Sophia Sachse

The effect of nanoclay on dust generation during drilling of PA6 nanocomposites

During the past decade, polymer nanocomposites have emerged as a novel and rapidly developing class of materials and attracted considerable investment in research and development worldwide. However, there is currently a lack of information available in the literature on the nano and ultrafine particle emission rates from these materials. In this paper, influence of nanoclay on mechanical drilling of PA6 composites, in terms of dust generation, has been reported. With the help of real-time characterization, submicrometer-sized particles (5.6-512 nm), size distribution, and number concentration emitted from polyamide 6/nanoclay composites during mechanical drilling are studied. Total particle concentration for the PA6/nanoclay composites was 20,000 cm-3, while unreinforced panel measured a total concentration of approximately 400,000 cm-3. While the airborne particle concentration for the PA6/nanoclay composites was 20 times lower than for the PA6 matrix, the concentration of deposited nanoparticles doubled for the nanocomposite. The results clearly show that more particles in the size range between 175 and 350 nm are generated, during drilling of the nanocomposites, and these particles deposit in a shorter time. It is likely that the presence of nanoclay in some way retains the formation of high quantity of airborne particles and promotes particle deposition.

Physical characteristics of nanoparticles emitted during drilling of silica based polyamide 6 nanocomposites

During the past decade, polymer nanocomposites have emerged as a novel and rapidly developing class of materials and attracted considerable investment in research and development worldwide. However, there is currently a lack of information available in the literature on the emission rates of particles from these material. In this study, real-time characterization of the size distribution and number concentration of sub-micrometer-sized particles (5.6-512 nm) emitted from polyamide 6 nanocomposites during mechanical drilling was made. For the first time, four different silica based filler of commonly use were assessed. Further, the respective emission rates were determined based on the particle population and the time. The measurements showed that the particle emission rates ranged from 1.16E+07 (min?1) to 1.03E+09 (min?1) and that the peak diameters varied from 29.6 to 75.1 nm. Airborne particles in the nanometer range (11.1-46.8 nm), in the ultrafine range (51.3-101.1 nm) and in the accumulation mode range (111.9-521 nm) accounted for 34.1% to 76.6%, 8.3% to 47% and 4.1% to 24.2% of the total emission rates, respectively, depending on the type of filler. Additionally, deposited particles were sampled and characterized, to explore any possible correlation between deposited and airborne particles. The result clearly showed that with increasing airborne particle concentration the deposit particle concentration decreased and vice verse.

Nanocomposites for Vehicle Structural Applications

Fiber-reinforced composites are a type of engineering material that has exhibited high strength–weight and modulus–weight ratios, even compared with some metallic materials. In the last two decades, some studies have shown the potential improvement in properties and performances of fiber reinforced polymer matrix materials in which nano and micro-scale particles were incorporated. This technology of nano and micro-scale particle reinforcement can be categorized into inorganic layered clay technology, single walled and multi-walled carbon nanotube, carbon nanofiber technology, and metal particle technology. To date, nanoparticle reinforcement of fiber reinforced composites has been shown to be a possibility, but much work remains to be performed in order to understand how nanoreinforcement results in major changes in material properties. The understanding of these phenomena will facilitate their extension to the reinforcement of more complicated anisotropic structures and advanced polymeric composite systems. Large quantity of nanomaterials (such as carbon nanotubes, nanofibers, SiO

On Nanoparticles Release from Polymer Nanocomposites for Applications in Lightweight Automotive Components

Nano and micro reinforced glass fibre-polymer composites have been manufactured to investigate different effect such as filler type, filler size and matrix materials on the particle emission during low velocity impact test. Nano and micro- silica, as well as nanoclay reinforced crash cones were prepared with a two step extrusion process and final injection moulding of the structures. The addition of secondary filler into the glass-fibre reinforced polymer composites had significant influence on the mechanical behaviour of the material as well as on the particle emission. In general, nano and ultrafine airborne particles were emitted from all investigated materials. However, composite filled with nanoclay emitted higher amounts of particles than those filled with nano and microsilica. One reason for the increase of particle emission of the nanoclay filled composites was the change of the failure behaviour of the matrix. However, similar results of particle emission were obtained for both nano and microsilica fillers, which in general did not vary significantly from the results obtained from traditionally reinforced glass fibres polymer composites.

