Epoxy thermoplastics properties

Cycloahphatic diamines react with dicarboxyUc acids or their chlorides, dianhydrides, diisocyanates and di- (or poly-)epoxides as comonomers to form high molecular weight polyamides, polyimides, polyureas, and epoxies. Polymer property dependence on diamine stmcture is greater in the linear amorphous thermoplastic polyamides and elastomeric polyureas than in the highly crosslinked thermo set epoxies (2—4). 

Polyamides containing amino groups are also excellent flexibihzers for epoxies since they co-react with the epoxy resin and introduce their inherent thermoplastic properties. 

The crosslinking reaction, which occurs in the production of thermosets, also provides good adhesion to other materials. Therefore, epoxy and polyester resin matrices are used for fibre-reinforced composites, amino resins are used for bonding chipboard, while phenolics are used for bonding fibres in brake pads, and sand for metal casting. These specialised products do not fit in well with the discussion of thermoplastic properties in this... 

Alessi, S., Dispenza, C., Spadaro, G., Thermal properties of e-beam cured epoxy/ thermoplastic matrices for advanced composite materials. Macromolecular Symposia 2007,247,238-243. 

These transformers may be PVC taped, thermoplastic (polypropylene) moulded, fibreglass taped, polyester resin cast or epoxy resin cast depending upon the system voltage and the surroundings. HT indoor transformers, for instance, are generally polyester or epoxy resin cast, and are economical with good dielectric properties. They are resistant to humid, chemically contaminated and hazardous areas. Outdoor HT transformers, how-ever. may be epoxy... 

The less simple polymers (like the epoxies, the polyesters and the formaldehyde-based resins) are networks each chain is cross-linked in many places to other chains, so that, if stretched out, the array would look like a piece of Belgian lace, somehow woven in three dimensions. These are the thermosets if heated, the structure softens but it does not melt the cross-links prevent viscous flow. Thermosets are usually a bit stiffer than amorphous thermoplastics because of the cross-links, but they cannot easily be crystallised or oriented, so there is less scope for changing their properties by processing. 

Certain plastics provide higher strength and stiffness a broad range of properties exit. Even though there are literally over 35,000 plastics available worldwide (for all plastic fabricating processes) only a few hundred are used in RPs. In turn only a few of those are predominantly used in most of the RPs. The thermoplastics (TPs) include principally nylons and polypropylenes, as well as polycarbonates, acetals and polyesters. Thermosets (TSs) include predominantly polyesters as well as epoxies, phenolics and urethanes. 

Phthalazinone, 355 synthesis of, 356 Phthalic anhydride, 101 Phthalic anhydride-glycerol reaction, 19 Physical properties. See also Barrier properties Dielectric properties Mechanical properties Molecular weight Optical properties Structure-property relationships Thermal properties of aliphatic polyesters, 40-44 of aromatic-aliphatic polyesters, 44-47 of aromatic polyesters, 47-53 of aromatic polymers, 273-274 of epoxy-phenol networks, 413-416 molecular weight and, 3 of PBT, PEN, and PTT, 44-46 of polyester-ether thermoplastic elastomers, 54 of polyesters, 32-60 of polyimides, 273-287 of polymers, 3... 

Glass fibres dominate this field either as long continuous fibres (several centimetres long), which are hand-laid with the thermoset precursors, e.g., phenolics, epoxy, polyester, styrenics, and finally cured (often called fibre glass reinforcement plastic or polymer (FRP)). With thermoplastic polymers, e.g., PP, short fibres (less than 1 mm) are used. During processing with an extruder, these short fibres orient in the extrusion/draw direction giving anisotropic behaviour (properties perpendicular to the fibre direction are weaker). 

Although the main use of impact modifiers is with thermoplastics, thermosets also benefit. The agent is added at the monomer stage. Thus epoxy polymers can be made less brittle by the addition of rubbers. Care has to be taken that the high temperature properties of the thermoset are not compromised. 

Experimental results are presented that show that high doses of electron radiation combined with thermal cycling can significantly change the mechanical and physical properties of graphite fiber-reinforced polymer-matrix composites. Polymeric materials examined have included 121 °C and 177°C cure epoxies, polyimide, amorphous thermoplastic, and semicrystalline thermoplastics. Composite panels fabricated and tested included four-ply unidirectional, four-ply [0,90, 90,0] and eight-ply quasi-isotropic [0/ 45/90]s. Test specimens with fiber orientations of [10] and [45] were cut from the unidirectional panels to determine shear properties. Mechanical and physical property tests were conducted at cold (-157°C), room (24°C) and elevated (121°C) temperatures. 

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