The thermal stress of the quartz oscillator module packaging isinvestigated using digital-im- age correlation method (DICM), and theexperimental results are given. Under the quartz oscillator modulepackaging, the quar...The thermal stress of the quartz oscillator module packaging isinvestigated using digital-im- age correlation method (DICM), and theexperimental results are given. Under the quartz oscillator modulepackaging, the quartz oscillator and the Fe-Sn-Cu alloy frame arejoined together with the electroconductive adhesive (PI), and theelectroconductive adhesive needs to be cured twice at 150 deg. C and275 deg. C respective- ly.展开更多
Three kinds of novel aromatic diamine-based benzoxazines containing naphthalene, propane-2,2-diyldibenzene and neopentyl groups in the backbone, respectively （designated as BAPNCP, BAPBACP and BAPNPGCP, respectively...Three kinds of novel aromatic diamine-based benzoxazines containing naphthalene, propane-2,2-diyldibenzene and neopentyl groups in the backbone, respectively （designated as BAPNCP, BAPBACP and BAPNPGCP, respectively）, were synthesized and characterized. In addition, the effects of backbone structures on curing behaviors of the monomers and thermal and flammability properties of the resulting polymers were systematically studied. The results indicated that BAPNPGCP displayed the highest enthalpy of the curing reaction associated with the ring-opening of benzoxazine, which was due to the effect of benzoxazine ring content per unit mass. Interestingly, the 5 wt% weight loss temperature and char residue after thermogravimetric test for poly（BAPNPGCP） were 8 ℃ and 7% higher than those of poly（BAPBACP）. Meanwhile, the total heat release of poly（BAPNPGCP） was less than half of that for poly（BAPBACP）, indicating the substantial effect of benzoxazine ring content on flammability and char formation. Furthermore, it was found that poly（BAPNCP） gave the best thermal stability and flame retardancy, which was due to the synergistic effect between naphthalene group and benzoxazine ring content. This study provides new insight into the curing behavior of benzoxazine and further understanding on the high performance of polybenzoxazine.展开更多
The average transient lifetime of a chaotic transient versus the Lyapunov dimension of a chaotic saddle is studied for high-dimensional nonlinear dynamical systems. Typically the average lifetime depends upon not only...The average transient lifetime of a chaotic transient versus the Lyapunov dimension of a chaotic saddle is studied for high-dimensional nonlinear dynamical systems. Typically the average lifetime depends upon not only the system parameter but also the Lyapunov dimension of the chaotic saddle. The numerical example uses the delayed feedback differential equation.展开更多
Leather is a collagen-based biomass prepared from raw skins or hides by a series of unit operations, in which the unhairing and fiber opening are extremely important operations. However, the conventional Na2S/Ca(OH)2 ...Leather is a collagen-based biomass prepared from raw skins or hides by a series of unit operations, in which the unhairing and fiber opening are extremely important operations. However, the conventional Na2S/Ca(OH)2 system used in unhairing and fiber opening has given rise to the pollution to the environment. It is necessary to develop substitute technology for the Na2S/Ca(OH)2. In the present study, 1-allyl-3-methylimidazolium chloride ([AMIm]Cl) was used to cooperate with dispase for cycle unhairing and one-pot beamhouse to recycle waste bovine hides and com-pared with conventional processing. During those processes, the mechanism of [AMIm]Cl-dispase synergistic unhair-ing and collagen fibers opening were studied. Besides, plant hazard, organic matter and [AMIm]Cl of wastewater from [AMIm]Cl-dispase process were respectively investigated and separated to evaluate the environmental and economic benefits of the [AMIm]Cl-dispase process. As a result, enzyme activity after unhairing by [AMIm]Cl-diapase system for using 5 times is higher than that by KCl-dispase system, and needs lower unhairing time, which is because of rapid penetration of [AMIm]Cl-dispase solution in bovine hides. For this reason, the tensile strength and elastic modulus of tanned leather from [AMIm]Cl-dispase process are higher than those from the KCl-diapase and conventional pro-cesses, and its hydrothermal shrinkage temperature is comparable to that of the conventional one. Because of the 58.13% lower wastewater discharge (WD), 66.60% lower total solids (TS), 97.23% lower ammonia nitrogen (NH3-N), non-toxic wastewater and organic matter recovery in wastewater are reached from [AMIm]Cl-dispase process, which is expected to be an alternative to the conventional process to reduce environmental pollution and realize the sustainable development of technology for leather manufacturing.展开更多
基金the Natural Science Foundation of Tianjin (013605211)
文摘The thermal stress of the quartz oscillator module packaging isinvestigated using digital-im- age correlation method (DICM), and theexperimental results are given. Under the quartz oscillator modulepackaging, the quartz oscillator and the Fe-Sn-Cu alloy frame arejoined together with the electroconductive adhesive (PI), and theelectroconductive adhesive needs to be cured twice at 150 deg. C and275 deg. C respective- ly.