Nanomaterials, nanofillers, and nanocomposites: types and properties

Abstract: Over the last two decades, nanoscience and nanotechnology have generated great scientific interest. Research in these fields has focused mainly on the development of nanoparticles with specific and/or tailored properties and their application in various areas. However, one crucial aspect that has not been afforded much attention is the influence of nanoparticles on the environment and human health. This chapter covers the physical and chemical properties of nanoparticles, which, from a toxicological perspective, may have an effect on the environment and human health. We consider the main types of nanoparticles, as well as their characteristic features. We also address the application of two types of nanoparticles in nanocomposites, on account of the improvement in the properties that they confer to the substrates.

Measurement and sampling techniques for characterization of airborne nanoparticles released from nano-enhanced products

Abstract: To identify the potential environmental pollution and health hazards of airborne particles, it is necessary to determine their physical and chemical properties and characteristics. In this chapter, we discuss the standard sampling and characterization techniques together with some of the issues and implementations associated with the measurement of ultrafine and nano-airborne particle properties. Recommendations are made for the sampling of airborne particles and the best approach to characterize their properties is addressed. A case study on nanorealease is also provided.

Energy absorption characteristics of nano-composite conical structures

The effect of the filler material on the energy absorption capabilities of polyamide 6 composite structures is studied in details in the present paper. The axial dynamic and quasi-static collapse of conical structures was conducted using a high energy drop tower, as well as Instron 5500R electro-mechanical testing machine. The impact event was recorded using a high-speed camera and the fracture surface was investigated using scanning electron microscopy (SEM). The obtained results indicate an important influence of filler material on the energy absorption capabilities of the polymer composites. A significant increase in specific energy absorption (SEA) is observed in polyamide 6 (PA6) reinforced with nano-silica particles (SiO2) and glass-spheres (GS), whereas addition of montmorillonite (MMT) did not change the SEA parameter.

The effect of matrix and reinforcement material selection on the tensile properties of hybrid composites.

This work was funded by the European Commission (FP7 Project- CP-FP; Project Reference: 228536-2). The authors also gratefully acknowledge the EPSRC for providing testing equipment, as well as Grado Zero Espace SRL and Laviosa Chimica Mineraria SPA for the preparation of the materials.

Energy Absorption and Low-Velocity Impact Performance of Nanocomposites: Cones and Sandwich Structures

The increasing need for high performance structures, in the energy and transport industry, demands a continuous development of new engineering materials. Unique mechanical properties together with low specific weight can be achieved by the combination of various constituent materials into one macroscopic composite material. Coupling of the high strength reinforcement with supporting matrix creates a novel material with the improved characteristics, which could never be obtained using either of the constituents separately. These types of materials are particularly desirable in structures where a high strength to weight ratio is of great importance. In this chapter, two case studies are provided one on nanophased sandwich composites with polyurethane/layered silicate foam cores and the other on thermoplastic glass-fibre and nano-silica reinforced nanocomposites.

Assessment of nanoparticle release and associated health effect of polymer-silicon composites

Little information is currently available on possible release of nanomaterials or/and nanoparticles (NP) from conventional and novel products and associated health effect. This study aimed to assess the possible release of NP during the application stage of conventional and nanoproducts. NP release was monitored during physical processing of polymer-silicon composites, and the toxicity of both the released NP and the raw silica nanomaterials that were used as fillers in the nanocomposites was assessed in vitro using human lung epithelial A549 cells. This study suggests that 1) NP can be released from the conventional and novel polymer-silicon composites under certain application scenario; 2) the level of NP release from polymer composites could be altered by different reinforcement materials; e.g. nanostructured MMT could reduce the release while SiO2 NP could increase the release; 3) working with polymer composites under certain conditions could risk inhalation of high level of polymer NP; 4) raw nanomaterials appeared to be toxic in the chosen in vitro system. Further study of the effect of novel filler materials on NP release from final polymer products and the effect of released NP on environment and human health will inform design of safe materials and minimization of negative impact on the environment and human health.