature and dryness of the samples. It was assumed that the temperature readings from the pilot coater could be correlated to the dry content of coating color.    The results from the study showed that by decreasing the dry content in a coating, a higher surface temperature was obtained during industrial- and laboratory drying due to the increase in heat transfer rate. Results showed also that when fraction of clay in a coating was decreased, a higher evaporation rate and higher surface temperature was obtained during drying.

Poly(vinyl alcohol) (PVA) is a polymer used in numerous applications, principally those in which its high water solubility is a desirable asset. However there are also areas where PVA is limited by its inherent solubility (for example some specific environments in the biomedical field). This work has sought to overcome such limits by manipulating the surface of PVA in order to propose various means by which the surface solvent resistance might be increased while maintaining the bulk properties of the polymer. Both chemical and physical modifications have been tried and in each case progress has been made towards insolubilizing a single surface of the polymer when in film form. Grafting various species onto the surface of PVA was successfully performed. It is believed that such species bonded to the PVA via attachment to the hydroxyl groups (though this has not been proven conclusively). The data contained herein has led to the conclusion that the primary factor in reducing solubility this way is the removal of the hydroxyl groups, and not the attachment of specifically highly hydrophobic molecules. Introducing permanent cross-links into the surface region has been attempted via various routes. The data recorded shows promise however the system is far from optimised. The biggest challenge remaining is to optimise the depth of material cross-linked. Some steps have been made towards understanding and controlling this parameter though there is much scope for further investigation. The methods used have built on those used for bulk cross-linking and as such are new for the case of surface specific treatment. An interesting phenomenon in some semi-crystalline polymers reported in recent years is that of surface specific crystallization. This effect has been successfully induced and observed in PVA to produce what is believed to be a highly crystalline surface layer, and crystalline regions of PVA are generally accepted to be more water resistant than amorphous ones. In summary, in this work several surface-specific treatments for PVA have been trialled, providing options for post-film forming modification to reduce the surface water sensitivity whilst retaining the bulk properties of the polymer.

Background. Between 2012 and 2017 the plastic supply in Sweden increased by almost 400000 metric tons. In 2017, the hospitals in Sweden contributed to 4550 metric tons of plastic waste, disposable gloves counted for 2100 metric tons, which is 358 million disposable gloves. The majority made in other countries than Sweden, which is not only contributing to a considerable waste stream but also vulnerability when the system is dependent on continuous material supplies. Aim and Purpose. The research aim has been to understand the challenges and opportunities of needs relating to plastic waste flows from the health care sector. From the needs, choose an area to develop an innovative solution that changes the current waste flow into value for the health care sector in Sweden. Method. For this thesis, the researcher has used the Design Research Methodology and the MSPI innovation process. Design Research Methodology has been used to find and validate crucial information about the problem, by the usage of literature research and Unstructured interviews within the research area. MSPI was iteratively used with DRM to design the intended support as well as building the actual support. Results. The final prototype proves that circularity for plastic materials in hospitals is reachable. The Needfinding highlights the need for circularity, regarding both an effective use of the material and the health care’s readiness levels where access to Personal Protection Equipment (PPE) is crucial, especially in times of crisis. Conclusions. During the time of crisis, the COVID-19 pandemic, it has been clear that changes regarding preparedness and access to PPE needs improvement. Circularity is one way of achieving greater control of the material flow, which affects the hospital's level of independence. The development has proven one way of