Polymer fibre array

The polymer fibre is considered to be composed of a parallel array of identical fibrils. A single fibril is a series arrangement of domains with a varying angle to the fibre axis described by the orientation function p(Q) in the unloaded state. The strength of a domain is supposed to be given by... 

The scope of UV analysis of dissolved polymer/additive matrices is thus quite restricted and mainly limited to special cases in which the additive package is known, e.g. the determination of Irganox 1098 in GFR-PA4.6 after dissolution in H2SO4/HNO3. Fibre-optic dissolution analysis by means of a UV diode array spectrometer is well known. In comparison to IR spectroscopy, UV spectrophotometry is better equipped to provide quantitative data. 

Intuitively, however, the RVE for an amorphous polymer may be expected to be no more than 10 nanometres or so. In an aligned fibre composite with continuous fibres we need to take a sample sufficiently large as to contain perhaps 30 to 50 fibres in a lateral dimension and in this case the coefficient of variation of stress as between fibres would enable a measure to be decided. In a random array of fibres however (chopped strand mat) the RVE must be of the order of a fibre length at least as is also the case for an aligned short fibre composite. 

Surface-enhanced Raman spectroscopy [252], a method based on an array of sensory polymers attached to fibre optics [253], has been used to determine down to 5 ppb and 100 ppb of 2,4-dinitrotoluene in soil. 

Catalysts and catalysis are fundamental to being able to produce the fuels, polymers, medicines, plant growth regulators and herbicides, paints, lubricants, fibres, adhesives and a vast array of other consumer products. As well as catalysis contributing some 20% to the Gross Domestic Product of the USA, it is also estimated that 80% of all chemicals processes, with a total value of more than US 1800 billion, involve a catalyst at some point. 

Despite the antiquity of filtration processes involving nonwovens, e.g. felts, laps, paper etc. media developmoits continue to appear involving modem fibres prepared from polymers, glass, fluorocarbons, etc. These are used alone, or in mixtures with traditional fibres such as wool, cotton, cellulose, etc., to produce a vast array of media aimed at solid-liquid separation. A detailed listing of the relevant phydcal properties of these fibres is available in the literature jPurchas, 1981]. 

Also, the electrospun fibres can be deposited either randomly to form a nonwoven web or in an oriented manner to give an aligned nanofibre array. Twisting nanofibre bundles can form nanofibre yarns. Within the fibre web, the nanofibres can be connected physically or bonded at cross-points to form an interconnected spider web . In addition, two polymer components have been combined to form side-by-side, or sheath-core, bicomponent electrospun fibres. 

For many polymeric materials, their mechanical properties are isotropic in other words, their behaviour is independent of the direction of measurement. Rubbers and glasses having chains in random orientation fall into this category. Crystalline polymers composed of a random array of crystalline units (i.e. polycrystalline polymers) are also isotropic, as are short-fibre reinforced plastics in which the fibres are randomly distributed within the material. ... 

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