Browsing by Author "Thampi, S"

Now showing 1 - 3 of 3
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    Mechanical characterization of high performance graphene oxide incorporated aligned fibro porous polycarbonate urethane membrane for potential biomedical applications
    (Journal of Applied Polymer Science, 2015-04) Thampi, S; Muthuvijayan, V; Ramesh, P
    In this article, we report the development of graphene oxide (GO) reinforced electrospun poly(carbonate urethane) (PCU) nanocomposite membranes intended for biomedical applications. In this study, we aimed to improve the mechanical properties of PCU fibroporous electrospun membranes through fiber alignment and GO incorporation. Membranes with 1, 1.5, and 3% loadings of GO were evaluated for their morphology, mechanical properties, crystallinity, biocompatibility, and hemocompatibility. The mechanical properties were assessed under both static and dynamic conditions to explore the tensile characteristics and viscoelastic properties. The results show that GO presented a good dispersion and exfoliation in the PCU matrix, contributing to an increase in the mechanical performance. The static mechanical properties indicated a 55% increase in the tensile strength, a 127% increase in toughness for 1.5 wt % GO loading and the achievement of a maximum strength reinforcement efficiency value at the same loading. Crystallinity changes in membranes were examined by X-ray diffraction analysis. In vitro cytotoxicity tests with L-929 fibroblast cells and percentage hemolysis tests with fresh venous blood displayed the membranes to be cytocompatible with acceptable levels of hemolytic characteristics. Accordingly, these results highlight the potential of this mechanically improved composite membrane’s application in the biomedical field
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    Mechanical characterization of high-performance graphene oxide incorporated aligned fibroporous poly(carbonate urethane) membrane for potential biomedical applications
    (JOURNAL OF APPLIED POLYMER SCIENCE, 2015) Thampi, S; Muthuvijayan, V; Parameswaran, R
    In this article, we report the development of graphene oxide (GO) reinforced electrospun poly(carbonate urethane) (PCU) nanocomposite membranes intended for biomedical applications. In this study, we aimed to improve the mechanical properties of PCU fibroporous electrospun membranes through fiber alignment and GO incorporation. Membranes with 1, 1.5, and 3% loadings of GO were evaluated for their morphology, mechanical properties, crystallinity, biocompatibility, and hemocompatibitity. The mechanical properties were assessed under both static and dynamic conditions to explore the tensile characteristics and visco-elastic properties. The results show that GO presented a good dispersion and exfoliation in the PCU matrix, contributing to an increase in the mechanical performance. The static mechanical properties indicated a 55% increase in the tensile strength, a 127% increase in toughness for 1.5 wt % GO loading and the achievement of a maximum strength reinforcement efficiency value at the same loading. Crystallinity changes in membranes were examined by X-ray diffraction analysis. In vitro cytotoxicity tests with L-929 fibroblast cells and percentage hemolysis tests with fresh venous blood displayed the membranes to be cytocompatible with acceptable levels of hemolytic characteristics. Accordingly, these results highlight the potential of this mechanically improved composite membrane's application in the biomedical field. (C) 2013 Wiley Periodicals, Inc.
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    Silanization induced inherent strain in graphene based filler influencing mechanical properties of polycarbonate urethane nanocomposite membranes
    (RSC ADVANCES, 2016) Thampi, S; Muthuvijayan, V; Parameswaran, R
    Nanosheet type fillers apart from their size and surface functional groups may have numerous attributes affecting the mechanical properties of polymeric nanocomposites. To study these, silane-functionalized graphene based fillers were synthesized by chemically grafting N-[3-(trimethoxysilyl) propyl] diethylenetriamine (TMPT) onto graphene oxide (GO) and carboxylated GO (GOCO) using different chemistries. Their respective silanization yielded nano-fillers with amine (GOSAM) and alkoxy (GOCSAL) groups. Further, hydroiodic acid (HI) treatment led to synthesis of their reduced counterparts GRSAM and GRCSAL. The resulting TMPT-functionalized nanosheets were characterized by Fourier transform infrared spectroscopy (FT-IR) confirmed silane functionalization. A blue shift in Raman spectra indicated that during silanization with different terminal groups an inherent compressive strain has developed, while reduction with HI caused a red shift indicating a tensile strain, in these nanosheets. Polycarbonate urethane nanocomposite electrospun membranes (PCU) incorporated with these respective fillers at different loadings were analyzed. Morphology of the nanocomposite membranes was observed under SEM and membranes were characterized by static and dynamic mechanical analysis. The study indicated that the exfoliation and dispersion of graphene sheets in PCU has significantly improved due to surface functionalization while it also exhibited a novel aspect, variations in their mechanical properties in respect to the type of strain present in incorporated nanosheet fillers. The nanosheet fillers with compressive strain contributed more to the mechanical property enhancement of nanocomposite membranes, than the fillers with tensile strain. A spring and molecule model was thus proposed as possible explanation to relate inherent strain in filler to that of nanocomposite membrane mechanical properties. In vitro non-cytotoxic and hemocompatible nature of these fibroporous nanocomposite membranes provided their potential in biomedical applications.