Poly -epoxy composite

Another approach employing concepts of continuum damage mechanics (e.g., Lemaitre and Chaboche 1994) was presented by Perreux and Suri (1997). Studying the effects of cyclic fatigue on [ 55°]3 glass fiber/poly epoxy composite pipes they noticed that in the absence of stress moisture uptake data could be modeled as a process of a two-phase diffusion (see Sect. 3.6). Damage in the axial direction was related to the decrease in the axial stiffness, namely and its effect on... 

Scherf, J., Cohen, Y. and Wagner, H.D. (1992). Interfacial strength measurements in poly (p-phenylene benzobisthiazole)/epoxy composites. Intern. J. Adhesion Adhesive, 12, 251-256. 

Figure 4. Stress/strain curve for an aligned poly DCHD/epoxy composite.

Figure 5. Variation of Youngs modulus, E with for poly DCHD/ epoxy composites. The lines V and R denote the Voigt and Reuss bounds respectively.

Thermal Stability and Conductivity. Thermal degradation temperature of PMMA, PS, and PVA (poly(vinyl alcohol)) nanocomposites shifts up by 10-100°C. During combustion [179], nanoparticles form a network of char layers that retards the transport of decomposition products. The thermal conductivity of epoxy composites is four times higher than that of the neat epoxy resin with 5 wt% loads. 

Fig. 11. Fracture surfaces ( x200) of fibre-epoxy composites using (a) glass fibre, (b) heat treated poly (p benzamide) fibre.

Finally, a word about the fracture properties of poly(p-benzamide) fibre. Not unexpectedly it appears that the extreme axial properties of the fibre have to be paid for in terms of very poor transverse properties. Indeed the higher the modulus the greater is the tendency for the fibre to exhibit a failure mode consisting of fibrillation and splintering. Words cannot describe this as well as the Stereoscan photograph (Fig. 10) and Fig. 11 which compares fracture surfaces in a glass fibre-epoxy composite (a) and a poly(p-benzamide)-epoxy composite (b) prepared in the authors laboratories. 

Bokobza, L. Burr, A. Garnaud, G. Perrin, M. Pagnotta, S. (2004) Fibre Reinforcement of Elastomers Nanocomposites Based on Sepiolite and Poly(hydroxyethyl acrylate). Polym. Int. Vol.53, N0.8, pp.1060-1065, ISSN 0959-810 Bonduel, D. Mainil, M. Alexandre, M. Monteverde, F. Dubois, P. (2005) Supvported Coordination Polymerisation A Unique Way to Potent Polyolefin Carbon Nanotube Nanocomposites. Chem. Commun. Vol.l4, No.6, pp.781-783 Bruckner, S. Meille, S. Petraccone, V. Pirozzi, B. (1991) Polymorphism in Isotactic Polypropylene. Prog. Polym. Sci. 16, No.2-3, pp.361-404 Bryning, M. Islam, M Kikkawa, J. Yodh, A. (2005) Very Low Conductivity Threshold in Bulk Isotropic Single-Walled Carbon Nanotube-Epoxy Composites. Ado. Mater. Vol.17, N0.9, pp.1186-1191... 

The effect of ultra-high molecular weight poly-(ethylene) (UHMWPE) the on mechanical and solid particle erosive wear behavior of aramid fabric reinforced-epoxy composites has been investigated [64]. A siUca sand of a size of 150-280 fim was used as an erodent. The erosive wear rate of UHMWPE in aramid-epoxy composite exhibits a lower value in comparison to neat composites. A maximum erosion rate was observed at an impingement angle 60 , and the material behaves in a semiductile manner. 

Such polymer conversion methods were used to prepare Ba, and Cu + complexes with poly(methacrylic acid)" " and YBC chelates with polyamides." "" " Gel formation with poly(vinyl alcohol) (PVA) can also be used." The superconducting ceramics based on these metallopolymers have values = 80-92K, and critical current densities (J ) of 150-160 A cm . Films and fibers in addition to powders, can be prepared from these ceramics. YBC-epoxy composites are also suitable for this pur-pose." ... 

Masoodi R, El-Hajjar RF, Pillai KM, Sabo R (2012) Mechanical characterization of cellulose nanofibca- and bio-based epoxy composite. Maha- Des 36 570-576 Melo Cd, Garcia PS, Grossmann MVE, YamashitaF, Dali Antonia LH, Mali S (2011) Properties of extraded xanthan-starch-clay nanocomposite films. Braz Arch Biol Technol 54 1223-1333 Mogri Z, Paul DR (2001) Water-vapor permeation in semicrystalhne and molten poly(octadecyl acrylate). J Polym Sci, Part B Polym Phys 39 979-984 Mohanty AK, Misra M, Drzal LT (2002) Sustainable bio-composites from renewable resources opportunities and challenges in the green mahaials worid. J Polym Environ 10 19-26... 

