Influence of sample thickness on fracture behaviour of polyketone and a polyketone-rubber blend

The influence of sample thickness on the fracture behaviour of an aliphatic polyketone and a blend of this polymer and 10 wt% core–shell\ud rubber was studied. The sample thickness was varied from 0.1 to 8 mm. The skin morphology was studied by SEM. The fracture behaviour\ud was studied on single edge notch specimen at a high strain rate (30 sK1) in the temperature range of K40 to 120 8C. The fracture stress,\ud fracture strain and fracture energies were determined. The temperature development in the notch area was followed with an Infra Red\ud camera. The cavitation of the rubber particles was studied on tensile bars with a laser setup.\ud With decreasing specimen thickness the fracture energies increased strongly and the brittle-ductile transition shifted to lower temperatures\ud this both for the aliphatic polyketone and the polyketone-rubber blend. The deformation in these materials in accompanied with a strong\ud temperature increase in the deformation zone. The addition of rubber particles decreases the sensitivity towards the thickness. However, in\ud very thin samples the cavitation of the rubber particles is more difficult and the rubber toughening effect decreases. The strong thickness\ud effects on the fracture toughness indicate for both the homo polymer and the blend indicate that data from a standard test with 4 mm thick\ud samples are not representative for thin walled applications

Fibre reinforced polymer nanocomposites

In this thesis the results are described of the research on a combination of two types of composites: thermoplastic nanocomposites and continuous fibre composites. In this three-phase composite the main reinforcing phase are continuous glass or carbon fibres, and the matrix consists of a polyamide 6 / layered silicate nanocomposite. To be able to produce and understand this new type of thermoplastic composite, the properties of the nanocomposite matrix materials have been investigated, followed by an investigation of the properties the new three-phase composite. The influence of the following parameters on the properties of the nanocomposites is studied: the type and concentration of the layered silicate, the surface modification of the particles, the type of polyamide and the testing temperature. The measured properties are the modulus, strength, toughness, moisture diffusion, melt viscosity and adhesion with the fibres. The moduli, diffusion coefficients en viscosities are related to the shape, size and degree of dispersion of the particles using various models. Based on the properties some nanocomposites have been selected and used as matrix for fibre composites. The flexural strength of the fibre composites with nanocomposite matrix has been measured over a large temperature range and with different amounts of absorbed moisture. Compared to normal PA6 fibre composites the strength is increased with more than 40% at elevated temperatures. The temperature at which these composites can be used at equal strength increases by 40-50 C. With the use of nanocomposites as matrix the properties of fibre composites can be strongly improved without any changes in the processing conditions.Applied Science

Nanocomposites with liquid crystalline polymer matrices

In this part we will summarise the open literature concerning research on systems involving liquid crystalline polymers and nanoparticles. © 2008 Nova Science Publishers, Inc. All rights reserved

Mechanical properties of polyketone terpolymer/rubber blends

Blends of aliphatic polyketone terpolymer and a core-shell rubber (CSR) were melt processed with varying CSR concentration of 0–\ud 40 wt%. The obtained morphology was of finely dispersed CSR particles in the polyketone matrix. The thermal properties of the matrix\ud polymer remained unaffected by the addition of the CSR phase. The crystallinity remained constant at 35 wt% and the melting temperature\ud was not changed. The tensile modulus and yield stress were decreased by the addition of the rubber phase to the aliphatic polyketone\ud polymer. The deformation was strongly delocalised with increasing CSR content. The temperature development during fracture was also\ud strongly reduced with increasing rubber concentration. The CSR phase was found to toughen the aliphatic polyketone matrix very effectively,\ud the brittle to ductile transition temperature was lowered from 90 to 240 8C with the highest rubber concentration (40 wt%). Cavitation\ud experiments revealed that the macroscopic cavitation strain remained constant with increasing rubber content. A study of the deformation\ud zone below the fracture surface showed that voids were produced by cavitation of the rubber phase. The voids were strongly deformed by the\ud plastic deformation of the matrix polymer. At high strain rates a relaxation layer was found below the fracture surface, where the voids were\ud no longer present. This relaxation zone was found to be due to the adiabatic temperature rise of the material during fracture at high strain\ud rates