Fillers Fibres

The adsorption of ionic polyelectrolytes by mineral fillers, fibres and fines is an essential first step in many chemical modification... 

The sensitivity of o-Ps to small holes and defects in the material renders PALS a potentially interesting technique for studying composites. If the adhesion between the filler/fibres and the matrix is poor, small voids or defects may be present at the interface which may be detected by the positrons. On the other hand, if the coupling between the constituents in the composite is good, there may be an... 

Nearly every polymeric system absorbs some moisture under normal atmospheric conditions from the air. This can be a difficult to detect, very small amount as for polyethylene or a few percent as measured for nylons. The sensitivity for moisture increases if a polymer is used in a composite system i.e. as a polymeric matrix with filler particles or fibres dispersed in it. Hater absorption can occur then into the interfacial regions of filler/fibre and matrix [19]. Certain polymeric systems, like coatings and cable insulation, are for longer or shorter periods immersed in water during application. After water absorption, the dielectric constant of polymers will increase due to the relative high dielectric constant of water (80). The dielectric losses will also increase while the volume resistivity decreases due to absorbed moisture. Thus, the water sensitivity of a polymer is an important product parameter in connection with the polymer s electrical properties. The mechanical properties of polymers are like the electrical properties influenced by absorption of moisture. The water sensitivity of a polymer is therefore in Chapter 7 indicated as one of the key-parameters of a polymeric system. 

From its very beginning, papermaking has been targeted to produce a homogeneous sheet structure out of large volumes of water containing small amounts of fibre and filler. Fibre concentrations of below 1% are quite common in this context. 

Table 8 Values of for Some Polymers, Colloids, Fillers, Fibres and Pigments... 

Compound A mixture of one or more polymers which encapsulates other ingredients (e.g., colorants, fillers, fibres, and stabilisers) that enhance the physical properties of the mixture. A compound is used as such by a plastics processor. 

A composite pigment-biopolymer structure with potential use in biocomposites can be formed by different techniques, such as precipitation, mixing, self-assembly, or hierarchical methods. There are many open questions about the production, use, and potential benefits of these filler-fibre complexes. In this chapter, we present some targeted work, which investigated biopolymer composites produced by in situ calcium carbonate precipitation and mixing techniques. 

Bonds (plus a gap-filler), fibre-reinforced composites, plus wood, steel, aluminium and concrete. Available for use with 3 different hardener systems, 273, 275 and 277 offering different gel and cure time. Dual cartridge system eliminates measuring and mixing. Colour change denotes full cure. 

Cellulose fibre is a possible choice as a replacement for glass fibre [1], Cellulose fibre has attractive characteristics of superior mechanical properties, low density, high aspect ratio, and nonabrasiveness. Besides, unlike other natural fillers/fibres, cellulose fibre contains little extractives, which may reduce emission of volatiles during processing and thus be suitable for extrusion or injection foaming process. However, the mechanical properties of cellulose fibre reinforced composites need to be further improved, especially impact strength. 

Microcellular or fine-celled foaming is one way to improve impact strength of natural filler/fibre composites [2,3] while reducing material weight and use. In order to achieve such improvement, it is essential to control cell morphology. However, there are technical difficulties in controlling the foam structure of natural filler/fibre... 

This includes wire enamels on a base of polyvinyl formal, polyurethane or epoxy resins as well as moulding powder plastics on phenol-formaldehyde and similar binders, with cellulose fillers, laminated plastics on paper and cotton cloth base, triacetate cellulose films, films and fibres of polyethylene terephthalate. 

This is also known as Bulk Moulding Compound (BMC). It is blended through a mix of unsaturated polyester resin, crosslinking monomer, catalyst, mineral fillers and short-length fibrous reinforcement materials such as chopped glass fibre, usually in lengths of 6-25 mm. They are all mixed in different proportions to obtain the required electromechanical properties. The mix is processed and cured for a specific time, under a prescribed pressure and temperature, to obtain the DMC. 

Fibrous fillers are often embedded in a laminar form. The fibres used have higher moduli than the resins in which they are embedded so that when the composite of resin plus fibre is strained in the plane of the fibrous layer the bulk of the stress is taken up by the fibre. This results in an enhancement of both strength and modulus when compared with the unfilled resin. 

Incorporation of fillers such as glass fibre, wood flour, etc. 

Both fibres and sphere fillers tend to improve self-extinguishing characteristics. 

Commercial grades of polymer may contain, in addition to glass fibre, fire retardants, impact modifiers and particulate reinforcing fillers. Carbon fibre may be used as an alternative to glass fibre. 

Several blends based on polysulphone materials have been marketed. Probably the most well known is Mindel, originally produced by Uniroyal, acquired by Union Carbide, but now marketed by Amoco. Whilst not exhibiting the heat resistance of the unblended homopolymer, Mindel materials, which are blends of polysulphone and ABS, are lower in cost, easier to process and have higher notched impact strengths. The Mindel A materials are unreinforced, the Mindel B grades contain glass fibre, and the Mindel M grades contain other mineral fillers. A related polysulphone/SAN blend has been marked as Ucardel. 

Industrial grade materials employ fillers such as asbestos, silica and glass fibre. These are incorporated by dry-blending methods similar to those used with woodflour-filled phenolic compositions. 

A large number of grades is available, one supplier alone offering about 40, including unreinforced, glass- and carbon-fibre reinforced, mineral filler reinforced, impact modified, elastomer modified, flame retardant and various combinations of the foregoing. 

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