Alternative foaming agents for fabrication of glass foam

Glass foam tablets were produced from container glass bottles (CGB) using eggshell waste (ESW) and perlite (P) as foaming agent in different portions. The ground raw materials (CGB, ESW, P) were homogenized and pressed with hydraulic piston press machine at different pressures (in the case of P containing tablets 30 MPa and ESW containing tablets 15 MPa, 30 MPa and 40 MPa were used).The obtained glass tablets were heat treated at different temperatures (in the case of P containing tablets 800 °C, 900°C, 1000°C and 1100°C, and ESW containing tablets 600 °C, 700 °C, 800 °C and 900 °C were used). The study shows the specimen density of tablets before and after heat treatment, as well as the true density of the powder mixtures before tableting and the abrasion resistance of the glass foam products.

Вплив орієнтаційного витягування на властивості сумішей поліефірів ПЕТg/ПЕТ

Rational conditions for orientational drawing of PETg/PET polyester blend during processing into tape products are established. Tensile strength and elongation at break for all test specimens were determined according to ISO 527-2: 2012. Tensile modulus - ISO 527-1: 2019, specimen density - PN-EN ISO 1183-1, change of linear dimensions of specimens - ISO 16012: 2015. It was found that the introduction of PET into PETg leads to an increase in tensile strength of the blend, which is probably due to the process of orientational crystallization of PET. When the orientations are higher than 5.5 times in the PETg /PET mixtures, cavitation foaming occurs, which leads to a decrease in the blend density, its turbidity and a decrease in tensile strength. Blends with a high content of PETg have a significant thermal shrinkage, which should be taken into account when processing and applying these polymers. Physical and mechanical properties of PETg/PET polyesters blend with different ratio in the process of orientational stretching are established. The tensile strength increases with the increase drawing ratio for blends with high PET content due to its orientation crystallization. The phenomenon of cavitation foaming in polyester blend with draw ratio more than 5.5 times is found, which is accompanied by a decrease in the density of the samples and their tensile strength. Presence of PETg in PET matrix decrease tensile strength and elongation and significantly increase thermal shrinkage. Low elongation at break found for PETg/PET blend specimen without orientation which increases dramatically with low draw ratios and then decrease with higher drawing ratio. The technological modes of realization of cavitation foaming for the PETg/PET mixture at orientation drawing ratio above 5.5 due to the different phase structure of the components of the mixtures have been established. The introduction of PETg into PET leads to a significant increase in thermal shrinkage and reduces the physical and mechanical performance of oriented products.

THE INFLUENCE OF PROCESS CONDITIONS ON GROUND COAL SLAG AND BLAST FURNACE SLAG BASED GEOPOLYMER PROPERTIES

In this study, the material characterization of Vietnamese ground coal slag and ground granulated blast furnace slag (GGBFS), such as particle size distribution, chemical composition, bulk density and particle density are shown. The geopolymer specimens were prepared by mixing an 80 m/m% mass of solid materials (ground coal slag and GGBFS in a different ratio) with 20 m/m % of a 10M NaOH alkaline activator. A systematic experimental series was carried out in order to optimize the preparation process. In that series, the heat curing temperature was 60°C for 6 hours, and then selected specimens were heat treated at a high temperature (1000 °C) for 1 hour. After 7 days of ageing, the physical properties of the geopolymer (compressive strength, specimen density) were measured. Also, after 180 days of ageing, the pH values of water in the geopolymer leaching preparation were determined. The results show that the geopolymer can be used for refractory applications due to its good heat resistance properties. However, geopolymers that were heated at 1000 °C had lower compressive strength, specimen density and pH values of water containing the geopolymer than those that were cured at 60 °C.

Production of Personalized Thyroid Cartilage Scaffold and Histological Analysis

To meet the bone defect on the personalized needs of implantation, this study presents the manufacture of personalized thyroid cartilage hydroxyapatite (HA) scaffold by the rapid prototyping(RP) technique combined with CT image reconstruction and employs the foaming of suspensions prior to the in situ polymerization of organic monomers contained in the compositions. The organic additives are eliminated at temperatures above 300°C, and sintering is carried out for consolidation of the ceramic matrix. Spherical interconnected cells with sizes ranging from 100μm to 250μm characterize the porous structure, depending on the specimen density. The biological properties of porous personalized scaffolds loaded with bone morphogenetic protein 2 (rhBMP-2) were evaluated, by which a simulated surgical method of thyroid cartilage defects in rabbits and repairing with artificial scaffolds, and compared with rhBMP-2 loaded dense personalized or porous non-personalized scaffolds. The results of the histological analysis and the electronic laryngoscope inspection of airway indicate that rhBMP-2/HA/ porous personalized scaffolds is a promising composite having osteogenic efficient enough for repairing thyroid cartilage defects.

DEM Study on Energy Allocation Behavior in Crushable Soils

Detailed knowledge of particle-scale energy allocation behavior under the influence of particle breakage is of fundamental importance to the development of micromechanics-based constitutive models of sands. This paper reports original results of the energy input/dissipation of an idealized crushable soil using 3D DEM simulations. Particle breakage is modeled as the disintegration of synthetic agglomerate particles which are made up of parallel-bonded elementary spheres. Simulation results show that the initial specimen density and crushability strongly affect the energy allocation of the soil both at small and large strains. The major role of particle breakage, which itself only dissipates a negligible amount of input energy, is found to advance the soil fabric change and promote the interparticle friction dissipation. Particularly, at small strains, particle breakage disrupts the strain energy buildup and thus reduces the mobilized shear strength and dilatancy of a granular soil. At large strains where particle breakage is greatly reduced, a steady energy dissipation by interparticle friction and mechanical damping is observed. Furthermore, it is found that shear bands develop in most dense crushable specimens at large strains, but they are only weakly correlated to the anisotropy of the accumulated friction dissipation.

EVALUATION OF BONE BIOMECHANICAL PROPERTIES IN DIFFERENT REGIONS OF THE EQUINE THIRD METACARPUS

Purpose: To compare biomechanical characteristics at different regions of the equine third metacarpal bone using standardized test specimens. Methods: Standardized test specimens were made from samples collected from each third metacarpal bone. Cortical bone samples were collected from the lateral (ts4L) and medial (ts4M) cortices of the mid-diaphysis and trabecular bone samples were collected from the distal (ts3) and proximal (ts2) epiphyses. A sample corresponding to the mid third of the third metacarpal bone was also collected (ts1). Test specimens were submitted to compressive testing for determination and comparison of biomechanical properties. Results: Stress and modulus of elasticity of ts4L and ts4M did not differ at the time of fracture. However, the modulus of elasticity of ts4L and ts4M differed from ts1. Maximum tension and modulus of elasticity differed between ts2 and ts3. A medium to high positive correlation between test specimen density and bone biomechanical properties was observed. Conclusion: The lateral and medial cortices of the equine third metacarpal bone have similar biomechanical characteristics. The proximal and distal epiphyses of the equine third metacarpal bone have different biomechanical properties that are correlated with bone density in these regions.