Application of graphene from exfoliation in kitchen mixer allows mechanical reinforcement of PVA/graphene film

Applied Nanoscience, Jun 2017

Mechanical properties of polyvinyl alcohol (PVA) can be reinforced from the addition of graphene into its matrix. However, pristine graphene lacks solubility in water and thus makes dispersion a challenging task. Notably, functionalisation of graphene is required to accommodate graphene presence in the water. In this work, we have used a kitchen mixer to produce gum Arabic–graphene (GGA) for the first time as filler for mechanical reinforcement of PVA. For the characterisation of exfoliated graphene, mean lateral size of GGA was measured from the imaging by transmission electron microscopy while the mean thickness of graphene was predicted from the obtained spectra by Raman spectroscopy. During the preparation of PVA/graphene film by solution casting, GGA was varied between 0, 0.05, 0.075, 0.10 and 0.15 wt% in concentration. We found that the presence of GGA in PVA improves the tensile stress and elastic modulus about 72–200 and 19–187% from the original values. The data from Halpin–Tsai meanwhile suggested that the mechanical reinforcement of PVA/graphene film is due to the random distribution network of GGA in PVA.

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Application of graphene from exfoliation in kitchen mixer allows mechanical reinforcement of PVA/graphene film

Appl Nanosci Application of graphene from exfoliation in kitchen mixer allows mechanical reinforcement of PVA/graphene film Zulhelmi Ismail 0 1 2 Abu Hannifa Abdullah 0 1 2 Anis Sakinah Zainal Abidin 0 1 2 Kamal Yusoh 0 1 2 0 & Zulhelmi Ismail 1 Faculty of Chemical Engineering and Natural Resources , Universiti Malaysia Pahang, 26300 Kuantan, Pahang , Malaysia 2 Faculty of Manufacturing Engineering , Universiti Malaysia Pahang, 26600 Pekan, Pahang , Malaysia Mechanical properties of polyvinyl alcohol (PVA) can be reinforced from the addition of graphene into its matrix. However, pristine graphene lacks solubility in water and thus makes dispersion a challenging task. Notably, functionalisation of graphene is required to accommodate graphene presence in the water. In this work, we have used a kitchen mixer to produce gum Arabicgraphene (GGA) for the first time as filler for mechanical reinforcement of PVA. For the characterisation of exfoliated graphene, mean lateral size of GGA was measured from the imaging by transmission electron microscopy while the mean thickness of graphene was predicted from the obtained spectra by Raman spectroscopy. During the preparation of PVA/graphene film by solution casting, GGA was varied between 0, 0.05, 0.075, 0.10 and 0.15 wt% in concentration. We found that the presence of GGA in PVA improves the tensile stress and elastic modulus about 72-200 and 19-187% from the original values. The data from Halpin-Tsai meanwhile suggested that the mechanical reinforcement of PVA/graphene film is due to the random distribution network of GGA in PVA. Graphene; Gum Arabic; Exfoliation; Kitchen mixer; Mechanical reinforcement; PVA/graphene Introduction Polyvinyl alcohol (PVA) is a synthetic polymer that is produced from the chemical conversion of polymerised vinyl acetate in a hydrous methanol (Cline et al. 1952) . In addition to zero toxicity, the presence of high number of OH bonds in PVA is also allowing high solubility of PVA in water. Despite these advantages, the reported values of tensile strength, r (15.7?74 MPa) for pristine PVA (Chen et al. 2005; Liang et al. 2009; Liu et al. 2005) are remarkably lower than that of industrial polymer such as nylon 6 (Cho and Paul 2001; Zhang et al. 2004) . To improve the mechanical characteristic of PVA, reinforcement by filler is very important as the selected filler must not only enhance the tensile strength of PVA, but also have good interfacial interactions with PVA. Due to the excellent mechanical properties of graphene, it is the most suitable candidate for mechanical improvement of PVA. However, pristine graphene is hydrophobic in nature and this makes the dispersion of graphene in a hydrophilic polymer like PVA unfeasible. To overcome this challenge, graphene oxide (GO) was commonly used as a filler for PVA due to high solubility of GO in water (Liang et al. 2009) . The H-bonding between PVA and GO was suggested as a major mechanism in homogeneous distribution of GO in the matrix of PVA. Moreover, the pre-dispersion of GO in PVA would allow reduction of GO to graphene, as been demonstrated by the change from a brownish film of PVA to opaque black after the reduction stage of the PVA/GO film (Kashyap et al. 2016; Zhou et al. 2011) . Currently, functionalisation of graphene with PVA has even been reported for better distribution of graphene in the matrix (Arao et al. 2016) . In their work, sonication and pressure homogeniser were used in the exfoliation of graphite to graphene. While better mechanical performance was observed for PVA with the incorporation of PVA?graphene synthesised by pressure homogeniser, the application of kitchen mixer as a tool for preparation of gum Arabic-graphene (GGA) in the mechanical reinforcement of PVA until now has never been discussed. A majority of works on PVA/graphene composite used sonication as a method for production of graphene (Al Islam et al. 2016; Jan et al. 2016) . It is expected that the presence of biocompatible GGA in the matrix would allow the future usage of PVA as material for biomedical and biological application. Therefore, it is important to show that the mechanical reinforcement of PVA can still be achieved from the incorporation of GGA by a kitchen mixer as an exfoliating device. Herein, we report the application of shear exfoliated GGA as filler for the mechanical reinforcement of PVA. The graphene was prepared from the mixing of graphite and gum Arabic in a kitchen mixer of 800 W. We found that GGA was easily dispersed in the solution of PVA and the resulting PVA/graphene film performed mechanically better than original PVA. In addition, the developed PVA/graphene film also has higher thermal stability than that of pure PVA. Results and discussion Characterisations of graphene To establish that the graphene indeed was produced during the exfoliation in a kitchen mixer, the imaging of graphene in the supernatant was carried out by transmission electron microsc (...truncated)


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Zulhelmi Ismail, Abu Hannifa Abdullah, Anis Sakinah Zainal Abidin, Kamal Yusoh. Application of graphene from exfoliation in kitchen mixer allows mechanical reinforcement of PVA/graphene film, Applied Nanoscience, 2017, pp. 317-324, Volume 7, Issue 6, DOI: 10.1007/s13204-017-0574-y