基金supported by the National Natural Science Foundation of China(No.51103129)the National Basic Research Program of China("973 Program",No.2010CB631105)+1 种基金the Ningbo Natural Science Foundation(No.2012A610084)the Open Fund of Zhejiang Provincial Top Key Discipline of New Materials and Process Engineering(No.20110939)
文摘Three kinds of novel aromatic diamine-based benzoxazines containing naphthalene, propane-2,2-diyldibenzene and neopentyl groups in the backbone, respectively （designated as BAPNCP, BAPBACP and BAPNPGCP, respectively）, were synthesized and characterized. In addition, the effects of backbone structures on curing behaviors of the monomers and thermal and flammability properties of the resulting polymers were systematically studied. The results indicated that BAPNPGCP displayed the highest enthalpy of the curing reaction associated with the ring-opening of benzoxazine, which was due to the effect of benzoxazine ring content per unit mass. Interestingly, the 5 wt% weight loss temperature and char residue after thermogravimetric test for poly（BAPNPGCP） were 8 ℃ and 7% higher than those of poly（BAPBACP）. Meanwhile, the total heat release of poly（BAPNPGCP） was less than half of that for poly（BAPBACP）, indicating the substantial effect of benzoxazine ring content on flammability and char formation. Furthermore, it was found that poly（BAPNCP） gave the best thermal stability and flame retardancy, which was due to the synergistic effect between naphthalene group and benzoxazine ring content. This study provides new insight into the curing behavior of benzoxazine and further understanding on the high performance of polybenzoxazine.
基金Supported by the Hu'nan Natural Science Foundation(No.SSY2066).
文摘The average transient lifetime of a chaotic transient versus the Lyapunov dimension of a chaotic saddle is studied for high-dimensional nonlinear dynamical systems. Typically the average lifetime depends upon not only the system parameter but also the Lyapunov dimension of the chaotic saddle. The numerical example uses the delayed feedback differential equation.
基金National Natural Science Foundation of China(No.51673177)National Key R&D Program of China(No.2017YFB0308500).
文摘Leather is a collagen-based biomass prepared from raw skins or hides by a series of unit operations, in which the unhairing and fiber opening are extremely important operations. However, the conventional Na2S/Ca(OH)2 system used in unhairing and fiber opening has given rise to the pollution to the environment. It is necessary to develop substitute technology for the Na2S/Ca(OH)2. In the present study, 1-allyl-3-methylimidazolium chloride ([AMIm]Cl) was used to cooperate with dispase for cycle unhairing and one-pot beamhouse to recycle waste bovine hides and com-pared with conventional processing. During those processes, the mechanism of [AMIm]Cl-dispase synergistic unhair-ing and collagen fibers opening were studied. Besides, plant hazard, organic matter and [AMIm]Cl of wastewater from [AMIm]Cl-dispase process were respectively investigated and separated to evaluate the environmental and economic benefits of the [AMIm]Cl-dispase process. As a result, enzyme activity after unhairing by [AMIm]Cl-diapase system for using 5 times is higher than that by KCl-dispase system, and needs lower unhairing time, which is because of rapid penetration of [AMIm]Cl-dispase solution in bovine hides. For this reason, the tensile strength and elastic modulus of tanned leather from [AMIm]Cl-dispase process are higher than those from the KCl-diapase and conventional pro-cesses, and its hydrothermal shrinkage temperature is comparable to that of the conventional one. Because of the 58.13% lower wastewater discharge (WD), 66.60% lower total solids (TS), 97.23% lower ammonia nitrogen (NH3-N), non-toxic wastewater and organic matter recovery in wastewater are reached from [AMIm]Cl-dispase process, which is expected to be an alternative to the conventional process to reduce environmental pollution and realize the sustainable development of technology for leather manufacturing.
