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Author:Heiniö, Teresa
Title:High filler content composites with microfibrillated cellulose
Publication type:Master's thesis
Publication year:2013
Pages:86 + [19]      Language:   eng
Department/School:Puunjalostustekniikan laitos
Main subject:Paperi- ja painatustekniikka   (Puu-21)
Supervisor:Maloney, Thaddeus
Instructor:Rantanen, Juuso
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
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Location:P1 Ark Aalto  2273   | Archive
Keywords:microfibrillated cellulose
PCC
composite
high filler content
drainage
mikrofibrillär cellulosa
komposit
hög fyllmedelshalt
avvattning
Abstract (eng): The aim of this thesis was to evaluate whether micro fibrillated cellulose (MFC) enables higher filler content in composites.
Due to the high filler content exceptional optical properties were anticipated.

The composites consisted of Masuko ground MFC, precipitated calcium carbonate (PCC), unrefined wood pulp and synthetic fiber.
The composites were formed by pressure filtration.
A membrane was used over a conventional wire in a standard laboratory sheet former.
The effect of MFC, fiber and PCC was evaluated in a three component mixture design on different measured properties of the prepared laboratory hand sheets.
In all test points a constant amount of 15 w-% of synthetic fibers was added, which was omitted from the model.
The data of the results was analysed by stepwise regression using a special cubic model.
All results were compared to laboratory or industrial reference as well.

The high surface area of MFC increased the bonding ability of the fibrillated material in the composites and hence increased the strength properties.
The tensile index was highest at the highest MFC levels; the test point containing 47 wt.-% MFC had a tensile index of 44 Nm/g.
The effect of the three dimensional networking ability of MFC was apparent in the z-directional strength measurements, as the test point with highest amount of MFC was almost three times higher than that of the industrial reference material.
Tear strength did not benefit from MFC additions, but the synthetic fiber raised the tear index linearly.

Virtually all optical properties exceeded those of the reference material.
Even the wet opacity was higher than the reference, although no titanium dioxide was added to the furnish.
The small size of MFC efficiently lowered the porosity of the composites.
This did not diminish the water uptake however; all test points were highly hydrophilic and had a water uptake of more than 100 wt.-%, higher than the reference.
The regression analyses on optical and strength properties were fairly reliable, since the explanatory degrees (R2-values) were high.
For roughness, porosity, water uptake and wet elongation the R2 values were lower.

Drainage testing revealed that the membrane in itself already slowed down the process and MFC even more so.
Future challenges include faster dewatering times.

In summary, the property space of the composites comprised of highly favourable proportion mixtures, which could be developed to fit industrial applications.
Abstract (swe): Syftet med detta diplomarbete var att bedöma ifall mikrofibrillar cellulosa (MFC) i kompositmaterial möjliggör en högre andel av fyllmedel.
Samtidigt förväntades exceptionella optiska egenskaper på grund av den höga fyllmedelshalten.

Kompositerna bestod av Masuko malen MFC, utfälld kalciumkarbonat (PCC), oraffinerade träfibrer och syntetiska fibrer.
Kompositerna framställdes genom övertycksfiltrering i en standard arkformare.
Ett membran användes ovanpå viran för bättre MFC-och fyllmedelsretention.
Effekten av MFC, PCC och fibrer utvärderades i en tredimensionell blandnings-modell för de olika mätta egenskaperna.
I alla testpunkter tillsattes en konstant mängd syntetisk fiber (15 vikt-%), som lämnades bort från modellen.
Datat för resultaten för de olika egenskaperna analyserades med en stegvis kubisk regression med programmet Minitab 16.
Alla resultat jämfördes även med en industriell-eller laboratoriereferens.

Den stora ytarealen av MFC ökade bindnings möjligheter i kompositen och därmed ökade styrke-egenskaperna.
Draghållfasthetsindexet var högst i området med mest MFC, i testpunkten med 47 vikt-% MFC var draghållfasthetsindexet 44 Nm/g.
Den tredimensionella nätverksförmågan, som MFC besitter, syntes synnerligen i den z-dimensionella styrkan.
Testpunkten med mest MFC hade nästan tredubbla delamineringsstyrka jämfört med det industriella referensmaterialet.
Däremot gynnades inte rivsstyrkan av MFC tillsättningar, å andra sidan höjde de långa syntetiska fibrerna riv-indexet linjärt.
Nästintill alla optiska egenskaper överskred referensmaterialets egenskaper på grund av den höga fyllmedelshalten.
Till och med den våta opaciteten var högre, även utan tillsättningar av titandioxid.
Då MFC innehar en väldigt liten partikelstorlek minskade den porositeten av kompositerna effektivt.
Detta minskade dock inte vattenabsorptionsförmågan då alla testpunkter var starkt hydrofiliska och absorberade vatten över 100 vikt-%, mera än vad referensmaterialet gjorde.
Regressionsanalysen för styrke-och optiska-egenskaperna var rätt pålitliga då förklaringsgraderna (R2-värden) var höga.
För ytråheten, porositeten, vattenabsorptionen och dimensionella stabiliteten vad R2-värden lägre.
Mätningar av avvattningstider visade att redan membranet i sig gör framställningsprocessen långsam och MFC även mera så.
Framtida utmaningar är bland annat snabbare avvattning.

Sammanfattningsvis kan konstateras att inom det utvärderade området påträffades i hög grad förträffliga komponentblandningar, som har potential att utvecklas till industriella applikationer.
ED:2013-07-30
INSSI record number: 46980
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