Carbon fibre blends

Let us consider one final example the application of atomic force microscopy (AFM) relating to nanoscale scratch and indentation tests on short carbon-fibre-reinforced PEEK/polytetrafluoroethylene (PTFE) composite blends (Han et al, 1999). In the scratch test, the tip was moved across the surface at constant velocity and fixed applied force to produce grooves with nanometre scale dimensions on the PEEK matrix surfaces. The grooves consisted of a central trough with pile-ups on each side. These grooves provide information about the deformation mechanisms and scratch resistance of the individual phases. In the nanoscale, indentation and... 

Hollow core carbon fibres were also prepared from heterogeneous Ugnin-poly(propylene) blends, whose morphology was generated by the selective thermal ablation of the polyolefin [68]. 

Figure 6.10c SEM photographs of the fracture surfaces of epoxy/HBP blend (15 wt% HBP) in carbon fibre-reinforced plastic (CFRP) form. Reprinted with permission from D. Ratna, Composites A, 2008, 39, 462. 2008, Elsevier...

Volnme resistivities have been reported on phenol-formaldehyde [37], carbon fibre reinforced ABS terpolymer [35], natural rubber [38], polystyrene (PS) [35], HDPE-natnral fibre composites [34], carbon black filled PP-epoxy-glass fibre composites [5], XLPE [32], nanoclay reinforced EPDM-g-TMEVS [31] and epoxy resin/PANI blends [33]. 

Electrical conductivity measurements have been reported on a wide range of polymers including carbon nanofibre reinforced HOPE [52], carbon black filled LDPE-ethylene methyl acrylate composites [28], carbon black filled HDPE [53], carbon black reinforced PP [27], talc filled PP [54], copper particle modified epoxy resins [55], epoxy and epoxy-haematite nanorod composites [56], polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA) blends [57], polyacrylonitrile based carbon fibre/PC composites [58], PC/MnCli composite films [59], titanocene polyester derivatives of terephthalic acid [60], lithium trifluoromethane sulfonamide doped PS-block-polyethylene oxide (PEO) copolymers [61], boron containing PVA derived ceramic organic semiconductors [62], sodium lanthanum tetrafluoride complexed with PEO [63], PC, acrylonitrile butadiene [64], blends of polyethylene dioxythiophene/ polystyrene sulfonate, PVC and PEO [65], EVA copolymer/carbon fibre conductive composites [66], carbon nanofibre modified thermotropic liquid crystalline polymers [67], PPY [68], PPY/PP/montmorillonite composites [69], carbon fibre reinforced PDMS-PPY composites [29], PANI [70], epoxy resin/PANI dodecylbenzene sulfonic acid blends [71], PANI/PA 6,6 composites [72], carbon fibre EVA composites [66], HDPE carbon fibre nanocomposites [52] and PPS [73]. 

Tensile properties of the HDPE/RET blend are shown in Table 8.2. The HDPE 100/0 carbon-fibre composite showed complete linear stress-strain behaviour up to its ultimate tensile strength and fracture at 10.3% strain. No definitive fracture was seen in the HDPE blends. This is due to the interfacial de-bonding between the constituents within the polymer. The apparent loss of cohesive strength of the matrix material resulted in fibre pull-out and interlaminar slip between the carbon-fibre plies. 

Banthia and Nandakumar (2003) have employed secondary polypropylene micro-fibres to enhance the deformation of steel fibre-reinforced concrete. More recently, Dawood and Ramli (2012) proposed the combination of steel fibres with synthetic and palm fibres as a means of reducing the corrosion problems of fibres and improving the flowing and mechanical properties of concrete. Lee et al. (2012) have shown that the blending of nylon and polypropylene fibres improves the spalling protection of FRC subjected to fire. Azhari and Banthia (2012) have blended carbon fibres and nanotubes in the development of smart stmcture materials, such as strain sensors. 

