Graphene nanoplatelets (xGnP) were investigated as a novel nano-reinforcement filler in poly(lactic acid)(PLA)/poly(ethylene glycol)(PEG) blends by the melt blending method. PLA was first plasticized by PEG in order to improve its flexibility and thereby overcome its problem of brittleness. Then, xGnP was incorporated into the PLA/PEG blend. The prepared nanocomposites exhibited a significant improvement in tensile properties at a low xGnP loading. The tensile properties demonstrated the addition of 0.3 wt% of xGnP led to an increase of up to 32.7%, 69.5% and 21.9% in tensile strength, tensile modulus and elongation at break of the nanocomposites respectively, compared to PLA/PEG blend. X-ray diffraction (XRD) patterns showed the presence of a peak around 26.5 ○ in PLA/PEG/xGnP nanocomposites which corresponds to the characteristic peak of xGnP. The nanocomposites also shows enhanced thermal stability compared with PLA/PEG blend in thermogravimetry analysis (TGA). The enhancement to some extent of the tensile properties of the PLA/PEG/xGnP nanocomposites can be ascribed to the homogeneous dispersion and orientation of the xGnP nanoplatelets in the polymer matrix and strong interfacial interaction between both components. The scanning electron microscopy (SEM) image of PLA/PEG/0.3 wt% xGnP displays good uniformity and more homogenous morphology. Good uniformity of composites indicates a good degree of dispersion of the xGnp and therefore results in good tensile and thermal properties.
References
[1]
Kuila, T.; Bhadra, S.; Yao, D.; Kim, N.H.; Bose, S.; Lee, J.H. Recent advances in graphene based polymer composites. Prog. Polym. Sci. 2010, 35, 1350–1375, doi:10.1016/j.progpolymsci.2010.07.005.
[2]
Singh, V.; Joung, D.; Zhai, L.; Das, S.; Khondaker, S.I.; Seal, S. Graphene based materials: Past, present and future. Prog. Mater. Sci. 2011, 56, 1178–1271, doi:10.1016/j.pmatsci.2011.03.003.
[3]
Salavagione, H.J.; Martínez, G.; Ellis, G. Recent advances in the covalent modification of graphene with polymers. Macromol. Rapid Commun. 2011, 32, 1771–1789, doi:10.1002/marc.201100527.
[4]
Chiang, M.-F.; Wu, T.-M. Synthesis and characterization of biodegradable poly(l-lactide)/layered double hydroxide nanocomposites. Compos. Sci. Technol. 2010, 70, 110–115, doi:10.1016/j.compscitech.2009.09.012.
[5]
Geim, A.K. Graphene: Status and prospects. Science 2009, 324, 1530–1534, doi:10.1126/science.1158877.
[6]
Kalaitzidou, K.; Fukushima, H.; Drzal, L.T. Mechanical properties and morphological characterization of exfoliated graphite-polypropylene nanocomposites. Compos. Part A Appl. Sci. Manuf. 2007, 38, 1675–1682, doi:10.1016/j.compositesa.2007.02.003.
[7]
Fukushima, H. Graphite nanoreinforcements in polymer nanocomposites. Ph.D. Thesis. 3092144, Michigan State University, Michigan, MI, USA, 2003.
[8]
Kalaitzidou, K.; Fukushima, H.; Drzal, L.T. A new compounding method for exfoliated graphite-polypropylene nanocomposites with enhanced flexural properties and lower percolation threshold. Compos. Sci. Technol. 2007, 67, 2045–2051, doi:10.1016/j.compscitech.2006.11.014.
[9]
Miloaga, D.G.; Hosein, H.-A.A.; Misra, M.; Drzal, L.T. Crystallization of poly(3-hydroxybutyrate) by exfoliated graphite nanoplatelets. J. Appl. Polym. Sci. 2007, 106, 2548–2558, doi:10.1002/app.25137.
[10]
Pinto, A.M.; Cabral, J.; Tanaka, D.A.P.; Mendes, A.M.; Magalh？es, F.D. Effect of incorporation of graphene oxide and graphene nanoplatelets on mechanical and gas permeability properties of poly(lactic acid) films. Polym. Int. 2013, 62, 33–40, doi:10.1002/pi.4290.
[11]
Gumus, S.; Ozkoc, G.; Aytac, A. Plasticized and unplasticized PLA/organoclay nanocomposites: Short- and long-term thermal properties, morphology, and nonisothermal crystallization behavior. J. Appl. Polym. Sci. 2011, 123, 2837–2848, doi:10.1002/app.34841.
[12]
Pluta, M.; Paul, M.-A.; Alexandre, M.; Dubois, P. Plasticized polylactide/clay nanocomposites. I. The role of filler content and its surface organo-modification on the physico-chemical properties. J. Polym. Sci. Part B Polym. Phys. 2006, 44, 299–311, doi:10.1002/polb.20694.
[13]
Sungsanit, K.; Kao, N.; Bhattacharya, S.N. Properties of linear poly(lactic acid)/polyethylene glycol blends. Polym. Eng. Sci. 2012, 52, 108–116, doi:10.1002/pen.22052.
[14]
Hu, Y.; Hu, Y.S.; Topolkaraev, V.; Hiltner, A.; Baer, E. Crystallization and phase separation in blends of high stereoregular poly(lactide) with poly(ethylene glycol). Polymer 2003, 44, 5681–5689, doi:10.1016/S0032-3861(03)00609-8.
Baiardo, M.; Frisoni, G.; Scandola, M.; Rimelen, M.; Lips, D.; Ruffieux, K.; Wintermantel, E. Thermal and mechanical properties of plasticized poly(L-lactic acid). J. Appl. Polym. Sci. 2003, 90, 1731–1738, doi:10.1002/app.12549.
[17]
Chieng, B.W.; Ibrahim, N.A.; Wan Yunus, W.M.Z.; Hussein, M.Z. Plasticized poly(lactic acid) with low molecular weight poly(ethylene glycol): Mechanical, thermal, and morphology properties. J. Appl. Polym. Sci. 2013, 130, 4576–4580.
[18]
Hu, Y.; Hu, Y.S.; Topolkaraev, V.; Hiltner, A.; Baer, E. Aging of poly(lactide)/poly(ethylene glycol) blends. Part 2. Poly(lactide) with high stereoregularity. Polymer 2003, 44, 5711–5720, doi:10.1016/S0032-3861(03)00615-3.
[19]
American Society for Testing and Materials. Standard Test Method for Tensile Properties of PlasticsASTM D638-02a. ASTM International: West Conshohocken, PA, USA, 2003.
Xu, Y.; Hong, W.; Bai, H.; Li, C.; Shi, G. Strong and ductile poly(vinyl alcohol)/graphene oxide composite films with a layered structure. Carbon 2009, 47, 3538–3543, doi:10.1016/j.carbon.2009.08.022.
[22]
Wang, H.; Qiu, Z. Crystallization kinetics and morphology of biodegradable poly(l-lactic acid)/graphene oxide nanocomposites: Influences of graphene oxide loading and crystallization temperature. Thermochim. Acta 2012, 527, 40–46, doi:10.1016/j.tca.2011.10.004.
[23]
Xu, H.-S.; Dai, X.J.; Lamb, P.R.; Li, Z.-M. Poly(L-lactide) crystallization induced by multiwall carbon nanotubes at very low loading. J. Polym. Sci. Part B Polym. Phys. 2009, 47, 2341–2352, doi:10.1002/polb.21830.
