The Experts below are selected from a list of 2037 Experts worldwide ranked by ideXlab platform
J. Raghavan - One of the best experts on this subject based on the ideXlab platform.
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Experimental study of tool―part interaction during autoclave processing of thermoset polymer composite structures
Composites Part A-applied Science and Manufacturing, 2010Co-Authors: V. Kaushik, J. RaghavanAbstract:Abstract Autoclave manufacturing of thermoset polymer matrix composite structures with high dimensional fidelity requires a good understanding of various parameters affecting process-induced warpage and application of this knowledge to minimize the warpage through appropriate process control. One important contributor is the interaction between a composite part and the tool on which the part is laid and Cured. This experimental study quantified the tool–part interaction by measuring the static and dynamic frictional coefficients as a function of process time, using a friction test fixture specially designed to simulate the autoclave environment. Temperature ramp rate was varied to understand the effect of autoclave Cure cycle on the friction coefficients. Measured friction coefficients were maximum at the start of the Cure cycle and varied as a function of degree of Cure (α) and ramp rate owing to change in the tool–part interface, Cure Shrinkage, resin/composite properties, residual stress, and mode of interface failure.
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experimental study of tool part interaction during autoclave processing of thermoset polymer composite structures
Composites Part A-applied Science and Manufacturing, 2010Co-Authors: V. Kaushik, J. RaghavanAbstract:Abstract Autoclave manufacturing of thermoset polymer matrix composite structures with high dimensional fidelity requires a good understanding of various parameters affecting process-induced warpage and application of this knowledge to minimize the warpage through appropriate process control. One important contributor is the interaction between a composite part and the tool on which the part is laid and Cured. This experimental study quantified the tool–part interaction by measuring the static and dynamic frictional coefficients as a function of process time, using a friction test fixture specially designed to simulate the autoclave environment. Temperature ramp rate was varied to understand the effect of autoclave Cure cycle on the friction coefficients. Measured friction coefficients were maximum at the start of the Cure cycle and varied as a function of degree of Cure (α) and ramp rate owing to change in the tool–part interface, Cure Shrinkage, resin/composite properties, residual stress, and mode of interface failure.
V. Kaushik - One of the best experts on this subject based on the ideXlab platform.
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Experimental study of tool―part interaction during autoclave processing of thermoset polymer composite structures
Composites Part A-applied Science and Manufacturing, 2010Co-Authors: V. Kaushik, J. RaghavanAbstract:Abstract Autoclave manufacturing of thermoset polymer matrix composite structures with high dimensional fidelity requires a good understanding of various parameters affecting process-induced warpage and application of this knowledge to minimize the warpage through appropriate process control. One important contributor is the interaction between a composite part and the tool on which the part is laid and Cured. This experimental study quantified the tool–part interaction by measuring the static and dynamic frictional coefficients as a function of process time, using a friction test fixture specially designed to simulate the autoclave environment. Temperature ramp rate was varied to understand the effect of autoclave Cure cycle on the friction coefficients. Measured friction coefficients were maximum at the start of the Cure cycle and varied as a function of degree of Cure (α) and ramp rate owing to change in the tool–part interface, Cure Shrinkage, resin/composite properties, residual stress, and mode of interface failure.
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experimental study of tool part interaction during autoclave processing of thermoset polymer composite structures
Composites Part A-applied Science and Manufacturing, 2010Co-Authors: V. Kaushik, J. RaghavanAbstract:Abstract Autoclave manufacturing of thermoset polymer matrix composite structures with high dimensional fidelity requires a good understanding of various parameters affecting process-induced warpage and application of this knowledge to minimize the warpage through appropriate process control. One important contributor is the interaction between a composite part and the tool on which the part is laid and Cured. This experimental study quantified the tool–part interaction by measuring the static and dynamic frictional coefficients as a function of process time, using a friction test fixture specially designed to simulate the autoclave environment. Temperature ramp rate was varied to understand the effect of autoclave Cure cycle on the friction coefficients. Measured friction coefficients were maximum at the start of the Cure cycle and varied as a function of degree of Cure (α) and ramp rate owing to change in the tool–part interface, Cure Shrinkage, resin/composite properties, residual stress, and mode of interface failure.
Sabu Thomas - One of the best experts on this subject based on the ideXlab platform.
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liquid rubber and silicon carbide nanofiber modified epoxy nanocomposites volume Shrinkage Cure kinetics and properties
Composites Science and Technology, 2014Co-Authors: Poornima P Vijayan, Jurgen Pionteck, A Huczko, Debora Puglia, J M Kenny, Sabu ThomasAbstract:A cyclic anhydride Cured epoxy modified with carboxyl-terminated poly (butadiene-co-acrylonitrile) liquid rubber (CTBN) and SiC nanofibers was developed by two different mixing strategies. In mixing method 1, SiC nanofibers were sonicated in epoxy/CTBN mixture, while in mixing method 2 the sonicated epoxy/SiC mixture was mechanically mixed with CTBN. The effects of liquid rubber, SiC nanofiber and their mixing methods on the Cure Shrinkage and Cure kinetics of an epoxy/nadic methyl anhydride system were studied using pressure–volume–temperature (PVT) analysis. The influence of SiC nanofiber and mixing method on cross-linking induced phase separation were investigated by means of optical microscopy. The glass transition temperature (Tg) and the thermal stability of nanocomposites were evaluated. The epoxy/SiC/CTBN nanocomposite prepared by method 2 exhibited enhanced Tg and thermal stability compared with neat epoxy and epoxy/CTBN blend. Moreover, improved impact strength was shown by epoxy/SiC/CTBN nanocomposites prepared by both methods, in comparison with epoxy/CTBN blend and epoxy/SiC nanocomposite. Additionally, fractographic analysis was carried out using scanning electron microscopy and a toughening mechanism for epoxy/SiC/CTBN nanocomposites was proposed.
