13 results on '"Lingström, Rikard"'
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2. Wettability changes in the formation of polymeric multilayers on cellulose fibres and their influence on wet adhesion
- Author
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Lingström, Rikard, Notley, Shannon M., and Wågberg, Lars
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- 2007
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3. Preparation of electrically conducting cellulose fibres utilizing polyelectrolyte multilayers of poly(3,4-ethylenedioxythiophene):poly(styrene sulphonate) and poly(allyl amine)
- Author
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Wistrand, Ingemar, Lingström, Rikard, and Wågberg, Lars
- Published
- 2007
- Full Text
- View/download PDF
4. Formation of polyelectrolyte multilayers on fibres: Influence on wettability and fibre/fibre interaction
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Lingström, Rikard, Wågberg, Lars, and Larsson, Per Tomas
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- 2006
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5. Polyelectrolyte Multilayers for Fibre Engineering
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Lingström, Rikard, primary, Johansson, Erik, additional, and Wågberg, Lars, additional
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- 2009
- Full Text
- View/download PDF
6. On the Adhesion Between Substrates Covered with Polyelectrolyte Multilayers
- Author
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Lingström, Rikard
- Subjects
atomic force microscopy ,multilayer ,paper strength ,fibre ,wettability ,Pappers-, massa- och fiberteknik ,Paper, Pulp and Fiber Technology ,polyelectorlyte ,contact angle ,surface force apparatus - Abstract
This thesis examines the formation of Polyelectrolyte Multilayers (PEM) on cellulose fibres as a new way of influencing the fibre surface and the adhesion between wood fibres. The aim of the study was to enhance the fundamental understanding of the adsorption mechanisms behind the formation of Polyelectrolyte Multilayers on cellulose fibres; to study how the properties of the layers can be influenced and to show how the properties of the layers influence the adhesion between the fibres and the strength of paper sheets made from the PEM treated fibres. Different polyelectrolyte systems are known to form PEMs with different properties, and in this work two different polymer systems were extensively studied: poly(dimethyldiallylammonium chloride) (PDADMAC) / poly(styrene sulphonate) (PSS), which are both strong polylectrolytes (i.e. are highly charged over a wide range of pH) and poly allylaminehydrochloride (PAH) /poly acrylic acid (PAA), which are both weak polyelectorlytes (i.e. sensitive to pH changes). PEMs were also formed from PAH/ poly(3,4-ethylenedioxythiophene):PSS (PEDOT:PSS), in order to form electrically conducting PEMs on fibres and PEM-like structures were formed from polyethylene oxide (PEO) and polyacrylic acid (PAA). In order to study the influence of the PEM on adhesion and paper strength, fibres were treated and used to form sheets which were physically tested according to determine the tensile index and strain at break. Both these systems were studied using different molecular mass fractions. High molecular mass PDADMAC/PSS (>500k/1000k) had a significantly greater influence as a function of the number of layers than low molecular mass PDADMAC/PSS (30k/80k). In contrast, sheets made from high molecular mass PAH/PAA (70k/240k) showed a significantly lower increase in strength than sheets made from low molecular PAH/PAA investigated earlier. Both these systems had a greater influence on paper strength when the cationic polyelectrolyte was adsorbed in the outermost layer. The amount of polyelectrolytes adsorbed on the fibres was determined using polylectrolyte titration (PET) and destructive analytical methods. Adsorption to model surfaces of silicon oxide was studied before the adsorption on fibres, in order to understand the influence on PEM properties of parameters such as salt concentration and adsorption time. Adhesion studies of surfaces coated with PAH/PAA using AFM, showed an increase in adhesion as a function of the number of adsorbed layers. The adhesion was higher when PAH was adsorbed in the outermost layers. Individual fibres were also partly treated using a Dynamic Contact Angle analyser (DCA) and were studied with regard to their wettability. In general, the wettability was lower when the cationic polymer was outermost. The level of adhesion and paper strength are discussed in terms of rigidity and wettability and the PEMs demonstrating a large number of free chain ends, a large chain mobility and a low wettability was found to have the greatest influence to adhesion and paper strength. QC 20100823
