Melamine fibres

Melamine fibres are primarily known for their inherent thermal resistance and outstanding heat blocking capability in direct flame applications. This high stability is due to the cross-linked nature of the polymer and the low thermal conductivity of melamine resin. The dielectric properties and its cross-sectional shape and distribution make melamine ideal for high temperature filtration applications. It is sometimes blended with aramid or other high strength fibres to increase final fabric strength. 

The generic thermosets are the epoxies and the polyesters (both widely used as matrix materials for fibre-reinforced polymers) and the formaldehyde-based plastics (widely used for moulding and hard surfacing). Other formaldehyde plastics, which now replace bakelite, are ureaformaldehyde (used for electrical fittings) and melamine-formaldehyde (used for tableware). 

The most popular and efficient are substantive to the fibre typical examples are N,N -diphenylacetamidine (10.179), which tends to yellow on exposure to oxides of nitrogen, and particularly the diphenylated diamines such as N.N -diphenylethylenediamine (10.180), which does not yellow. Non-substantive inhibitors applied by padding and drying, such as triethanolamine (10.126) and melamine (10.181), have also been used despite the fact that they are removed on washing. The demand for and commercial availability of gas-fume inhibitors have declined. 

The earliest polymeric cationic aftertreatments stemmed from the development of crease-resist finishes for cellulosic fibres. One such, promoted specifically for its colour fastness improvements when applied as an aftertreatment to direct dyeings, was a condensation product of formaldehyde with dicyandiamide (Scheme 10.82). Many similar compounds followed, such as condensation products of formaldehyde with melamine (10.212), polyethylene imine) with cyanuric chloride (10.213) and alkyl chlorides with polyethylene imine) (10.214 R = alkyl). 

Glass fibre reinforced polyester melamine-formaldehyde laminate with copper foil attached is used for printing circuits. 

Korai (2001) also considered the importance of density profile of composites made from acetylated fibres in determining mechanical properties. Fibres of yellow cedar were acetylated with vapour-phase acetic anhydride and fibreboards were made from these, bonded with melamine formaldehyde resin. The results from this study indicated that bonding between fibres was the most important property determining mechanical properties. 

Dyes can also be incorporated into hydrogen-bonded superstructures using the complementarity of the hydrogen bond donors and acceptors. The addition of a perylene bisimide dye to chiral dialkyl melamine derivatives leads to aggregates (Fig. 26) which show induced circular dichroism in the dye part of the assembly in methylcyclohexane as well as the formation of mesoscopic fibres when the solvent is evaporated [227]. The melamine compounds... 

Braun, U., Schartel, B., Fichera, M.A., and Jaeger, C. 2007. Flame retardancy mechanisms of aluminium phosphinate in combination with melamine polyphosphate and zinc borate in glass-fibre reinforced polyamide 6,6. Polym. Deg. Stab. 92 1528-1545. 

Overlay Paper. Overlay paper is a-cellulose paper of high purity, with substance weight in the range 20 to 80 g m-2. An essential feature is the refractive index, which is virtually identical with that of melamine-formaldehyde resin hence, after lamination—when all the fibres of the paper are wetted and consolidated with resin devoid of air—the overlay becomes transparent. It forms a durable, hard, clear layer to protect the decorative print layer below. 

The swelling of cellulosic fibres by moisture can be reduced by the application of self crosslinking urea or melamine products as well as by products that mainly crosslink with cellulose molecules. Without such a crosslinking finish, cellulose fibres can take up more than 10 % of their weight in water. As the fibres swell, the fabric must crease and shrink to relieve the internal stresses caused by the swelling. 

The KAURIT types are either free or etherified N-methylol compounds of urea or of melamine. They are used mainly for the resin finishing of regenerated cellulose fibres, alone and in blends with synthetics. The term "self-crosslinking agents" characterizes their mode of reaction. 

The MFE type is an aminoplast based on melamine-formaldehyde resin and glass fibre. 

The Proban finish is of a similar nature and consists of padding with a solution which, to quote an example, is made up as follows 15-8 per cent THPC, 9-5 per cent methyloi melamine, 3-0 per cent triethanolamine, 9-9 per cent urea. The cloth, after impregnation, is dried and baked at 140° to 160°C (284° to 320°F). The fastness to washing of this finish is due to the fact that the phosphorus is contained within a polymer deposited in the fibre of the general structure ... 

Polymers and Life Sciences polyethylene polypropylene hydrocarbons fibre intermediates melamine agrochemicals. 

Haide A (2008) Novel Wood/Melamine Composites - Influence of Additives on Processing Behaviour and Material Properties. Lecture at the 7th Global WPC and Natural Fibre Composites Congress, June 18th-19th, Kassel, Institut fiir Werkstofftechnik Bledzki AK, Sperber VE (Ed)... 

The general paucity of FR polyamides reflects their high melt reactivities and hence poor potential flame retardant additive compatibilities. The only additive currently marketed as a potential flame retardant for polyamide fibres is Clarianf s Exolit OP930/935, which is based on a fine particulate (Dj(, 2-3pm), aluminium diethyl phosphinate. This phosphinate may be used alone or combined with melamine polyphosphate, although in bulk polymers total levels of 15wt% or so are required for acceptable levels of flame retardancy. To date it is not known whether commercially successful PA6 and PA6.6 fibres based on this agent are available. 

Cross-linking of fibres by use of polymerizable wet-strength resins such as urea-formaldehyde, melamine-formaldehyde and polymeric amine-epichlorohydrin resin systems. 

Fig. 2.22 Temperature dependence of oxygen index for various plastics 1 rigid PVC, can not be measured above 105 due to softening 2 asbestos-filled phenol/form-aldehyde moulding compound 3 epoxy-modified melamine moulding compound 4 phenol/ formaldehyde moulding compound filled with wood flour 5 glass fibre-filled epoxy resin moulding...

The flammability of polyamide fibres is usually reduced in the finishing process. Rigid yams are dressed by applying urea, thiourea, or melamine/formaldehyde resins. On the surface of flexible polyamide fibres, about 10 per cent of ammonium bromide is fixed by a urea/formaldehyde resin. Specific flame-retardant finishing is not usual. ... 

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