The durability of carbon fiber/epoxy composites under hydrothermal ageing

Studies on fibre reinforced composites are now receiving greater attention. Industrial applications have been successful in areas like aerospace, automobile, marine, construction and sporting goods. The first generation of epoxy resins for use in carbon fibre composites are able to achieve optimized high stiffness modules and high heat resistance by a high crosslink density, reached through thermal curing. However, these formulations can be very toxic and brittle with low crack resistance, which was a major disadvantage for structural applications. In the last years the use of ionizing radiation as alternative to thermal curing has been proposed as an environmentally friendly process. Furthermore, in order to enhance toughness mechanical requirements for their applications, the formulation generally consists of blends of epoxy resins and engineering thermoplastics. In terms of durability (service life and reliability), in these materials it depends on different environmental conditions (temperature, moisture, etc.), and it is very important to know how their properties are modified after the exposure to different temperature and moisture absorption cycles. In this work carbon fibre composites produced by ionizing radiation induced curing of the epoxy based matrices have been subjected to thermal and moisture absorption ageing and the influence of these treatments on the thermal and mechanical properties has been investigated through dynamic mechanical thermal analysis and mechanical fracture toughness tests

Studies of network organization and dynamics of e-beam crosslinked PVPs: From macro to nano

In this work the influence of poly(N-vinylpyrrolidone)(PVP)concentration in water on the organization and dynamics of the corresponding macro-/nanogel networks has been systematically investigated. Irradiation has been performed at the same irradiation dose(within the sterilization dose range)and dose rate. In the selected irradiation conditions, the transition between macroscopic gelation and micro/nanogels formation is observed just below the critical overlap concentration(1 wt%),whereas the net prevalence of intramolecular over intermolecular crosslinking occurs at a lower polymer concentration(below 0.25 wt%). Dynamic\u2013mechanical spectroscopy has been applied as a classical methodology to estimate the network mesh size for macrogels in their swollen state, while 13C NMR spin\u2013lattice relaxation spectroscopy has been applied on both the macrogel and nanogel freeze dried residues to withdraw interesting information of the network spatial organization in the passage of scale from macrotonano

An overview of chemical additives present in plastics: Migration, release, fate and environmental impact during their use, disposal and recycling

Over the last 60 years plastics production has increased manifold, owing to their inexpensive, multipurpose, durable and lightweight nature. These characteristics have raised the demand for plastic materials that will continue to grow over the coming years. However, with increased plastic materials production, comes increased plastic material wastage creating a number of challenges, as well as opportunities to the waste management industry. The present overview highlights the waste management and pollution challenges, emphasising on the various chemical substances (known as “additives”) contained in all plastic products for enhancing polymer properties and prolonging their life. Despite how useful these additives are in the functionality of polymer products, their potential to contaminate soil, air, water and food is widely documented in literature and described herein. These additives can potentially migrate and undesirably lead to human exposure via e.g. food contact materials, such as packaging. They can, also, be released from plastics during the various recycling and recovery processes and from the products produced from recyclates. Thus, sound recycling has to be performed in such a way as to ensure that emission of substances of high concern and contamination of recycled products is avoided, ensuring environmental and human health protection, at all times

The Processing of Biometric Data in the Polish Legal Framework

Niniejszy artykuł ma na celu przedstawienie problematyki przetwarzania danych biometrycznych na tle rozporządzenia Parlamentu Europejskiego i Rady 2016/679 w sprawie ochrony osób fizycznych w związku z przetwarzaniem danych osobowych i w sprawie swobodnego przepływu takich danych oraz uchylenia dyrektywy 95/46/WE oraz przepisów prawa krajowego mających na celu zapewnienie skuteczności stosowania tego rozporządzenia. Artykuł przybliża pojęcie i podstawowe zasady przetwarzania danych biometrycznych osób fizycznych, z uwzględnieniem problematycznej kwestii dobrowolności zgody pracownika na przetwarzanie jego danych biometrycznych przez pracodawcę.This article aims to cover the issue of the processing of biometric data in the context of Regulation 2016/679 of the European Parliament and of the Council (EU) of 27 April 2016 on the protection of natural persons with regard to the processing of personal data and on the free movement of such data, and repealing Directive 95/46/EC and the provisions of the relevant Polish law intended to ensure effective application of the regulation in question. The paper is to familiarize the readers with the notion and the fundamental principles of the processing of the biometric data of natural persons, taking into account the problematic issue of voluntary consent given by employees to their biometric data being processed by their employers