making the flow of disposable gloves circular by developing an inhouse recycling machine. This thesis work is just one angle of approach towards circularity and more efficient usage of material. To prove the concept in a hospital environment, future development is required. / Bakgrund. Mellan åren 2012 och 2017 har plastförsörjningen i Sverige ökat med nästan 400 000 ton. Under 2017 bidrog sjukhusen i Sverige till 4550 ton plastavfall varav engångshandskar bidrog med 2100 ton, vilket motsvarar 358 miljoner engångshandskar. Majoriteten är tillverkade i andra länder än Sverige, vilket inte bara bidrar till en stor avfallsström, utan också sårbarhet när systemet är beroende av kontinuerlig materialförsörjning. Syfte och Mål. Forskningens syfte har varit att förstå utmaningarna och möjligheterna med plastavfallsflöden från vårdsektorn. Från behoven väljs ett område för att utveckla en innovativ lösning som stöder cirkularitet inom hälso-sjukvården i Sverige. Metod. Denna avhandling har genomförts med hjälp av DRM- och MSPI-innovationsprocess. DRM, Design Research Methodology, har använts för att hitta och validera avgörande information kring problemet och har också gett akademisk trovärdighet. Detta har gjorts med litteraturforskning och ostrukturerade intervjuer inom forskningsområdet. MSPI har använts tillsammans med DRM på iterativt sätt för att utforma det avsedda stödet och bygga det faktiska stödet. Resultat. Projektets prototyp bevisar att cirkularitet för plastmaterial på sjukhus kan nås. Behovsundersökningen visar på behovet av cirkularitet, både när det gäller materiell effektivitet och beredskapsnivåer på sjukhus där tillgången till personlig skyddsutrustning är avgörande. Speciellt i kristider. Slutsatser. Under kristiden, covid-19-pandemin, har det varit tydligt att förändringar avseende beredskap och tillgång till personlig skyddsutrustning måste göras. Cirkularitet är ett sätt att uppnå större kontroll över materialflödet som påverkar sjukhusens självständighetsnivå. Projektet har visat ett sätt att göra flödet av engångshandskar cirkulärt genom att utveckla ett system för remanufacturing. Detta är bara en inställningsvinkel mot cirkularitet och en mer effektiv användning av material. För att bevisa konceptet i en riktig sjukhusmiljö krävs vidareutveckling.

[pt] O presente estudo busca definir uma relação de mistura estável utilizando aditivos poliméricos à base de álcool polivinílico (PVOH) para controlar a perda de filtrado, antiespumante e dispersante, caracterizando a influência de cada adição na cinética de hidratação, propriedades mecânicas, físicas e reologia da mistura. Além disso, foi caracterizado o comportamento das pastas de cimento em condições de cura que simulam a situação do poço até 6100 m de profundidade, seguindo as recomendações da API, e o comportamento do material nos estados in situ, utilizando pressões confinantes para realizar os ensaios de compressão. Por fim, propôs-se a inclusão de microfibras de álcool polivinílico (PVA) para melhorar o desempenho mecânico das pastas cimentícias, avaliando diferentes tipos de carregamento e definindo os impactos da adição de fibras na viscosidade e tixotropia das misturas. Verificou-se que o uso de PVOH como aditivo de perda de filtrado não influencia na cinética de hidratação para concentrações de até 0,4% em peso de cimento, mas à medida que a quantidade de PVOH é aumentada na mistura, o processo de hidratação da pasta de cimento pode ser modificado por causa do mecanismo de absorção do PVOH. Além disso, novas fases de produtos de hidratação aparecem com o aumento da temperatura e pressão de cura: dellaite, hydroxyellestadite e alpha-C2SH. A última fase (alpha-C2SH) está relacionada à perda de capacidade de resistência das amostras curadas a 149°C, simulando o caso do poço de petróleo de 6100 m de profundidade. Para os ensaios triaxiais, a pressão de confinamento conferiu às amostras um comportamento diferente do caso uniaxial, implicando em uma considerável melhora da plasticidade no comportamento tensão-deformação. Embora se observe algum reforço por atrito devido a tensões de cisalhamento no plano das fissuras, o efeito mais importante do confinamento é suportar a deformação dúctil, mesmo para o caso da pasta de cimento reforçada com fibra de PVA. Finalmente, o estudo mostrou que as fibras de PVA conferem um leve aumento da viscosidade da pasta de cimento, uma fase plástica prolongada aparentemente sem perda de capacidade de carga em testes triaxiais e uma capacidade aprimorada de absorver energia ao avaliar cargas de tração e cisalhamento. / [en] The