COST FP1205 Training School Pretreatment and dissolution of cellulose 7-9 April Jena, Germany. Orçun Çağlar Kurtuluş, Sedat Ondaral, Güliz Hocaoğlu

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1 7-9 April Jena, Germany Orçun Çağlar Kurtuluş, Sedat Ondaral, Güliz Hocaoğlu

2 Cellulose Nanofibrillated cellulose Carboxymethylation Literature Conclusion

3 Recent years sustainable, more and more attention have been paid for green and environmental friendly materials. For this purpose, biomass fibers are standing out.

4 Cellulose is the most abundant biopolymer on the earth. Cellulose is composed of β-d glucose units. Lineer polymer. Contain amorf and crystal zones Annual production of cellulose is estimated 10 over 7,5 x 10 tons. The Degree of polymerization(dp) is up to and also it varies and in wood.

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6 What is nano fibrillated cellulose?

7 Nano fibrillated cellulose term is used for cellulose that at least one dimension is on nano scale. The synonym of nano fibrillated cellulose is; nanofibril, microfibril, microfibrillated cellulose. Diameter: 5-60 nm Length: several micrometers

8 Renewable Economical value Biodegradable High mechanical properties Good optical properties High aspect ratio Low thermal expansion Low density

9 According to unique properties nanofibrillated cellulose is used; Nanocompozites Papermaking Coating additives Security papers Food Packaging Gas Barrier

10 Nano scale cellulose fibers can be produced by homogenization as a mechanical process.! High energy consumption

11 To overcome this problem reaearchers combined some methods such as; Refining(mechanical) Enzyme treatment (cellobiohydrolases, endoglucanases) Chemical treatment (Alkaline)

12 NFC producing needs intensive mechanical traetment. According to process and raw material chemical, enzymatic or mechanical pretreatment can be applied.

13 Mechanical process for producing NFC ; Homogenizing Microfluidization Grinding Cryocrushing High intensity ultrasonication

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17 Another mechanical fibrillation process is cryocrushing. In this process water swolen celulosic fibres immerse in liquid nitrogen and then crush by mortar and pestle. Application of high impact forces to frozen cellulosic fibers leads to rupture of cell wall.

18 Oscillating power is used to isolate cellulose fibrils by hydrodynamic forces of ultrasound.

19 We need carboxymethylation; Hydrophilic nature of nano size cellulose aggregates in hydrophobin nature polymeric compozites. So surface modification of cellulose solve this drawback.

20 The surfaces of cellulosic fibers can be modified by carboxymethylation process. This process; makes the surfaces negatively charged, promotes formation of stable suspansion from carboxymethylated fibers increases the breakup of lignocellulosic fibers to nano size.

21 In carboxymethylation process; Monocloroacetic acid NaOH Ethanol Isopropanol Methanol

22 1) Dissolving the cellulose in water 2) Washing the cellulose by ethanol to change the solvent. 3) Mixing Methanol Isopropanol Monocloroacetic acid Fibre 4) Adding NaOH 5) Reaction in a water or oil bath 60 ⁰C 2-3 hours

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24 6) Washing a) Deionized water b) Acetic acid c) Deionized water 7) Filtration on Buhner funnel

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26 Wagberg et al.(2008) reported the carboxymethylation of cellulosic fibers. They found that cylindirical cross section NFC with diameter of 5-15 nm could be produced by passing carboxymethylated fibers through a homogenizer. They also found that very high concentration of the salt or too low ph could cause a rapid agglomeration of the fibers. Thus, they concluded that ph and the concentration of salt were two key factors for this procedure.

27 Aulin et al. (2009) produced carboxymethylated NFC and compared its dimensions with that of non-pretreated NFC. The carboxymethylation treatment makes the fibrils highly charged and easier to liberate.

28 Eyholzer et al.(2010) evaluated the effect of carboxymethylaton before(route 2) and after (route 1) homogenizaton on refined bleached beech pulp. Results of sedimantation test showed that NFC from route 2 dispersed easily compared to route 1. The crystalinity index of materials produced from route 2 was also lesser than route 1. Also FTIR peak at 1595 cm -1 confirmed the carboxymethylation of fibers. In addition to FTIR, SEM images displayed less agglomeration and lower diameter of fibers came from route 2 in comparison with route 1.

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30 Siro at al.(2011) studied the effect of multiple homogenization steps on the properties of carboxymethylated softwood pulp. The morphological analysis of the study exhibited a diminution in fiber aggregates by increasing homogenization steps. Two or three additional homogenizaton increased elasticity, tensile strength and modulus of elasticity of films whereas oxygen permeability did not change significantly. They summarized that carboxymethylated NFC gels had the potentiality to convert extremely transparent and oxygen barrier films.

31 Nanofibrillated cellulose is produced by similar methods. All the methods are based on mechanical defibrilation of cellulose in nano scale. Using NFC in compozites have some disadvantages such as agglomeration. In this issue homogenous dispersion of cellulose is the key factor. Application of different surface modifications are considered to be solution of this problem. Carboxymethylation is one of the important surface modification and this process introduce anionic groups on the surface of cellulose.

32 THANK YOU Assoc. Prof. Sedat ONDARAL Res. Assist. Orçun Çağlar KURTULUŞ MSc. Güliz Hocaoğlu