Preparation and Characterization of Poly(L-lactic acid) Films Plasticized with Glycerol and Maleic Anhydride
Corresponding email: hikmatunn@gmail.com
Published at : 24 May 2019
Volume : IJtech
Vol 10, No 3 (2019)
DOI : https://doi.org/10.14716/ijtech.v10i3.2936
Ni'mah, H., Rochmadi, R., Woo, E.M., Widiasih, D.A., Mayangsari, S., 2019. Preparation and Characterization of Poly(L-lactic acid) Films Plasticized with Glycerol and Maleic Anhydride. International Journal of Technology. Volume 10(3), pp. 531-540
| Hikmatun Ni'mah | Department of Chemical Engineering, Faculty of Industrial Technology, Institut Teknologi Sepuluh Nopember, Kampus ITS Sukolilo, Surabaya 60111, Indonesia |
| Rochmadi Rochmadi | Department of Chemical Engineering, Faculty of Engineering, Gadjah Mada University, Jl. Grafika No.2, Yogyakarta 55281, Indonesia |
| Eamor M. Woo | Department of Chemical Engineering, College of Engineering, National Cheng Kung University, Tainan 701, Taiwan |
| Dian Amalia Widiasih | Department of Chemical Engineering, Faculty of Industrial Technology, Institut Teknologi Sepuluh Nopember, Kampus ITS Sukolilo, Surabaya 60111, Indonesia |
| Siska Mayangsari | Department of Chemical Engineering, Faculty of Industrial Technology, Institut Teknologi Sepuluh Nopember, Kampus ITS Sukolilo, Surabaya 60111, Indonesia |
In this study,
poly(L-lactic acid) (PLLA) was blended with glycerol as a plasticizer by the
solution blending technique to form blend films. The glycerol content was
varied in order to evaluate the effect of glycerol content on the PLLA
properties and to obtain an optimum weight ratio of PLLA/glycerol (PLLA/Gly)
blend films with improved properties. The effect of the addition of
compatibilizer on the properties of the composite films was also observed. The
properties of the films obtained were characterized by using FTIR, XRD, DMA and
SEM. The FTIR spectra showed an increase in the intensity of the characteristic
peak of glycerol with increasing glycerol content, indicating that the blending
ratio and technique were precise. Based on the XRD analysis, the degree of
crystallinity generally increased with the addition of glycerol. DMA analysis
showed that the addition of glycerol reduced the value of tensile strength and
Young’s modulus of the PLLA/Gly films, but increased the elongation at break.
The optimum weight ratio was reached by the sample of PLLA/Gly (80/20) with the
value of tensile strength, Young’s modulus and elongation at break being 13.43
MPa, 747.8 MPa and 1.96%, respectively. The addition of compatibilizer slightly
increased the flexibility of the composite films. DSC analysis showed an
increase in flexibility after the addition of glycerol, indicated by a decrease in Tg,
which supports the results of the DMA analysis. SEM analysis was made of the
porous morphology on the fracture surface of the films after the addition of
glycerol; the porous structure was more pronounced in the PLLA/Gly (80/20) film
with compatibilizer, which could therefore be considered for application as a
scaffold in tissue engineering after further analysis has been conducted.
Blend; Glycerol; Maleic anhydride; Plasticizer; Poly(L-lactic acid)
Poly(L-lactic acid) (PLLA) has
become an interesting material in some specific applications due to its
excellent properties, such as biocompatibility, biodegradability, high
mechanical properties and processability. However, PLLA still has some drawbacks, such
as brittleness due to its high crystallinity, hydrophobicity, and low thermal
stability, which lead to limitations in its utilization. One of the approaches
to overcome these drawbacks is by combining PLLA
Plasticizers have
been reported to have been blended with PLLA to improve its mechanical
properties (Sitompul et al., 2016). Plasticizers are additive materials that
can increase the flexibility and durability of a material. For certain issues
and applications, biodegradable plasticizers have become favored for use as
PLLA modifiers. In biomedical applications, various PLLA blends have been
investigated for application in drug delivery, implants, surgical sutures,
orthopaedic devices and scaffolds in tissue engineering (Saini et al., 2016).
