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Nripati Ranjan Bose - One of the best experts on this subject based on the ideXlab platform.

  • static and dynamic mechanical properties of vinylester Resin Matrix Composites reinforced with shellac treated jute yarns
    Industrial & Engineering Chemistry Research, 2006
    Co-Authors: Dipa Ray, A K Rana, Suparna Sengupta, Nripati Ranjan Bose
    Abstract:

    Natural fiber-reinforced Composites are currently used for various types of applications. However, to improve the fiber/Resin bonding at the interface, some suitable chemical modification of the fibers is required. In the present study, an attempt has been made to use an inexpensive, easily available, and water-soluble (in alkaline medium) natural Resin shellac for the surface treatment of jute yarns. Jute yarns were treated with 1%, 2%, and 5% shellac solution, and these treated jute yarns were used as reinforcing material in vinylester Resin Matrix Composites. The Composites were subjected to flexural tests, and the flexural properties were found to be highest in the case of 1% treated Composites. A dynamic mechanical study also showed the same trend, and the storage modulus was found to be highest for the 1% treated Composites at room temperature. The fractured surfaces of the Composites, as observed by SEM, were correlated with the mechanical properties.

  • effect of guar gum treatment on mechanical properties of vinylester Resin Matrix Composites reinforced with jute yarns
    Journal of Applied Polymer Science, 2005
    Co-Authors: Dipa Ray, Nripati Ranjan Bose, A K Rana, Suparna Sengupta
    Abstract:

    The focus of this work was to use an inexpensive and easily available water-soluble natural Resin like guar gum as a surface treating agent for jute yarns and to study their effect on the mechanical properties of the treated jute yarn reinforced vinylester Resin Matrix Composites. Jute yarns were treated with 0.1, 0.2, and 0.3% guar gum solution at room temperature for 30 min. The Composites were fabricated with the untreated and treated yarns and the vinylester Resin having 36 wt % fiber loading. Maximum improvement was observed in the 0.2% guar-gum treated, jute yarn reinforced Composites. The flexural modulus and flexural strength improved by 23.85 and 7.7%, respectively, for the 0.2% treated Composites. The fracture behavior of the Composites differed considerably, depending on the concentration of guar gum that was used. The experimental results gave a positive indication that simple ecofriendly chemicals like guar gum can be used effectively as surface treating agents of jute yarns for enhancement of the mechanical properties of the jute Composites and can be a success from the technocommercial point of view. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 557–563, 2005

  • impact fatigue behaviour of vinylester Resin Matrix Composites reinforced with alkali treated jute fibres
    Composites Part A-applied Science and Manufacturing, 2002
    Co-Authors: Bijit Kumar Sarkar, Nripati Ranjan Bose
    Abstract:

    Abstract An impact fatigue study has been made for the first time on 35% jute/vinylester Composites containing both untreated and alkali treated fibres. Longer alkali treatment removed the hemicellulose and improved the crystallinity and gave better fibre dispersion. The flexural strength properties of the Composites made from treated fibre were superior. 4 h alkali treated jute fibres gave the optimum combination of improved interfacial bonding and fibre strength properties. However this was not reflected in their impact fatigue behaviour. On the contrary, the Composites reinforced with 8 h alkali treated fibres displayed superior impact fatigue properties. Here, the fibres suffered catastrophic fracture with microfibrillar pull-out at some places and improved the fatigue resistance property of the Composites as evident from SEM micrographs.

  • impact fatigue behaviour of vinylester Resin Matrix Composites reinforced with alkali treated jute fibres
    Composites Part A-applied Science and Manufacturing, 2002
    Co-Authors: Bijit Kumar Sarkar, Nripati Ranjan Bose
    Abstract:

    Abstract An impact fatigue study has been made for the first time on 35% jute/vinylester Composites containing both untreated and alkali treated fibres. Longer alkali treatment removed the hemicellulose and improved the crystallinity and gave better fibre dispersion. The flexural strength properties of the Composites made from treated fibre were superior. 4 h alkali treated jute fibres gave the optimum combination of improved interfacial bonding and fibre strength properties. However this was not reflected in their impact fatigue behaviour. On the contrary, the Composites reinforced with 8 h alkali treated fibres displayed superior impact fatigue properties. Here, the fibres suffered catastrophic fracture with microfibrillar pull-out at some places and improved the fatigue resistance property of the Composites as evident from SEM micrographs.

