Extruded biodegradable films based on Poly (butylene adipate-co-terephthalate) (PBAT) and Cassava starch (CS) at varying weights were prepared, and their relevant properties for packaging applications are here reported. Neither the peak position nor the intensity of the film’s distinctive infrared absorption peaks was altered by the addition of CS to PBAT. Therefore, adding CS to PBAT is solely a physical process. Experimental results show that the increase in CS content, the tensile strength, elongation at break, and the tear resistance of the composite are decreased. The "30% CS” included composite film was selected as the optimized composition since it is cost-effective while acquiring the required physical properties to be a better fit as a packaging material. However, the overall migration of residue on the surface of the “30% CS/PBAT” sample wasn’t in the acceptable range (<10 mg/dm2). Therefore, the developed product is suitable for use as a packaging material except for food packaging. Thus, the extrusion process needs to be further modified to be used as food packaging.

Nanocomposites of natural rubber (NR) with reduced graphene oxide (rGO) were prepared by varying their ratios intending to improve the electrical and mechanical properties of natural rubber. rGO was prepared through oxidation and subsequent reduction of high purity Sri Lankan vein graphite. The prepared nanocomposites were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. The SEM images viewed a uniform homogeneous surface of the nanocomposite while FTIR and XRD spectral signatures substantiated its chemical functionalities and structural traits respectively. Mechanical properties such as tensile stress & strain, elongation at break, hardness, Young's modulus, and strain of the nanocomposite, were also investigated. Here the electrical conductivity was measured using the two-probe method. The nanocomposite started conducting at 2% rGO in rubber and increased conducting with increasing rGO. The hardness of the composites continuously increased with increasing rGO in rubber. Despite the tensile strength and elongation at break, Young's modulus also increased with increasing the rGO percentage up to 1.5 % and was optimized at the particular ratio. The highest strength of 15.91MPa was obtained at 1.5% of rGO. A detailed property investigation of rGO/NR nanocomposite has not been reported previously for the best of our knowledge. Hence, the study expected to be well supportive for future industrial developments including electronics, electrical devices, batteries, capacitors, as well as in heavy equipment including aerospace and automobiles.

The present study was aimed to obtain the optimum yield of graphene oxide (GO) from Kahatagaha graphite by optimizing oxidation time, and to effectively utilize hydrothermal microwave irradiation technique to produce high quality reduced graphene oxide (rGO) with the optimum level of reduction from Kahatagaha graphene oxide. Kahatagaha vein graphite was specifically selected for the study due to its remarkable morphological, structural, compositional and carbon isotropic variations from the other types of graphite. Oxidation time of Kahatagaha graphite was optimized and subsequently, microwave irradiation time was optimized to obtain maximumly reduced graphene oxide from the synthesized GO. XRD, SEM, FTIR and gravimetric analyses were employed to characterize the synthesized GO and rGO. The optimized oxidation time for the complete conversion of Kahatagaha graphite to GO was 5 hours that resulted in a yield of 170 % (w/w) with respect to the amount of graphite used. This level of yield would be highly beneficial for commercial productions of GO. The maximum level reduction of GO (production of rGO) was achieved in 20 minutes of microwave irradiation at 160 ºC with the microwave power of 500 W. Microwave-assisted hydrothermal reduction of graphene oxide is highly beneficial in term of energy consumption (low temperature and short processing time) and eco-friendliness (no solvents involved).

After exfoliation of graphite and discovered graphene in 2004 by Novoselov and Geim, the attention of graphene by the global scientific community enhanced progressively as a multifunctional wonder material in the world due to its unique extraordinary properties. Numerous methods apart from the discovered method have been investigated to synthesize the graphene in mass scale for variety of applications. Consequently, we believe that an adequate knowledge is necessary to choose a proper method of synthesis for a particular application. The main objective of the present review is to summarize the feasible methods followed in synthesis of graphene, discussing their properties, applications, advantages, and disadvantages for future prospects.

This study was focused on evaluation of conducting and tensile properties of rGO/ Polybutylene adipate terephthalate (PBAT) nanocomposite intended to use in electronic applications which require biodegradability. This study was also considered to be worthwhile since very little work has been done in this regard so far. PBAT was specifically selected for the study as it is an extensively used biodegradable polymer for variety of applications. The solvent casting method was employed to prepare rGO/PBAT nanocomposites where rGO was dispersed in a solution of PBAT by ultrasonication followed by evaporation of the solvent components. Electrical conductivity (σ) of rGO/PBAT nanocomposites showed a percolation behavior as rGO content was increased from the 0.5 % to 1.5 % (σ increased drastically with the increase of rGO content). The percolation threshold was approximately 0.0045, (i.e., 0.75 w/w % of rGO). The average critical exponent (t) related to the percolation theory was 1.49 ± 0.19 which is well within the expected range 1< t < 2. According to impedance studies, the electrical impedance of GO/PBAT composites decreased with the increasing rGO content, which agreed well with the behavior of the electrical conductivity investigated previously. The same equivalent circuit was shown by each composite except the values for constant phase element CPE and resistor R; the equivalent electrical circuit was a parallel combination of CPE and R. The dielectric analysis of the composites indicated that dielectric parameters ϵ”, ϵ’ and dissipation factor increased significantly with increasing rGO content. The tensile strength of the composites was better than that of neat PBAT up to 1.5 % of rGO loading and decreased on further increasing of rGO. However, their tensile strain at break decreased with increasing rGO content. The results indicated that PBAT/rGO polymer composite is promising candidate for various electronic applications.

Official journal of the Institute of Physics - Sri Lanka. Full text articles are available. The journal also has a website at http://www.ip-sl.org/sljp/The new email for the Editor is eic.ipsl@gmail.com.

The present study focuses on an efficient eco-friendly method for reducing graphene oxide (rGO) using Coffea arabica leaf extract for bio-medical applications for the first time to the best of our knowledge. The reduction of graphene oxide (GO) using Coffea arabica leaves was verified through Raman, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM). The XRD peaks corresponding to GO at 2 =10º have dissapeared on reduction of GO to rGO and the formation of rGO was verified through a new broad peak at 2 =26º. FTIR revealed functional group changes in reducing GO to rGO. The SEM images of rGO showed a ribbed form instead of the rigid appearance of the GO flakes. The analysis revealed that the current green method is a feasible method for reducing GO to rGO and formation of the Coffea arabica/rGO nanocomposite. The composite prepared from young coffee leave exhibited higher antioxidant capacity than matured leave against scavenging 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radicals. Fascinatingly, the Coffea arabica/rGO nanocomposite showed an anti-inflammatory activity as well suggesting that the Coffea arabica /rGO nanocomposite is promising candidate for bio-medical applications in near future.

Official journal of the Institute of Physics - Sri Lanka. Full text articles are available. The journal also has a website at http://www.ip-sl.org/sljp/The new email for the Editor is eic.ipsl@gmail.com.