Radiation-induced effects in segmented polyurethane for biomedical purposes

Celem prezentowanej pracy było badanie wpływu promieniowania jonizującego na wybrane fizyko-chemiczne właściwości segmentowego poliuretanu (PU). Poliuretan scharakteryzowano przy użyciu elektronowego rezonansu paramagnetycznego (EPR), pomiaru kąta zwilżania i badania właściwości termicznych i mechanicznych. Wyniki otrzymane przy zastosowaniu powyższych metod wskazują na niewielki wpływ procesów radiacyjnych na strukturę i właściwości badanego polimeru do dawki 112kGy. Zatem również ekspozycja poliuretanu na dawkę sterylizacyjną 25kGy nie zmienia właściwości chemicznych i mechanicznych.The purpose of the presented study was to investigate the effect of ionizing radiation on selected physicochemical properties of segmented polyurethane (PU). Polyurethane was characterized by electron paramagnetic resonance (EPR), measurement of dynamic contact angle and investigation of thermal and mechanical properties. The results obtained by these techniques revealed insignificant influence of radiation on structure and features of investigated polymer up to 112kGy. Thus it was confirmed that upon exposition to a sterilization dose of about 25kGy polyurethane does not change chemical and mechanical properties

The influence of ionizing radiation on the thermal properties of segmented polyurethanes for biomedical purposes

Badano termiczne właściwości segmentowego poliuretanu po ekspozycji na promieniowanie jonizujące przy użyciu różnicowej kalorymetrii skaningowej (DSC) i analizy termograwimetrycznej (TGA). W celu zbadania termicznej degradacji poliuretanu określono energię aktywacji metodą Kissingera i Flynn-Wall-Ozawa. Na podstawie uzyskanych wyników można wnioskować, że sterylizacja radiacyjna nie ma znaczącego wpływu na termiczne właściwości badanych poliuretanów.Thermal properties of segmented polyurethane (PU) were investigated upon exposure to ionizing radiation by differencial scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Additionally, the activation energy of PU was determined using Kissinger’s and Flynn-Wall-Ozawa’s methods to study the thermal degradation. On a basis of the obtained results it can be stated that radiation sterilization have not significant influence on thermal properties of investigated polyurethanes

Radiation processing of polymers and semiconductors at the Institute of Nuclear Chemistry and Technology

R&D studies in the field of radiation technology in Poland are mostly concentrated at the Institute of Nuclear Chemistry and Technology (INCT). The results of the INCT works on polymer and semiconductor modification have been implemented in various branches of national economy, particularly in industry and medicine. Radiation technology for polymer modification was implemented in the middle of the 1970-ties. Among others, the processes of irradiation and heat shrinkable products expansion have been developed. The transfer of this technology to Polish industry was performed in the middle of the 1980-ties. The present study aims at the formulation of new PE composites better suited to new generation of heat shrinkable products, for example, a new generation of hot-melt adhesives has been developed to meet specific requirements of customers. Modified polypropylene was used for the production of medical devices sterilized by radiation, especially disposable syringes, to overcome the low radiation resistance of the basic material. Modified polypropylene (PP-M) has been formulated at the INCT to provide material suitable for medical application and radiation sterilization process. Modification of semiconductor devices by EB was applied on an industrial scale since 1978 when the INCT and the LAMINA semiconductor factory successfully adopted that technology to improve specific semiconductor devices. This activity is continued on commercial basis where the INCT facilities served to contract irradiation of certain semiconductor devices according to the manufacturing program of the Polish factory and customers from abroad