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1

Thermal characterization of curing process in unsaturated polyester resin based polymer concrete

Smoleń Jakub, Tomaszewska Klaudia, Desisa Debela Geneti

Composites Theory and Practice

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2022

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R. 22, nr 3

166--171

EN

This paper presents a description of the temperature changes that take place in the curing system of polymer concrete. The research used polymer concrete composed of 30% by volume unsaturated polyester resin acting as a binder for powder fillers. Among the powder fillers, ground glass waste and sand in a volume ratio of 1:1 were used. The investigations were carried out for three volumes, 10, 100 and 1000 cm3, respectively. The temperature in the central point of the volume (the highest temperature) was measured by the ATD method using a NiCr-NiAl thermocouple, and the temperature on the polymer concrete surface was measured using a thermal imaging camera. The temperature-time course recorded for both the measuring points allowed evaluation of the curing system parameters (gelation time, maximum curing temperature, time to maximum temperature), important for the processing of polymer concrete. Additionally, the knowledge of the temperature curves enabled a mathematical description of the heat flow between the measuring points. The conducted studies proved that the volume of the mold is important for the maximum temperature and curing time. The work is a continuation of previous research focused on polymer concrete and is an extension of information oriented to the industrial aspect. Knowledge of the temperaturę peaks and curing time will allow adjustments to be made to the manufacturing processes.

2

Effect of glass fibre presence on curing process of unsaturated polyester resin

Kozioł M., Gradoń P.

Composites Theory and Practice

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2018

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R. 18, nr 4

191--195

EN

The paper presents an attempt to estimate the difference in the intensity of the curing process of a polyester resin: without any filler and filled with fragmented glass fabric. Curing of the resin samples was carried out at room temperature. The temperature-time course of the process and gel time were recorded for each sample. On the basis of the obtained results and the conducted observations, it was found that filling the resin with fragmented glass fabric caused a decrease in the peak temperature of the curing process and increased the time of reaching this temperature. These effects were found to intensify with an increase in filler weight (inhibitory effect of the filler). A slightly longer gelation time was also found for the filled resin in comparison to the unfilled one. The observed effects indicate an increase in the thermal insulation of the curing mass along with an increase in filler content. They also indicate that the presence of fibers leads to stabilization (improvement of repeatability) of the resin curing process. The work is a continuation of earlier work aimed at experimental evaluation of the behavior of curing resins, which in turn will help to systematize the practical knowledge in this field. Thus, it finally meets the expectations of users and processors of curable resins.

PL

Zaprezentowano próbę oszacowanie różnicy w intensywności procesu sieciowania żywicy poliestrowej bez żadnego napełniacza oraz napełnionej rozdrobnioną tkaniną szklaną. Utwardzanie próbek żywicy prowadzono w temperaturze pokojowej i rejestrowano przebieg temperaturowo-czasowy procesu oraz czas żelowania. Na podstawie uzyskanych wyników i poczynionych obserwacji stwierdzono, że napełnienie żywicy rozdrobnioną tkaniną szklaną spowodowało zmniejszenie temperatury szczytu procesu utwardzania oraz wydłużyło czas osiągania tej temperatury. Stwierdzono postępowanie tych efektów ze zwiększeniem masy napełniacza (inhibicyjne działanie napełniacza). Dla żywicy napełnionej stwierdzono też nieznaczne wydłużenie czasu żelowania. Zaobserwowane efekty wskazują na zwiększenie izolacyjności termicznej sieciującej masy wraz ze wzrostem zawartości napełniacza. Wskazują też, że obecność włókien prowadzi do stabilizacji (poprawy powtarzalności) procesu sieciowania żywicy. Praca jest kontynuacją wcześniejszych prac, mających na celu eksperymentalną ocenę zachowania się utwardzanej żywicy, co z kolei pomoże usystematyzować praktyczną wiedzę w tym zakresie i wyjść naprzeciw oczekiwaniom użytkowników oraz przetwórców żywic utwardzalnych.

3

Wpływ objętości próbki chemoutwardzalnej żywicy poliestrowej na przebieg jej utwardzania

Kozioł M., Mocek P., Jankowski P.

Polimery

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2016

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T. 61, nr 2

133--141

PL

Zbadano wpływ objętości próbki żywicy poliestrowej na przebieg zmian temperatury oraz na czas utwardzania. Stwierdzono, że wraz ze zwiększającą się objętością próbki żywicy (do 120 cm3) skraca się czas sieciowania i rośnie temperatura maksymalna (szczytu egzotermicznego). Sztywność żywicy utwardzanej za pomocą aktywniejszego inicjatora maleje ze wzrostem objętości próbki, natomiast w przypadku zastosowania mniej aktywnego inicjatora — się zwiększa. Przeprowadzono modelowanie matematyczne termodynamicznego procesu utwardzania żywicy za pomocą modelu układu o parametrach rozłożonych, opisującego sieciowanie determinowane chemicznie z dyfuzją ciepła. Stwierdzono duży wpływ chłodzenia konwekcyjnego na przebieg procesu.

EN

The paper presents an experimental evaluation of the influence of polyester resin specimen volume on the time and temperature of curing process. It was found that the maximum peak temperature increased with an increase of the resin volume up to 120 cm³ (Figs. 4—6) while the curing time was decreased. The stiffness of the resin cured with the use of a more active initiator decreased with an increase in the resin volume and increased when a less active initiator was employed (Figs. 9 and 10). The mathematical modelling of the thermodynamics of curing process was performed using a model of distributed parameters system, describing the chemically determined curing process with heat diffusion. A strong influence of convective cooling on the course of the process was found.

4

Determination of constant parameters of copper as power-law hardening material at different test conditions

Kowser M. A., Mahiuddin M.

International Journal of Applied Mechanics and Engineering

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2014

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Vol. 19, no. 4

687--698

EN

In this paper a technique has been developed to determine constant parameters of copper as a power-law hardening material by tensile test approach. A work-hardening process is used to describe the increase of the stress level necessary to continue plastic deformation. A computer program is used to show the variation of the stress-strain relation for different values of stress hardening exponent, n and power-law hardening constant, α . Due to its close tolerances, excellent corrosion resistance and high material strength, in this analysis copper (Cu) has been selected as the material. As a power-law hardening material, Cu has been used to compute stress hardening exponent, n and power-law hardening constant, α from tensile test experiment without heat treatment and after heat treatment. A wealth of information about mechanical behavior of a material can be determined by conducting a simple tensile test in which a cylindrical specimen of a uniform cross-section is pulled until it ruptures or fractures into separate pieces. The original cross sectional area and gauge length are measured prior to conducting the test and the applied load and gauge deformation are continuously measured throughout the test. Based on the initial geometry of the sample, the engineering stress-strain behavior (stress-strain curve) can be easily generated from which numerous mechanical properties, such as the yield strength and elastic modulus, can be determined. A universal testing machine is utilized to apply the load in a continuously increasing (ramp) manner according to ASTM specifications. Finally, theoretical results are compared with these obtained from experiments where the nature of curves is found similar to each other. It is observed that there is a significant change of the value of n obtained with and without heat treatment it means the value of n should be determined for the heat treated condition of copper material for their applications in engineering fields.