• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2352-2358
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• 2012

A high-nitrogen energetic salt, 1-amino-1-hydrazino-2,2-dinitroethylene guanidine salt [G(AHDNE)], was synthesized by reacting of 1-amino-1-hydrazino-2,2-dinitroethylene (AHDNE) and guanidine hydrochloride in sodium hydroxide aqueous solution. The theoretical investigation on G(AHDNE) was carried out by B3LYP/$6-311+G^*$ method. The thermal behaviors of G(AHDNE) were studied with DSC and TG-DTG methods, and the result presents an intense exothermic decomposition process. The enthalpy, apparent activation energy and pre-exponential constant of the process are $-1060J\;g^{-1}$, $148.7kJ\;mol^{-1}$ and $10^{15.90}s^{-1}$, respectively. The critical temperature of thermal explosion of G(AHDNE) is $152.63^{\circ}C$. The specific heat capacity of G(AHDNE) was studied with micro-DSC method and theoretical calculation method, and the molar heat capacity is $314.69J\;mol^{-1}K^{-1}$ at 298.15 K. Adiabatic time-to-explosion of G(AHDNE) was calculated to be a certain value between 60-72 s. The detonation velocity and detonation pressure were also estimated. G(AHDNE) presents good performances.

• 한국광물학회지
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• 제11권1호
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• pp.1-12
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• 1998

In Pohang area, basaluminite accompanying a little amounts of hydrobasalumnite, super-genetically occurs as whitish cryptocrystalline (2-4 $\mu\textrm{m}$) clay-like aggregates in the vicinity of altered carbonate concretions embedded within mudstones of the Tertiary Yeonil Group. A hydrobasaluminite changed readily into a basaluminite at room temperature in air, and, in turn, into a metabasaluminite when heating to 150$^{\circ}$~30$0^{\circ}C$. For the basaluminite, a monoclinic unit-cellparameters (a=14.845$\AA$, b=10.006$\AA$, c=11.082$\AA$, $\beta$=122.15$^{\circ}$) were calculated by X-ray powder diffraction data. Its basal reflections (001 and 002) are XRD analyses strongly indicate that the aluminum sulphate mineral has a layer structure and, at least, three types of water, i.e., (1) interlayer water (9.0 wt %), (2) crystal water (8.0 wt %), and (3) structural water (19.0 wt %). may present in its lattice. Based on TG-DTG data combined with EDS and IR analyses, a new chemical formula of Al5SO4(OH)134H2O was given to the basaluminite. Field occurrence and stable isotope data ($\delta$18O, $\delta$D, $\delta$34S) for the basaluminite seem to reflect that it was formed by the leached meteoric solution from surrounding mudstones during or after uplifting. An interaction of the acid solution with carbonate concretion and the resultant local neutralization of the fluid rich in Al3+ and SO42- are major controls on the basaluminite formation.

• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2342-2348
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• 2014

Poly(lactic-co-glycolic acid) (PLGA) were grafted to both ends of Pluronic$^{(R)}$ F68 ($(EO)_{75}(PO)_{30}(EO)_{75}$) triblock copolymer to produce poly{(lactic acid)$_m$-co-(glycolic acid)$_n$}-b-poly(ethylene oxide)$_{75}$-b-poly(propylene oxide)$_{30}$-b-poly(ethylene oxide)$_{75}$-b-poly{(lactic acid)$_m$-co-(glycolic acid)$_n$} (PLGA-F68-PLGA) pentablock copolymers. Molecular weights of PLGA blocks were controlled and five kinds of pentablock copolymers with different PLGA block lengths were synthesized using in-situ ring-opening polymerization of D,L-lactide and glycolide with tin(II) 2-ethylhexanoate ($Sn(Oct)_2$) catalyst. PLGA-F68-PLGA pentablock copolymers were characterized by $^1H$- and $^{13}C$-NMR, GPC, and TGA. The numbers (2m, 2n) of repeating units for lactic acid and glycolic acid inside PLGA segments were obtained as (48, 17), (90, 23), (125, 40), (180, 59), and (246, 64), with $^1H$-NMR measurement. From NMR data, the resultant molecular weights were determined in the range of 12,700-29,700, which were similar to those obtained from GPC. Polydispersity index was increased in the range of 1.32-1.91 as the content of PLGA blocks increased. TG and DTG thermograms showed discrete degradation traces for PLGA and F68 blocks, which indicate the weight fractions of PLGA blocks in pentablock copolymers can be calculated by TG profile and it is possible to remove PLGA block selectively. Hydrodynamic radius and radius of gyration of pentablock copolymer micelle were obtained in the range of 46-68 nm and 31-49 nm, respectively, in very dilute (i.e. 0.005 wt %) aqueous solution of THF:$H_2O$ = 10:90 by volume at $25^{\circ}C$.

• 대한기계학회논문집B
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• 제40권1호
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• pp.31-37
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• 2016

최근 바이오매스와 석탄의 혼소 기술이 화력 발전의 주요한 연소 기술 중 하나로 떠오르고 있다. 그러나 혼소는 실제 발전용 보일러 적용시 많은 검증들을 필요로 한다. 본 연구에서는 바이오매스 혼소시 연소 특성을 알아보기 위해 열중량 분석기(Thermogravimetric analyzer, TGA)와 하향분류층 반응기(Drop tube furnace, DTF)를 사용하였으며, TGA의 TG/DTG 분석을 통한 반응성과 DTF를 이용한 UBC를 측정하여 연소 특성을 분석하였다. 특히 석탄과 바이오매스 혼소율(Biomass blending ratio) 및 바이오매스 입자 크기 변화에 따른 특성을 분석하였다. 그 결과, 바이오매스의 혼소율이 증가함에 따라 산소 부족으로 인한 반응 특성이 나타났으며, 이는 바이오매스가 가진 초기의 빠른 연소 특성 때문이다. 또한, 본 연구 결과를 통해 바이오매스의 최적 혼소 조건(UBC 발생량 기준)은 5%로 나타났으며, 산소 부화 조건은 바이오매스 혼소시 발생하는 산소 부족 현상을 저감시켜 미연분 상승을 완화시켜줄 수 있다.