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Nath D.C.D.,University of New South Wales | Bandyopadhyay S.,University of New South Wales | Yu A.,Research and Ash Development | Blackburn D.,Research and Ash Development | White C.,Research and Ash Development
Journal of Applied Polymer Science | Year: 2010

A study on nonisothermal crystallization kinetics in fly ash (FA) filled isotactic-polypropylene (PP) composites has revealed some interesting phenomena. Composites made by injection moulding of PP with 0, 20, 45, and 60 wt % of FA were nonisothermally studied using differential scanning calorimetry at cooling rates 10°C, 15°C, and 20°C per min from a melt temperature of 200°C cooled to -30 °C. Whilst neat PP showed a mono modal a crystalline phase- only structure, presence of FA led to bimodal thermographs revealing partial transcrystallisation of a into b, to maximum 14%. The onset and peak crystallization temperatures of all samples decreased by ∼ 3°C with each 5°C/min increase in cooling rate. Parameters such as crystal growth rate, dimensions, and activation energy were determined using a series of established models. The Avrami graphs showed that contrary to the published data, there are two sets of straight lines (a) with a lower slope at low cooling rate and (b) with a distinctly higher slope for high cooling rate. Activation energy of the materials reached a maximum at 45% FA. © 2009 Wiley Periodicals, Inc. Source


Nath D.C.D.,University of New South Wales | Bandyopadhyay S.,University of New South Wales | Rider J.,University of New South Wales | Yu A.,University of New South Wales | And 2 more authors.
Macromolecular Research | Year: 2011

isotactic-Polypropylene (PP) composites reinforced with 20, 45, and 60 wt% fly ash (FA) were prepared by injection molding at 483 K. The thermo-mechanical and morphological behaviors of PP and composites were examined. The addition of FA led to significant enhancement of both storage (E′) and loss modulus (E″) of the composites compared to those of PP at a given temperature, supporting the view of the formation of an interfacial interaction between the surfaces of PP and FA. By increasing the temperature from 303 to 423 K, these properties decreased exponentially, and indicated the temperature-activated mobility of segmental chains of PP. The tangent δ curves of PP and composites showed broader patterns. The glass transition temperature (T g ) was assigned at 343 K for PP and 245-246 K for the composites. In the theoretical calculation of the storage modulus and tangent δ, the modifications were required in the existing equations to fit the experimental data well. Scanning electron microscopy (SEM) revealed a uniform distribution of spherical FA particles in the composites. The calculated interfacial interaction between the FA and PP surfaces was 1.85, which is similar with other composite systems. [Figure not available: see fulltext.] © 2011 The Polymer Society of Korea and Springer Netherlands. Source


Nath D.C.D.,University of New South Wales | Bandyopadhyay S.,University of New South Wales | Boughton P.,University of New South Wales | Yu A.,University of New South Wales | And 2 more authors.
Journal of Applied Polymer Science | Year: 2010

We prepared biodegradable composite films of poly(vinyl alcohol) (PVA) and fly ash (FA) spanning 5, 10, 15, 20, and 25 wt % concentrations by casting aqueous solutions. The tensile strengths of the composite films were increased proportionally via the addition of FA. The strength of the film was enhanced by 193% with 20% FA compared to the neat PVA control. Further addition of FA deviated from the linear trend. The moduli of the composites also increased proportionally with FA addition to 212% at 20 wt % FA addition compared to the control. The percentage strain at break exponentially decreased with the addition of FA. In the dynamic mechanical behavior, the storage and loss moduli both increased with FA content. The tan δ peaks corresponding to the glass-transition temperature shifted 5-10°C higher above the control sample (73°C). This shift was attributed to a reduction in the mobility of PVA segments because they were anchored by the FA surface. The reductions in mobility manifested in strong interfacial interactions were indicative of hydrogen bonding. Broadening and reduction in the intensities of the stretching and bending peaks of -OH, -CH and -C=O of PVA in the Fourier transform infrared spectra were observed. This suggested that hydrogen bonding was active between the functional groups in the FA and PVA chains. VC 2010 Wiley Periodicals, Inc. Source


Nath D.C.D.,University of New South Wales | Bandyopadhyay S.,University of New South Wales | Boughton P.,University of New South Wales | Yu A.,University of New South Wales | And 2 more authors.
Journal of Materials Science | Year: 2010

Composite films of poly(vinyl alcohol) (PVA) and chemically modified fly ash (MFA) by sodium hydroxide were prepared by aqueous cast method with 5, 10, 15, 20 and 25 wt% MFA treated with 1 wt% cross-linking agent (glutaraldehyde, GLA). The tensile strengths of the composite films were found to increase proportionally with MFA and the maximum strength attained was 414% higher in the case of 20 wt% MFA than that in neat PVA film. The percentage of strain at break exponentially decreased with addition of MFA. The modulus of the composites was determined to increase proportionally up to a maximum 685% at 20 wt% MFA compared to that of neat PVA film. Interfacial networking between the MFA and PVA was evident from scanning electron microscopy (SEM) images of tensile-fractured surfaces, which was not observed for the unmodified fly ash (FA) system. Atomic force microscopy (AFM) analysis showed that the mean square surface roughness of the composite films of PVA-MFA was 53% smoother than the films with FA. © 2010 Springer Science+Business Media, LLC. Source


Nath D.C.D.,University of New South Wales | Bandyopadhyay S.,University of New South Wales | Campbell J.,University of New South Wales | Yu A.,University of New South Wales | And 2 more authors.
Applied Surface Science | Year: 2010

Composite films of poly(vinyl alcohol) (PVA) reinforced with 5, 10, 15, 20 and 25 wt.% surface-coated fly ash by surfactant, sodium lauryl sulphate (SLS-FA) along with 1 wt.% cross-linking agent, glutaraldehyde (GLA) were prepared by aqueous casting method. The tensile strengths of the composite films were increased proportionally with the addition of SLS-FA. The maximum 75% higher strength of the composite with 20 wt.% was achieved compared to that of neat PVA. The modulus of the composites was also increased proportionally with SLS-FA and the maximum 218% reached in composite with 20 wt.%, but the strain at break was decreased with addition of SLS-FA. Changes in FTIR spectra reflect the chemical and/or physical bonding in the ternary PVA, SLS-FA and GLA component systems. In the study of surface morphology, the connectivity was visualized in SEM images along with interstitial voids. The films with SLS-FA show 53% smoother surface calculated with AFM compared to unmodified FA composite films. © 2010 Elsevier B.V. All rights reserved. Source

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