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- 2008
7. Formation and properties of polyelectrolyte multilayers on wood fibres : influence on paper strength and fibre wettability
- Author
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Lingström, Rikard
- Subjects
reflectance ,multilayer ,adsorption ,paper ,Chemical Sciences ,dynamics ,Kemi ,mechanical properties ,individual ,contact angle ,polyelectrolyte ,wood fibre - Abstract
The work in this licentiate thesis examines the adsorption of polyelectrolyte multilayers (PEM) onto wood fibres as a new way to influence the properties of the fibre surfaces and hence the fibres. Fundamental aspects of PEM formation on wood fibres have been studied, and discussed in terms of paper strength and wood fibre wettability. PEMs have been formed from three different polymer systems: 1) two strong polyelectrolytes (i.e., fully charged over a wide pH range), polydimethyldiallylammonium chloride (PDADMAC) and polystyrene sulphonate (PSS); 2) polyethylene oxide (PEO) and polyacrylic acid (PAA), formed at low pH and held together by hydrogen bonding; and 3) two weak polyelectrolytes, polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA). The PEMs formed from PDADMAC/PSS and PEO/PAA were studied using Stagnation Point Adsorption Reflectometry (SPAR), with SiO2 as the substrate. This was done to establish the formation of PEMs and, using PDADMAC/PSS, also to predict the influence of salt concentration during PEM formation. The amount of PDADMAC/PSS adsorbed was found to increase with salt concentration up to approximately 0.1 M NaCl. The formation of PEMs from PAH/PAA has already been studied in terms of structure; amount adsorbed, and influence on paper strength. Sheets were formed from fibres treated with either PDADMAC/PSS or PEO/PAA PEMs and tested to determine paper tensile strength. Both PEM systems increased the tensile index and strain at break in the range of 100% when approximately 10 layers had been adsorbed. After several PEM layers had been adsorbed, the sheets made of fibres treated with PDADMAC/PSS differed in tensile strength depending on the polymer adsorbed in the outermost layer. A higher tensile strength was detected when PDADMAC rather than PSS was adsorbed in the outermost layer. Sheets made of fibres treated with PEO/PAA displayed a linear increase in strength, independent of which polymer that was adsorbed in the outermost layer. The amount of adsorbed PDADMAC/PSS, as analysed using nitrogen and sulphur analysis, respectively, increased linearly, but with a higher amount adsorbed in the first layer. A comparison of the adsorption onto the SiO2-surfaces (SPAR-measurements) and fibres shows some differences. This is apparent both regarding the adsorption in the first layer and in the change in adsorbed amount with salt concentration. Despite this, one can conclude that SiO2 and wood fibres show very similar trends, and that SiO2 can be used as a convenient model surface in predicting PEM formation on wood fibres. Individual fibres were also partially treated using a Dynamic Contact Angle Analyser, and the treated and untreated parts were analysed in terms of wettability and surface structure. The differences in wettability are significant, depending on the polymer system used and, with PAH/PAA PEMs, the pH strategy show a large influence in wettability. PDADMAC/PSS and PAH/PAA PEMs both had a large influence on wettability, depending on the polymer adsorbed in the outermost layer, wettability being lower when the cationic polymer was adsorbed in the outermost layer. With the PEO/PAA system, however, the polymer adsorbed in the outermost layer caused no detectable difference. These results, when compared against the paper strength results, indicate that the strongest sheets are formed of the fibres with the lowest wettability. This may be explained in terms of wet adhesion: since the fibre networks are formed in water, lower wettability would give a stronger force between the fibres during consolidation, resulting in