FIBRE TREATMENT

More controlled and efficient fixation is possible when the reactant is applied as a pretreating agent [146]. If nylon given such a pretreatment is subsequently dyed with the conventional chlorotriazine dye Cl Reactive Red 3 (7.2), the substantivity and fixation of the latter are markedly lowered because the anionic XLC residues have reacted with N-terminal amino groups in the fibre. Treatment of the modified nylon with ammonia, however, restores some degree of dyeability. Opposite effects are observed if Cl Reactive Red 3 is reacted with ethylenediamine to form an aminoalkyl derivative (7.131). This nucleophilic dye exhibits a high degree of fixation only on the modified nylon that has been pretreated with XLC. 

Miettinen, T.A. and Tarpila, S. 1989. Serum lipids and cholesterol metabolism during guar gum, plantago ovata and high fibre treatments. Clin. Chim. Acta 183, 253-262. 

The value of Ys for the virgin fibre is in agreement with other published values (18-201. but is lower than values obtained for graphite (211. One reason for this may be the mild conditions of the fibre treatment in the column (105°C for 20 h). However, it must be noted that these conditions can be considered relevant in view of the curing conditions applied to the composite. 

Since the start of papermaking, fibre treatment has been almost a qualitative art form dependent on the skill and artistry of the operator. Fibre development has been described... 

Together, these properties will influence retention, dewatering and paper strength developments, as well as liquid-paper interactions important in converting, printing and end use applications (see Sections 3-7 below). Some illustrative examples of the interrelationship between fibre treatment processes and fibre properties are given below. 

Figure 19.8 Reaction mechanism involved during the treatment of cellulose fibres with PP maleic anhydride copolymer (MAPP) (a) activation of MAPP (T = 170°C) before fibre treatment and (b) esterification of cellulose.

Aitkin ID, Rhodes G, Spencer AP, Improvements in or relating to carbon fibre treatment, Brit. Pat., 1,353,596, 23 Sep 1970. 

Rong MZ, Zhang MQ, Liu Y, Yang GC, Zeng HM et al (2001) Effect of fibre treatment on the mechanical properties of unidirectiraial sisal-reinforced epoxy ctnnposiles. Compos Sci Technol 61 1437-1447... 

Beckermann GW, Pickering KL (2008) Engineering and evaluation of hemp fibre reinforced polypropylene composites fibre treatment and matrix modification. Compos Part A 39 979-988... 

Van de Weyenberg I, Truong T, Vangrimde B, Verpoest I (2006) Improving the properties of UD flax fibre reinforced composites by applying an alkaline fibre treatment Compos A Appl Sci 37 (9) 1368-1376... 

Jute fibre treatment Water/arr contact angle Polar surface energy (mJ m ) Flexural strength of polyester composites (MPa)... 

D. Bachtiar, S. Sapuan, and M. Hamdan, The effect of alkaline treatment on tensile properties of sugar palm fibre reinforced epoxy composites. Mater. Des. 29(7), 1285-1290 (2008). D. Bachtiar, S. Sapuan, and M. Hamdan, The influence of alkaline surface fibre treatment on the impact properties of sugar palm fibre-reinforced epoxy composites. Polym. Plast. Techn ol. Eng. 48(4), 379-383 (2009). 

Fig. 3. The surface concentration of (a) oxygen atoms, (b) oxygen atoms combined as carboxylic acid groups, (c) adsorptive sites, as a fraction (in %) of 40,000 carbon atoms contained in a graphitic segment 3.5 nm thick. DFT - degree of fibre treatment...

Fig. 6. Effect of surface treatment (degree of fibre treatment, DFT) on the mechanical performance of Type n carbon fibre epoxy composites. (1) Interlaminar shear strength of a unidirectional composite, (2) impact strength (3) notched tensile strength, of a...

Some authors have shown that not only the durability of the fibre but also the fibre-matrix adhesion may be improved with fibre treatment (Ghavami, 1995 Coutts, 2005 Tonoli et al., 2009). This is the case for natural fibres. The bonding of synthetic fibres (nylon, polyester and polypropylene) within the concrete matrix is essentially mechanical, as there is no chemical bond. In this case, the modulus of elasticity and Poisson s ratio of each material will govern the bonding properties as will the fibre geometry. 

The most studied case is where a tri-alkoxy silane is deliberately pre-hydrolysed before coating the filler, as is common practice in glass-fibre treatment. Plueddemann has given a particularly good description of the processes involved [56] and only a brief outline will be given here. 

PAEK compounds contain fibres, fillers and other effect additives. A range of compounds is available from PAEK producers and general compounders. There are also speciality products produced by a number of custom compounders - such as RTP and Lehman and Voss. Polymics produces compounds based on PEEK, PEKK and their new high temperature PAEKs. As true thermoplastics, PAEK can be compounded using conventional single-screw and twin-screw equipment. The normal effects of fillers and additives apply in PAEK as they do in other thermoplastics. However, temperature is an important limitation. Many fillers, additives, fibre treatments, etc., are too volatile or thermally unstable to be used at 400 °C. In some cases these problems could be overcome by redesign of the molecules, for example to reduce volatility, but the size of the PAEK market is relatively small and so relatively unattractive to additive developers. 

Dhakal HN, Zhang ZY, Bennett N. Influence of fibre treatment and glass fibre hybridisation on thermal degradation and surface energy characteristics of hemp/unsaturated polyester composites. Compos Part B 2012 43 2757-2761. 

Cantero G, Arbelaiz A, Llano-Ponte R, Mondragon I. Effects of fibre treatment on wet-tabihty and mechanical behaviour of flax/polypropylene composites. Compos Sci Technol 2003 63 1247-1254. 

Fernandes EM, Mano JF, Reis RL. Hybrid cork-polymer composites containing sisal fibre morphology, effect of the fibre treatment on the mechanical properties and tensile failure prediction. Compos Struct 2013 105 153-162. 

These data were collected some years ago and fibre treatments/ coatings are likely to have improved, thus improving strain capability of the fibre/matrix interface. 

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