Search results for "THERMOSET"
showing 10 items of 42 documents
Thermal and rheological characterisation of a thermoset matrix for filament winding modelling
2004
Rheo-kinetic behaviour of an epoxy resin, coupled with an aliphatic polyamines hardener, used in fibre reinforced plastics, was analysed comparing experimental data to theoretical models. Then the modelling of technological filament winding process for thermoset matrix composites, developed through a numerical code realized with MATLAB, is reported. The model includes winding and curing phase decoupling the manufacturing process into sub-models. Four sub-models are used: fibre motion, thermal, kinetic and rheological model. Considerable differences are obtained in process condition, using several thermal treatments. The numerical modelling helps to detect the process conditions to optimise…
Sustainable access to biobased biphenol epoxy resins by electrochemical dehydrogenative dimerization of eugenol
2019
Limited fossil resources require innovative monomers and polymers derived from renewable feedstocks such as plant biomass. Thermosetting epoxy resins largely rely on petrochemical bisphenol-type monomers, which give high performance materials but are controversial due to their effects on human health. Herein, we present two biobased epoxy resins by direct dehydrogenative dimerization of eugenol, the main component of clove oil. Taking the Principles of Green Chemistry into account, we developed electrochemical dehydrodimerization at reticulated vitreous carbon (RVC) electrodes using methanol as environmentally benign solvent. Thus, fluorinated solvents such as 1,1,1,3,3,3-hexafluoroisopropa…
Properties of radiation-modified blends of polyethylene with elastomers and liquid crystalline copolyester
2001
The results are given on the effect of γ-irradiation on properties of blends of high and low-density polyethylene (HDPE, LDPE) with elastomers -ethylene/propylene/diene rubber (EPDM) and chlorinated polyethylene (CPE), and thermotropic liquid crystalline polymer (LCP). The morphological, thermal, mechanical properties (including thermosetting properties) and adhesion properties of blended composites were investigated. A special attention was paid to the applicability of the blends as thermosetting materials (TSM). The LCP used was a copolyester of poly(ethylene terephthalate) with p-(hydroxybenzoic acid) in the ratio 40: 60. It was found that addition of LCP essentially influenced the therm…
Curing of an epoxy resin modified with nanoclay monitored by dielectric spectroscopy and rheological measurements
2006
Dielectric and rheological measurements have been performed in “real-time” to follow curing reaction on blends of a diglycidyl ether of bisphenol-A epoxy resin with 4,4-methylene bis(2,6-diethylaniline) hardener and different amounts of organically modified nanoclay (Nanofil 919) as modifier. The effect of the modifier and its amount on the curing reaction, as well as that of the curing temperature has been studied. Changes in molecular mobility in the reaction mixture have been investigated by dielectric relaxation spectroscopy. Evolutions of ionic conductivity and main relaxation have been analyzed and vitrification times have been obtained and compared with those obtained by rheological …
Simultaneous measurement of temperature and strain in glass fiber/epoxy composites by embedded fiber optic sensors: I. Cure monitoring
2007
In this paper (Part I) the use of fiber optic sensors for real-time monitoring of the cure kinetics of GFRP composites is explored. The proposed sensing system allows the simultaneous measurement of both temperature and strain by monitoring the change in reflected wavelength from two coupled fiber Bragg grating (FBG) sensors that have been embedded into the composite laminate. Instrumented GFRP laminates with 12, 18 and 24 reinforcing plies, respectively, were prepared by means of the vacuum bagging technique. Samples were cured in a thermally controlled oven at 80 degrees C and 30 kPa for 240 min (isothermal stage) and then cooled down to ambient temperature by turning off the heating sour…
The effect of a liquid CTBN rubber modifier on the thermo-kinetic parameters of an epoxy resin during a pultrusion process
2003
Abstract Rheo-kinetic behaviour of an epoxy resin, coupled with an anhydride hardener, with different CTBN liquid rubber concentration (0–15 phr), used in fibre reinforced plastics, was analysed comparing experimental data with theoretical models. The modelling of technological pultrusion process for thermoset matrix composites, developed through a numerical code realised with MATLAB, is reported, too. The model includes conduction and cure heat, degree of cure and viscosity evolution during the curing within the die. Considerable differences in process condition, using different rubber amount, are obtained. The numerical modelling of process conditions shows that the CTBN rubber presence i…
Fracture Toughness of Hydrothermally Aged Epoxy Systems with Different Crosslink Density
2015
Abstract The present work investigates the fracture toughness behaviour of Single Edge Notched Bending (SENB) samples of epoxy systems subject to water uptake aging. Two epoxy systems with a significantly different Glass Transition Temperature, T g , are in particular considered: a typical commercial non-aeronautical grade resin matrix for composite applications, reaching a T g of 90 °C, and a DGEBA+DDS epoxy system achieving a T g of 230 °C.The materials have been conditioned by hydrothermal aging in a thermal bath at the temperature of 50 °C. TransmissionPhotoelastic Stress Analysisis carried outon SENB samples during water aging, monitoring the presence and evolution of swelling stresses…
New concept in bioderived composites: Biochar as toughening agent for improving performances and durability of agave-based epoxy biocomposites
2021
Biocomposites are increasingly used in the industry for the replacement of synthetic materials, thanks to their good mechanical properties, being lightweight, and having low cost. Unfortunately, in several potential fields of structural application their static strength and fatigue life are not high enough. For this reason, several chemical treatments on the fibers have been proposed in literature, although still without fully satisfactory results. To overcome this drawback, in this study we present a procedure based on the addition of a carbonaceous filler to a green epoxy matrix reinforced by Agave sisalana fibers. Among all carbon-based materials, biochar was selected for its environment…
Thermomechanical properties of radiation-modified blends of polyethylene with liquid crystalline copolyester
1999
The results of investigation of gamma irradiated blends of high-density polyethylene (PE) with thermotropic polymer liquid crystal (PLC) are presented. The PLC used was a copolyester of 40% poly(ethylene terephthalate) with 60% p-(hydroxy-benzoic acid). The PLC content in the blends was 0, 5, and 10 wt%. The constituents were blended with the use of a single screw extruder. The specimens were prepared by compression molding. The irradiation of the samples was performed by a Co 60 γ-radiation source in inert atmosphere (argon) up to absorbed relatively low doses (up to 200 kGy: 1 Mrad = 10 kGy). The morphological, thermal, and mechanical properties were investigated for irradiated and unirra…
Study and comparison of interaction parameters and phase behavior of epoxy/polystyrene and epoxies copolymer polystyrene-b-poly(methyl methacrylate) …
2008
Thermodynamic studies in terms of phase separation behavior and interaction parameters, in mixtures of epoxy resins (thermoset materials) with thermoplastic additives, consisting of polystyrene (PS) or polystyrene-b-poly(methyl methacrylate) P(S-MMA) (with small proportion of MMA), have been carried out. It can be confirmed that the solubility of P(S-MMA) is an improvement on that of PS, with the prepolymer epoxy resins. Moreover, the interaction parameters are positive at temperatures in which phase separation is observed, but negative at temperatures in which the phase separation window disappears, in the corresponding phase diagram. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engine…