RESUMEN
In the context of novel environmental and energy regulations in construction (RE2020), biocomposites derived from bamboo fibers, bamboo powders, and biodegradable poly(lactic)acid polymer, all of which are renewable resources, have been investigated to meet the criteria of the novel regulations. In this work, the biocomposites were manufactured by twin-screw internal mixing at 170 °C for 5 min with a rotation speed of 60 rpm. The composites sheets were then shaped on a hydraulic press at 185 °C. Pore characterization including pore volume fraction, 3D-pore structure and morphology, and pore distribution of these materials were investigated using X-ray tomography combined with image processing (Avizo). The results show that when the bamboo fibers content is increased, an augmentation in the pore volume fraction and the number of large-volume pores could be observed. In turn, the bamboo powder-containing sheet had a significant increase in pore volume fraction, while a higher quantity of smaller pores, with uniform size, could be observed. The water absorption capacity of these composite increases with the increase of the amount of pore distribution, pore connection, and pore volume fraction. In addition, the orientation of the fibers in 3D observation, flexural mechanical properties, and thermal stability of the biocomposites are also reported in this study.
RESUMEN
This study aims to produce novel composite artificial marble materials by bulk molding compound processes, and improve their thermal and mechanical properties. We employed stearic acid as an efficient surface modifying agent for CaCO3 particles, and for the first time, a pretreated, recycled, polyethylene terephthalate (PET) fibers mat is used to reinforce the artificial marble materials. The innovative aspects of the study are the surface treatment of CaCO3 particles by stearic acid. Stearic acid forms a monolayer shell, coating the CaCO3 particles, which enhances the compatibility between the CaCO3 particles and the matrix of the composite. The morphology of the composites, observed by scanning electron microscopy, revealed that the CaCO3 phase was homogeneously dispersed in the epoxy matrix under the support of stearic acid. A single layer of a recycled PET fibers mat was pretreated and designed in the core of the composite. As expected, these results indicated that the fibers could enhance flexural properties, and impact strength along with thermal stability for the composites. This combination of a pretreated, recycled, PET fibers mat and epoxy/CaCO3-stearic acid could produce novel artificial marble materials for construction applications able to meet environmental requirements.
RESUMEN
Silica powder at nanoscale was obtained by heat treatment of Vietnamese rice husk following the sol-gel method. The rice husk ash (RHA) is synthesized using rice husk which was thermally treated at optimal condition at 600°C for 4 h. The silica from RHA was extracted using sodium hydroxide solution to produce a sodium silicate solution and then precipitated by adding H2SO4 at pH = 4 in the mixture of water/butanol with cationic presence. In order to identify the optimal condition for producing the homogenous silica nanoparticles, the effects of surfactant surface coverage, aging temperature, and aging time were investigated. By analysis of X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, the silica product obtained was amorphous and the uniformity of the nanosized sample was observed at an average size of 3 nm, and the BET result showed that the highest specific surface of the sample was about 340 m2/g. The results obtained in the mentioned method prove that the rice husk from agricultural wastes can be used for the production of silica nanoparticles.
