Recent advances and perspectives on starch nanocomposites for packaging applications

Starch nanocomposites are popular and abundant materials in packaging sectors. The aim of this work is to review some of the most popular starch nanocomposite systems that have been used nowadays. Due to a wide range of applicable reinforcements, nanocomposite systems are investigated based on nanofiller type such as nanoclays, polysaccharides and carbonaceous nanofillers. Furthermore, the structures of starch and material preparation methods for their nanocomposites are also mentioned in this review. It is clearly presented that mechanical, thermal and barrier properties of plasticised starch can be improved with well-dispersed nanofillers in starch nanocomposites

Tooling design and microwave curing technologies for the manufacturing of fiber-reinforced polymer composites in aerospace applications

The increasing demand for high-performance and quality polymer composite materials has led to international research effort on pursuing advanced tooling design and new processing technologies to satisfy the highly specialized requirements of composite components used in the aerospace industry. This paper reports the problems in the fabrication of advanced composite materials identified through literature survey, and an investigation carried out by the authors about the composite manufacturing status in China’s aerospace industry. Current tooling design technologies use tooling materials which cannot match the thermal expansion coefficient of composite parts, and hardly consider the calibration of tooling surface. Current autoclave curing technologies cannot ensure high accuracy of large composite materials because of the wide range of temperature gradients and long curing cycles. It has been identified that microwave curing has the potential to solve those problems. The proposed technologies for the manufacturing of fiber-reinforced polymer composite materials include the design of tooling using anisotropy composite materials with characteristics for compensating part deformation during forming process, and vacuum-pressure microwave curing technology. Those technologies are mainly for ensuring the high accuracy of anisotropic composite parts in aerospace applications with large size (both in length and thickness) and complex shapes. Experiments have been carried out in this on-going research project and the results have been verified with engineering applications in one of the project collaborating companies

Synthesis and Characterization of a Poly (styrene-block-methylacrylate-random-octadecylacrylate-block-styrene) Shape Memory ABA Triblock Copolymer

A new shape memory polymer (SMP) was prepared from an ABA triblock copolymer with polystyrene (PS) end blocks and a random copolymer midblock of poly(methylacrylate-random-octadecylacrylate) (PMA-r-PODA). The self-assembly of the triblock copolymer generates a three-dimensional, physically cross-linked network by the bridging of the midblocks across the glassy PS domains, which is used as the permanent network in the SMP. A second reversible network is generated by the side-chain crystallization of the PODA side-chains. Shape memory testing by uniaxial deformation and recovery of molded tensile bars demonstrated that shape fixities greater than 96% and shape recoveries greater than 98% were obtained for extensional strains up to 300%. Although some loss of properties was observed with cycling, the entirely physically cross-linked nature of the polymer allowed erasing of the sample history and recovery of the initial properties by annealing the sample at elevated temperature

Optimization of a variable-stiffness skin for morphing high-lift devices

One of the possibilities for the next generation of smart high-lift devices is to use a seamless morphing structure. A passive composite variable-stiffness skin as a solution to the dilemma of designing the structure to have high enough stiffness to withstand aerodynamic loading and low stiffness to enable morphing is proposed. The variable-stiffness skin is achieved by allowing for a spatial fibre angle and skin thickness variation on a morphing high-lift system. The stiffness distribution is tailored to influence the deformation of the structure beneficially. To design a realistic stiffness distribution, it is important to take aerodynamic and actuation loads into account during the optimization. A two-dimensional aero-servo-elastic framework is created for this purpose. Skin optimization is performed using a gradient-based optimizer, where sensitivity information is found through application of the adjoint method. The implementation of the aero-servo-elastic environment is addressed and initial optimization results presented. The results indicate that a variable-stiffness skin increases the design space. Moreover, the importance of taking the change in aerodynamic loads due to morphing skin deformation into account during optimization is demonstrated.Department of Aerospace StructuresAerospace Engineerin