a greater contact area and thus probably a stronger dry adhesion between the fibres in the formed sheet. This is furthermore also supported by wet adhesion measurements using Atomic Force Microscopy where PEMs formed from PAH/PAA, show that the pull-off force is increased when PAH is adsorbed in the outermost layer, compared to when PAA is adsorbed in the outermost layer. Denna licentiatavhandling behandlar adsorption av polyelektrolytmultiskikt (multiskikt) på cellulosafibrer som ett nytt sätt att påverka en fibers ytegenskaper. Grundläggande förutsättningar för bildandet av multiskikt på fibrer diskuteras i termer av pappersstyrka och fibervätning. Multiskikt har bildats med hjälp av tre olika polymerkombinationer; 1.) två starka polyelektrolyter, polydiallyldimetylammoniumklorid (PDADMAC) och polystyrensulfanat (PSS), 2.) polyetylenoxid (PEO) och polyakrylsyra (PAA), adsorberade vid lågt pH och sammanhållna av icke elektrostatiska vätebindningar, och 3.) två svaga polyelektrolyter, polyallylaminhydroklorid (PAH) och PAA. Uppbyggnaden av multiskikt bestående av PDADMAC/PSS och PEO/PAA på kiseloxid studerades med Stagnationspunktsreflektometri (SPAR) för att undersöka att uppbyggnad av PEM skett, samt att studera hur uppbyggnaden påverkas av koncentrationen NaCl i polymerlösningen. Försöken visade att den adsorberade mängden PDADMAC/PSS ökade med saltkoncentrationen upp till 0,05-0,1 M NaCl. Uppbyggnaden av multiskikt bestående av PAH/PAA är sedan tidigare studerad undersöks därför inte specifikt i detta arbete. Laboratorieark tillverkades av fibrer som behandlats med multiskikt bestående av PDADMAC/PSS, respektive PAH/PAA. Fysikalisk pappersprovning av arken visade för båda systemen en ökning med cirka 100 % i dragindex för ark som tillverkats av fibrer som behandlats med cirka tio lager, jämfört med ark som tillverkats av icke-behandlade fibrer. Ark tillverkade från PDADMAC/PSS-behandlade fibrer visade att när 5-7 lager adsorberats, ett högre dragindex då PDADMAC adsorberats i det yttersta lagret, jämfört med då PSS adsorberats i det yttersta lagret. Ark tillverkade från fibrer behandlade med PEO/PAA visade ingen skillnad i dragindex beroende av vilken polymer som adsorberats i det yttersta lagret. Den adsorberade mängden PDADMAC/PSS på fibrerna bestämdes med hjälp av kväve- respektive svavelanalys. Den adsorberade mängden polymer ökad linjärt som en funktion av antalet adsorberade lager, men med en högre adsorberad mängd i det första lagret. Dessa resultat har jämförts med den adsorberade mängden för multiskikt uppbyggda med SPAR på kiseloxid. Jämförelsen visade att det finns skillnader i uppbyggnaden mellan skikt byggda på kiseloxid och fibrer, men att kiseloxid med god tillförlitlighet kan användas som modellyta för att förutsäga generella trender för adsorptionen av samma polymersystem på cellulosafibrer. Multiskikt har också bildats på enskilda fibrer med hjälp av en dynamisk kontaktvinkelmätare (DCA). Genom att behandla en del av en fiber, och jämföra den behandlade delen med den obehandlade delen på samma, kan ett multiskikts inverkan på fiberns ytstruktur och vätningsegenskaper studeras. De olika polymersystemen visade en avsevärd skillnad i förmågan att påverka en fibers vätningsegenskaper. För fibrer behandlade med PAH/PAA är också pH av stor betydelse för graden inverkan på fiberns vätningsegenskaper. Fibrer behandlade med PDADMAC/PSS och PAH/PAA, visade en sämre vätningsförmåga då den katjoniska polymeren adsorberats i det yttersta lagret, och vice versa. För enskilda fibrer behandlade med PEO/PAA, kunde inte konstateras någon skillnad beroende av vilken polymer som adsorberats i det yttersta lagret. Vid en jämförelse mellan vätningsförmåga och pappersstyrka kan konstateras att de ark som visade den högsta styrkan tillverkats av fibrer där den lägsta vätningsförmågan har kunnat konstateras. Denna skillnad kan diskuteras med utgångspunkten i att en lägre vätningsförmåga resulterar i en högre våt adhesion och därmed en starkare interaktion mellan de polymerbehandlade ytorna i vått tillstånd. Det föreslås i avhandlingen att den ökade kraft som detta resulterar i vid bildandet av en fiber-fiberfog ger upphov till en högre kontaktarea och därmed, förmodligen, också en högre torr adhesion. Kraftmätningar i vått tillstånd för behandlade kiselmodellytor med hjälp av atomkraftsmikroskopi (AFM) har för PAH/PAA visat att den våta adhesionen är högre då PAH är adsorberats i det yttersta lagret, jämfört med då PAA adsorberats i det yttersta lagret. Detta stödjer hypotesen att en lägre vätning gynnar uppkomsten av en stark fiber-fiberfog. QC 20101118
