Abstract.A modified process for the dry spinning of carbon nanotube (CNT) yarn is reported. The approach gives an improved structure of CNT bundles in the web drawn from the CNT forest and in the yarn produced from the twisted web leading to improved mechanical properties of the yarn. The process enables many different mechanical and physical treatments to be applied to the individual stages of the pure CNT spinning system, and may allow potential for the development of complex spinning processes such as polymer-CNT based composite yarns. The tensile strength and yarn/web structure of yarn spun using this approach have been investigated and evaluated using standard tensile testing methods along with scanning electron microscopy. The experimental results show that the tensile properties were significantly improved. The effect of heat treatments and other yarn constructions on the tensile properties are also reported.

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We consider the implications of a kinetic scheme, recently proposed by Billingham and Coveney (J. Billingham and P. V. Coveney, J. Chem. SOC., Faraday Trans., 1993, 89, 3021), for the hydration of cement slurries from a molecular modelling perspective. We study a range of known phosphonate cement-setting retarders which display widely differing capabilities, and in the first part of this paper we rationalise the relative efficacies of these compounds. To do this, we deployed a range of molecular modelling techniques, including energy minimisation using semi-empirical quantum mechanical and empirical force-field calculations, for both isolated molecules and molecules interacting with appropriate surfaces of ettringite. Molecular dynamics has also been used to seek out optimal conformations of these molecules on the surfaces in question. The implications of this docking mechanism for the resulting ettringite crystal morphology are also considered.Our work provides an explanation for the relative order of effectiveness of these retarders, which is confirmed by experimental studies. We have also been able to identify a powerful phosphonate retarder on the basis of this work. Using the same modelling methods as a basis for molecular design, we propose some new phosphonate retarders which might be expected to act as effective retarders. These include novel phosphonates based on the hexaaza-18-crown-6 macrocycle. One of these exotic molecules has now been synthesised and found to display significant retardation capabilities. The synthesis of related compounds is currently in progress.

Composite textiles composed of materials such as Kevlar, Dyneema and Zylon are extensively used in many force/impact protection applications, such as body armor, and automobile and airplane engine fragment resistant containment. Significant effort has been devoted to ballistic testing of composite fabrics made from various manufacturing processes and designs. Performing comprehensive ballistic and impact tests for these composite textiles is a very time-consuming and costly task. Numerical models are presented in this research, thereby providing predictive capability for the manufacturer and designer to minimize field testing, as well as shedding light on to the damage mechanisms of composite fabrics subjected to ballistic impact. Several representative composite fabric architectures (such as plain weave, basket weave and knitted fabrics) are generated for finite element analysis. Numerical investigation is conducted on these fabric structures of the same mass per unit area subjected to projectile impacts. Failure patterns of woven and knitted fabrics obtained from numerical simulations are compared with those observed experimentally. Performances of the representative textile structures are evaluated based on the resultant velocity of the projectile, as well as various energy components. The influences of yarnyarn and yarn-projectile friction properties on the ballistic performance of various textile structures are presented. To highlight the effects of projectile geometry and angular rotation on the fracture of woven and knitted fabrics, a series of simulations are also performed with three distinctive projectiles of the same mass and impact energy.

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