  • The mechanical properties of vinylester Resin Matrix Composites reinforced with alkali-treated jute fibres
    Composites Part A-applied Science and Manufacturing, 2000
    Co-Authors: Bijit Kumar Sarkar, A K Rana, Nripati Ranjan Bose
    Abstract:

    Jute fibres were subjected to alkali treatment with 5% NaOH solution for 0, 2, 4, 6 and 8 h at 30°C. The modulus of the jute fibres improved by 12, 68 and 79% after 4, 6 and 8 h of treatment, respectively. The tenacity of the fibres improved by 46% after 6 and 8 h treatment and the % breaking strain was reduced by 23% after 8 h treatment. For 35% Composites with 4 h-treated fibres, the flexural strength improved from 199.1 to 238.9 MPa by 20%, modulus improved from 11.89 to 14.69 GPa by 23% and laminar shear strength increased from 0.238 to 0.283 MPa by 19%. On plotting different values of slopes obtained from the rates of improvement of flexural strength and modulus, against NaOH treatment time, two different failure modes were apparent before and after 4 h of NaOH treatment. In the first region between 0 and 4 h, fibre pull out was predominant whereas in the second region between 6 and 8 h, transverse fracture occurred with minimum fibre pull out. This observation was well supported by the SEM investigations of the fracture surfaces.

Bijit Kumar Sarkar - One of the best experts on this subject based on the ideXlab platform.

  • thermal behavior of vinyl ester Resin Matrix Composites reinforced with alkali treated jute fibers
    Journal of Applied Polymer Science, 2004
    Co-Authors: Bijit Kumar Sarkar, R K Basak, A K Rana
    Abstract:

    The thermal behavior of vinyl ester Resin Matrix Composites reinforced with jute fibers treated for 2, 4, 6, and 8 h with 5% NaOH was studied with Thermo-gravimetric analysis and differential scanning calorimetry. The moisture desorption peak shifted to a higher temperature, from 37 to 58.3°C, for all the treated-fiber Composites because of improved wetting of the fibers by the Resin and stronger bonding at the interface. The degradation temperature of the vinyl ester Resin in the Composites was lowered to 410.3°C from that of the neat Resin, 418.8°C. The X-ray diffraction studies showed increased crystallinity of the treated fibers, which affected the enthalpy of the α-cellulose and hemicellulose degradation. The hemicellulose degradation temperature remained the same (299.7°C) in all the treated-fiber Composites, but the enthalpy associated with the hemicellulose degradation showed an increasing trend in the treated Composites with a small increase in the weight loss. This could be attributed to the increased hydrogen bonding between the more accessible OH groups of the hemicellulose in the noncrystalline region of the jute fiber and the Resin. The degradation temperature of α-cellulose was lowered from 364.2 to 356.8°C in the treated Composites. The enthalpy of α-cellulose degradation showed a decreasing trend with a lowering of the weight loss. The crystalline regions of the fiber, consisting of closely packed α-cellulose chains, were bonded with the Resin mainly on the surface through hydrogen bonds and became more resistant to thermal degradation; this reduced the weight loss. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 123–129, 2004

  • fracture behavior of vinylester Resin Matrix Composites reinforced with alkali treated jute fibers
    Journal of Applied Polymer Science, 2002
    Co-Authors: Dipa Ray, Bijit Kumar Sarkar, A K Rana
    Abstract:

    Jute fibers were treated with 5% NaOH solution for 4 and 8 h, respectively, to study the mechanical and impact fatigue properties of jute-reinforced vinylester Resin Matrix Composites. Mechanical properties were enhanced in case of fiber Composites treated for 4 h, where improved interfacial bonding (as evident from scanning electron microscopy [SEM]) and increased fiber strength properties contributed effectively in load transfer from the Matrix to the fiber; but their superior mechanical property was not retained with fatigue, as they showed poor impact fatigue behavior. The fracture surfaces produced under a three-point bend test and repeated impact loading were examined under SEM to study the nature of failure in the Composites. In case of untreated fiber Composites, interfacial debonding and extensive fiber pullout were observed, which lowered the mechanical property of the Composites but improved their impact fatigue behavior. In Composites treated for 4 h under repeated impact loading, interfacial debonding occurred, followed by fiber breakage, producing a sawlike structure at the fracture surface, which lowered the fatigue resistance property of the Composites. The Composites with fibers treated with alkali for 8 h showed maximum impact fatigue resistance. Here, interfacial debonding was at a minimum, and the fibers, being much stronger and stiffer owing to their increased crystallinity, suffered catastrophic fracture along with some microfibrillar pullout (as evident from the SEM micrographs), absorbing a lot of energy in the process, which increased the fatigue resistance property of the Composites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2588–2593, 2002

