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- Nordenström, Malin
(författare)
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Colloidal interactions and arrested dynamics of cellulose nanofibrils
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Over the past decades, concerns for the environment have increased and efforts to achieve a sustainable society have intensified. One particular challenge is to replace fossil-based plastics with biodegradable materials produced from renewable resources. Cellulose nanofibril (CNF)-based materials are strong candidates due to their excellent mechanical properties, nano-dimensions and molecular structure, which is suitable for modification. CNFs can be obtained from wood and are elongated, often charged, particles which are usually handled in aqueous dispersions. The colloidal stability is sensitive, and instability results in aggregation or transition to an arrested state. Since the properties of CNF-based materials rely on dispersion of the CNFs, an understanding of the colloidal behaviour is crucial.This work has focused on the interactions and dynamics of CNFs in different colloidal states. Arrested states of CNFs were studied in detail and it was found that two types of arrested state exist, with different colloidal interactions and mechanisms governing their formation. The dynamics in arrested and dispersed states were studied by tracer diffusion measurements, and it was found that small amounts of CNFs can constitute an excellent stabiliser for other particle dispersions according to a so far unexplored mechanism.The effects of altering the colloidal interactions using different strategies were also evaluated. The counterions of CNFs were exchanged and the impact on the swelling behaviour was measured. Based on the results, different contributions to the counterion-dependent interactions are discussed. Two strategies for using polymers to alter the interactions were furthermore studied. Polyethylene glycol (PEG) was grafted to CNFs in order to increase the arrested state threshold concentration. PEG, carboxymethyl cellulose and lignin, were also used as additives which improved the redispersion of dried CNF, especially in the case of samples containing lignin.
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- Nordenström, Malin, et al.
(författare)
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Colloidal interactions in nanocellulose systems
- 2016
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Ingår i: Abstracts of Papers of the American Chemical Society. - : AMER CHEMICAL SOC. - 0065-7727. ; 251
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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- Bolling, Anne, et al.
(författare)
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FORMAT - Optimerat vägunderhåll : del I: Praktisk guide för optimerat underhåll, del II: Teknisk slutrapport
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- EU-projektet FORMAT (Fully Optimised Road Maintenance) ingick i EU:s femte ramprogram; "Task 2.2.2/11, Road infrastructure pavement maintenance management" under "Uthållig rörlighet och förändring". Projektet startade den 1 februari 2002 och pågick i tre år.Den översättning och sammanfattning som redovisas i detta VTI notat har delats upp i två delar; Praktisk guide för optimerat vägunderhåll och Teknisk slutrapport.FORMAT-projektet hade följande tekniska och vetenskapliga målsättningar: - Ta fram bättre fungerande, innovativa underhållsåtgärder och metoder som minskar trafikstörningar, i form av köbildning och förbättrad säkerhet, i samband med vägarbeten - Utveckla en heltäckande "cost-benefit" analys som tar hänsyn till alla viktiga aspekter av vägunderhåll, inklusive trafikantkostnader - Utveckla strategier, för säkerheten vid vägarbeten, som omfattar utformningen av vägavstängningar och tidpunkten för åtgärdens genomförande på ett sådant sätt att säkerheten för trafikanter och vägarbetare maximeras - Föreslå metoder, tillvägagångssätt och utrustning för mätning av vägars tillstånd i normal körhastighet för att minimera antalet störande vägavstängningar som krävs för insamling av tillståndsdata.
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| 5. |
- Chen, Chao, 1989-, et al.
(författare)
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Bactericidal surfaces prepared by femtosecond laser patterning andlayer-by-layer polyelectrolyte coating
- 2020
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Ingår i: Journal of Colloid and Interface Science. - : Academic Press. - 0021-9797 .- 1095-7103. ; 575, s. 286-297
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Tidskriftsartikel (refereegranskat)abstract
- Antimicrobial surfaces are important in medical, clinical, and industrial applications, where bacterial infection and biofouling may constitute a serious threat to human health. Conventional approaches against bacteria involve coating the surface with antibiotics, cytotoxic polymers, or metal particles. However, these types of functionalization have a limited lifetime and pose concerns in terms of leaching and degradation of the coating. Thus, there is a great interest in developing long-lasting and non-leaching bactericidal surfaces. To obtain a bactericidal surface, we combine micro and nanoscale patterning of borosilicate glass surfaces by ultrashort pulsed laser irradiation and a non-leaching layer-by-layer polyelectrolyte modification of the surface. The combination of surface structure and surface charge results in an enhanced bactericidal effect against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. The laser patterning and the layer-by-layer modification are environmentally friendly processes that are applicable to a wide variety of materials, which makes this method uniquely suited for fundamental studies of bacteria-surface interactions and paves the way for its applications in a variety of fields, such as in hygiene products and medical devices.
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| 6. |
- Granberg, Hjalmar, et al.
(författare)
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Dynamics of moisture interaction with polyelectrolyte multilayers containing nanofibrillated cellulose
- 2012
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 27:2, s. 496-499
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Tidskriftsartikel (refereegranskat)abstract
- Recent findings have shown that it is possible to use the Layer-by-Layer technique to create nanofibrillated cellulose / polyethyleneimine interference films whose colour change with relative humidity. This study uses different optical models to describe spectral ellipsometry measurements data of interference films and how the film properties alter in dry and humid environments. The results indicate that water condensation initially is filling the surface pores within seconds whereas relaxation of the film to adjust to the added water is a slower process that reaches a steady state after ~20 min. The maximum swelling ratio of the LbL films is almost independent of the number of layers within the film, but decreases considerably by crosslinking via heat treatment. The films show a distinct birefringence with optical axis perpendicular to the surface. Analysis of the moisture response with different optical models indicates that the films swell uniformly in the thickness direction with no separate water film on top. The results provide important understanding for the design of NFC based LbL films for visual moisture sensors and interactive security paper.
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