present study seeks to define a stable mixing ratio using powder Polyvinyl Alcohol (PVOH) based polymeric additives to control the loss of filtrate, defoamer, and dispersant, characterizing the influence of each addition on hydration kinetics, mechanical and physical properties, and rheology of the mix. The behavior of cement pastes under curing conditions that simulate the wellbore situation up to 6100 m depth was also evaluated, following API recommendations. Moreover, the behavior of the material under in situ states, using confining pressures to perform the compression tests, was characterized. Finally, the inclusion of Polyvinyl Alcohol (PVA) microfibers is proposed to improve the mechanical performance of cement pastes, evaluating different types of loading and defining the impacts of the fiber addition on the viscosity and thixotropy of the mixtures. It was found that the use of PVOH as a fluid loss additive does not influence hydration kinetics for concentrations up to 0.4% by weight of cement, but as the amount of PVOH is increased in the mixture, the hydration process of the cement paste may be modified because of the PVOH absorptive mechanism. Moreover, new hydration products phases appear with increasing curing temperature and pressure: dellaite, hydroxyellestadite, and alpha-C2SH. The last phase (alpha-C2SH) is related to the loss of strength capacity of the samples cured at 149°C, simulating a 6100 m depth wellbore. For the triaxial tests, the confining pressure gave the samples a behavior markedly different from the uniaxial case, implying a considerable improvement in the plasticity of the stress-strain behavior. Although some frictional reinforcement is observed due to shear stresses in the cracks surface, the most important effect of confinement is to withstand ductile deformation, even in the case of PVA fiber-reinforced cement paste. Finally, the study has shown that PVA fibers impart a slight viscosifying effect on the cement slurry, a prolonged plastic phase with apparently no loss of load-carrying capacity in triaxial tests, and an improved ability to absorb energy when evaluating tensile and shear loads.

No description available.

Tesis por compendio / [ES] La presente tesis doctoral plantea distintas estrategias para el desarrollo y aplicación de envases activos portadores de agentes de biocontrol, con el fin de inhibir la proliferación de microorganismos como bacterias y hongos patógenos y alterantes y así, conseguir aumentar la seguridad y prolongar la vida útil de los alimentos. El desarrollo de envases activos antibacterianos se llevó a cabo incorporando bacterias ácido lácticas productoras de bacteriocinas, Lactococcus lactis y Lactobacillus sakei en diferentes matrices formadoras de películas. Previa a la preparación de las películas activas, se estudió la actividad antimicrobiana de los agentes naturales seleccionados frente a Listeria monocytogenes. Los resultados sugirieron que, a partir de una determinada concentración inicial de bacterias viables, estos microorganismos son buenos candidatos para ser utilizados como aditivos naturales en materiales de envasado de alimentos, siendo una alternativa al uso de aditivos de origen sintético. En este trabajo se observó que la viabilidad inicial de las bacterias ácido lácticas (LAB) es esencial para obtener una buena capacidad antibacteriana por lo que la optimización de la composición de las películas o recubrimientos fue crucial para su aplicación con éxito. El polímero escogido como base para hacer las películas y recubrimientos mediante la técnica de casting, fue el alcohol polivinílico, (PVOH) mezclado con diferentes proteínas, gelatina y caseinato sódico y sus versiones hidrolizadas añadidas en diferentes proporciones. En este estudio L. lactis demostró tener una mayor resistencia a la deshidratación durante la preparación y almacenamiento de las películas que L. sakei. Las películas de PVOH mezcladas con gelatina hidrolizada y caseína hidrolizada dotaron de protección a las bacterias ácido lácticas durante el secado y demostraron tener una mayor efectividad antilisteria. Por último, se varió la proporción de caseína hidrolizada obteniendo una mayor viabilidad de las bacterias en las películas prolongada en el tiempo a mayor proporción de HCas. Para desarrollar un envase activo antilisteria, se adaptaron las matrices para ser aplicadas como recubrimiento sobre ácido poliláctico (PLA) con el objetivo de desarrollar bolsas activas antilisteria para crema de setas y como separadores de lonchas de jamón cocido. Los recubrimientos demostraron tener