  • dynamic mechanical and thermal analysis of vinylester Resin Matrix Composites reinforced with untreated and alkali treated jute fibres
    Composites Science and Technology, 2002
    Co-Authors: Dipa Ray, Bijit Kumar Sarkar, Siddhartha Das, A K Rana
    Abstract:

    Abstract Vinylester-Resin-Matrix Composites reinforced with untreated and 5% NaOH treated jute fibres for 4 and 8 h with different fibre loading were subjected to dynamic mechanical and thermal analysis to determine their dynamic properties as a function of temperature. For all the Composites the storage modulus, E′, decreased with increase in temperature, with a significant fall in the temperature range 110°–170 °C. For the treated Composites, the rate of fall, dE′/dT, had an inverse relationship with the defect concentrations in the Composites. The lowest defect concentrations in the 4 h treated Composites corresponded to the highest rate of fall. The glass transition temperature, Tg, of the unreinforced Resin, corresponding to the loss modulus peak, was 101.2 °C, whereas that of the Composites increased by nearly 28 °C on account of the restricted mobility of the Resin molecules in the presence of the fibres. In the case of the treated Composites, the Tg value showed a decreasing trend (128 to 125 °C). Unlike the plain Resin, a tiny hump was observed in the loss modulus, E″, curves of all the Composites around 166 °C, which became broader and more prominent with increase in the jute fibre content. The very high tanδ value of the Resin decreased in the Composites, indicating that the addition of the fibres lowered the damping capacity of the Composites.

  • impact fatigue behaviour of vinylester Resin Matrix Composites reinforced with alkali treated jute fibres
    Composites Part A-applied Science and Manufacturing, 2002
    Co-Authors: Bijit Kumar Sarkar, Nripati Ranjan Bose
    Abstract:

    Abstract An impact fatigue study has been made for the first time on 35% jute/vinylester Composites containing both untreated and alkali treated fibres. Longer alkali treatment removed the hemicellulose and improved the crystallinity and gave better fibre dispersion. The flexural strength properties of the Composites made from treated fibre were superior. 4 h alkali treated jute fibres gave the optimum combination of improved interfacial bonding and fibre strength properties. However this was not reflected in their impact fatigue behaviour. On the contrary, the Composites reinforced with 8 h alkali treated fibres displayed superior impact fatigue properties. Here, the fibres suffered catastrophic fracture with microfibrillar pull-out at some places and improved the fatigue resistance property of the Composites as evident from SEM micrographs.

  • impact fatigue behaviour of vinylester Resin Matrix Composites reinforced with alkali treated jute fibres
    Composites Part A-applied Science and Manufacturing, 2002
    Co-Authors: Bijit Kumar Sarkar, Nripati Ranjan Bose
    Abstract:

    Abstract An impact fatigue study has been made for the first time on 35% jute/vinylester Composites containing both untreated and alkali treated fibres. Longer alkali treatment removed the hemicellulose and improved the crystallinity and gave better fibre dispersion. The flexural strength properties of the Composites made from treated fibre were superior. 4 h alkali treated jute fibres gave the optimum combination of improved interfacial bonding and fibre strength properties. However this was not reflected in their impact fatigue behaviour. On the contrary, the Composites reinforced with 8 h alkali treated fibres displayed superior impact fatigue properties. Here, the fibres suffered catastrophic fracture with microfibrillar pull-out at some places and improved the fatigue resistance property of the Composites as evident from SEM micrographs.

Dipa Ray - One of the best experts on this subject based on the ideXlab platform.