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pvt behavior of thermoplastic poly styrene co acrylonitrile modified epoxy systems relating polymerization induced viscoelastic phase separation with the Cure Shrinkage performance
Journal of Physical Chemistry B, 2008Co-Authors: Jesmy Jose, Kuruvilla Joseph, Jiirgen Pionteck, Sabu ThomasAbstract:The volume Shrinkage during polymerization of a thermoplastic modified epoxy resin undergoing a simultaneous viscoelastic phase separation was investigated for the first time by means of pressure−volume−temperature (PVT) analysis. Varying amounts (0−20%) of poly(styrene-co-acrylonitrile) (SAN) have been incorporated into a high-temperature epoxy−diamine system, diglycidyl ether of bisphenol A (DGEBA)−4,4′-diaminodiphenyl sulfone (DDS) mixture, and subsequently polymerized isothermally at a constant pressure of 10 MPa. Volume Shrinkage is highest for the double-phased network-like bicontinuous morphology in the SAN-15% system. Investigation of the epoxy reaction kinetics based on the conversions derived from PVT data established a phase-separation effect on the volume Shrinkage behavior in these blends. From subsequent thermal transition studies of various epoxy−DDS/SAN systems, it has been suggested that the behavior of the highly intermixed thermoplastic SAN-rich phase is the key for in situ Shrinkage co...
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pvt behavior of thermoplastic poly styrene co acrylonitrile modified epoxy systems relating polymerization induced viscoelastic phase separation with the Cure Shrinkage performance
Journal of Physical Chemistry B, 2008Co-Authors: Jesmy Jose, Kuruvilla Joseph, Jiirgen Pionteck, Sabu ThomasAbstract:The volume Shrinkage during polymerization of a thermoplastic modified epoxy resin undergoing a simultaneous viscoelastic phase separation was investigated for the first time by means of pressure-volume-temperature (PVT) analysis. Varying amounts (0-20%) of poly(styrene-co-acrylonitrile) (SAN) have been incorporated into a high-temperature epoxy-diamine system, diglycidyl ether of bisphenol A (DGEBA)-4,4'-diaminodiphenyl sulfone (DDS) mixture, and subsequently polymerized isothermally at a constant pressure of 10 MPa. Volume Shrinkage is highest for the double-phased network-like bicontinuous morphology in the SAN-15% system. Investigation of the epoxy reaction kinetics based on the conversions derived from PVT data established a phase-separation effect on the volume Shrinkage behavior in these blends. From subsequent thermal transition studies of various epoxy-DDS/SAN systems, it has been suggested that the behavior of the highly intermixed thermoplastic SAN-rich phase is the key for in situ Shrinkage control. Various microscopic characterizations including scanning electron microscopy, atomic force microscopy, and optical microscopy are combined to confirm that the Shrinkage behavior is manipulated by a volume Shrinkage of the thermoplastic SAN-rich phase undergoing a viscoelastic phase separation during Cure. Consequently, a new mechanism for volume Shrinkage has been visualized for the in situ polymerization of a thermoplastic-modified epoxy resin.
Jesmy Jose - One of the best experts on this subject based on the ideXlab platform.
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pvt behavior of thermoplastic poly styrene co acrylonitrile modified epoxy systems relating polymerization induced viscoelastic phase separation with the Cure Shrinkage performance
Journal of Physical Chemistry B, 2008Co-Authors: Jesmy Jose, Kuruvilla Joseph, Jiirgen Pionteck, Sabu ThomasAbstract:The volume Shrinkage during polymerization of a thermoplastic modified epoxy resin undergoing a simultaneous viscoelastic phase separation was investigated for the first time by means of pressure−volume−temperature (PVT) analysis. Varying amounts (0−20%) of poly(styrene-co-acrylonitrile) (SAN) have been incorporated into a high-temperature epoxy−diamine system, diglycidyl ether of bisphenol A (DGEBA)−4,4′-diaminodiphenyl sulfone (DDS) mixture, and subsequently polymerized isothermally at a constant pressure of 10 MPa. Volume Shrinkage is highest for the double-phased network-like bicontinuous morphology in the SAN-15% system. Investigation of the epoxy reaction kinetics based on the conversions derived from PVT data established a phase-separation effect on the volume Shrinkage behavior in these blends. From subsequent thermal transition studies of various epoxy−DDS/SAN systems, it has been suggested that the behavior of the highly intermixed thermoplastic SAN-rich phase is the key for in situ Shrinkage co...