Bullions TA, Loos AC, McGrath JE (2003) Moisture sorption effects on and properties of a carbon fiber-reinforced phenylethynyl-terminated poly(etherimide). J Compos Mater 37(9) 791-809 Carpenter IF (1973) Moisture sensitivity of epoxy composites and structural adhesives. 

He J, Wang J (2009) Preparation and characterization of epoxidate poly(l,2-butadiene) -toughened diglycidyl ether bisphenol-a epoxy composites. J Appl Polym Sci 113 3165-3170. doi 10.1002/app... 

Poly(p-phenylene terephthalamide) fibres currently have three major applications, namely as reinforcement in radial tyres and mechanical rubber goods, in ballistic protective fabrics and ropes, and as reinforcement in polymer (particularly epoxy) composites for aircraft and aerospace components. 

In addition to carbon and glass fibers ia composites, aramid and polyimide fibers are also used ia conjunction with epoxy resias. Safety requirements by the U.S. Federal Aeronautics Administration (FAA) have led to the development of flame- and heat-resistant seals and stmctural components ia civiUan aircraft cabias. Wool blend fabrics containing aramids, poly(phenylene sulfide), EDF, and other inherently flame-resistant fibers and fabrics containing only these highly heat- and flame-resistant fibers are the types most frequently used ia these appHcations. 

Pyrotechnic mixtures may also contain additional components that are added to modify the bum rate, enhance the pyrotechnic effect, or serve as a binder to maintain the homogeneity of the blended mixture and provide mechanical strength when the composition is pressed or consoHdated into a tube or other container. These additional components may also function as oxidizers or fuels in the composition, and it can be anticipated that the heat output, bum rate, and ignition sensitivity may all be affected by the addition of another component to a pyrotechnic composition. An example of an additional component is the use of a catalyst, such as iron oxide, to enhance the decomposition rate of ammonium perchlorate. Diatomaceous earth or coarse sawdust may be used to slow up the bum rate of a composition, or magnesium carbonate (an acid neutralizer) may be added to help stabilize mixtures that contain an acid-sensitive component such as potassium chlorate. Binders include such materials as dextrin (partially hydrolyzed starch), various gums, and assorted polymers such as poly(vinyl alcohol), epoxies, and polyesters. Polybutadiene mbber binders are widely used as fuels and binders in the soHd propellant industry. The production of colored flames is enhanced by the presence of chlorine atoms in the pyrotechnic flame, so chlorine donors such as poly(vinyl chloride) or chlorinated mbber are often added to color-producing compositions, where they also serve as fuels. 

Fig. 19. Inlerfacial shear strengths of various fiber/matrix composites as a function of the work of adhesion as determined by IGC. 1, glass fiber-poly (ethylene) 2, carbon fiber-epoxy B 3, carbon fiber-epoxy A and 4, carbon fiber-PEEK. Redrawn from ref. [102].

Although a majority of these composite thermistors are based upon carbon black as the conductive filler, it is difficult to control in terms of particle size, distribution, and morphology. One alternative is to use transition metal oxides such as TiO, VO2, and V2O3 as the filler. An advantage of using a ceramic material is that it is possible to easily control critical parameters such as particle size and shape. Typical polymer matrix materials include poly(methyl methacrylate) PMMA, epoxy, silicone elastomer, polyurethane, polycarbonate, and polystyrene. 

Fig, 29. Dependence of the impact strength of the composition poly(vinyl chloride), epoxy resin, nitrile rubber on rubber content. 1 0% of SKN18M 2 5% of SKN18M 3 10% of... 

There are a number of inert binders such as polyester, epoxy, polysulfide, polyurethane which have been reported as binders for composite propellants and plastic bonded explosives (PBXs). At present, hydroxy-terminated polybutadiene (HTPB) is regarded as the state-of-the-art workhorse binder for such applications. However, the recent trend is to use energetic binders such as poly [3,3-bis(azidomethyl oxetane)] [poly(BAMO)], poly (3-azidomethyl-3-methyl oxetane) [poly(AMMO)], PNP, GAP diol and triol, nitrated HTPB(NHTPB), poly(NiMMO), poly(GlyN) and nitrated cyclodextrin polymers poly(CDN) for PBXs and composite propellants in order to get better performance. 

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