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1.
Polymer Nanoparticle Sizes from Dynamic Light Scattering and Size Exclusion Chromatography: The Case Study of Polysilanes.
Artem Badasyan, Andraž Mavrič, Irena Kralj Cigić, Tim Bencik, Matjaž Valant, 2018, izvirni znanstveni članek

Opis: Dynamic Light Scattering (DLS) and Size Exclusion Chromatography (SEC) are among the most popular methods for determining polymer sizes in solution. Taking dendritic and network polysilanes as a group of least soluble polymer substances, we critically compare and discuss the difference between nanoparticle sizes, obtained by DLS and SEC. Polymer nanoparticles are typically in poor solution conditions below the theta point and are in globular conformation therefore. Determination of particle sizes in presence of attractive interactions is not a trivial task. The only possibility to measure aggregation-free, a true molecular size of polymer nanoparticles in such regime of solution, is to operate with the dilute solution of globules (below theta point and above the miscibility line). Basing on results of our polysilane measurements, we come to a conclusion that DLS provides more reliable results than SEC for the dilute solution of globules. General implications for the size measurements of polymer nanoparticles in solutions are discussed.
Ključne besede: Polymer Nanoparticle, Dynamic Light Scattering, Size Exclusion Chromatography, Polysilanes
Objavljeno v RUNG: 16.05.2018; Ogledov: 5094; Prenosov: 19
.pdf Celotno besedilo (3,17 MB)

2.
KINETICS OF CELLULOSE DEGRADATION STUDIED USING SIZE EXCLUSION CHROMATOGRAPHY
Aneta Balažic Fabjan, 2016, magistrsko delo

Opis: For more than five centuries, paper has been the predominant carrier of information and numerous medieval manuscripts bear witness of its durability. However, increasing demand for paper led to several changes in its production in the 19th century. High quality rag fibres were replaced by inferior wood-originating ones. Acid manufacturing technology was introduced which, due to its simplicity and low cost, continued to be used until the end of the 20th century. Inherently stable paper rapidly degrades in the presence of acids and its decay is further promoted by the poor storage conditions and environmental pollutants. As a result, the amount of degraded paper in libraries, archives and museums is reaching enormous proportions. In order to prolong the usable time of the vast quantities of original materials, paper collections may be deacidified and/or stored at lower temperatures. While preservation options are known, lack of the competent comparative studies leaves collection keepers hesitant of their use. The introductory part of the project is focused on development of analytical methodologies and model materials, representative of historical acid paper. As uniqueness and inherent value of cellulose-based cultural heritage limits the use of analytical methodologies to the non-destructive or micro-destructive ones. A new methodology for determination of the condition of paper was developed. The analytical technique-size exclusion chromatography for the first time allows us to reproducible determine the condition of paper which contains a significant amount of wood derived lignin. A few fibres suffice for the analysis, which renders the methodology suitable for characterisation of historical materials. The results of the research will represent the effect of deacidification processes with use of micro destructive analytical methodologies. As written word is all what we have for our legacy from generation to generation, evaluating preservation strategies for decaying collections, safekeeping and long term access to the endangered written cultural heritage is one of the most important facts.
Ključne besede: paper, size exclusion chromatography, kinetics, deacidification process
Objavljeno v RUNG: 02.09.2016; Ogledov: 7194; Prenosov: 287
.pdf Celotno besedilo (1,33 MB)

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