For the last of these applications, some of the aspects that should be
considered in using polyesters and their composites in tissue engineering are
biodegradability, biocompatibility and morphology, as well as processability
and the mechanical properties of the materials (Pavia et al., 2012). Some studies have reported the blending of PLLA with
biopolymers, which have a plasticizing effect for biomedical applications. Chen
et al. (2015) report the preparation of a porous scaffold from blend of PLLA
and poly(ethylene glycol) (PEG) by supercritical CO2 foaming and
particle leaching. The addition of PEG to the PLLA matrix has a plasticizing
effect on the PLLA, indicated by the decrease in Tg in it. Another
study by Frydrych et al. (2015) showed that blends of PLLA and poly(glycerol
sebacate) (PGS) provide a porous microstructure, good hydrophilic
characteristics, and good mechanical properties, which have potential for
application as scaffolds in tissue engineering. PGS is a biodegradable and
biocompatible synthetic elastomer, which shows mechanical behavior resembling
the properties of soft tissue (Wang et al., 2002; Rai et al., 2012). PGS is also a non-toxic
material and contains monomers of glycerol.
In blending two or
more components, one of the problems that should be tackled is the low
compatibility between two or more components, which will influence the physical
properties of the composites. To enhance this compatibility, the addition of a compatibilizer
is a simple approach that can be taken. The compatibilizer used can be one or
all the components that have been surface-modified by the grafting technique. Wang et al. (2012) report
that composites of MA-grafted PLLA and cellulose acetate have good mechanical
properties and are biocompatible.
MA is a non-toxic material which has been used in the biomedical field. In addition, for
wood-plastic composites (blends of polypropylene and polyethylene), grafting MA
onto the composite plastics has led to improvements in the mechanical
properties of the composites because of the enhancement of interfacial bonding
and dispersion of wood in the matrix (Gao et al., 2012).
In this study,
glycerol (Gly) as a plasticizer was added to PLLA to improve its properties,
including an increase in its flexibility and strength. The selected plasticizer
is a miscible, biocompatible and biodegradable material. PLLA grafted with
maleic anhydride (MA) (PLLA-g-MA) was also added to the PLLA/Gly blend as a compatibilizer.
In the molecular structure of the composites, the addition of MA was expected
to be able to increase the number of carbonyl groups that would perform
specific bonding with other components, so
that it could be used as a
compatibilizer (Zhang & Sun, 2004).
Therefore, the effects of the addition of PLLA-g-MA as a compatibilizer on the
properties of the PLLA and PLLA/Gly blends were also investigated. To the best
of our knowledge, no information is provided in the literature about the
modification of PLLA with glycerol and PLLA-g-MA, so this study will contribute
to research development in the polymer field.
Blend
films of PLLA and glycerol with and without MA modification have been prepared
and characterized in term of their properties. The physical properties,
including thermal and mechanical ones, and the crystallinity of the films show
improvement after the addition of glycerol, and further enhancement after the
addition of compatibilizer (PLLA-g-MA). The decrease in tensile strength and
Young’s modulus, and the increase in elongation at break for the composite
films, show that they become softer and more flexible. The enhanced mechanical
properties were caused by the improvement in interfacial bonding in the blend
samples. Moreover, the
morphology of the blend films displays a porous structure, which is similar to the
characteristic three-dimensional structure of scaffolds in tissue engineering. Therefore, the biodegradable composite films with porous structures and
excellent physical properties have the potential to be considered as scaffolds
in tissue engineering applications, after further analysis has been conducted.
This work has been financially supported by
a “Penelitian Pasca Doktor (Grant
Number: 503/PKS/ITS/2017)” research grant for year 2017 from DRPM, Indonesia,
to which the authors express their gratitude.
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