Kil/Kitosan ve Organokil/Kitosan nanokompozitlerinin üretimi ve karakterizasyonu

• Published in: İTÜ dergisi/c, (Fen bilimleri) Vol. 7; no. 1; pp. 45 - 53
• Main Authors: GÜNGÖR, Nurfer, CANBAZ, Ebru, Günister
• Format: Journal Article
• Language: Turkish
• Published: İstanbul Teknik Üniversitesi 2009
• Subjects: biopolymer; Biyopolimer; chitosan; clay; Deney; experiment; Fizikokimya; Kil; Kitozan; Metalik Malzemeler; Metallic Materials; Montmorillonit; montmorillonite; nanocomposites; Nanokompozitler; Organic Chemistry; Organik Kimya; Organoclay; Organokil; Physical Chemistry
• ISSN: 1303-7021

Bu çalışmanın amacı, tıpta ve endüstride pek çok farklı kullanım alanı olan kitosan biyopolimerinin
özelliklerini tabakalı yapıdaki montmorillonit kili katkısı ile geliştirmektir. Kil tanelerinin kitosan
içinde en ideal şekilde dağıldığı ve iki bileşenin en iyi şekilde etkileşebildiği uygun koşullar
reolojik, elektrokinetik ve morfolojik yapı çalışmaları ile araştırılmıştır. Öncelikle montmorillonit
tipi kil; sedimantasyon, santrifuj, diyaliz, kurutma ve öğütme işlemleri ile saflaştırılmış ve boyutları
küçültülerek saf kil (SMt) elde edilmiştir. Hidrofilik yapıda olan SMt kilinin kitosan biyopolimeri ile
optimum etkileşimini sağlamak amacı ile, kil katyonik bir yüzeyaktif olan hekzadesiltrimetil amonyum
bromür (HDTABr) ile modifiye edilerek organofilik yapıya dönüştürülmüş ve HDTABr/kil
(OSMt) organokili elde edilmiştir. SMt ve OSMt killerinin su bazlı dispersiyonlarında reolojik,
elektrokinetik ölçümler ve mikroyapı analizleri yapılarak özellikleri belirlenmiştir. Çözeltilerin birleştirilmesi
yöntemi ile kil ve organokil, kitosan polimeri ile etkileştirilerek nanokompozit filmler
elde edilmiştir. Kil ve organokil miktarı farklı olarak sentezlenen kil/kitosan nanokompozit filmlerinin
mikro yapıları X ışını kırınımı (XRD) ve geçirmeli elektron mikroskobu (TEM) analizleri ile,
termal özellikleri diferansiyel taramalı kalorimetri (DSC) ve termogravimetrik analiz (TGA) yöntemleriyle
belirlenmiştir. Kompozitler kilin veya organokilin kitosan biyopolimeri ile etkileşimine
göre yapraklanmış veya tabakalaşmış nanokompozitler olarak tanımlanmışlardır. Sentezlenen
nanokompozit filmlerin geçirgenlikleri ve kilin polimer içinde ne şekilde dağıldığının anlaşılması
için UV spektrofotometre ile de optik geçirgenlik testleri yapılmıştır. Filmlerin sert ve kırılgan özelliğinin
giderilmesi, elastikliklerinin arttırılması için yapılan gliserin ilavesinin optik geçirgenliği
azaltması nedeniyle; filmlerde UV geçirgenliğinin engellenmesi için gliserin kullanılabileceği anlaşılmıştır.
Nowadays, the physical and engineering properties
of polymers are improved by additon of nanosize
clay to the clay/polymer nanocomposite materials.
Clay/polymer nanocomposites exhibit various superior
properties such as high strength, high modulus,
and a high distortion temperature, compared to the
pristine polymer. Montmorillonite (Mt) is the most
widely used layered silicate in polymer nanocomposites
due to its higher ion exchange capacity, surface
area, and adsorption capacity, moreover that is
friendly of environment, natural abundant and economic.
Mt is composed of silicate sheets of 1 nm
thickness with adsorbed exchangeable cations. The
intercalation with organic materials increases the
spacing between the silicate sheets and even lead to
the complete dissociation of the sheets to form a
Mt/organic composite with a nanometer scale. These
nanoparticles have high aspect ratios (length-todiameter
(L/D) ratio for Mt clay ~ 220). Clay can be
dispersed in polymeric matrix as conventional filler
with aggregated particles, intercalated clay, ordered
exfoliated nanocomposites, or disordered exfoliated
nanocomposites. At very low loadings of nanoclay
(~2-10 %), nanocomposites exhibit to increase in
mechanical, thermal, electrical or barrier properties.
Strong materials can be produced with inherent
bioproperties (biocompatibility, biodegradability,
antimicrobial) due to the completely biomolecular
nature of the material.
Biodegradable polymers which are provied from
natural sources are desired polymers to make
clay/polymer nanocomposite. Researches which
were made to develope the properties of biopolymers
are showed that the usage of clays, an inorganic
material, as an additive gives positive effects. Physical
and engineering properties of polymers can be
improven by even a few amount of clay addition because
of the crystal layer structure and characteristic
properties of clays. The distribution of nano-size
clay particles in polymers gets a strong interaction
between clay and polymer that caused by superior
properties clay/polymer nanocomposites.
Chitosan is a biopolymer derived from chitin by
N−deacylation. Chitin and chitosan are natural biodegradable
and non-toxic linear heteropolysaccharides
and waste products of the crab and shrimp industry.
Chitosan is used in applications from health
to agriculture to dyes for fabrics, because of its
chemical and biological properties. There are even
medical applications.
The aim of this study, to improve the properties of
the chitosan polymer, which has huge applications
at medical and industrial fields, by adding clay particles.
Clay particles were distributed homogenous
in chitosan and suitable conditions for the best interaction
of these two component are examined with
using rheological, electrokinetical and morphological
structure experiments.
The clay samples were purified by using sedimentation,
centrifuge, dialize, drying and grinding processes
and called SMt. The purrified clay SMt and
organoclay form of it, which was manifuctured by
interaction of HDTABr surfactant with the aim of
having optimum interaction between hydrophilic
structured clay minerals and chitosan biopolymer
were formed with chitosan. The micro structures of
the composites were determined by using X-ray diffractometer
(XRD) and transmission electron microscope
(TEM) analysis. In addition, thermal properties
of these samples were determined by using classical
methods like differential scanning calorimetry
(DSC) and thermogravimetric analysis (TGA). Both
rheological and electrokinetical properties of nanocomposite
dispersions were obtaine and optical
transparancy tests of nanocomposite films were experimented
by using Ocean Optic HR 4000
UV/Visible spectrophotometer to determine light
transmission of nanocomposite films beside how
clay is distributed in polymer.
The composite products were characterized by XRD,
TEM to determine the microstructure, and DSC,
TGA to find out the thermal properties. Besides,
rheological and electrokinetic properties and optical
transparancy of the nanocomposites were determined.
We suggested that optical transparancy
could help us to understand the distribution of the
clay in polymer. The optical transparency tests was
done and seen that the the transparancy of the films
were decrease due to the aggregation of the particles.
Also, glycerin which used to prepare the films
caused to decrease the transparancy of the chitosan
biopolymer, so it is determined that the films can be
used as a UV light stopper materials.