- Published
- 2006
8. Adhesive Interaction between Polyelectrolyte Multilayers of Polyallylamine Hydrochloride and Polyacrylic Acid Studied Using Atomic Force Microscopy and Surface Force Apparatus
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Johansson, Erik, Blomberg, Eva, Lingström, Rikard, Wågberg, Lars, Johansson, Erik, Blomberg, Eva, Lingström, Rikard, and Wågberg, Lars
- Abstract
In the present work, the adhesion between substrates treated with identical polyelectrolyte multilayers (PEM) from polyallylamine hydrochloride (PAR) and poly(acrylic acid) (PAA) was studied using atomic force microscopy (AFM) and the Surface force apparatus (SFA). The AFM measurements, conducted under wet conditions for PEMs formed at pH 7.5, showed a higher adhesion (pull-off force) when PAH was adsorbed in the outermost layers. There was also a difference depending on the Molecular mass of the polymers, demonstrating a greater adhesion for the low molecular mass combination of polyelectrolytes. Furthermore, die time in contact showed to be of importance, with increasing pull-off forces with contact time at maximum load. The SFA measurements were conducted under dry conditions, at 100% RH, and under wet conditions for PEMs adsorbed at pH 7.5/3.5. The SFA adhesion measurements showed that under dry conditions, the adhesive forces between two high energetic mica substrates were lowered when they were covered by PEMs before the measurements. The thickness of the adsorbed layers was also measured using SFA. This showed that there was a significant swelling when the dry layers were exposed to 100% RH or to wet conditions. The swelling was higher, indicating a less rigid layer, when PAH was adsorbed in the outermost layer than when the PEM was capped with PAA., QC 20100823. Uppdaterad från manuskript till artikel (20100823). Tidigare titel: The Adhesive Interaction between Polyelectrolyte Multilayers of Polyallylamine Hydrochloride and Polyacrylic Acid studied using Atomic Force Microscopy (AFM) and Surface Force Apparatus (SFA)
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- 2009
- Full Text
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9. A comparison of polyelectrolyte complexes and multilayers : Their adsorption behaviour and use for enhancing tensile strength of paper
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Ankerfors, Caroline, Lingström, Rikard, Wågberg, Lars, Ödberg, Lars, Ankerfors, Caroline, Lingström, Rikard, Wågberg, Lars, and Ödberg, Lars
- Abstract
This paper compares the adsorption behaviour and paper-strength-enhancing properties of polyelectrolyte complexes (PECs) and polyelectrolyte multilayers (PEMs) of polyallylamine hydrochloride and polyacrylic acid. Model adsorption experiments using SPAR (stagnation point adsorption reflectometry) and QCM-D (quartz crystal microbalance with dissipation) showed that the amount of complexes adsorbed was lower than the amount adsorbed when forming a multilayer using the same polymer system. From these experiments, in combination with AFM and ESEM imaging, it was concluded that the PEC adsorption stopped before full surface coverage was reached. Tensile testing of handsheets treated with PECs and PEM showed a significant increase in both tensile index and strain-at-break using both systems. The largest strength improvement was achieved with the fibres treated with the largest number of PEMs, but the largest effect per adsorbed amount of polymer was achieved by PEC treatment., QC 20100819. Tidigare titel: A comparison between polyelectrolyte complexes and multilayers: their adsorption behaviour and use for enhancing tensile strength properties of paper.Correction in: Nordic Pulp & Paper Research Journal, vol. 24, issue. 2, p. 246
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- 2009
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10. Polyelectrolyte Multilayers for Fibre Engineering
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Lingström, Rikard, Johansson, Erik, Wågberg, Lars, Lingström, Rikard, Johansson, Erik, and Wågberg, Lars
- Abstract
QC 20140225
- Published
- 2009
- Full Text
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11. Preparation of electrically conducting cellulose fibres utilizing polyelectrolyte multilayers of poly(3,4-ethylenedioxythiophene) : poly(styrene sulphonate) and poly(allyl amine)
