Andrzej Czulak

Detailed study on interfacial interactions in epoxy composites cured with 1-buthylimidazole containing functionalized carbon nanotubes

This work provides a detailed information on the preparation process and characterization of functionalized multiwalled carbon nanotubes/Epidian 6 nanocomposites using ARES rheometer, TGA, and DSC measurements, with the imidazole derivative as a curing agent. Scanning electron microscopy of the fracture surfaces of the composites with a total nanofiller concentration below 0.5 wt.% reveals a uniform dispersion of MWCNT with only some minor agglomerates. At the same time, the TEM analysis of the composite with a total concentration of MWCNT–COOH higher than 0.5 wt.% confirmed the presence of carbon nanotube aggregates along with a large number of places without any presence of nanoparticles in the whole volume of the epoxy matrix. Mechanical tests (bending as well as dynamic mechanical analysis) show that compared with the neat epoxy resin, the bending strength of the composite was improved by about 30 and 21% after incorporating as little as only 0.1 and 0.2 wt.% MWCNT–COOH, respectively. The work presented hereby is a continuation of a previous study on epoxy-based nanocomposites with different types of multiwalled carbon nanotubes and it is a part of a wider project on precise charting of the influence of carbon nanotubes (particularly multiwalled carbon nanotubes) in the system of epoxy resin with 1-buthylimidazole, as a curing agent.

Characterisation of CF/AL-MMC Manufactured by Means of Gas Pressure Infiltration

Constantly rising demands on extremely stressed lightweight structures, particularly in traffic engineering as well as in machine building and plant engineering, increasingly require the use of continuous fibre-reinforced composite materials. Due to their selectively adaptable characteristics profiles, they are clearly superior to conventional monolithic materials. Composites with textile reinforcement offer the highest flexibility for adaptation to reinforcing structures in to complex loading conditions. This study shows that the gas pressure infiltration technique was successfully assessed for manufacture of carbon fibre reinforced aluminium metal composites (CF/Al-MMCs), consisting of unidirectional as well as bidirectional Ni-coated carbon fibres with different Al-alloy matrix systems. As wail as investigating of the deformation and failure behaviour of CF/Al-MMCs, their thermo-physical properties, were determined such as the coefficient of thermal expansion. Furthermore, fractographic analysis and closer microscopic inspections indicate they fail with a brittle fracture.

SMART composite high pressure vessels with integrated optical fiber sensors

In this paper application of integrated Optical Fiber Sensors for strain state monitoring of composite high pressure vessels is presented. The composite tanks find broad application in areas such as: automotive industry, aeronautics, rescue services, etc. In automotive application they are mainly used for gaseous fuels storage (like CNG or compressed Hydrogen). In comparison with standard steel vessels, composite ones have many advantages (i.e. high mechanical strength, significant weight reduction, etc). In the present work a novel technique of vessel manufacturing, according to this construction, was applied. It is called braiding technique, and can be used as an alternative to the winding method. During braiding process, between GFRC layers, two types of optical fiber sensors were installed: point sensors in the form of FBGs as well as interferometric sensors with long measuring arms (SOFO®). Integrated optical fiber sensors create the nervous system of the pressure vessel and are used for its structural health monitoring. OFS register deformation areas and detect construction damages in their early stage (ensure a high safety level for users). Applied sensor system also ensured a possibility of strain state monitoring even during the vessel manufacturing process. However the main application of OFS based monitoring system is to detect defects in the composite structure. An idea of such a SMART vessel with integrated sensor system as well as an algorithm of defect detection was presented.

Investigation of Selected Properties of Injection-Molded Parts Subjected to Natural Aging

This article provides general information about the aging process of polymer plastics. It also reports the experimental results of investigations undertaken to determine changes in the mechanical properties of polypropylene injection-molded samples with the oxo-biodegradable additive d2w which were subjected to natural aging for two years. A decrease of tensile strength and elongation at yield as well as an increase of hardness were observed during the experiment.