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Author:Karppinen, Anni
Title:Nanoselluloosan modifiointi kationisilla polyelektrolyyteillä
Modification of microfibrillated cellulose by cationic polyelectrolytes
Publication type:Master's thesis
Publication year:2010
Pages:x + 110      Language:   fin
Department/School:Kemian laitos
Main subject:Polymeeriteknologia   (Kem-100)
Supervisor:Seppälä, Jukka
Instructor:Pietikäinen, Pirjo
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
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Location:P1 Ark Aalto  3529   | Archive
Keywords:microfibrillated cellulose
amphiphilic polyelectrolyte
selluloosan nanokuidut
amfifiilinen polyelektrolyytti
Abstract (eng): Microfibrillated cellulose (MFC) is nanofiber material developed from cellulose.
MFC has many hydroxyl groups on its surface, which makes it very hydrophilic.
Due to the hydroxyl groups, MFC can bind a large amount of water to itself and form a gel-like structure.
During a drying process, nanofibers aggregate and form hydrogen bonds to each other, and the properties of MFC cannot be restored after redispersion.
On the other hand, MFC can be modified to more hydrophobic by chemical reactions to the hydroxyl groups.
Hydrophobization can help to redisperse MFC, and it is also needed, if MFC is mixed with hydrophobic polymer matrix to form nanocomposite.

In this Master's Thesis, MFC was modified with cationic polyelectrolytes.
The polyelectrolytes used in this Thesis were amphiphilic copolymers of trimethylaminoethyl methacrylate (TMAEMA) and stearyl methacrylate (SMA), as well as PTMAEMA and its nonquaternized form.
Polyelectrolyte was expected to adsorb on the MFC fibers by electronic interactions between cationic polyelectrolyte and slightly negative surface of MFC without a covalent bond.
Composite films were prepared from the polyelectrolytes and MFC, and their morphology was studied by atomic force microscopy (AFM), the mechanical properties by dynamic mechanical analysis (DMA), the thermal properties by DMA and differential scanninc calorimetry (DSC), and the redispersion of MFC was studied by rheometry.

It seemed that the polyelectroIytes adsorbed on the MFC surface, and the amphiphilic polyelectrolyte seemed to prevent the aggregation of MFC during drying.
However, the polyelectrolytes did not manage to restore the properties of MFC after redispersion.
The polyelectrolytes had an influence on the rheological properties of MFC.
Abstract (fin): Mikrofibrilloitu selluloosa (MFC) on selluloosasta kehitetty nanokuitu.
Selluloosaketjujen pinnalla on paljon hydroksyyliryhmiä, jotka tekevät MFC:sta hyvin hydrofiilisen.
Tämän takia MFC pystyy sitomaan paljon vettä itseensä ja muodostaa geelimäisen rakenteen.
Kuivauksen yhteydessä kuidut tarttuvat tiukasti toisiinsa kiinni, eikä rakennetta ja ominaisuuksia pystytä palauttamaan uudelleendispergoinnissa.
Toisaalta hydroksyyliryhmät mahdollistavat kemiallisen modifioinnin, jonka avulla MFC:a voidaan muokata hydrofobisemmaksi.
Hydrofobointi estää kuitujen aggregoitumista kuivauksen aikana, ja erityisen tärkeää se on, jos MFC:a halutaan sekoittaa hydrofobisen polymeerimatriisin kanssa nanokomposiitiksi.

Tässä työssä MFC:a pyrittiin muokkaamaan amfifiilisten polyelektrolyyttien avulla.
Polyelektrolyytteinä käytettiin amfifiilisiä trimetyyliaminoetyylimetakrylaatin (TMAEMA) ja stearyylimetakrylaatin (SMA) kopolymeerejä sekä PTMAEMA:a ja sen kvaternisoimatonta muotoa.
Polyelektrolyytin adsorptio MFC:n pinnalle oletettiin tapahtuvan sähköisten vuorovaikutusten avulla, jolloin kemiallista reaktiota ei tarvittaisi modifiointiin.
MFC:sta ja polyelektrolyytistä valmistettiin komposiittikalvoja, ja niistä mitattiin atomivoimamikroskoopilla (AFM) morfologia, dynaamismekaanisella analyysillä (DMA) mekaaniset ominaisuudet, DMA:lla ja differentiaalisella pyyhkäisykalorimetrillä (DSC) termiset ominaisuudet ja reologisia mittauksia hyväksikäyttäen uudelleendispergoitavuus.

Polyelektrolyytit tarttuivat MFC-kuituihin, ja amfifiilinen polyelektrolyytti esti kuitujen aggregoitumista kuivauksen yhteydessä.
Polyelektrolyytit eivät kuitenkaan onnistuneet säilyttämään MFC:n ominaisuuksia uudelleendispergoinnissa.
Polyelektrolyyteillä oli selvä vaikutus MFC:n reologisiin ominaisuuksiin.
ED:2010-02-19
INSSI record number: 39029
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