Thermal and thermo-oxidative decomposition and decomposition kinetics of flame retardant high impact polystyrene （HIPS） with triphenyl phosphate （TPP） and novolac type epoxy resin （NE） were characterized using t...Thermal and thermo-oxidative decomposition and decomposition kinetics of flame retardant high impact polystyrene （HIPS） with triphenyl phosphate （TPP） and novolac type epoxy resin （NE） were characterized using thermo-gravimetric experiment. And the flammability was determined by limited oxygen indices （LOI）. The LOI results show that TPP and NE had a good synthetic effect on the flame retardancy of HIPS. Compared with pure HIPS, the LOI values of HIPS/NE and HIPS/TPP only increased by about 5%, and the LOI value of HIPS/TPP/NE reached 42.3%, nearly 23% above that of HIPS. All materials showed one main decomposition step, as radical HIPS scission predominated during anaerobic decomposition. TPP increased the activity energy effectively while NE affected the thermal-oxidative degradation more with the help of the char formation. With both TPP and NE, the materials could have a comparable good result of both thermal and thermal-oxidative degradation, which could contribute to their effect on the flame retardancy.展开更多
Evolution and fractal character of the phase morphology of high impact polystyrene/poly（cis-butadiene） rubber （HIPS/PcBR） blends during melting and mixing were investigated using scanning electron microscopy （SEM...Evolution and fractal character of the phase morphology of high impact polystyrene/poly（cis-butadiene） rubber （HIPS/PcBR） blends during melting and mixing were investigated using scanning electron microscopy （SEM）. The characteristic length L was defined as the size of particles of the dispersed phase in blends. Different fractal dimensions, Df and Din, were introduced to study the distribution width of phase dimensions in the dimensionless region and the uniformity of the spatial distribution of particles, respectively. The results showed that the average characteristic length Lm and Df increase as the volume fraction of the dispersed phase increases, when the volume fraction of the dispersed phase is lower than 50%. In other words, the size of particles increases and their distribution in the dimensionless region becomes more uniform. Meanwhile, the uniformity of the spatial distribution becomes more perfect as the volume fraction increases. At a certain composition, Lm decreases in the initial stage of the mixing and levels off in the late stage. In the initial stage, Df becomes large rapidly with the process of blending, which means that the distribution of L in the dimensionless region becomes more uniform. Meanwhile, the spatial distribution tends to be ideal rapidly in the early stage and fluctuates in a definite range in the late stage of the mixing.展开更多
In this work,aramid nanoparticles(ANPs)were prepared in dimethyl formamide(DMF)solution containing high impact polystyrene(HIPS)via a bottom-up approach.Transmission electron microscopy(TEM)images showed that the obta...In this work,aramid nanoparticles(ANPs)were prepared in dimethyl formamide(DMF)solution containing high impact polystyrene(HIPS)via a bottom-up approach.Transmission electron microscopy(TEM)images showed that the obtained ANPs were evenly distributed in the HIPS matrix without any agglomeration.Chemical composition of the ANPs,i.e.,poly(p-phenyl-p-phenylenediamine)(PPTA),was confirmed by Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and X-ray diffractometer(XRD).The ANP/HIPS composites,obtained after ethanol precipitation,were added to neat HIPS as fillers to fabricate ANP/HIPS composite sheets.The surface roughness and the glass transition temperature(T_g)of the sheets were characterized by atomic force microscope(AFM)and differential scanning calorimetry(DSC),respectively.Compared with neat HIPS,the mechanical properties of the composite sheet were significantly improved,and the Young's modulus increased from 246.55 MPa to 2025.12 MPa,the tensile strength increased from 3.07 MPa to 29.76 MPa,and the toughness increased from 0.32 N/mm^2 to 3.92 N/mm^2,with an increase rate of 721%,869%and 1125%,respectively.Moreover,the thermal stability of the composites improved with the increase in ANP content.展开更多
The practical application of all-inorganic semiconductor lead halide perovskite nanocrystals(LHP NCs)has been limited by their poor stability.Recently,a lot of research on core-shell structure has been done to improve...The practical application of all-inorganic semiconductor lead halide perovskite nanocrystals(LHP NCs)has been limited by their poor stability.Recently,a lot of research on core-shell structure has been done to improve the stability of perovskite NCs,but the effect was far from the application requirements.Herein,we,for the first time,report a convenient approach to synthesize organic-inorganic double shell CsPbBr_(3)@SiO_(2)@polystyrene(PS)NCs with an inter-core of CsPbBr_(3),the intermediate layer of SiO_(2)shell,and outmost PS shell.Particularly,the CsPbBr_(3)@SiO_(2)@PS NCs maintained more than 90%of their initial photoluminescence(PL)intensity under one month's ultraviolet lamp irradiation or in 85℃ and 85%relative humidity(RH)condition.The white-light-emitting-diodes(WLEDs)were fabricated by encapsulating commercial InGaN chip with CsPbBr_(3)@SiO_(2)@PS NCs and K2SiF6:Mn^(4+)(KSF:Mn^(4+))phosphor with a luminous efficacy of~100 lm/W at 20 mA current and a color gamut of 128%of the National Television Standards Committee(NTSC)standard.In addition,these WLEDs still maintain 91%of the initial luminous efficacy after 1200 h of continuous lighting.These results demonstrated that double shell-protected CsPbBr_(3)perovskite NCs have great potential in the field of WLEDs.展开更多