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pvt behavior of thermoplastic poly styrene co acrylonitrile modified epoxy systems relating polymerization induced viscoelastic phase separation with the Cure Shrinkage performance
Journal of Physical Chemistry B, 2008Co-Authors: Jesmy Jose, Kuruvilla Joseph, Jiirgen Pionteck, Sabu ThomasAbstract:The volume Shrinkage during polymerization of a thermoplastic modified epoxy resin undergoing a simultaneous viscoelastic phase separation was investigated for the first time by means of pressure-volume-temperature (PVT) analysis. Varying amounts (0-20%) of poly(styrene-co-acrylonitrile) (SAN) have been incorporated into a high-temperature epoxy-diamine system, diglycidyl ether of bisphenol A (DGEBA)-4,4'-diaminodiphenyl sulfone (DDS) mixture, and subsequently polymerized isothermally at a constant pressure of 10 MPa. Volume Shrinkage is highest for the double-phased network-like bicontinuous morphology in the SAN-15% system. Investigation of the epoxy reaction kinetics based on the conversions derived from PVT data established a phase-separation effect on the volume Shrinkage behavior in these blends. From subsequent thermal transition studies of various epoxy-DDS/SAN systems, it has been suggested that the behavior of the highly intermixed thermoplastic SAN-rich phase is the key for in situ Shrinkage control. Various microscopic characterizations including scanning electron microscopy, atomic force microscopy, and optical microscopy are combined to confirm that the Shrinkage behavior is manipulated by a volume Shrinkage of the thermoplastic SAN-rich phase undergoing a viscoelastic phase separation during Cure. Consequently, a new mechanism for volume Shrinkage has been visualized for the in situ polymerization of a thermoplastic-modified epoxy resin.
Frédéric Jacquemin - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the Cure Shrinkage, reaction kinetics, bulk modulus and thermal conductivity of thermoset resin from a single experiment
Journal of Materials Science, 2013Co-Authors: Yasir Nawab, Nicolas Boyard, Pascal Casari, Frédéric JacqueminAbstract:The use of thermoset composites has increased remarkably during the recent past in naval, automobile and aeronautical applications. Despite superior mechanical behaviour, certain problems, e.g. shape distortion, fibre buckling and matrix cracking, are induced in composite part, especially during fabrication due to the heterogeneous nature of such materials. Excellent control of the curing process is required for production of a composite part with required shape and properties. For an accurate simulation of the curing process, exact knowledge of Cure-dependent polymer properties and heat transfer is needed. Several instruments are required to identify these parameters, which is time consuming, and costly. In the present study, results on the simultaneous characterization of bulk modulus, chemical Shrinkage and degree of Cure of vinylester resin using PVT-alpha device are presented. Determination of Cure and temperature-dependent thermal conductivity of the matrix using the same device is also discussed. The obtained results are compared with the available literature results.
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Determination and modelling of the Cure Shrinkage of epoxy vinylester resin and associated composites by considering thermal gradients
Composites Science and Technology, 2012Co-Authors: Yasir Nawab, Nicolas Boyard, Pascal Casari, Frédéric JacqueminAbstract:Quantification and understanding of the evolution of chemical Shrinkage of thermoset polymers is of crucial importance for modelling of residual strains and stresses. Thermal properties of resin and the strong coupling between chemical reactions and thermal fields lead to non-negligible thermal and curing degree gradients in the part. In this paper, modelling of the volume chemical Shrinkages of an unsaturated epoxy vinylester resin and associated glass fibre composites is proposed, by taking into account the coupling between volume variation and thermal gradients. Modelling is also compared with the measurements done with a home-made instrument (PVT-alpha). Results suggest that chemical Shrinkage is non linear as a function of degree of Cure. Moreover, for an equal mass of resin, chemical Shrinkage of resin carrying fibres is lesser than the neat resin.
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A device to measure the Shrinkage and heat transfers during the curing cycle of thermoset composites
Advanced Materials Research, 2011Co-Authors: Yasir Nawab, Nicolas Boyard, Pascal Casari, Frédéric Jacquemin, Vincent SobotkaAbstract:Residual stresses development during manufacturing of composites depends mostly on the Shrinkage behaviour of the polymer matrix from the point where stresses cannot be relaxed anymore. The matrix Shrinkage may have a thermal and/or chemical origin and can leads to dimensional instability, ply cracking, delamination and fibre buckling. The approaches for measuring Cure Shrinkage can be classified as volume and non-volume dilatometry. Each technique has corresponding advantages and drawbacks but volume dilatometry is the one that is mostly used. In the present article, we report a home-built apparatus, named PVT-α mould, on which temperature, volume change and reaction conversion degree are measured simultaneously for an applied pressure. It can also be used to study the composite during curing and for the bulk samples having several millimetre thicknesses. The instrument is preferred over other techniques as it works in conditions close to the industrial ones. This device was used to measure Cure Shrinkage of resin and thermoset composite material with different fibre fractions as a function of temperature and reaction conversion degree. The heat of Cure of the resin measured by PVT-α mould was compared to the results obtained by DSC.