  • thermal and electrical behavior of vinylester Resin Matrix Composites filled with fly ash particles
    Polymer Composites, 2008
    Co-Authors: Dipa Ray, Sourish Banerjee, Amar K. Mohanty, Manjusri Misra
    Abstract:

    Vinylester Resin Matrix Composites were fabricated with 30, 40, 50, and 60% fly ash loading by room temperature casting method. The Composites were subjected to thermogravimetric analysis. The 30 and the 60% Composites showed a faster degradation at a lower temperature, whereas, the 40 and the 50% Composites showed a higher onset temperature. The activation energy was calculated following Broido's equation and was found to be lowered in all the Composites compared to the unfilled Resin. The residue increased in all the Composites proportionately with the increase in the fly ash content. The temperature variation resistance of the unfilled Resin, 30 and 60% filled Composites were measured and all the samples showed semi conducting nature in 40–60°C temperature range. POLYM. COMPOS., 29:58–62, 2008. © 2007 Society of Plastics Engineers

  • friction and wear behavior of vinylester Resin Matrix Composites filled with fly ash particles
    Journal of Reinforced Plastics and Composites, 2007
    Co-Authors: Dipa Ray, R Gnanamoorthy
    Abstract:

    Fly ash filled vinylester Resin Matrix Composites were prepared with a filler loading of 40 and 50 wt%. The friction and wear behavior of neat Resin and fly ash filled Composites were studied with the help of a pin-on-disc wear tester with the composite pin sliding over an abrasive sheet under three different normal loads. Wear behavior was quantified in terms of weight loss, linear wear, and coefficient of friction of the test samples; these were much higher in neat Resin compared to Composites. Among the Composites, a better wear resistance was shown by the 40% filled Composites with a lower wear loss, lesser linear wear, and a minimum value of the coefficient of friction. It was evident that the linear wear increased steadily in the case of vinylester Resin with increase in sliding distance, whereas linear wear was much less and was almost constant in the Composites with the increase in sliding distance under all three different normal loads. It was also observed that the difference between the coeffic...

  • static and dynamic mechanical properties of vinylester Resin Matrix Composites filled with fly ash
    Macromolecular Materials and Engineering, 2006
    Co-Authors: Dipa Ray, Debadrita Bhattacharya, Amar K. Mohanty, Lawrence T Drzal, Manjusri Misra
    Abstract:

    Vinylester Resin Matrix Composites were prepared with a fly ash loading of 30, 40, 50 and 60 wt.-%. Flexural properties of the Composites were investigated. It was found that the flexural strength was lowered in all the filled Composites, but the flexural modulus showed a significant increase of 10, 57, 112% in case of 30,40 and 50 wt.-% fly-ash-loaded Composites respectively, compared to the neat Resin. However, there was a decrease in the mechanical properties in case of 60 wt.-% fly-ash-filled Composites. The dynamic mechanical analysis was carried out to obtain information about the Matrix-filler interaction at the interface. The storage modulus value at room temperature was highest for the 50 wt.-% fly-ash-filled Composites, corroborating with the observed flexural modulus value. The fractured surfaces were examined under SEM and were correlated with the mechanical properties.

  • static and dynamic mechanical properties of vinylester Resin Matrix Composites filled with fly ash
    Macromolecular Materials and Engineering, 2006
    Co-Authors: Dipa Ray, Debadrita Bhattacharya, Amar K. Mohanty, Lawrence T Drzal, Manjusri Misra
    Abstract:

    Vinylester Resin Matrix Composites were prepared with a fly ash loading of 30, 40, 50 and 60 wt.-%. Flexural properties of the Composites were investigated. It was found that the flexural strength was lowered in all the filled Composites, but the flexural modulus showed a significant increase of 10, 57, 112% in case of 30,40 and 50 wt.-% fly-ash-loaded Composites respectively, compared to the neat Resin. However, there was a decrease in the mechanical properties in case of 60 wt.-% fly-ash-filled Composites. The dynamic mechanical analysis was carried out to obtain information about the Matrix-filler interaction at the interface. The storage modulus value at room temperature was highest for the 50 wt.-% fly-ash-filled Composites, corroborating with the observed flexural modulus value. The fractured surfaces were examined under SEM and were correlated with the mechanical properties.

