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Siti Rohana Binti Ahmad

Bio: Siti Rohana Binti Ahmad is an academic researcher from University of Manchester. The author has contributed to research in topics: Tensile testing & Young's modulus. The author has an hindex of 2, co-authored 2 publications receiving 79 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a detailed analysis has been undertaken of the mechanisms of reinforcement of polypropylene (PP) by the addition of graphene nanoplatelets (GNP) and it was found that the GNPs increased the thermal stability of the PP and aided crystal nucleation.
Abstract: A detailed analysis has been undertaken of the mechanisms of reinforcement of polypropylene (PP) by the addition of graphene nanoplatelets (GNP) The PP/GNP nanocomposites were processed by melt mixing followed by injection moulding and microstructure was fully characterized It was found that the GNPs increased the thermal stability of the PP and aided crystal nucleation The mechanical properties of the nanocomposites were evaluated using both tensile testing and dynamic mechanical thermal analysis The addition of GNPs led to a significant increase in the Young’s modulus of the PP, coupled with a decrease in the yield stress and a reduction in the elongation to failure Stress transfer from the PP matrix to the GNP reinforcement was followed from stress-induced shifts of the 2D Raman band and the effective Young’s modulus of the GNPs in the nanocomposites was found to be about 100 GPa, shown to be consistent with the expected value

80 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of filler loading and average surface area of filler in PP/GnP composites on Raman spectrum and tensile properties were studied, and increased of graphene nanoplatelets loading have increased the value of modulus of elasticity, whereas tensile strength, elongation at break of composites reduced.
Abstract: Graphene/Polypropylene nanocomposites were prepared at different filler loading and different average surface diameter 5, 15 and 25μm of graphene nanoplatelets by using Haake Minilab mixer at 180C and rotor speed 50rpm. Besides, Haake MiniJet is used to obtain dumbbell shape specimen. The effect of filler loading and average surface area of filler in PP/GnP composites on Raman spectrum and tensile properties were studied. Raman spectrum of graphene particles indicate three major spectrums such as D, G and 2D band. In addition, PP/GnP composites shows the Raman band shift quite strong by increasing GnP loading. In general, increased of graphene nanoplatelets loading have increased the value of modulus of elasticity, whereas tensile strength, elongation at break of composites reduced.

28 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the current status of the intrinsic mechanical properties of the graphene-family of materials along with the preparation and properties of bulk graphene-based nanocomposites is thoroughly examined.

1,531 citations

Journal ArticleDOI
16 Dec 2015
TL;DR: In this paper, the dispersion behavior of the D and G' Raman bands, that is, their shift to higher frequencies with increasing laser excitation energy, is used to assess the interfacial properties between the filler and the surrounding polymer in the composites.
Abstract: Carbon-based nanomaterials have emerged as a subject of enormous scientific attention due to their outstanding mechanical, electrical and thermal properties. Incorporated in a polymeric matrix, they are expected to significantly improve physical properties of the host medium at extremely small filler content. In this work, we report a characterization of various carbonaceous materials by Raman spectroscopy that has become a key technique for the analysis of different types of sp2 nanostructures, including one-dimensional carbon nanotubes, two-dimensional graphene and the effect of disorder in their structures. The dispersion behavior of the D and G’ Raman bands, that is, their shift to higher frequencies with increasing laser excitation energy, is used to assess the interfacial properties between the filler and the surrounding polymer in the composites.

266 citations

Journal ArticleDOI
TL;DR: In this paper, a detailed study has been undertaken of the mechanisms of stress transfer in polymeric matrices with different values of Young's modulus, Em, reinforced by graphene nanoplatelets (GNPs).

205 citations

Journal ArticleDOI
TL;DR: In this paper, an accurate nonlinear buckling analysis of a functionally graded porous graphene platelet reinforced composite cylindrical shells under axial compressive load is performed, and the stability equation is established according to a unified shell theory including the classical thin shell theory and the high order shear deformation theory.

112 citations

Journal ArticleDOI
Yun-Seok Jun1, Jun Geun Um1, Gaopeng Jiang1, Gregory Lui1, Aiping Yu1 
TL;DR: In this paper, a polypropylene (PP)/graphene nanoplatelet (GnPs) nanocomposites with very large sized GnPs (∼150μm) are prepared by melt extrusion followed by injection molding.
Abstract: In this study, polypropylene (PP)/graphene nanoplatelet (GnPs) nanocomposites with very large sized GnPs (∼150 μm) are prepared by melt extrusion followed by injection molding. A number of characteristics including thermal, mechanical, and electrical properties are analyzed. DSC shows that the introduction of GnPs facilitates the crystallization of polymer matrix due to a role of GnPs that serves as seeds for heterogeneous nucleation, and XRD reveals that GnPs have a minor induction effect of β crystals. Taking advantage of the large size and high aspect ratio of GnPs, a relatively low percolation threshold of ∼2.99 vol% is obtained with highly increased in-plane and through-plane electrical conductivity. The fitting of experimental data to the percolation theory indicates that GnPs are three dimensionally dispersed within the polymer matrix. The composites exhibit relatively limited mechanical enhancement due to compromising of GnPs by the shear force introduced during the compounding process. Overall, the usage of large sized GnPs is clearly beneficial for obtaining high electrical conductivity with a less amount of filler, but an enhanced dispersion of fillers with controlled morphology is required to achieve great physical and mechanical properties of the PP/GnPs composites.

80 citations