Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl ...Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.展开更多
A kind of modifier was synthesized to modify the surface of nanometer calcium carbonate （abbreviated as nano-CaCO3）, which is used in architectural coatings. The modification technology of the nano-CaCO3 was studied...A kind of modifier was synthesized to modify the surface of nanometer calcium carbonate （abbreviated as nano-CaCO3）, which is used in architectural coatings. The modification technology of the nano-CaCO3 was studied through orthogonal experimental methods. The factors studied were rotation speed, modifier dosage, emulsification temperature, emulsification time and heat aging time after emulsification. Optimized conditions for modification of the surface were： rotation speed 16000 r/min; modifier dosage 3%; emulsification temperature 75 ℃; emulsification time 60 min and aging time 40 min. The modified nano-CaCO3 was also studied by size-distribution measurements, transmission electron microscopy, infrared spectroscopy and thermal analysis. The results show that the size distribution of the modified nano-CaCO3 is uniform and that there are chemi-sorption and physi-sorption between the nano-CaCO3 and the modifier. Compared to traditional architectural coatings without nano-CaCO3, the nanometer composite coatings are obviously improved in respect to dirt resistance, scrub resistance, thixotropy, water resistance, alkalinity resistance and aging resistance.展开更多
The chrome-containing corundum castables specimens with different nano-CaCO3 additions （0-1.6 wt%） were prepared using tabular corundum,alumina powder,chrome oxide micropowder （average particle size 〈 5 μm）,calc...The chrome-containing corundum castables specimens with different nano-CaCO3 additions （0-1.6 wt%） were prepared using tabular corundum,alumina powder,chrome oxide micropowder （average particle size 〈 5 μm）,calcium aluminate cement （Secar71）,commercial nano-CaCO3 （average particle size 〈100 nm） as main starting materials and FS10 as water reducer. The specimens heat treated at 1 000 ℃ and 1 600 ℃ were characterized in terms of apparent porosity,bulk density,cold and hot strengths,and microstructure. The results show that,when the nano-CaCO3 addition is no more than 1.0 wt%,the apparent porosity of the castables increases with nano-CaCO3 addition increasing,both the cold and hot strengths are enhanced; however,when the nano-CaCO3 addition excesses 1.0 wt%,both the cold and hot strengths go down remarkably with nano-CaCO3 addition increasing; the thermal shock resistance is gradually improved with nano-CaCO3 addition increasing in chosen range.展开更多
文摘Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.
文摘A kind of modifier was synthesized to modify the surface of nanometer calcium carbonate （abbreviated as nano-CaCO3）, which is used in architectural coatings. The modification technology of the nano-CaCO3 was studied through orthogonal experimental methods. The factors studied were rotation speed, modifier dosage, emulsification temperature, emulsification time and heat aging time after emulsification. Optimized conditions for modification of the surface were： rotation speed 16000 r/min; modifier dosage 3%; emulsification temperature 75 ℃; emulsification time 60 min and aging time 40 min. The modified nano-CaCO3 was also studied by size-distribution measurements, transmission electron microscopy, infrared spectroscopy and thermal analysis. The results show that the size distribution of the modified nano-CaCO3 is uniform and that there are chemi-sorption and physi-sorption between the nano-CaCO3 and the modifier. Compared to traditional architectural coatings without nano-CaCO3, the nanometer composite coatings are obviously improved in respect to dirt resistance, scrub resistance, thixotropy, water resistance, alkalinity resistance and aging resistance.
文摘The chrome-containing corundum castables specimens with different nano-CaCO3 additions （0-1.6 wt%） were prepared using tabular corundum,alumina powder,chrome oxide micropowder （average particle size 〈 5 μm）,calcium aluminate cement （Secar71）,commercial nano-CaCO3 （average particle size 〈100 nm） as main starting materials and FS10 as water reducer. The specimens heat treated at 1 000 ℃ and 1 600 ℃ were characterized in terms of apparent porosity,bulk density,cold and hot strengths,and microstructure. The results show that,when the nano-CaCO3 addition is no more than 1.0 wt%,the apparent porosity of the castables increases with nano-CaCO3 addition increasing,both the cold and hot strengths are enhanced; however,when the nano-CaCO3 addition excesses 1.0 wt%,both the cold and hot strengths go down remarkably with nano-CaCO3 addition increasing; the thermal shock resistance is gradually improved with nano-CaCO3 addition increasing in chosen range.
