ZnO-B2O3-SiO2-Al2O3-Na2O glass doped with nucleating agent TiO2 was prepared with melting-quenching method and the effect of nucleating agent on the crystallization behavior and phase evolution of this glass was inves...ZnO-B2O3-SiO2-Al2O3-Na2O glass doped with nucleating agent TiO2 was prepared with melting-quenching method and the effect of nucleating agent on the crystallization behavior and phase evolution of this glass was investigated by differential thermal analysis(DTA),X-ray diffraction(XRD),and scanning electron microscopy(SEM).The experimental results show that the glass transition temperature and the first crystallization temperature decrease from 630 ℃ and 765 ℃ to 595 ℃ and 740 ℃,respectively,with introduction of TiO2 into glass.There is no diffraction peaks in the XRD pattern but it is no longer transparent for the base glass without nucleating agent after heat treatment,which suggests the serious phase separation occurred,and the observation by SEM indicates that the phase separation is developed by nucleation and growth mechanism.However,there are two different crystals ZnAl2O4 and NaAlSiO4 present in the glass containing TiO2 after heat treating at 575 ℃ for 2 h and 740 ℃ for 6 h,respectively.What is interesting is that NaAlSiO4 disappears as the crystallization time at 740 ℃ increases from 6 h to 12 h,and more ZnAl2O4 crystal is formed,namely,the further formation of ZnAl2O4 is at cost of NaAlSiO4 with increasing crystallization time.And observation of the morphology of glass ceramics shows great difference with increasing crystallization time.Moreover,the ability of ZnO-B2O3-SiO2-Al2O3-Na2O glass ceramics against attacking of 1M HCl solution is increased by the crystals precipitated in heat treatment process.展开更多
Differential fast scanning calorimetry(DFSC) was employed on the study of self-nucleation behavior of poly(butylene succinate)(PBS).The ultra-fast cooling ability of DFSC allows investigating the effect of self-...Differential fast scanning calorimetry(DFSC) was employed on the study of self-nucleation behavior of poly(butylene succinate)(PBS).The ultra-fast cooling ability of DFSC allows investigating the effect of self-nucleation on the isothermal crystallization kinetics over a wide temperature range.Crystallization half-time,instead of crystallization peak temperature,was used to describe the self-nucleation behavior,and the self-nucleation domain for the samples crystallized at different temperatures was determined.Due to the competition between homogenous nucleation and self-nuclei,the effect of self-nucleation was less pronounced at high supercooling than that for the sample isothermally crystallized at higher temperature.An efficiency scale to judge the efficiency of nucleating agents from the crystallization half-time was also introduced in this work.展开更多
Ultra-high molecular weight polyethylene(UHMWPE)/chitin nanocrystal(CNC) fibers were prepared. Compared with the pure UHMWPE fibers, the ultimate tensile strength and Young's modulus of UHMWPE/CNC fibers are impr...Ultra-high molecular weight polyethylene(UHMWPE)/chitin nanocrystal(CNC) fibers were prepared. Compared with the pure UHMWPE fibers, the ultimate tensile strength and Young's modulus of UHMWPE/CNC fibers are improved by 15.7% and 49.6%, respectively, with the addition of chitin nanocrystals(CNCs) of 1 wt%. The melting temperature(Tm) of UHMWPE/CNC fibers was higher than that of pure UHMWPE fibers. Pure UHMWPE fibers and UHMWPE/CNC fibers were characterized with respect to crystallinity, orientation and kebab structure by wide-angle X-ray diffraction(WAXD), small-angle X-ray scattering(SAXS) and scanning electron microscopy(SEM). It is found that the CNCs act as the shish structure in UHMWPE/CNC fibers and the kebab crystals are grown around the CNCs. There was almost no difference between pure UHMWPE fibers and UHMWPE/CNC fibers in orientation. But the degree of crystallinity of various stages of UHMWPE/CNC fibers was respectively higher than the corresponding stage of pure UHMWPE fibers. Moreover, the addition of 1 wt% CNCs improved the thickness of kebab crystals and accelerated the transformation of kebab to shish.展开更多
Continuous precision casting is an important trend in modern industrialization.Clustering effects in glassforming metallic liquids tremendously influence the properties of rapidly quenched ribbons;therefore,much atten...Continuous precision casting is an important trend in modern industrialization.Clustering effects in glassforming metallic liquids tremendously influence the properties of rapidly quenched ribbons;therefore,much attention has been paid to the study of Fe-based glass-forming melts at high temperatures.Recent investigations of these melts are categorized and reviewed.It is concluded that more efforts are still required to reveal the discipline of amorphization brought about by rapid quenching of Fe-based glass-forming melts.展开更多
