Browsing by Author "Laine, Christiane"

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  • Enhancement of translucence in fiber-based packaging materials
    (2022-08-23) Tallinen, Saila
     Kemian tekniikan korkeakoulu | Master's thesis
    The utilization of fiber-based packages has started to take more place at the packaging sector but is still restricted by a lack of transparency. Today this challenge is tried to be solved by paying more attention on the characteristics of nanofibers and their possibilities. The usage of nanofibers is, however, facing issues such as long dewatering times, demand to modify pulp fibers and changes in production line machines. Therefore, the purpose of this study is to bring up new insights how to enhance the translucence in fiber-based packaging materials by an impregnation treatment without fiber modification, long dewatering time or toxic impregnation compounds. Four compounds sucrose octaacetate (SOA), sucrose acetate isobutyrate (SAIB), α-D-glucose pentaacetate (GPA) and polyvinylalcohol (PVA) were impregnated into a yellowish uncalendared base paper without surface sizing. The hypothesis was that it is possible to achieve significantly higher translucence of a glassine paper (>>50 %) by impregnation of a compound with a similar refractive index to cellulose and calendering. This study confirmed the hypothesis when calendered 23 % blade coated SAIB samples resulted in translucence over 64 %. At the same time, it was noticed that increase in density did not explain the increased translucence, but more important requirements were the properties of the impregnated compound such as melting point at room temperature, viscosity, amorphous structure and additives of the paper. It was also found that SAIB did not cause negative impacts on tensile strength or contact angle measurements. The results of this study offered fundamental information for the possible future steps towards transparent paper without pulp fiber modifications.
  • Structures of hemicelluloses and pectins in wood and pulp
    (2005-06-10) Laine, Christiane
     Doctoral dissertation (article-based)
    This work aims to fill gaps in the present knowledge of the structures of wood polysaccharides of potential importance in mechanical and chemical pulping. The detailed structures of the polysaccharide components from wood that dissolve during mechanical pulping were determined. The structures of polysaccharide components linked to residual lignin in chemical pulp were also determined. Methylation analysis as linkage analysis was further developed and verified for this purpose using the procedure methylation, methanolysis, silylation and GC/MS analysis. Water-soluble arabinogalactans obtained from spruce and pine heartwood were analyzed using methylation analysis, NMR spectroscopy and carbohydrate composition analysis. The arabinogalactans isolated were acidic and had a backbone of β-(1→3)-linked D-galactopyranose units, highly branched at C6. Water-soluble galactoglucomannans were extracted from spruce wood and TMP. Based on both methylation analysis and NMR spectroscopic analysis, the main C6-branched unit was D-mannopyranose. Some C6-branched D-glucopyranose units were also detected by methylation analysis. The polysaccharides that dissolved during oxygen delignification of pine kraft pulp comprised mainly xylan, together with galactans, 1,3-linked glucan, arabinan and glucomannan. This indicated that the glucose units present in the dissolved polysaccharides did not originate from cellulose but from a 1,3-linked glucan. This was a new and unexpected finding indicating that the content of dissolved glucose is not related to the degree of cellulose degradation. Polysaccharides in the corresponding filtrates from birch kraft pulp also contained mainly xylan. An indication was found for the presence of bonds between lignin and position C3 of the backbone units in birch xylan. Residual lignin-carbohydrate complexes (RLCCs) isolated from spruce and pine kraft pulps contained oligosaccharides representing the main polysaccharides in softwood. In addition, 1,4-linked and 1,3/6-linked galactans were present in considerable amounts, together with smaller amounts of 1,3-linked glucan and 1,5-linked arabinan, and possibly also xyloglucan. 1,4-linked galactan was enriched in the RLCC of spruce fiber surface material. Towards the inner part of the fiber, 1,3/6-linked galactan became the major lignin-bound galactan structure. Some differences related to the alkaline cooking method used were detected in the carbohydrate component of pine pulp RLCCs. Oxygen delignification removed 1,3/6-linked galactan from the inner parts of fiber in preference to 1,4-linked galactan.
  • Surface Activity and Foaming Capacity of Aggregates Formed between an Anionic Surfactant and Non-Cellulosics Leached from Wood Fibers
    (2019-06-10) Xiang, Wenchao; Preisig, Natalie; Laine, Christiane; Hjelt, Tuomo; Tardy, Blaise L.; Stubenrauch, Cosima; Rojas, Orlando J.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This study relates to the release of non-cellulosic components (cell wall heteropolysaccharides, lignin, and extractives) from swollen wood fibers in the presence of an anionic surfactant (sodium dodecyl sulfate, SDS) at submicellar concentrations. Highly surface-active aggregates form between SDS and the leached, non-cellulosic components, which otherwise do not occur in the presence of cationic or nonionic surfactants. The in situ and efficient generation of liquid foams in the presence of the leached species is demonstrated. The foaming capacity and foam stability, as well as the foam's structure, are determined as a function of the composition of the aqueous suspension. The results indicate that naturally occurring components bound to wood fibers are extractable solely with aqueous solutions of the anionic surfactant. Moreover, they can form surface-active aggregates that have a high foaming capacity. The results further our understanding of residual cell wall components and their role in the generation of foams.
  • Synthetic Studies on Indole Alkaloids of Geissoschizine Type
    (1998) Laine, Christiane
     Helsinki University of Technology | Licentiate thesis