Search results for "Epoxy"
showing 10 items of 384 documents
Dielectric properties of a filled epoxy resin: Effect of thermal treatments
1982
Dielectric measurements have been performed at several frequencies on samples of a cycloaliphatic epoxy resin filled with aluminum hydroxide. The samples were thermally treated at three different temperatures for times up to 2,000 hours. At low aging temperatures and times an improvement of the characteristics is observed due perhaps to an assessment of the bulk of the polymer and more precisely to a change in the free volume. At high temperatures and times a thermo-oxidation involving layers deeper and deeper becomes the predominant mechanism responsible of the decrease in the properties with respect to the virgin material.
Epoxy resins as a matrix material in advanced fiber-reinforced polymer (FRP) composites
2013
Abstract: This chapter discusses the epoxy resins which, thanks to their good and versatile properties, can be considered nowadays the most important class of thermosetting polymers. In particular the chapter first reviews both the epoxy resins commonly available on the market, including a new class of bio-derived epoxy resins, and the most-used curing agents. it then describes the principal characteristics of the epoxy resins and how it is possible to enhance them by adding several fillers to the epoxy system. Finally, the chapter analyzes the main engineering fields in which epoxy resins find application today and their possible future utilization.
Distribution of molecularly imprinted polymer layers on macroporous silica gel particles by STEM and EDX
2005
Abstract Using transmission electron microscopy (TEM) in parallel and scanning mode (STEM) combined with energy dispersive X-ray spectroscopy (EDX) the distribution of molecularly imprinted polymer layers covalently grafted on the inner and outer surface of macroporous silica gel particles was observed. The grafting was achieved using a special initiator system ( iniferter ) and applied on a well known model system producing molecularly imprinted layers with l -phenyl alanine analide ( l -PA) as template. By staining the sample with RuO 4 before its embedment in epoxy resin and cutting ultra thin slices it was possible to identify the stained grafted polymer on the silica matrix by EDX. Bas…
Hydrothermal ageing of radiation cured epoxy resin-polyether sulfone blends as matrices for structural composites
2010
Abstract The hydrothermal ageing of epoxy–thermoplastic blends, used as matrices for carbon fibre composites, cured by electron beam, has been studied. Two different thermoplastic percentages have been adopted. A suitable choice of both curing process and formulation parameters allows to carry out irradiation at mild temperature with several advantages, coming from a “non thermal” process, for both the final properties of the materials and the environment. Nevertheless the occurring of vitrification phenomena needs the use of a short thermal treatment after irradiation on the already solid materials, in order to complete the cure reactions. Radiation cured epoxy based matrices have been sub…
Electrospun rubber/thermoplastic hybrid nanofibers for localized toughening effects in epoxy resins
2020
Synthetic rubber/thermoplastic blends were electrospun from their solutions. The rubber was a solid acrylonitrile/butadiene/acrylic acid copolymer and the thermoplastic was polyacrylonitrile. The aims of this study were to identify suitable systems and processing conditions for obtaining rubber-based electrospun nanofibers, to investigate the ability of an epoxy resin system to impregnate and swell selected hybrid rubber/thermoplastic mats, and to assess the impact of the nanofibers on the resin morphology and curing behavior. In particular, electrospinning trials were carried out varying the composition of the feed solution and process parameters, such as the applied voltage, the flow rate…
Carbon fibre composite materials produced by gamma radiation induced curing of epoxy resins
2008
It is well known that ionizing radiation can initiate polymerization of suitable monomers for many applications. In this work an epoxy dlfunctional monomer has been used as matrix of a carbon fibre composite in order to produce materials through gamma radiation, for aerospace and advanced automotive applications. Radiation curing has been performed at different absorbed doses and, as comparison, also thermal curing of the same monomer formulations has been done. Furthermore some Irradiated samples have been also subjected to a post Irradiation thermal curing in order to complete the polymerization reactions. The properties of the cured materials have been studied by moisture absorption isot…
Partial Discharge Tests Using CIGRE Method II Upon Nanocomposite Epoxy Resins
2007
Nanocomposite polymers are becoming a new family of dielectric materials with promising insulating properties. In order to apply this technology to insulation systems, a study about the material longterm endurance (life) is needed. In this paper results from comparative life tests performed upon base and nanostructured epoxy resin samples are presented. The nanofiller is a organophillic-modified ultra-clean montmorillonite. Specimens were subjected to ageing under surface discharge phenomena using a standard electrode configuration, that is the CIGRE method II. Life data and partial discharge phase resolved patterns, acquired during time under stress, are presented and commented, in order t…
Experimental Studies for Modelling the Phase Behaviour of Monomer/Polymer/Disc Composites
2010
Nanoparticles do not stabilize the mixtures of epoxy monomer (prepolymer)/thermoplastic modifier (PS) and the ones of thermoplastic modifier dispersed within cured epoxy matrix. A small amount of thermoplastic co-polymer poly(styrene-b-methyl methacrylate) [P(S-b-MMA)] of MMA 4-22 wt.%, mixed with PS, makes compatible the mixtures with monomer epoxy precursor and cured epoxy matrix. The mixtures of cured epoxy matrix with thermoplastic consisting of PS and P(S-b-MMA), with nanofil 1%, are stable: the instability produced by the nanofil is overcome by the stability provided by the co-polymer. A model by Balazs' group to explain the phase behaviour of polymer/clay composites is extended.
Propargyl-functional aliphatic polycarbonate obtained from carbon dioxide and glycidyl propargyl ether.
2013
The synthesis of propargyl-functional poly(carbonate)s with different content of glycidyl propargyl ether (GPE) units is achieved via the copolymerization of propargyl glycidyl ether and carbon dioxide. A new type of functional poly(carbonate) synthesized directly from CO(2) and the glycidyl ether is obtained. The resulting polymers show moderate polydispersities in the range of 1.6-2.5 and molecular weights in the range of 7000-10 500 g mol(-1). The synthesized copolymers with varying number of alkyne functionalities and benzyl azide are used for the copper-catalyzed Huisgen-1,3-dipolar addition. Moreover, the presence of vicinal alkyne groups opens a general pathway to produce functional …
High energy radiation cure of resin systems for structural adhesives and composite applications
2002
Abstract Radiation cure polymerisation of a commercial diglycidyl ether of bisphenol F epoxy resin has been achieved using a 60Co irradiation source, compounding the monomer with few percentage of an onium salt catalyst. The cure process has been monitored by a gamma-calorimetric technique and systems irradiated at doses corresponding to different positions in the gamma-calorimetric curve have been characterised via solubility tests and dynamic mechanical torsion analysis. Changes in both the measured gel fractions and tan δ values were associated with the progress of polymerisation and crosslinking reactions and these were dose dependent. Furthermore, systems irradiated at lower doses exhi…