Effects of ultrasound time on the properties of methylcellulose-montmorillonite films
Int Nano Lett
Effects of ultrasound time on the properties of methylcellulose- montmorillonite films
Akbar Jokar 0 1 2 3
Mohamad Hossyn Azizi 0 1 2 3
Zohre Hamidi Esfehani 0 1 2 3
Solyman Abbasi 0 1 2 3
Film X-ray 0 1 2 3
0 Food Science, Agriculture Engineering Research Department, Fars Agricultural and Natural Resources Research and Education Center , Shiraz , Iran
1 Zohre Hamidi Esfehani
2 Mohamad Hossyn Azizi
3 Department of Food Science, College of Agriculture, Tarbiat Modares University , Tehran , Iran
Methylcellulose-montmorillonite films were prepared via solvent casting method. The effects of different ultrasound times (0, 15, 30, 45, 60, and 75 min) on the properties of methylcellulose-montmorillonite films were evaluated. Fourier transform infrared and X-ray diffraction were applied to investigate and prove the effects of ultrasound time. The films were characterized by mechanical properties, opacity, water vapor permeability, yellowness index, and color. Ultrasound time significantly affected the characteristics of the films, except for elongation. Maximum tensile strength, opacity, YI, and b* as well as minimum L* and water vapor permeability were related to 60 min. The results from X-ray diffraction and Fourier transform infrared verified the effects of sonication time on the films properties, especially for 60 min. The Fourier transform infrared spectrum related to 60 min had more new and sharper peaks. The maximum compactness and strength of methylcellulose-montmorillonite films and the highest X-ray diffraction peak were also attributed to 60 min. Using ultrasound radiation for the production of such films is strongly recommended. To obtain the best quality and reach the required properties, considering the aim of the films, optimization of sonication time is mandatory.
Ultrasound time; Methyl cellulose; Montmorillonite; Fourier transform infrared diffraction
Introduction
Recently, composites such as polymer-layered silicate have
become prevalent. Silicate layers should have at least one
dimension of less than 100 nm [
1–3
]. Montmorillonite
(MMT) is a type of silicate clay that has been widely used
in polymer composites. High intercalation chemistry,
strength, abundance in nature, low gas permeability, safety,
and economic properties of MMT have led to the
widespread use of this material [
4–7
].
Many investigations have shown that incorporating
nanoscaled silicate layers into polymers increases their mechanical
properties, heat, and moisture resistance, and decreases their
moisture adsorption, permeability, and flammability [
6, 8
].
Depending on silicate dispersion, two types of composite, i.e.,
intercalated and exfoliated, can be obtained. The latter is known
as delaminated silicate and is preferred to the former because of
having better barrier and mechanical properties [
7, 9, 10
].
Producing clay composites can be achieved by four
methods: in situ interactive polymerization, in situ
synthesis, melt intercalation, and solution intercalation.
Researchers have applied suitable blending methods, such
as shear, high pressure, centrifuge, and ultrasonication
mixing, for producing a high performance composite.
Ultrasonication is one of the most important methods for
increasing intergallery spacing between silicate layers and
dispersing them in the polymers. Ultrasound treatment can
help in terms of easily achieving exfoliated clay structure
and increasing d-spacing in comparison to non-sonicated
samples [
11, 12
]. Furthermore, ultrasonication widely
affects the polymer itself, and as a result, changes
composite properties. Therefore, power and time of sonication
are critical and should be seriously considered in composite
preparations [
13–15
]. Acoustic cavitations, bubbles, and
their collapses are the main reasons for chemical reactions
(sonochemistry) and physical changes in the substances
which are exposed to ultrasound radiation. Bubble violent
explosion generates extreme temperatures and pressures
inside the bubbles and solvent. So, the materials in the
solvent are disintegrated and several highly reactive
radicals would be generated. Several chemical reactions can
occur between these active radicals and substances in the
medium. Finally, more chemical bonds, like H and
covalent bonds will be generated [
14, 16, 17
].
Alshabanat et al. found that increasing sonication time in
polystyrene resulted in the creation of crystalline structures
in the amorphous region. The maximum peak intensity in
X-ray diffraction (XRD) was obtained after 1 h of sonicating
polystyrene-MMT composite, which showed higher
interaction and chemical bonds with MMT [
1
]. Intergallery
spacing of epoxy-clay composite increased with increasing
sonication time at low clay loading (2%). Dispersion of
MMT at high sonication times was significantly better.
Increasing sonication time enhanced tensile strength, while
hardness did not change [
18
]. Chen et al. revealed that
15 min ultrasound ti (...truncated)