An electrophoretic deposition (EPD) prototype was developed aiming at the continuous production of carbon nanotube (CNT) deposited carbon fiber fabric. Such multi-scale reinforcement was used to manufacture carbon fiber-reinforced polymer (CFRP) composites. The overall objective was to improve the mechanical performance and functionalities of CFRP composites. In the current study, the design concept and practical limit of the continuous EPD prototype, as well as the flexural strength and interlaminar shear strength, were the focus. Initial mechanical tests showed that the flexural stiffness and strength of composites with the developed reinforcement were significantly reduced with respect to the composites with pristine reinforcement. However, optical microscopy study revealed that geometrical imperfections, such as waviness and misalignment, had been introduced into the reinforcement fibers and/or bundles when being pulled through the EPD bath, collected on a roll, and dried. These defects are likely to partly or completely shadow any enhancement of the mechanical properties due to the CNT deposit. In order to eliminate the effect of the discovered defects, the pristine reinforcement was subjected to the same EPD treatment, but without the addition of CNT in the EPD bath. When compared with such water-treated reinforcement, the CNT-deposited reinforcement clearly showed a positive effect on the flexural properties and interlaminar shear strength of the composites. It was also discovered that CNTs agglomerate with time under the electric field due to the change of ionic density, which is possibly due to the electrolysis of water (for carboxylated CNT aqueous suspension without surfactant) or the deposition of ionic surfactant along with CNT deposition (for non-functionalized CNT aqueous suspension with surfactant). Currently, this sets time limits for the continuous deposition.

Itis important within the composite community to improve out-of-plane performance ofcomposites dominated by polymer matrix and properties of matrix-rich regions formed in the gapsbetween the interlaced fibre bundles. These properties are difficult to modify with traditional fibrereinforcement. Various nanoscale materials have been explored for such purpose, among which carbonnanotube (CNT) has been suggested as an ideal candidate because of its outstanding mechanical,electrical and thermal properties (1). Electrophoretic deposition (EPD) is considered as a cost-effectivemethod to deposit CNTs onto substrates with mild working conditions, requiring relatively simpleequipment and being amenable to scaling up (2,3). Due to the shortcoming of existing laboratory setupwhich corresponds to a non-continuous process, EPD has not been used at even a pilot plant scale fornano-coated fibre reinforcement. The current work presents the development of a prototype andmethod for continuous EPD process. Geometric defect of fibre reinforcement introduced during thedeposition, which can shadow the reinforcing effect of CNT deposit, was discovered. Enhancement ofcomposite properties by the CNT deposit was hence shown.

A new concept, Re-Fib, was developed within an EU project, REFORM, to recycle carbon and glass fibres from polymeric composite structures, aiming to reduce energy consumption and degradation of fibre properties during recycling. The optimized thermolysis treatment, 24 h at 380 °C, was verified able to recover clean fibres from most tested composite structures containing different thermoset resins (epoxy, vinyl ester, and polyester) and various core materials such as polyvinyl chloride (PVC), polyurethane (PU), and wood. Single-fibre test was performed in dynamic mechanical analysis (DMA). The reduction of strength was found around 26% for carbon fibres and 34–40% for glass fibres. Thermally recycled glass fibres were melt-compounded with recycled polypropylene (rPP); the resultant composites showed promising mechanical properties.

A race towards a more sustainable society is going on worldwide, and decreasing dependence on fossil resources in energy and transport sectors are main goals. One path to decreased oil usage is development of lightweight materials from renewable resources like bio-based composites. However, these new bio-based materials not only have to compete in mechanical performance but also have to restrain environmental loads like moisture and temperature over time. In this study, two bio-based composites have been compared to an oil-based composite in terms of long-term properties and water absorption behaviour. The long-term behaviour is determined by dynamic mechanical thermal analysis, DMTA and time temperature superposition, TTSP. The water uptake is determined by submersion of specimens into water and tracking their weight change over time. The moisture influence is characterised in form of water uptake and change in the master curves created by TTSP procedure. The results show that there is a significant difference in long-term performance between the bio-based and oil-based composites. It is realised that the bio-based composites can be a good alternative for some applications especially when taking their eco-friendly nature into account. © 2014 Springer Science+Business Media New York.