  • static and dynamic mechanical properties of vinylester Resin Matrix Composites reinforced with shellac treated jute yarns
    Industrial & Engineering Chemistry Research, 2006
    Co-Authors: Dipa Ray, A K Rana, Suparna Sengupta, Nripati Ranjan Bose
    Abstract:

    Natural fiber-reinforced Composites are currently used for various types of applications. However, to improve the fiber/Resin bonding at the interface, some suitable chemical modification of the fibers is required. In the present study, an attempt has been made to use an inexpensive, easily available, and water-soluble (in alkaline medium) natural Resin shellac for the surface treatment of jute yarns. Jute yarns were treated with 1%, 2%, and 5% shellac solution, and these treated jute yarns were used as reinforcing material in vinylester Resin Matrix Composites. The Composites were subjected to flexural tests, and the flexural properties were found to be highest in the case of 1% treated Composites. A dynamic mechanical study also showed the same trend, and the storage modulus was found to be highest for the 1% treated Composites at room temperature. The fractured surfaces of the Composites, as observed by SEM, were correlated with the mechanical properties.

A K Rana - One of the best experts on this subject based on the ideXlab platform.

  • static and dynamic mechanical properties of vinylester Resin Matrix Composites reinforced with shellac treated jute yarns
    Industrial & Engineering Chemistry Research, 2006
    Co-Authors: Dipa Ray, A K Rana, Suparna Sengupta, Nripati Ranjan Bose
    Abstract:

    Natural fiber-reinforced Composites are currently used for various types of applications. However, to improve the fiber/Resin bonding at the interface, some suitable chemical modification of the fibers is required. In the present study, an attempt has been made to use an inexpensive, easily available, and water-soluble (in alkaline medium) natural Resin shellac for the surface treatment of jute yarns. Jute yarns were treated with 1%, 2%, and 5% shellac solution, and these treated jute yarns were used as reinforcing material in vinylester Resin Matrix Composites. The Composites were subjected to flexural tests, and the flexural properties were found to be highest in the case of 1% treated Composites. A dynamic mechanical study also showed the same trend, and the storage modulus was found to be highest for the 1% treated Composites at room temperature. The fractured surfaces of the Composites, as observed by SEM, were correlated with the mechanical properties.

  • effect of guar gum treatment on mechanical properties of vinylester Resin Matrix Composites reinforced with jute yarns
    Journal of Applied Polymer Science, 2005
    Co-Authors: Dipa Ray, Nripati Ranjan Bose, A K Rana, Suparna Sengupta
    Abstract:

    The focus of this work was to use an inexpensive and easily available water-soluble natural Resin like guar gum as a surface treating agent for jute yarns and to study their effect on the mechanical properties of the treated jute yarn reinforced vinylester Resin Matrix Composites. Jute yarns were treated with 0.1, 0.2, and 0.3% guar gum solution at room temperature for 30 min. The Composites were fabricated with the untreated and treated yarns and the vinylester Resin having 36 wt % fiber loading. Maximum improvement was observed in the 0.2% guar-gum treated, jute yarn reinforced Composites. The flexural modulus and flexural strength improved by 23.85 and 7.7%, respectively, for the 0.2% treated Composites. The fracture behavior of the Composites differed considerably, depending on the concentration of guar gum that was used. The experimental results gave a positive indication that simple ecofriendly chemicals like guar gum can be used effectively as surface treating agents of jute yarns for enhancement of the mechanical properties of the jute Composites and can be a success from the technocommercial point of view. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 557–563, 2005

  • thermal behavior of vinyl ester Resin Matrix Composites reinforced with alkali treated jute fibers
    Journal of Applied Polymer Science, 2004
    Co-Authors: Bijit Kumar Sarkar, R K Basak, A K Rana
    Abstract:

    The thermal behavior of vinyl ester Resin Matrix Composites reinforced with jute fibers treated for 2, 4, 6, and 8 h with 5% NaOH was studied with Thermo-gravimetric analysis and differential scanning calorimetry. The moisture desorption peak shifted to a higher temperature, from 37 to 58.3°C, for all the treated-fiber Composites because of improved wetting of the fibers by the Resin and stronger bonding at the interface. The degradation temperature of the vinyl ester Resin in the Composites was lowered to 410.3°C from that of the neat Resin, 418.8°C. The X-ray diffraction studies showed increased crystallinity of the treated fibers, which affected the enthalpy of the α-cellulose and hemicellulose degradation. The hemicellulose degradation temperature remained the same (299.7°C) in all the treated-fiber Composites, but the enthalpy associated with the hemicellulose degradation showed an increasing trend in the treated Composites with a small increase in the weight loss. This could be attributed to the increased hydrogen bonding between the more accessible OH groups of the hemicellulose in the noncrystalline region of the jute fiber and the Resin. The degradation temperature of α-cellulose was lowered from 364.2 to 356.8°C in the treated Composites. The enthalpy of α-cellulose degradation showed a decreasing trend with a lowering of the weight loss. The crystalline regions of the fiber, consisting of closely packed α-cellulose chains, were bonded with the Resin mainly on the surface through hydrogen bonds and became more resistant to thermal degradation; this reduced the weight loss. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 123–129, 2004