una efectividad similar a la obtenida con las películas in vitro. Sin embargo, su eficacia disminuyó ligeramente al ser aplicadas en la crema de champiñones y el jamón cocido debido a la complejidad de las matrices alimentarias utilizadas, pero siendo una buena herramienta para, junto a otras estrategias de conservación, asegurar la salubridad de los alimentos. Se llevaron a cabo ensayos sensoriales con consumidores y se obtuvo una buena aceptación de ambos productos. Sin embargo, los consumidores percibieron una alteración del sabor debido a la generación de ácido láctico en la crema de champiñones, acidez que puede ser controlada mediante correctores de acidez sin modificar la efectividad antimicrobiana. Para desarrollar envases que aumentaran la vida útil, se trabajó para ampliar el espectro de acción de L. lactis frente a las bacterias Gram-negativas, normalmente responsables de la descomposición de los alimentos. Combinar el agente de biocontrol productor de nisina, L. lactis, con una baja concentración de ácido fítico, sustancia quelante y desestabilizadora de la membrana bacteriana, amplió el espectro antimicrobiano de L. lactis frente a las bacterias Gram-negativas obteniendo una nueva herramienta para garantizar la seguridad alimentaria y prolongar la vida útil de los alimentos. / [CA] La present tesi doctoral planteja diferents estratègies per al desenvolupament i aplicació d'envasos actius portadors d'agents de biocontrol, amb la finalitat d'inhibir la proliferació de microorganismes com a bacteris i fongs patògens i alteradors i així, aconseguir augmentar la seguretat i prolongar la vida útil dels aliments. El desenvolupament d'envasos actius antibacterians, es va dur a terme incorporant bacteris àcid làctics productores de bacteriocines, Lactococcus lactis i Lactobacillus sakei en diferents matrius formadores de pel·lícules. Prèvia a la preparació de les pel·lícules actives, es va estudiar l'activitat antimicrobiana dels agents naturals seleccionats enfront de Listeria monocytogenes. Els resultats van suggerir que, a partir d'una determinada concentració inicial de bacteris viables, aquests microorganismes són bons candidats per a ser utilitzats com a additius naturals en materials d'envasament d'aliments, sent una alternativa a l'ús d'additius d'origen sintètic. En aquest treball es va observar que la viabilitat inicial dels bacteris àcid làctics (LAB) és essencial per a obtindre una bona capacitat antibacteriana pel que l'optimització de la composició de les pel·lícules o recobriments va ser crucial per a la seua aplicació amb èxit. El polímer triat com a base per a fer les pel·lícules i recobriments mitjançant la tècnica de càsting, va ser l'alcohol polivinílic, (PVOH) mesclat amb diferents proteïnes, gelatina i caseinat sòdic i les seues versions hidrolitzades afegides en diferents proporcions. En aquest estudi L. lactis va demostrar tindre una major resistència a la deshidratació durant la preparació i emmagatzematge de les pel·lícules que L. sakei. Les pel·lícules de PVOH mesclades amb gelatina hidrolitzada i caseina hidrolitzada van dotar de protecció als bacteris àcid làctics durant l'assecat i van demostrar tindre una major efectivitat antilistèria. Finalment, es va variar la proporció de caseïna hidrolitzada obtenint una millor resposta de les pel·lícules no sols des d'un punt de vista antimicrobià, sinó també de les propietats fisicoquímiques de les pel·lícules, a major proporció de caseïna hidrolitzada.Per a desenvolupar un envàs actiu antilistèria, es van adaptar les matrius per a ser aplicades com a recobriment sobre àcid polilàctic (PLA) amb l'objectiu de desenvolupar bosses actives antilistèria per a crema de bolets i com a separadors de rodanxes de pernil cuit. Els recobriments van demostrar tindre una efectivitat similar a l'obtinguda amb les pel·lícules in vitro. No obstant això, la seua eficàcia va disminuir lleugerament en ser aplicades en la crema de xampinyons i el pernil cuit a causa de la complexitat de les matrius alimentàries utilitzades, però sent una bona eina per a, al costat d'altres estratègies de conservació, assegurar la salubritat dels aliments. Es van dur a terme assajos sensorials amb consumidors i es va obtindre una bona acceptació de tots dos productes, però una alteració del sabor degut a la generació d'àcid làctic en la crema de xampinyons corregible mitjançant correctors d'acidesa sense modificació de l'efectivitat antimicrobiana. Per a desenvolupar envasos que augmentaren la vida útil, es va treballar per a ampliar l'espectre d'acció de L. lactis enfront dels bacteris