Modifikovanje površine celuloznih vlakana primenom dielektričnog barijernog pražnjenja
Surface modification of cellulose fibers using dielectric barrier discharge
Author
Kramar, Ana D.
Mentor
Kostić, Mirjana
Committee members
Obradović, Bratislav
Asanović, Koviljka

Dimitrijević, Suzana

Janjić, Svetlana
Metadata
Show full item recordAbstract
U teorijskom delu doktorske disertacije sistematizovani su najznačajniji
literaturni podaci vezani za strukturu i reaktivnost celuloze i celuloznih vlakana.
Posebna paţnja je posvećena mogućnostima modifikacije celuloznih vlakana sa
akcentom na sve više zastupljeno korišćenje netermalne plazme u obradi celuloznih
tekstilnih materijala. Dat je uporedni pregled karakteristika ureĎaja za dobijanje
netermalne plazme kao i karakteristika same plazme dobijene u različitim
konfiguracijama i tehničkim rešenjima. Posebna paţnja je posvećena dielektričnom
barijernom praţnjenju (DBD), kao trenutno najperspektivnijoj tehnici dobijanja plazme
na atmosferskom pritisku imajući u vidu potencijalnu primenu u obradi tekstilnih
materijala. Proučeni su literaturni navodi i sistematizovani rezultati drugih istraţivačkih
grupa dobijeni proučavanjem interakcije tekstilnih materijala sa DBD-em u različitim
gasovima (vazduh, azot i kiseonik).
U eksperimentalnom delu doktorske disertacije proučavan je uticaj DB...D-a na
strukturu, svojstva i reaktivnost prirodnih i regenerisanih celuloznih vlakana, odnosno
pamuka i viskoze. Kao izvor plazme, korišćena su dva ureĎaja, prvi u kome se kao radni
gas koristi vazduh, uz dodatak zeolita u radno polje praţnjenja radi kontrole vlaţnosti
prilikom praţnjenja i u kome razmak izmeĎu elektroda iznosi 3 mm; drugi koji pruţa
mogućnost obrade u različitim gasovima, od kojih su korišćeni vazduh, azot i kiseonik i
gde je razmak izmeĎu elektroda podešen na 0,5 mm u cilju dobijanja homogenijeg
praţnjenja. Nakon modifikovanja DBD-em ispitivane su morfološke promene (SEM,
AFM), promene u strukturi uzorka (GPC-MALLS), promene u strukturi površine
uzorka (ATR-FTIR, XPS), promene u sorpcionim svojstvima (brzina kvašenja, sadrţaj
vlage, sposobnost zadrţavanja vode). Na odabranim uzorcima vršena je sorpcija srebra,
bakra i cinka, u cilju dobijanja biološki aktivne celuloze. UtvrĎeno je da predtretman
DBD-em poboljšava sorpciju pomenutih jona u uzorcima, shodno čemu je i
antimikrobna aktivnost poboljšana. TakoĎe, uvoĎenjem jona Ag+, Cu2+ i Zn2+ sniţava se
specifična zapreminska električna otpornost uzoraka, što je takoĎe eksperimentalno
utvrĎeno. Starenje uzoraka nakon tretiranja plazmom dovodi do povećane sorpcije jona
metala što moţe imati značajnu ulogu u industrijskoj primeni. Pored povećane sorpcije,
utvrĎena je i selektivnost u antimikrobnoj aktivnosti prema odreĎenim patogenima u
iii
zavisnosti od vremena starenja nakon tretiranja plazmom koje prethodi sorpciji metala
iz vodenih rastvora.
Kao posledica delimičnog uklanjanja primarnog zida sa pamučnih vlakana
tokom obrade plazmom u kiseoniku, došlo je do značajnog poboljšanja rastvorljivosti
pamučnih vlakana u sistemu DMAc/LiCl. Istovremeno, modifikovan je postupak
rastvaranja vlakana viskoze u pomenutom sistemu čime se pruţa mogućnost
nesmetanog rastvaranja vlakana viskoze bez destrukcije celuloznih lanaca.
Veoma značajnom se pokazala obrada celuloze u DBD-u sa azotom kao radnim
gasom, pri čemu su dobijena multifunkcionalna svojstva ispitivanih celuloznih vlakana.