Over the past half century,the semiconductor chips have deeply influenced our everyday life through increasingly sophisticated electronic products.The central driving force underlying the remarkable evolution in semic...Over the past half century,the semiconductor chips have deeply influenced our everyday life through increasingly sophisticated electronic products.The central driving force underlying the remarkable evolution in semiconductor industry is Moore’s Law,nowadays referring to a doubling of transistor counts per chip every 18 months.Sustaining Moore’s Law is economically beneficial;while the manufacturing cost per chip has been held constant,展开更多
In this article, high impact polystyrene/organo Fe-montmorillonite （HIPS/Fe-OMT） nanocomposites were prepared by melting intercalation. The thermal stability of HIPS/Fe-OMT nanocomposites increased significantly com...In this article, high impact polystyrene/organo Fe-montmorillonite （HIPS/Fe-OMT） nanocomposites were prepared by melting intercalation. The thermal stability of HIPS/Fe-OMT nanocomposites increased significantly compared to that of HIPS examined in thermal degradation conditions. Kinetic evaluations were performed by Kissinger, Flynn-Wall-Ozawa, Friedman methods and multivariate nonlinear regression. Apparent kinetic parameters for the overall degradation were determined. The resuRs showed that the activation energy of HIPS/Fe-OMT nanocomposites was higher than that of HIPS. A very good agreement between experimental and simulated curves was observed in dynamic conditions. Their decomposition reaction model was a single-step process of an nth-order reaction展开更多
Styrene emulsion polymerization using an alkyl-9-BBN, synthesized by reacting 9-BBN（9-borabicyclo-[3.3.1]-nonane） and styrene, in an aqueous sodium dodecyl sulfate（SDS） solution was studied. Ultra-high-molecular-w...Styrene emulsion polymerization using an alkyl-9-BBN, synthesized by reacting 9-BBN（9-borabicyclo-[3.3.1]-nonane） and styrene, in an aqueous sodium dodecyl sulfate（SDS） solution was studied. Ultra-high-molecular-weight（〉 1.0 × 10~7） polystyrene was synthesized using a radical initiator formed through the aerobic oxidation of this alkyl-9-BBN in a high yield（〉 80%）. The kinetics of this emulsion polymerization of styrene with the alkyl-9-BBN was investigated. We confirmed that in the initial stage of the polymerization, the initial reaction rate followed first-order kinetics. The activation energy for this emulsion polymerization of styrene was approximately 56.2 kJ/mol.展开更多
基金Guangdong Province Natural Sciences Fundation(No.39672)
文摘Thermal and thermo-oxidative decomposition and decomposition kinetics of flame retardant high impact polystyrene （HIPS） with triphenyl phosphate （TPP） and novolac type epoxy resin （NE） were characterized using thermo-gravimetric experiment. And the flammability was determined by limited oxygen indices （LOI）. The LOI results show that TPP and NE had a good synthetic effect on the flame retardancy of HIPS. Compared with pure HIPS, the LOI values of HIPS/NE and HIPS/TPP only increased by about 5%, and the LOI value of HIPS/TPP/NE reached 42.3%, nearly 23% above that of HIPS. All materials showed one main decomposition step, as radical HIPS scission predominated during anaerobic decomposition. TPP increased the activity energy effectively while NE affected the thermal-oxidative degradation more with the help of the char formation. With both TPP and NE, the materials could have a comparable good result of both thermal and thermal-oxidative degradation, which could contribute to their effect on the flame retardancy.
基金This work was supported by the National Natural Science Foundation of China (No. 50390090).
文摘Evolution and fractal character of the phase morphology of high impact polystyrene/poly（cis-butadiene） rubber （HIPS/PcBR） blends during melting and mixing were investigated using scanning electron microscopy （SEM）. The characteristic length L was defined as the size of particles of the dispersed phase in blends. Different fractal dimensions, Df and Din, were introduced to study the distribution width of phase dimensions in the dimensionless region and the uniformity of the spatial distribution of particles, respectively. The results showed that the average characteristic length Lm and Df increase as the volume fraction of the dispersed phase increases, when the volume fraction of the dispersed phase is lower than 50%. In other words, the size of particles increases and their distribution in the dimensionless region becomes more uniform. Meanwhile, the uniformity of the spatial distribution becomes more perfect as the volume fraction increases. At a certain composition, Lm decreases in the initial stage of the mixing and levels off in the late stage. In the initial stage, Df becomes large rapidly with the process of blending, which means that the distribution of L in the dimensionless region becomes more uniform. Meanwhile, the spatial distribution tends to be ideal rapidly in the early stage and fluctuates in a definite range in the late stage of the mixing.