Gram-negatives, normalment responsables de la descomposició dels aliments. Combinar l'agent de biocontrol productor de nisina, L. lactis, amb una baixa concentració d'àcid fític, substància quelant i desestabilitzadora de la membrana bacteriana, va ampliar l'espectre antimicrobià de L. lactis enfront dels bacteris Gram-negatives obtenint una nova eina per a garantir la seguretat alimentària i prolongar la vida útil dels aliments. / [EN] This doctoral thesis proposes different strategies for the development and application of active packaging containing biocontrol agents, to inhibit the proliferation of microorganisms such as pathogenic and spoilage bacteria and fungi, thus increasing the safety and increasing the shelf life of foodstuffs. The development of antibacterial active packaging was carried out by incorporating bacteriocin-producing lactic acid bacteria, Lactococcus lactis and Lactobacillus sakei in different film-forming matrices. Prior to the preparation of the active films, the antimicrobial activity of the selected natural agents against Listeria monocytogenes was studied. The results suggested that, from a certain initial concentration of viable bacteria, these microorganisms are good candidates to be used as natural additives in food packaging materials, being an alternative to the use of additives of synthetic origin. In this work it was observed that the initial viability of lactic acid bacteria (LAB) is essential to obtain a good antibacterial capacity, so the optimization of the composition of the films or coatings was crucial for their successful application. The polymer chosen as a base to make the films and coatings by casting technique was polyvinyl alcohol (PVOH) mixed with different proteins, gelatin and sodium caseinate and their hydrolysed versions added in different proportions. In this study L. lactis showed higher resistance to dehydration during film preparation and storage than L. sakei. PVOH films mixed with hydrolysed gelatin and hydrolysed casein provided protection to lactic acid bacteria during drying and were shown to have a greater antilisteria effectiveness. Finally, the proportion of hydrolysed casein was varied, obtaining a better response of the films not only from an antimicrobial point of view, but also from the physicochemical properties of the films, the higher the proportion of HCas. To develop an antilisteria active packaging, the matrices were adapted to be applied as a coating on polylactic acid (PLA) with the objective of developing antilisteria active bags for cream of mushroom soup and as separator liner for cooked ham slices. The coatings showed similar effectiveness to that obtained with in vitro films. However, their effectiveness decreased slightly when applied to mushroom soup and cooked ham due to the complexity of the food matrices used, but being a good tool to, together with other preservation strategies, ensure food wholesomeness. Sensory tests were carried out with consumers and a good acceptance of both products was obtained. However, an alteration of taste due to the generation of lactic acid was detected in the mushroom soup that could be corrected by means of acidity correctors without modifying the antimicrobial effectiveness. Finally, life cycle analysis of conventional and active packaging for pastry cream was studied. In any case, despite the limitations regarding the waste product estimation, shelf-life extension through packaging innovation could significantly reduce the environmental impacts of the entire food packaging system. In the present thesis, the potential use of indigenous yeasts with antifungal capacity for the control of Penicillium expansum and the control of the mycotoxin they generate, called patulin, was also explored. In the present investigation, three new yeast strains isolated from the surface of apples were selected for their efficacy against P. expansum. The yeasts were identified as Metschnikowia pulcherrima being 3 different strains. The ability of these yeasts for patulin biodegradation was also demonstrated. Then, different studies on the viability of the yeast and its antifungal effectiveness on different films made with biopolymers naturally present in apples (pectin, cellulose ethers, and apple pomace) were carried out. / The authors acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness (AGL2015-64595-R and RTI2018-093452-B-I00). / Settier Ramírez, L. (2021). Envases activos portadores de microorganismos para la bioconservación de alimentos [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/175807 / TESIS / Compendio