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ST.LIDETA LEMARIYAM MEDICAL AND BUSINESS COLLEGE
PHARMACY DEPARTEMENT
Cellulose Modification
reaction and their value
CHEMISTRY NATURAL PRODUCT
SECTION – C(II)
GROUP MEMBRANCE
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ID
YESEHAK ABRAHAM……………………………………………………………………………………DPHR/325/12
YABSRA MULAT…………………………………………………………………………………………..DPHR/315/12
TSION DERIBEW………………………………………………………………………………………….DPHR/126/12
ZEYEBA GETNET…………………………………………………………………………………………..DPHR/151/12
SEBLE KEBEDE…………………………………………………………………………………………….DPHR/129/12
SEIDA MUSEFA……………………………………………………………………………………………DPHR/137/12
SAMUEL YIRGU……………………………………………………………………………………………DPHR/552/12
Yohans Samuel-------------------------------------------------------------------------------DPHR531/12
SUBMITTED TO – Mr. Besufikad
SUB.DATE 18/10/2013
TABLE OF CONTENT
page
1.
Introduction ……………………….,…………………..……2
2.
Cellulose Modification reaction and their value….................3
2.1 Solution properties of cellulose in [Amim]Cl……............3
2.2 Preparation of Cellulose Solutions……………........4
2.3 Cellulose Hybrid Chemical Modification……………………4
REFRENCE
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1. Introduction
Cellulose is the most abundant polymer on Earth, which makes it also the most
common organic compound. Annual cellulose synthesis by plants is close to 1012
tons.1 Plants contain approximately 33% cellulose whereas wood contains
around 50 per cent and cotton contains 90%. Most of the cellulose is utilised as a
raw material in paper production. This equates to approximately 108 tons of pulp
produced annually.2 From this, only 4 million tons are used for further chemical
processing annually.3 It is quite clear from these values that only a very small
fraction of cellulose is used for the production of commodity materials and
chemicals. This fact was the starting point of our research into understanding,
designing, synthesizing and finding new alternative applications for this wellknown but underused biomaterial.
Modified cellulose refers to chemical modifications of mainly hydroxyl groups in
the cellulose backbone. There are primary and secondary hydroxyl groups in each
cellulose unit, where the C6-hydroxyl group, being the primary one, exhibits
higher reactivity. Typical reactions of hydroxyl groups in cellulose, including
oxidation, esterification, etherification, urethanization, amidation, and noncovalent modifications
Direct dissolution of cellulose without derivatization applied for dry-wet/wet
spinning of polymer solutions has been emerged to an efficient tool for the
design of textile functional materials.[1–3] With the advancement of essential
technological know-how for the manufacturing of cellulosic staple and endless
fibres in a technical range (Lyocell process) in the foreground, the development
tends to innovative functional fibres from the late ‘90s of last century. The
ongoing progress yields on one side textile processible fibres with novel crosssections and innovative dry-wet shaping techniques, e. g. blow casting and melt
blowing, and on the other hand a series of completely new cellulosic functional
fibers.
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2.Cellulose Modification reaction and their value
Cellulose is a very common, natural component of all living organisms. It is
a carbohydrate and a polysaccharide found in the cell walls of plants. It is
the most abundant organic compound on earth and can be found in many
types of plants such as seaweed, trees, and some fruits. The cellulose
family has been used since its discovery for things like paper production to
cloth making to filter aids for oil fields. The modification reaction process
was created to modify cellulosic materials for new applications following
their invention in 1937 by Henri Braconnot through hydrolysis with sulfuric
acid or sodium sulfate.
2.1
Solution properties of cellulose in [Amim]Cl
The very first step in this study was to investigate the solubility properties
of cellulose in several ILs. Based on those results, the next step was to
select a few ILs to be used in cellulose modification reactions. The
constraints for dissolution procedure were that it has to be achieved with
temperatures below 100°C to prevent the hydrolysis of cellulose during the
dissolution, which ruled out all high-melting ILs such as 2-halide-3-alkyl-1methylimidazolium chlorides. It was also clear from the literature that
imidazolium-based ILs would be an obvious choice with chloride anions as
they exhibit the strongest solubilizing power for cellulose. After screening
out numerous ILs based on the above criteria, we were left with three
imidazolium-based ILs, namely [Amim]Cl, [Bmim]Cl and [Mmim]Me2PO4
from which [Amim]Cl was the most extensively used in this study. This is
due to the fact that [Bmim]Cl is a solid (m.p. 65°C) at room temperature,
which reduces its practicality. In contrast, [Mmim]Me2PO4 dissolves
cellulose very quickly, but it was soon realised that this IL was a relatively
poor medium for modification reactions. [Amim]Cl proved to be a superior
solvent possessing a high solubilisation capacity for cellulose solutions with
concentrations up to 40% (w/w) could be prepared. In addition, it seemed
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to be a feasible reaction medium because it has an intermediate viscosity
suitable for stirring and mixing in addition to being quite inert.
2.2 Preparation of Cellulose Solutions
The preparation of cellulose solutions was carried out in a special vertical
kneader system, linked with a RHEOCORD 9000 (HAAKE). Temperature,
torque moment and revolutions per minute (rpm) vs. reaction time were
determined on-line. For the dissolution process the cellulose
was disintegrated by means of an ultraturrax shearing step in water, was
separated from excessive water and was transferred in
the aqueous N-methylmorpholine-N-oxide
or ionic liquid. The obtained stable suspension was poured in the vertical
kneader system. Afterwards the water was removed at temperatures
between 90 and 1308C, a reduced pressure between 700 and 5 mbar
and a shearing rate of 10 to 80 rpm. The resulting cellulose solution was
analytically characterized and used for a further dry-wet shaping process.
The details of the solution preparation were described in previous
publications.
2.3
Cellulose Hybrid Chemical Modification
The major advantage of the presented modification approach is the fact that commonly
known chemical treatment of cellulose fibers with MA was broadened with the physical
modification (pre-swelling) in media of various polarity and structure (ethanol and
hexane) enabling more efficient
treatment and improvement in polymer composite performance.
The presented study covers a few problems: effect of the solvent exchange (different
polarity of ethanol and hexane) on the properties of cellulose fibers, impact of the
dehydration process on the filler modification process, the combined influence of
drying, solvent exchange and MA grafting on
the properties of both the cellulose and filled polymer composites.
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REFERENCE
1. Zhong, Z.; Qin, J.; Ma, J. Cellulose acetate/hydroxyapatite/chitosan
coatings for improved corrosion resistance
and bioactivity. Mater. Sci. Eng. C 2015, 49, 251–255.
2. M. V. Podzorova, Yu. V. Tertyshnyaya, and A. A. Popov, Russ. J. Phys.
Chem. B 8, 726 (2014).
3. A. I. Laletin, L. S. Gal’braikh, and Z. A. Rogovin, Vysokomol. Soedin., Ser.
A 10, 652 (1968).
4. https://bioresources.cnr.ncsu.edu
5. www.diva-portal.org
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