- Author
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Wistrand, Ingemar, Lingström, Rikard, Wågberg, Lars, Wistrand, Ingemar, Lingström, Rikard, and Wågberg, Lars
- Abstract
The primary goal with this work is to create electrically conductive cellulose fibres, this has been done to explore possible new applications for fibre based material. This research uses various methods to create polyelectrolyte multilayers (PEMs) on bleached softwood fibres and on SiO2 model surfaces, by sequentially treating these materials with poly(3,4ethylenedioxythiophene):poly(styrene sulphonate) (PEDOT:PSS) and poly(allyl amine) (PAH). Paper sheets were then produced from the PEM-modified pulp and evaluated in terms of tensile strength, adsorbed amount of polymer, and electrical conductivity. To evaluate the influence of fibre charge on the measured paper properties, pulps of two different initial fibre charge densities were prepared via carboxymethylation. Because of the bluish colour of PEDOT:PSS, the build-up of PEM could be easily followed, since the fibres grew increasingly darker blue throughout the modification sequence. The conductivity of the fibre network increased by 2-3 orders of magnitude when the pulp of a higher fibre charge density was used. This suggests that it is more important to create a fibrous network with a high fibre-fibre joint strength and a large total joined area in the sheet rather than to maximize the adsorbed amount of PEDOT:PSS. A difference in conductivity could also be noted depending on the polyelectrolyte adsorbed in the outer layer, PAH lowered the conductivity compared to PEDOT:PSS. Evaluating the mechanical properties revealed that the use of PEDOT:PSS reduces the tensile strength of the paper. When five double layers had been adsorbed onto the carboxymethylated sample in which PEDOT:PSS formed the outer layer, calculations indicated a 25% decrease in tensile strength compared to that of reference material without PEMs. ESEM studies indicate that PEM treatment produces a significantly changed and somewhat smoother fibre surface., QC 20100525
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- 2007
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12. A comparison of polyelectrolyte complexes and multilayers: Their adsorption behaviour and use for enhancing tensile strength of paper
- Author
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Ankerfors, Caroline, primary, Lingström, Rikard, additional, Wågberg, Lars, additional, and Ödberg, Lars, additional
- Published
- 2009
- Full Text
- View/download PDF
13. Adhesive interaction between polyelectrolyte multilayers of polyallylamine hydrochloride and polyacrylic acid studied using atomic force microscopy and surface force apparatus.
- Author
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Johansson E, Blomberg E, Lingström R, and Wågberg L
- Abstract
In the present work, the adhesion between substrates treated with identical polyelectrolyte multilayers (PEM) from polyallylamine hydrochloride (PAH) and poly(acrylic acid) (PAA) was studied using atomic force microscopy (AFM) and the surface force apparatus (SFA). The AFM measurements, conducted under wet conditions for PEMs formed at pH 7.5, showed a higher adhesion (pull-off force) when PAH was adsorbed in the outermost layers. There was also a difference depending on the molecular mass of the polymers, demonstrating a greater adhesion for the low molecular mass combination of polyelectrolytes. Furthermore, the time in contact showed to be of importance, with increasing pull-off forces with contact time at maximum load. The SFA measurements were conducted under dry conditions, at 100% RH, and under wet conditions for PEMs adsorbed at pH 7.5/3.5. The SFA adhesion measurements showed that under dry conditions, the adhesive forces between two high energetic mica substrates were lowered when they were covered by PEMs before the measurements. The thickness of the adsorbed layers was also measured using SFA. This showed that there was a significant swelling when the dry layers were exposed to 100% RH or to wet conditions. The swelling was higher, indicating a less rigid layer, when PAH was adsorbed in the outermost layer than when the PEM was capped with PAA.
- Published
- 2009
- Full Text
- View/download PDF
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