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Geopolymers (GPs) have an important applications in the construction and medical fields owing to their attractive physical and thermal properties. However, the compressive strength of GP is usually less than 80 MPa; therefore, it should be further strengthened to improve the mechanical strength and structural properties of end products. This study presents a facile method to enhance the compressive strength of GP by incorporating aluminum dihydrogen triphosphate (ATP) into the GP matrix during the geopolymerization of metakaolin. The microstructure, thermal properties, and compressive properties of the doped GPs (D-GPs) are investigated. The results show that the ATP is transformed to many granules, bonded and surrounded by GP gel, and the unique microstructure increases the compressive strength of D-GP to 160 MPa with an optimum 1.0 wt% ATP, which is a 108% increase as compared to pure GP. The superhigh compressive strength of ATP-reinforced GP makes them potential alternatives for existing high-strength cement materials. [ABSTRACT FROM AUTHOR]

Poly (ethylene glycol)-grafted multi-walled carbon nanotubes (PEG-MWNTs) were prepared and added into poly(L-lactide) (PLLA)/aluminum nitride (AlN) composites to obtain PLLA/AlN/PEG-MWNTs nanocomposites. Microstructure and thermal conductivity of the composites were investigated on the basis of the influence of PEG-MWNTs incorporated. The results showed that PEG-MWNTs were well-dispersed in the PLLA matrix and had strong interfacial adhesion with the matrix. The addition of PEG-MWNTs improved the thermal conductivity of PLLA/AlN composites. When 3 wt.% of PEG-MWNTs and 50 wt.% of AlN were both added into the PLLA matrix, the thermal conductivity reached 0.7734 W/mK with enhancement almost by 400% as compared to a neat PLLA. However, the thermal conductivity is 0.3401 W/mK for the PLLA composite with 3 wt.% of PEG-MWNTs and 0.4286 W/mK for the one with 50 wt.% of AlN. The synergistic effect of aggregated AlN particles and well-dispersed MWNTs could form efficient thermal conductive paths for improving the thermal conductivity of PLLA composites greatly. [ABSTRACT FROM AUTHOR]

Metakaolin geopolymer (MGP) is a cementitious material which possesses attractive properties and great application potential with low carbon emission. The performance of the steel slag modified geopolymer (SSMG) is not well acknowledged. In this study, the steel slag powder was introduced into MGP as a filler to substitute part of the metakaolin powder. Then the curing process and mechanical properties of the composite SSMG were investigated. The results showed that the moist curing can ensure better SSMG mechanical properties compared to exposed curing and sealed curing. The optimum mass proportion of the steel slag powder in SSMG was 10%, its curing time was accelerated by 100% as compared to that of the MGP. In addition, the final bending strength of SSMG was increased by 8% when the final compressive strength remained unchanged compared to MGP. Moreover, micro-morphology and crystal structure of geopolymers indicated that the physical and chemical reactions existed between the active constituent of steel slag powder and the MGP base component. These reactions were beneficial to strength improvement for composite SSMG. [ABSTRACT FROM AUTHOR]