  • fracture behavior of vinylester Resin Matrix Composites reinforced with alkali treated jute fibers
    Journal of Applied Polymer Science, 2002
    Co-Authors: Dipa Ray, Bijit Kumar Sarkar, A K Rana
    Abstract:

    Jute fibers were treated with 5% NaOH solution for 4 and 8 h, respectively, to study the mechanical and impact fatigue properties of jute-reinforced vinylester Resin Matrix Composites. Mechanical properties were enhanced in case of fiber Composites treated for 4 h, where improved interfacial bonding (as evident from scanning electron microscopy [SEM]) and increased fiber strength properties contributed effectively in load transfer from the Matrix to the fiber; but their superior mechanical property was not retained with fatigue, as they showed poor impact fatigue behavior. The fracture surfaces produced under a three-point bend test and repeated impact loading were examined under SEM to study the nature of failure in the Composites. In case of untreated fiber Composites, interfacial debonding and extensive fiber pullout were observed, which lowered the mechanical property of the Composites but improved their impact fatigue behavior. In Composites treated for 4 h under repeated impact loading, interfacial debonding occurred, followed by fiber breakage, producing a sawlike structure at the fracture surface, which lowered the fatigue resistance property of the Composites. The Composites with fibers treated with alkali for 8 h showed maximum impact fatigue resistance. Here, interfacial debonding was at a minimum, and the fibers, being much stronger and stiffer owing to their increased crystallinity, suffered catastrophic fracture along with some microfibrillar pullout (as evident from the SEM micrographs), absorbing a lot of energy in the process, which increased the fatigue resistance property of the Composites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2588–2593, 2002

  • dynamic mechanical and thermal analysis of vinylester Resin Matrix Composites reinforced with untreated and alkali treated jute fibres
    Composites Science and Technology, 2002
    Co-Authors: Dipa Ray, Bijit Kumar Sarkar, Siddhartha Das, A K Rana
    Abstract:

    Abstract Vinylester-Resin-Matrix Composites reinforced with untreated and 5% NaOH treated jute fibres for 4 and 8 h with different fibre loading were subjected to dynamic mechanical and thermal analysis to determine their dynamic properties as a function of temperature. For all the Composites the storage modulus, E′, decreased with increase in temperature, with a significant fall in the temperature range 110°–170 °C. For the treated Composites, the rate of fall, dE′/dT, had an inverse relationship with the defect concentrations in the Composites. The lowest defect concentrations in the 4 h treated Composites corresponded to the highest rate of fall. The glass transition temperature, Tg, of the unreinforced Resin, corresponding to the loss modulus peak, was 101.2 °C, whereas that of the Composites increased by nearly 28 °C on account of the restricted mobility of the Resin molecules in the presence of the fibres. In the case of the treated Composites, the Tg value showed a decreasing trend (128 to 125 °C). Unlike the plain Resin, a tiny hump was observed in the loss modulus, E″, curves of all the Composites around 166 °C, which became broader and more prominent with increase in the jute fibre content. The very high tanδ value of the Resin decreased in the Composites, indicating that the addition of the fibres lowered the damping capacity of the Composites.

D C Watts - One of the best experts on this subject based on the ideXlab platform.

  • the relationship between cyclic hygroscopic dimensional changes and water sorption desorption of self adhering and new Resin Matrix Composites
    Dental Materials, 2013
    Co-Authors: Yong Jie Wei, Nick Silikas, Zhen Ting Zhang, D C Watts
    Abstract:

    Abstract Objectives This study evaluated the relationship between mass changes and hygroscopic dimensional changes during water sorption/desorption cycles in new Resin Composites. Methods A silorane posterior composite (Filtek ® Silorane, FS), two micro-fine hybrid Composites (GC Gradia Direct Anterior, GDA; GC Gradia Direct Posterior, GDP), a universal composite (GC Kalore, GCK), and a self-adhering flowable composite (Vertise ® Flow, VF) were evaluated. 25 ( n  = 5) disk specimens (15 mm × 2 mm) were prepared according to ISO 4049. Water sorption was measured gravimetrically. Hygroscopic expansions were measured by a laser micrometer regularly during 150 d water storage and 40 d recondition periods, all at 37 °C. Data were analyzed by repeated measures ANOVA, one-way ANOVA and Tukey's post hoc test ( p Results Mass changes after 150 d water immersion ranged from 0.68% (±0.02) for FS to 2.83% (±0.11) for VF and the corresponding hygroscopic expansions were from 0.74% (±0.05) for FS to 4.79% (±0.18) for VF. The differences were significant for all materials ( p Significance Relationships between hygroscopic expansion and mass change were determined for some diverse Resin-Matrix Composites. The initial non-linearity for all materials suggests a lower expansion rate due to occupancy of internal free volume by water ingress. The silorane composite FS showed statistically the lowest mass change and hygroscopic dimensional change.

  • hygroscopic dimensional changes of self adhering and new Resin Matrix Composites during water sorption desorption cycles
    Dental Materials, 2011
    Co-Authors: Yong Jie Wei, Nick Silikas, Zhen Ting Zhang, D C Watts
    Abstract:

    Abstract Objectives To study hygroscopic dimensional changes in new Resin-Matrix Composites during water sorption/desorption cycles. Methods Five materials were examined: a self-adhering flowable composite: Vertise ® Flow (VF), a universal composite: GC Kalore (GCK), two micro-fine hybrid Composites: GC Gradia Direct Anterior (GDA) and GC Gradia Direct Posterior (GDP), and a posterior restorative composite: Filtek ® Silorane (FS). Five disk-shaped specimens of each material were prepared (15 mm diameter × 2 mm thickness) according to ISO 4049. The mean diameter of each specimen was measured by a custom-built laser micrometer (to a resolution of 200 nm) periodically over 150 d water immersion and 40 d recondition periods at (37 ± 1) °C. Perspex controls were used. Data analysis was performed by repeated measures ANOVA, one-way ANOVA and Tukey's post hoc test ( p Results Differences in hygroscopic expansion were found for all test materials during sorption, ranging from 0.74% (±0.05) for FS to 4.82% (±0.13) for VF. The differences were significant for all materials ( p Significance The silorane composite FS had the lowest hygroscopic expansion. The extent of compensation of polymerization shrinkage by hygroscopic expansion depends on materials, specimen dimensions and time-scale. So the clinical situation must be taken into consideration in the application of these findings.

  • diffusion and concurrent solubility of self adhering and new Resin Matrix Composites during water sorption desorption cycles
    Dental Materials, 2011
    Co-Authors: Yong Jie Wei, Nick Silikas, Zhen Ting Zhang, D C Watts
    Abstract:

    Abstract Objectives To investigate the kinetic process of water diffusion and mass change in new Resin–Matrix Composites during water sorption/desorption cycles. Methods Five new Resin–Matrix Composites were investigated [Filtek® Silorane (FS), GC Gradia Direct Anterior (GDA), GC Gradia Direct Posterior (GDP), GC Kalore (GCK), Vertise® Flow (VF)]. Five disk-shaped specimens, per material (15.0 ± 0.1) mm diameter by (2.0 ± 0.1) mm, were prepared according to ISO 4049. Each disk was immersed separately in de-ionized water for 150 d and then reconditioned for 75 d; all at (37 ± 1) °C. Mass was measured at different time intervals. Perspex disks were used as control. Data analysis was done by repeated measures ANOVA, one-way ANOVA and Tukey's post hoc test (p  Results The water sorption (μg/mm3) after 150 d immersion ranged from 13.51 μg/mm3 (±0.40) for FS to 71.96 μg/mm3 (±0.90) for VF. The solubility ranged up to 16.95 μg/mm3 (±0.79) for VF. A significant mass reduction occurred in VF after the peak value [73.63 μg/mm3 (±0.31)] of water sorption was reached at 42 d. VF had the highest diffusion-coefficient for sorption: 5.23 × 10−9 cm2/s (±0.38) and desorption: 11.72 × 10−9 cm2/s (±0.16). Percentage sorption differences were significant for all materials (p  Significance Each Resin–Matrix composite varied in sorption/desorption cycles which may affect clinical service. A concurrent solubility process occurred during sorption of the self-adhering composite VF. The silorane composite FS exhibited minimal sorption.