Biomedical Engineering Reference
In-Depth Information
E
XPERIMENTAL
C
ONDITIONS
The study objects are the films based on block- and grafted copolymers of chitosan with
vinyl monomers (methylacrylate monomers (methylacrylate, acrylamide, acrylonitrile) and
mixtures based on them.
The synthesis of the (co)polymers involved chitosan (CTS) [“Биопрогресс”
(“Bioprogress”) and “Биокомбинат” (Biocombinat), Moscow DC], produced form crab
shells with the molecular mass (ММ)
120 10
3
and the deacetylation degree 80-82%. The
refinement of the vinyl monomers was standard.
The chitosan grafted copolymers with methylacrylate (MA) (sample №1 - Grafted,
Grafted CTS - MA), acrylonitril (AN)(sample №5 - Grafted, Grafted CTS - AN) were
produced in aqueous-acetous solutions of the polysaccharide 3% and acetic acid 6%. The
initiator was 2.2' -azobisisobutyronitrile (0.01 mole per liter) at 333K within 3-4h. The
proportion [MA]/[the element of glycosamine]=3 mole/base mole.
Sample №2. The block-copolymers of chitosan with methylacrylate (Block CTS-MA)
were produced in aqueous-acetous solutions of the polysaccharide 3% and acetic acid 6%. at
291-296K with redox initiating system ( (С
6
Н
8
О
6
)/ (Н
2
О
2
)=1 in mole, (the element of
glycosamine)/ (Н
2
О
2
)=50 in base mole/mole added, the proportion variation [MA]/[the
element of glycosamine] was ranged from 2.5 to 3.3 mole/base mole).
Sample №3. To synthetise the grafted copolymer of chitosan with acrylamide (Grafted
CTS-AA)
1% polysaccharide solution in 0.4% aqueous solution of acetic acid was used. The
necessary amount of the chitosan solution was placed in the reactor after which 9.5 mole of
AA per a mole of the glycosamine elements was added. The system was agitated until
complete resolvation of AA, was blown through with argon during 20 min., the temperature
in the reactor was raised up to 328K and after that the initiator (NH
4
)
2
S
2
O
8
(0.5*10
-3
М)
resolved in water was added into the reaction mixture. The process lasted for 3h.
Sample №4 is a mixture of the grafted copolymer chitosan-acrylamide with
polyacrylamide (PAA) in the mass proportion of 1:1.7.
The films based on block and grafted copolymers of chitosan with vinyl monomers were
produced by pouring their solutions on glass substrates. To transform a saline form of
chitosan into an unprotonated one the sample films №1,2,5 were processed with 5% NaOH
solution (for 5 min) and ater that rinsed with distilled water until pH 7.
The mechanical strength of the films (before and after the effect of the fungi) was
analysed with the tensile-testing machine ZWIC Z005 (State Standard 270-64) at the
extension rate of 50 mm/min. The tensile strength (σ) and relative extension (
ε
) of the films
was calculated by the following formulae:
P
,
l
l
1
0
100
,
S
l
0
Search WWH ::
Custom Search