Browsing by Author "Hromasová, Monika"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- ItemAcoustic, Mechanical and Thermal Properties of Green Composites Reinforced with Natural Fibers Waste(MDPI, 2020-03) Hassan, Tufail; Jamshaid, Hafsa; Mishra, Rajesh; Khan, Muhammad Qamar; Petrů, Michal; Novák, Jan; Chotěborský, Rostislav; Hromasová, MonikaThe use of acoustic panels is one of the most important methods for sound insulation in buildings. Moreover, it has become increasingly important to use green/natural origin materials in this area to reduce environmental impact. This study focuses on the investigation of acoustic, mechanical and thermal properties of natural fiber waste reinforced green epoxy composites. Three different types of fiber wastes were used, e.g., cotton, coconut and sugarcane with epoxy as the resin. Different fiber volume fractions, i.e., 10%, 15% and 20% for each fiber were used with a composite thickness of 3 mm. The sound absorption coefficient, impact strength, flexural strength, thermal conductivity, diffusivity, coefficient of thermal expansion and thermogravimetric properties of all samples were investigated. It has been found that by increasing the fiber content, the sound absorption coefficient also increases. The coconut fiber-based composites show a higher sound absorption coefficient than in the other fiber-reinforced composites. The impact and flexural strength of the cotton fiber-reinforced composite samples are higher than in other samples. The coefficient of thermal expansion of the cotton fiber-based composite is also higher than the other composites. Thermogravimetric analysis revealed that all the natural fiber-reinforced composites can sustain till 300 degrees C with a minor weight loss. The natural fiber-based composites can be used in building interiors, automotive body parts and household furniture. Such composite development is an ecofriendly approach to the acoustic world.
- ItemMaterial utilization of cotton post-harvest line residues in polymeric composites(MDPI, 2019) Müller, Miroslav; Valášek, Petr; Kolář, Viktor; Šleger, Vladimír; Kagan Gürdil, Gürkan Alp; Hromasová, Monika; Hloch, Sergej; Moravec, Jaromír; Pexa, MartinThis paper deals with a research focused on utilization of microparticle and short-fiber filler based on cotton post-harvest line residues in an area of polymeric composites. Two different fractions of the biological filler (FCR-reinforced cotton filler) of 20 and 100 μm and the filler with short fibers of a length of 700 μm were used in the research. The aim of the research was to evaluate mechanical characteristics of composites and adhesive bonds for the purpose of gaining new pieces of knowledge which will be applicable in the area of material engineering and assessing application possibilities of residues coming into being from agricultural products processing. Mechanical properties of the composite material produced by a vacuum infusion and tested at temperatures 20, 40, and 60 °C and adhesive bonds which were exposed to a low-cyclic loading, i.e., 1000 cycles at 30% to 70% from reference value of the maximum strength, were evaluated. Composite systems with the FCR adjusted in 5% water solution of NaOH showed higher strength values on average compared to untreated FCR. Unsuitable size of the FCR led to a deterioration of the strength. The filler in the form of 700 FCR microfibers showed itself in a positive way to composite materials, and the particle in the form of 20 FCR did the same to adhesive bonds. Results of adhesive bond cyclic tests at higher stress values (70%) demonstrated viscoelastic behavior of the adhesive layer.