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2 Composites Theory and Practice

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Effect of preparation method and polymer impregnation on form stability of expanded perlite/paraffin composite

Marchewka Izabela, Downar-Zapolska Ewa, Pichór Waldemar

Composites Theory and Practice

2023

R. 23, nr 3

153--157

Interest in the use of phase change materials in construction materials is constantly increasing. However, the problem is to develop an effective method to introduce them. The challenge is to obtain shape-stabilized composites with a high heat storage capacity. In this paper, expanded perlite was proposed as a potential carrier of phase change material (paraffin). The effectiveness of two impregnation techniques - vacuum and immersion - was compared. Composites with various amounts of paraffin were prepared, and then their properties were characterized. It has been shown that the vacuum impregnation method can be used to obtain composites with better shape stability. Despite this, leakage was observed in the materials with high proportions of paraffin. It was been proven that, regardless of the impregnation method, the application of a thin polymer dispersion coating can effectively protect the composite against leakage of the phase change material. Thanks to the use of epoxy resin, a stable composite was obtained with a paraffin content of over 80% by weight. The high PCM content and no leakage effect during the phase transition make the presented composite show great potential for many different applications.

Thermal, mechanical and moisture properties of polimer plaster modified with lightweight fillers

Marchewka Izabela, Downar-Zapolska Ewa, Pichór Waldemar

Composites Theory and Practice

2022

R. 22, nr 3

160--165

Thermally insulating lightweight plasters are urgently needed for the development of sustainable energy-saving buildings. The creation of such a material is possible because of the use of lightweight fillers, which are of interest to many researchers. As a result of their porous structure, it is possible to lower the density and thermal conductivity of various materials. The aim of this work is to analyze the influence of hollow glass microspheres in two granulations and expanded glass on the parameters of polymer plaster. Composites containing various amounts of lightweight fillers were prepared. Then, their parameters were compared in terms of the mechanical properties, thermal conductivity, vapor permeability, and water absorption. All three lightweight fillers successfully reduced the density of the polymer mass and improved plaster insulation. The best effect was achieved with both types of hollow glass microspheres. The weight of the polymer binder was reduced by up to 80%. In the case of expanded glass, the density was only reduced by 38%. At the same time, the composites were studied in terms of their mechanical and moisture properties. The specimens with the highest amount of lightweight filler showed significant deterioration in elasticity due to disturbance of the pigment:binder ratio. They cracked at lower deflection angles. By not exceeding 20% of the filler, no effect on flexibility was observed in any of the three investigated fillers. Interpretation of the research results indicates that the studied lightweight fillers allow a plaster mass to be obtained with an extremely low thermal conductivity coefficient, less than 0.086 W/mK. However, while ensuring the optimal proportion between fillers and polymer binder, it is possible to reduce the coefficient to 0.261 W/mK without noticeable deterioration of the mechanical properties.