Abstract
In this study, a hydrothermal hot pressing (HHP) method was used for the preparation of molded composites with high CaCO3 content. Specifically, composites consisting of chemically synthesized CaCO3 and chitosan and scallop shells milled with a ball mill were molded by the HHP method; the structures, mechanical properties, and vibration absorption characteristics of the resulting disc‐shaped molded composites were investigated. All the composites had high CaCO3 contents (93%); flexural strengths (several megapascals) comparable to those of limestone and cement; and vibration absorption characteristics (logarithmic attenuation factors of 0.07–0.18) superior to those of aluminum alloys, stainless steel, and ceramics (which have logarithmic attenuation factors of <0.01). The composites prepared from the CaCO3‐chitosan composites can be expected to find application as light‐control materials, as materials for controlling the propagation of light, sound, and vibration waves including vibration‐isolating materials and as CO2‐fixation materials.
Highlights
E hydrothermal hot pressing (HHP) method has the potential to be useful for this purpose. e HHP method was devised for producing composites with high mechanical strength by compressing water-containing inorganic powders under external pressure to densify them by squeezing out the water and, at the same time, compacting the particles [10, 11]
thermogravimetric analysis (TGA). e CaCO3-chitosan composites and the scallop shells were subjected to TGA (Figure 3), which revealed successive mass losses due to the removal of absorbed water and acetic acid, degradation of organic compounds, and decomposition of CaCO3 [12]. e gradual weight loss from 200 to 500°C was due to dehydration reactions of organic compounds. e amounts of CaO and ash produced were calculated from the weight loss when CaCO3 decomposed into CaO and CO2 at 600–700°C [12]
E overall percentages of CaCO3 in the composites were estimated to be 93.0, 93.2, and 93.5 wt.% for discs fabricated from the CaCO3-chitosan composites prepared at 4 and 95°C and the scallop shell disc, respectively; that is, the CaCO3 contents were high. is is noteworthy because producing nanocomposites containing large amounts of inorganic materials is difficult via conventional mixing processes [13]
Summary
E hydrothermal hot pressing (HHP) method has the potential to be useful for this purpose. e HHP method was devised for producing composites with high mechanical strength by compressing water-containing inorganic powders under external pressure to densify them by squeezing out the water and, at the same time, compacting the particles [10, 11]. E hydrothermal hot pressing (HHP) method has the potential to be useful for this purpose. E HHP method was devised for producing composites with high mechanical strength by compressing water-containing inorganic powders under external pressure to densify them by squeezing out the water and, at the same time, compacting the particles [10, 11]. In the HHP method, water-containing powdered inorganic compounds in an autoclave under hydrothermal conditions are pressurized from outside the autoclave at a pressure higher than the water vapor pressure inside the autoclave. The HHP method was used to prepare molded composites with high CaCO3 content. Advances in Materials Science and Engineering molded by the HHP method; and the structures, mechanical properties, and vibration absorption characteristics of the resulting disc-shaped composites were investigated
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