In this study, three different types of bio-based resins are compared to a conventional oil-based epoxy in terms of moisture uptake, long-term properties and its influence of moisture and glass transition temperature, T g. Moisture uptake is determined by means of gravimetric method, time temperature superposition (TTSP), and T g data obtained in dynamic mechanical thermal analysis (DMTA). Moisture uptake show Fickian diffuison behavour for all resins, saturation level and diffusion coefficient however differ. The long-term properties is characterised by creep compliance master curves created by means of TTSP. The examined bio-based resins are compatible to the reference epoxy in term of stability up to 3-10 years. Comparison between master curves for virgin, wet, and dried material show that moisture present in the specimen increases creep rate, and that some of this increase remains after drying of samples. T g measurements show that moisture inside the specimen decreases T g; this is anticipated because of the plasticizing effect of water. The overall conclusions are that the bio-based resins of polyester, and epoxy type are comparable in performance with oil-based epoxy, LY556 and they can be used to develop high-performance composites.

The objective of this investigation is to predict mechanical behavior of bio-based composites and their constituents by generalizing existing models to capture their time-dependent behavior. In order to identify and quantify parameters needed for the modeling, extensive damage tolerance tests as well as creep experiments are carried out.

Regenerated cellulose fibres and their composites exhibit highly nonlinear behaviour. The mechanical response of these materials can be successfully described by the model developed by Schapery for time-dependent materials. However, this model requires input parameters that are experimentally determined via large number of time-consuming tests on the studied composite material. If, for example, the volume fraction of fibres is changed we have a different material and new series of experiments on this new material are required. Therefore the ultimate objective of our studies is to develop model which determines the composite behaviour based on behaviour of constituents of the composite. This paper gives an overview of problems and difficulties, associated with development, implementation and verification of such model.

In this work, organoclay reinforced high density polyethylene (HDPE) nanocomposites were prepared at laboratory scale using a batch mixer. Processing conditions, maleic anhydride modified polyethylene (MAPE) type and MAPE/clay weight ratio were optimised. The microstructure of the resultant nanocomposites was analysed by X-ray diffraction and melt rheology tests, and flexural properties and thermal stability were evaluated. Three types of MAPEs with different melt flow indices (MFI) and maleic anhydride contents all improved the interaction between HDPE and clay and promoted clay dispersion. Nanocomposites where the MAPE with MFI most similar to HDPE was used showed the best exfoliation of clay and the strongest HDPE/clay interface. Mechanical properties were slightly improved, while thermal stability was distinctly enhanced in these HDPE nanocomposites compared with neat HDPE and HDPE nanocomposite without MAPE. The prepared HDPE nanocomposites show the potential to improve the thermal stability of wood-plastic composites for structural applications. © 2013 Institute of Materials, Minerals and Mining.

Barrier and mechanical properties of wood powder composites based on recycled polyethylene (RPE) were modified using a commercial nanoclay masterbatch. X-ray diffraction, dynamic rheology and thermogravimetric analysis measurements showed that nanoclay from the selected masterbatch was well dispersed and formed a percolation network in both virgin and RPEs. The resulting nanocomposites promoted the thermal stability of matrix significantly. Modification efficiency of nanoclay, however, was evidently influenced by the type of matrix, where the strongest effect was achieved in a low viscosity virgin high density PE. The masterbatch was incorporated into an industrial formula designed extrusion quality RPE/wood flour composite. Processing procedures, mainly compounding cycles, and material composition, mainly clay content and type of coupling agent, were optimised. Two extrusion cycles led to higher uniformity of resulting composites than one cycle. Addition of a coupling agent, which has medium viscosity and plenty functional groups, led to enhanced tensile strength. The twice compounded composites were well stiffened and strengthened via combination of 6 wt-% clay and medium viscosity coupling agent. All composites without the addition of nanoclay burned faster after ignition and dripped much earlier and more compared to the composites containing nanoclay even with as small amount as 3 wt-% and being compounded once. The material with 6 wt-% clay showed the best sample integrity and burned slowest of all the tested composites. Furthermore, no dripping during combustion was seen for this material. This study shows that the incorporation of nanoclay using the selected masterbatch can effectively improve the flame retarding properties of RPE based wood composites.