Visokofunkcionalizovana površina vlakana utiče na redukovanje jona srebra te dolazi
do in situ formiranja čestica nanometarskih dimenzija nakon sorpcije jona srebra na
modifikovanim uzorcima. TakoĎe, uz obradu jonima bakra, na površini vlakana viskoze
nakon obrade DBD plazmom u N2 i nakon sorpcije jona kalcijuma, dolazi do formiranja
mikročestica bakra zvezdastog oblika. Mikročestice su nastale spajanjem mikropločica
bakra i vezane za funkcionalizovanu površinu vlakana pokazale su odličnu stabilnost pri
pranju. Celulozna vlakna, nakon obrade plazmom u N2, pokazuju smanjenu hidrofilnost
i smanjenu moć sorpcije metalnih jona što je direktna posledica ablacije hidroksilnih
grupa sa površine materijala pomoću plazme, bez narušavanja drugih značajnih
sorpcionih svojstava (sposobnosti zadrţavanja vode, sadrţaja vlage). Uprkos smanjenoj
sorpciji jona metala, antimikrobna aktivnost uzoraka obraĎenih u DBD plazmi u N2
ostaje skoro nepromenjena. Posebno je značajno što se kod uzoraka viskoze nakon
tretiranja pomoću N2 DBD i jonima bakra javlja takozvani efekat „latice ruţe‖ (eng.
pettal effect), gde se kapi vode zadrţavaju na površini materijala bez kvašenja.
Predloţeni način obrade omogućava dobijanje hidrofobnog materijala korišćenjem
netoksičnih hemikalija tokom jednostavnog postupka modifikovanja.
In the theoretical part of doctoral dissertation, the most significant literature data
concerning cellulose structure and properties have been systematically reviewed.
Special attention has been given to the possibilities of cellulose fibers modification with
an emphasis on more and more popular use of non-thermal plasma for cellulosic textile
materials treatment. Comparative overview of various devices and characteristics of non
thermal plasmas, obtained in different device configuration and technical
characteristics, is given. Having in mind potential industrial application, special
attention is devoted to the most perspective technique for obtaining atmospheric
pressure plasma, so called dielectric barrier discharge (DBD). Literature data and results
from other research groups regarding interaction of textile materials with DBD obtained
in various gasses (air, nitrogen and oxygen) were studied systematically.
The influence of DBD treatment on the structure, properties and reactivity... of
natural and regenerated cellulose fibers, i.e. cotton and viscose, was studied in the
experimental part of doctoral dissertation. Two types of devices were used as plasma
source; first device was operating in atmospheric air, with addition of zeolite granules in
the field of discharge for the humidity control during the discharge and in which
electrode gap was 3 mm; second device offers possibility of using different gasses for
treatment, of which air, nitrogen and oxygen were used and electrode gap was 0.5 mm
for obtaining more homogenous discharge. After DBD treatment, morphological
changes (SEM, AFM), changes in the samples structure (GPC-MALLS), surface
changes (ATR-FTIR, XPS), changes in sorption properties (wettability, moisture
sorption, water retention value) have been investigated. On the chosen samples, a
sorption of silver, copper and zinc has been performed in order to obtain biologically
active cellulose. It was found that DBD pretreatment significantly improves sorption of
aforementioned ions, and consequently, the antimicrobial activity is also improved.
Also, addition of Ag+, Cu2+ and Zn2+ ions to the cellulose leads to a decrease of
volume resistivity of samples which was also measured. The ageing of samples after
plasma treatment leads to improved sorption of metal ions and this can have serious
impact in industrial application. Beside improved sorption of ions, selectivity of
antimicrobial activity against specific pathogens has been determined and found to be
v
dependent on days of ageing after the plasma treatment which precedes sorption of
metals form aqueous solution.
As a consequence of partial removal of primary wall in cotton fibers during
plasma treatment in oxygen, significant improvement of solubility was achieved in
DMAc/LiCl solvent. At the same time, the standard procedure of viscose dissolution in
the above mentioned solvent has been modified which provided easier dissolution of
viscose fibers without destruction of cellulose chains.
Cellulose treatment in nitrogen DBD proved to be a very significant for
obtaining multifunctional properties of cellulose fibers. Highly functionalized surface of
fibers induces reduction of silver ions on modified samples and in situ formation of
silver particles of nanometer size. Also, treatment with copper ions, after N2 DBD
plasma treatment and calcium sorption, leads to the formation of star-shaped
microparticles of copper on the viscose fibers surface. Microparticles were formed by
assembling of trigonal microplates of copper and bonded to the functionalized surface
of fibers exhibited excellent stability toward washing. Cellulose fibers, after nitrogen
plasma treatment, show reduced hydrophilicity and reduced ability to bind metal ions
from solution which is direct consequence of etching and ablation of hydroxyl groups
from the surface of fibers using plasma, without significant deterioration of other
sorption properties (water retention value, moisture sorption). However, antimicrobial
activity of samples treated in N2 DBD plasma, despite decreased metal ions sorption,
remains almost unchanged, with a much lower consumption of ions. Especially
significant result is the appearance of so called ―petal effect‖ after N2 DBD treatment of
viscose with subsequent sorption of copper, when during wetting of modified viscose, a
drop of water sticks to the surface. Proposed procedure enables obtaining hydrophobic
material using non-toxic chemicals during simple process of modification.
Faculty:
Универзитет у Београду, Технолошко-металуршки факултетDate:
29-10-2015Projects:
- Functionalization, characterization and application of cellulose and cellulose derivatives (RS-172029)