基金Funded by the National Natural Science Foundation of Ch ina(51202104 and 51362019)the Natural Science Foundation of the Inner Mongolia Autonomous Region(2016JQ05)the Young Talents of Inner Mongolia Autonomous Region,Inner Mong olia University of Science and Technology(2014QNGG02)
文摘ZnO-B2O3-SiO2-Al2O3-Na2O glass doped with nucleating agent TiO2 was prepared with melting-quenching method and the effect of nucleating agent on the crystallization behavior and phase evolution of this glass was investigated by differential thermal analysis(DTA),X-ray diffraction(XRD),and scanning electron microscopy(SEM).The experimental results show that the glass transition temperature and the first crystallization temperature decrease from 630 ℃ and 765 ℃ to 595 ℃ and 740 ℃,respectively,with introduction of TiO2 into glass.There is no diffraction peaks in the XRD pattern but it is no longer transparent for the base glass without nucleating agent after heat treatment,which suggests the serious phase separation occurred,and the observation by SEM indicates that the phase separation is developed by nucleation and growth mechanism.However,there are two different crystals ZnAl2O4 and NaAlSiO4 present in the glass containing TiO2 after heat treating at 575 ℃ for 2 h and 740 ℃ for 6 h,respectively.What is interesting is that NaAlSiO4 disappears as the crystallization time at 740 ℃ increases from 6 h to 12 h,and more ZnAl2O4 crystal is formed,namely,the further formation of ZnAl2O4 is at cost of NaAlSiO4 with increasing crystallization time.And observation of the morphology of glass ceramics shows great difference with increasing crystallization time.Moreover,the ability of ZnO-B2O3-SiO2-Al2O3-Na2O glass ceramics against attacking of 1M HCl solution is increased by the crystals precipitated in heat treatment process.
基金financially supported by the National Natural Science Foundation of China(Nos.21474049,51673094 and 21404055)the Shenzhen Science and Technology Innovation Committee(Nos.JCYJ20160531151102203 and JCYJ20160608140827794)Tianshan Scholars Program by Yili Normal University
文摘Differential fast scanning calorimetry(DFSC) was employed on the study of self-nucleation behavior of poly(butylene succinate)(PBS).The ultra-fast cooling ability of DFSC allows investigating the effect of self-nucleation on the isothermal crystallization kinetics over a wide temperature range.Crystallization half-time,instead of crystallization peak temperature,was used to describe the self-nucleation behavior,and the self-nucleation domain for the samples crystallized at different temperatures was determined.Due to the competition between homogenous nucleation and self-nuclei,the effect of self-nucleation was less pronounced at high supercooling than that for the sample isothermally crystallized at higher temperature.An efficiency scale to judge the efficiency of nucleating agents from the crystallization half-time was also introduced in this work.
基金financially supported by the National Natural Science Foundation of China(Nos.51273210,51003117 and 5140030545)Open Research Fund of State Key Laboratory of Polymer Physics and Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of SciencesK.C.Wong Magna Fund in Ningbo University
文摘Ultra-high molecular weight polyethylene(UHMWPE)/chitin nanocrystal(CNC) fibers were prepared. Compared with the pure UHMWPE fibers, the ultimate tensile strength and Young's modulus of UHMWPE/CNC fibers are improved by 15.7% and 49.6%, respectively, with the addition of chitin nanocrystals(CNCs) of 1 wt%. The melting temperature(Tm) of UHMWPE/CNC fibers was higher than that of pure UHMWPE fibers. Pure UHMWPE fibers and UHMWPE/CNC fibers were characterized with respect to crystallinity, orientation and kebab structure by wide-angle X-ray diffraction(WAXD), small-angle X-ray scattering(SAXS) and scanning electron microscopy(SEM). It is found that the CNCs act as the shish structure in UHMWPE/CNC fibers and the kebab crystals are grown around the CNCs. There was almost no difference between pure UHMWPE fibers and UHMWPE/CNC fibers in orientation. But the degree of crystallinity of various stages of UHMWPE/CNC fibers was respectively higher than the corresponding stage of pure UHMWPE fibers. Moreover, the addition of 1 wt% CNCs improved the thickness of kebab crystals and accelerated the transformation of kebab to shish.
基金Item Sponsored by National Natural Science Foundation of China(51501043)National Scientific and Technological Support Projects of China(2013BAE08B01)Science and Technology Program of Beijing of China(Z141100003814007)
文摘Continuous precision casting is an important trend in modern industrialization.Clustering effects in glassforming metallic liquids tremendously influence the properties of rapidly quenched ribbons;therefore,much attention has been paid to the study of Fe-based glass-forming melts at high temperatures.Recent investigations of these melts are categorized and reviewed.It is concluded that more efforts are still required to reveal the discipline of amorphization brought about by rapid quenching of Fe-based glass-forming melts.