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The Effect of the Aging Process on Selected Properties of Polypropylene Modified by Natural Fillers

Samujło Bronisław

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 4

139--147

EN

The purpose of the research was to determine the aging-induced changes in the selected mechanical properties and flammability of polypropylene modified with natural fillers (sunflower husk, wheat bran, pine sawdust and talc). The fillers were introduced into polypropylene in a mechanical mixing process (weight content 20%). The samples were obtained with the use of an Allrounder 320 C500–170 laboratory injection molding machine. The aging process under artificial sample conditions was carried out in the laboratory chamber (aging time of 0, 60, 120, 240, 360 hours). The tests of the mechanical properties included the measurements of hardness, impact strength and tensile strength. The flammability tests were carried out with a vertical and horizontal alignment of the sample according to the PN-EN 60695–11–10 standard. As a result of the research, a significant impact of the introduction of natural fillers in the form of sunflower husks, wheat bran and pine sawdust on the selected properties of polypropylene was demonstrated. A large decrease in the impact toughness, a relatively small decrease in the short-term tensile strength as well as an increase in the elastic modulus and stress at rupture caused by the introduction of the natural fillers mentioned, were found. A beneficial effect was the relatively small impact of aging on the mechanical properties and flammability of the modified polypropylene fillers.

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Case Study on the Unavailability of a Ship Propulsion System under Aging Effects and Maintenance

Okazaki T.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2016

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Vol. 10, no. 3

501--508

EN

Unavailability of a ship propulsion system under aging effects and proper maintenance is estimated using GO-FLOW. GO-FLOW is an effective software tool for the unavailability analysis of complex systems. Aging effects are incorporated into GO-FLOW using a time-dependent technique and assuming a linear aging model. The results show that the aging effects and improper maintenance can potentially increase the frequency of accidents due to a malfunction of the propulsion system by a factor of three.

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Uproszczona metoda kalibracji przetworników do pomiaru stężenia gazów z czujnikami półprzewodnikowymi rezystancyjnymi

Urzędniczok H.

Pomiary Automatyka Kontrola

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2014

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R. 60, nr 5

269--271

PL

W artykule opisano wyniki badań zmian czasowych typowego półprzewodnikowego rezystancyjnego czujnika gazów przeprowadzone w odstępie dwóch lat. Ze względu na znaczne zmiany charakterystyk, konieczna jest częsta kalibracja przetworników z takimi czujnikami. Opisano skrótowo metodę wyznaczania współczynników modelu odwrotnego uwzględniającego podstawowe wielkości wpływające. Wykazano, że pomimo znacznych zmian charakterystyk czujnika z upływem czasu, nie jest konieczna pełna ponowna kalibracja. Możliwa jest kalibracja uproszczona, zmierzająca do wyznaczenia mniejszej liczby współczynników niż liczba współczynników modelu pierwotnego. Pozwala to znacznie ograniczyć czasochłonność i pracochłonność kalibracji, co ma istotne znaczenie w przypadku przetworników do pomiaru stężenia gazów będących w ciągłej eksploatacji.

EN

A very important feature of the resistive semiconductor gas sensors is ageing effect, sometimes very considerable. From a practical point of view, this results in the need for frequent calibration of gas concentration (C) measuring transducers equipped with such sensors. Calibration is typically laborious and time-consuming, due to the long response times of sensors [2], and to the impact of influence quantities (mainly temperature T and humidity H [3, 4]). The results of studies of temporal changes of a typical SnO2 based gas sensor carried out at an interval of two years are described in this paper. They indicate the possibility of a simplified calibration when the previously calibrated transducer is recalibrated after a long period of operation. Determination of all the coefficients of the complete model (formula 1), which allows the calculation of the measurement result, requires at least nine points of calibration in space (C, T, H). The simplification consists in the introduction of four additional correction factors determined in each recalibration, which allows scaling the output voltage of the converter according to the formula 4. The nine main coefficients in model (1), which was determined in the first calibration, remain constant. As a result, it is enough to recalibrate four points in space (C, T) instead nine points. The comparison of characteristics of Figure 5 shows that the proposed method is effective.