基金financially supported by Innovation Project for graduate students of Ludong University(No.IPGS2024-058)the National Natural Science Foundation of China(Nos.52073135,51673089 and 51903114)。
文摘In this work,aramid nanoparticles(ANPs)were prepared in dimethyl formamide(DMF)solution containing high impact polystyrene(HIPS)via a bottom-up approach.Transmission electron microscopy(TEM)images showed that the obtained ANPs were evenly distributed in the HIPS matrix without any agglomeration.Chemical composition of the ANPs,i.e.,poly(p-phenyl-p-phenylenediamine)(PPTA),was confirmed by Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and X-ray diffractometer(XRD).The ANP/HIPS composites,obtained after ethanol precipitation,were added to neat HIPS as fillers to fabricate ANP/HIPS composite sheets.The surface roughness and the glass transition temperature(T_g)of the sheets were characterized by atomic force microscope(AFM)and differential scanning calorimetry(DSC),respectively.Compared with neat HIPS,the mechanical properties of the composite sheet were significantly improved,and the Young's modulus increased from 246.55 MPa to 2025.12 MPa,the tensile strength increased from 3.07 MPa to 29.76 MPa,and the toughness increased from 0.32 N/mm^2 to 3.92 N/mm^2,with an increase rate of 721%,869%and 1125%,respectively.Moreover,the thermal stability of the composites improved with the increase in ANP content.
基金This work was supported by the Priority Research Project of Xiamen(No.3502Z20191015)the Science and Technology Major Project of Fujian Province(No.2021HZ021013)the Major Research Project of Mindu Innovation Laboratory(No.2021ZZ114).
文摘The practical application of all-inorganic semiconductor lead halide perovskite nanocrystals(LHP NCs)has been limited by their poor stability.Recently,a lot of research on core-shell structure has been done to improve the stability of perovskite NCs,but the effect was far from the application requirements.Herein,we,for the first time,report a convenient approach to synthesize organic-inorganic double shell CsPbBr_(3)@SiO_(2)@polystyrene(PS)NCs with an inter-core of CsPbBr_(3),the intermediate layer of SiO_(2)shell,and outmost PS shell.Particularly,the CsPbBr_(3)@SiO_(2)@PS NCs maintained more than 90%of their initial photoluminescence(PL)intensity under one month's ultraviolet lamp irradiation or in 85℃ and 85%relative humidity(RH)condition.The white-light-emitting-diodes(WLEDs)were fabricated by encapsulating commercial InGaN chip with CsPbBr_(3)@SiO_(2)@PS NCs and K2SiF6:Mn^(4+)(KSF:Mn^(4+))phosphor with a luminous efficacy of~100 lm/W at 20 mA current and a color gamut of 128%of the National Television Standards Committee(NTSC)standard.In addition,these WLEDs still maintain 91%of the initial luminous efficacy after 1200 h of continuous lighting.These results demonstrated that double shell-protected CsPbBr_(3)perovskite NCs have great potential in the field of WLEDs.
文摘Over the past half century,the semiconductor chips have deeply influenced our everyday life through increasingly sophisticated electronic products.The central driving force underlying the remarkable evolution in semiconductor industry is Moore’s Law,nowadays referring to a doubling of transistor counts per chip every 18 months.Sustaining Moore’s Law is economically beneficial;while the manufacturing cost per chip has been held constant,
文摘In this article, high impact polystyrene/organo Fe-montmorillonite （HIPS/Fe-OMT） nanocomposites were prepared by melting intercalation. The thermal stability of HIPS/Fe-OMT nanocomposites increased significantly compared to that of HIPS examined in thermal degradation conditions. Kinetic evaluations were performed by Kissinger, Flynn-Wall-Ozawa, Friedman methods and multivariate nonlinear regression. Apparent kinetic parameters for the overall degradation were determined. The resuRs showed that the activation energy of HIPS/Fe-OMT nanocomposites was higher than that of HIPS. A very good agreement between experimental and simulated curves was observed in dynamic conditions. Their decomposition reaction model was a single-step process of an nth-order reaction
文摘Styrene emulsion polymerization using an alkyl-9-BBN, synthesized by reacting 9-BBN（9-borabicyclo-[3.3.1]-nonane） and styrene, in an aqueous sodium dodecyl sulfate（SDS） solution was studied. Ultra-high-molecular-weight（〉 1.0 × 10~7） polystyrene was synthesized using a radical initiator formed through the aerobic oxidation of this alkyl-9-BBN in a high yield（〉 80%）. The kinetics of this emulsion polymerization of styrene with the alkyl-9-BBN was investigated. We confirmed that in the initial stage of the polymerization, the initial reaction rate followed first-order kinetics. The activation energy for this emulsion polymerization of styrene was approximately 56.2 kJ/mol.