This technique has found the following applications in addition to those discussed in Sections 10.1 (resin cure studies on phenol urethane compositions) [65], 12.2 (photopolymer studies [66-68]), and 13.3 (phase transitions in PE) [66], Chapter 15 (viscoelastic and rheological properties), and Section 16.4 (heat deflection temperatures) epoxy resin-amine system [67], cured acrylate-terminated unsaturated copolymers [68], PE and PP foam [69], ethylene-propylene-diene terpolymers [70], natural rubbers [71, 72], polyester-based clear coat resins [73], polyvinyl esters and unsaturated polyester resins [74], polyimide-clay nanocomposites [75], polyether sulfone-styrene-acrylonitrile, PS-polymethyl methacrylate (PMMA) blends and PS-polytetrafluoroethylene PMMA copolymers [76], cyanate ester resin-carbon fibre composites [77], polycyanate epoxy resins [78], and styrenic copolymers [79]. 

PEEK and polytetrafluoroethylene (PTFE) are highly incompatible. However, fine PTFE powder is commonly added to PAEK to act as an internal lubricant in tribiological applications. The PTFE smears across the wear surface and reduces interfacial friction. This reduces interfacial forces and the heat build-up that can lead to failure by melting. PTFE is particularly suitable in applications where there is no external lubricant and the compounds are often reinforced with carbon fibre. PEEK can also be added to PTFE to improve the wear properties of PTFE - although other less expensive polymers can have similar effects. More recently PAEK and PTFE have been blended so as to produce melt-processable PTFE which has a number of interesting properties [24]. This is perhaps the most luilikely example of the use of PAEK to improve the melt-processability of an otherwise hard-to-process material. 

Taipalus, R., Harmia, T, Zhang, M. Q. et al. 2001. The electrical conductivity of carbon-fibre-reinforced polypropylene/polyaniUne complex-blends Experimental characterisation and modelling. Composite Science and Technology 61 801-814. 

Fibres and fabrics, among the most difficult materials to handle via transmission spectroscopy, are quite amenable to being studied via IRS. Multiple-bounce ATR-FTIR is of importance in identifying fibres, showing quantitative blend ratios, and in the analysis of fabric additives. ATR-FTIR was used to characterise the surface of graphitised carbon fibres [186]. 

Ozaki J, Endo N, Ohizumi W, Igarashi K, Nakahara M, Ohya A, Yoshida S, lizuka T (1997) Novel preparation method for the production of mesoporous carbon fibre from a polymer blend. Carbon 35 (7) 1031-1033... 

Other recent applications of ToF-SIMS without XPS include the examination of PS [6, 17-19], polyethylene (PE) [20], carbon fibre reinforced epoxy resins [21], polyalkyl methacrylates [22], alkylketene dimers [23], perfluorinated polymers [24], perflnorinated ethers [25], polyethylene glycol (PEG) oligomers [15, 25-29], rubber [30], ethylene-tetrafluoroethylene copolymer [30], Nylon-6 [31], PC [32,33], PDMS [34], polypyrrole coated PS [35], poly-p-phenylene vinylene [36], butyl rubber [37], poly(4-vinyl phenol)/poly(4-vinyl pyridine blends) [38], polypyrrole-silica gel composites [39], y-glycidoxypropyl trimethoxy silane [40], triblock copolymer poly(ethylene glycol)- 3 poly(phenylene ethylene)- 3 poly(ethylene glycol) [41], ethylene-terephthalate-hydroxybenzoate copolymer [42], PS-polyvinyl methyl ether, polycarbonate - PS blends [43] and PDMS-urethane [44],... 

A ribbed structure substrate was made by United Technologies Corporation (UTC). Pitch based carbon fibre about 0.12-0.25 mm long was blended with phenolic resin powder and laid on a steel belt for curing in a belt press. This was subsequently graphitized. This thick ribbed substrate (around 2-3 mm) was successfully used in UTCs 40 kw PC-18 power plants. The main purpose for such high thickness was to hold sufficient phosphoric acid and to have the flow fields (the ribbed structure) embedded on the substrate itself. Thus, costly high density graphite plates that were otherwise required for flow field and separator plate can be reduced in thickness for cost efficacy. 

Comments GF = glass fibres, HI = high impact, SL = self lubricated, MF = mineral filler, CF = carbon fibres. 5200 series available for blends. 

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