A novel intumescent flame retardant, containing ammonium polyphosphate (APP), and poly(hexamethylene terephthalamide) (PA6T), was prepared for flame retarding polypropylene (PP). The flame retardation of the PP composites was characterized by limiting oxygen index (LOI). The thermal degradation of the composites was investigated by means of thermogravimetric analysis (TG) and TG coupled with Fourier transform infrared spectroscopy (TG-FTIR). The morphology of the char obtained after combustion of the composites was studied by scanning electron microscopy. It has been found the intumescent flame retardant showed good flame retardancy, with the LOI value of the PA6T/APP/PP (5/25/70) system increasing from 17.5 to 32. Meanwhile, the TG and TG-FTIR work indicated that PA6T could be effective as a carbonization agent and there was a synergistic reaction between PA6T and APP, which effectively promoted the char formation of the PP composites. Moreover, it was revealed that uniform and compact intumescent char layer was formed after combustion of the intumescent flame retarded PP composites.
A novel charring agent poly(p-propane terephthalamide) (PPTA) was synthesized by using terephthaloyl chloride and 1,3-propanediamine through solution polycondensation and it was used together with ammonium polyphosphate (APP) to prepare a novel intumescent flame retardant (IFR) for ABS. The thermal degradation behaviour and flame retardancy were investigated, the results showed that PPTA could be effective as a charring agent, the flame retardancy of ABS and the mass of residues improved greatly with the addition of IFR. When the content of APP was 22.5 mass% and PPTA was 7.5 mass%, the limiting oxygen index (LOI) value of IFR-ABS system was found to be 32.4, and class V-0 of UL-94 test was passed. Moreover, the synergistic effects of two different adjuvants AlPi and MnO2 in IFR-ABS system have been studied.
The atmospheric deposition fluxes of 7Be, 210Pb and 210Po at Xiamen were measured. The samples were collected from March 2004 to April 2005 and the sampling period was one month.
The 7Be and 210Pb activity were measured using HPGe γ-spectrometer after concentration using Fe(OH)3 co-precipitation method. The 210Po was counted with an α-spectrometer after the sample was digested and spontaneous plated onto a silver planchet. At Xiamen,
the atmospheric deposition fluxes of 7Be varied between 0.11 and 2.93 Bq·m−2·d−1 and the average was 1.64 Bq·m−2·d−1; 210Pb fluxes varied between 0.04 and 0.85 Bq·m−2·d−1, and the average was 0.51 Bq·m−2·d−1; 210Po fluxes varied between 0.002 and 0.133 Bq·m−2·d−1, and the average was 0.061 Bq·m−2·d−1. There were positive correlations between the deposition fluxes of 7Be, 210Pb or 210Po and the amount of precipitation. The residence time of aerosols varied between 6.0 and 54.0 days with a mean of 27.1 days,
which were calculated by 210Po/210Pb fluxes ratios.
228Ra levels in the Yellow Sea and East China Sea were determined using the emanation method. The seawater radium was concentrated
using an Mn-fiber and the 224Ra ingrowth was measured after about half a year when the initial 224Ra in the sample would have decayed. The 224Ra activity in the sample was evaluated using the decay dynamics relationship between parent 228Ra and daughter 228Th. The concentration and distribution feature of 228Ra in the Yellow Sea and East China Sea were studied and the 228Ra concentrations in the surface seawater of the Yellow Sea and the East China Sea were in the range 0.09–15.0 Bq/m3 with an average of 6.84 Bq/m3 during the summer cruise, and in the range 0.09–16.9 Bq/m3 with an average of 6.37 Bq/m3 during the winter cruise. The 228Ra distribution in the northern Yellow Sea was different from the southern Yellow Sea and East China Sea. The highest 228Ra activity of surface water was located in the middle of the northern Yellow Sea, but for the southern Yellow Sea and East
China Sea, it decreased with increasing distance from China continent.
Authors:Hantao Zou, Changhai Yi, Luoxin Wang, Hongtao Liu and Weilin Xu
Thermal decomposition of poly(lactic acid) (PLA) has been studied using thermogravimetry coupled to Fourier transform infrared
spectroscopy (TGA-FTIR). FTIR analysis of the evolved decomposition products shows the release of lactide molecule, acetaldehyde,
carbon monoxide and carbon dioxide. Acetaldehyde and carbon dioxide exist until the end of the experiments, whereas carbon
monoxide gradually decreases above the peak temperature in that the higher temperature benefits from chain homolysis and the
production of carbon dioxide. A kinetic study of thermal degradation of PLA in nitrogen has been studied by means of thermogravimetry.
It is found that the thermal degradation kinetics of PLA can be interpreted in terms of multi-step degradation mechanisms.
The activation energies obtained by Ozawa–Flynn–Wall method and Friedman’s method are in good agreement with that obtained
by Kissinger’s method. The activation energies of PLA calculated by the three methods are 177.5 kJ mol−1, 183.6 kJ mol−1 and 181.1 kJ mol−1, respectively.
Authors:Li Xi, Liu Yi, Wu Jun, Liang Huigang and Qu Songsheng
The action of three kinds of the selenomorpholine compounds on a strain ofEscherichia coli was studied by microcalorimetry. Differences in their capacities to affect the metabolism of this bacterium were observed.
The extent and duration of the effect on the metabolism as judged from the rate constant (k) of Escherichia coli (in log phase) varied with the different drugs. The kinetics show that selenomorpholine compounds had an effect on the metabolism
process of Escherichia coli. The k of Escherichia coli in the presence of the drugs increased with the increasing concentrations of the drugs (C) at low concentration; but at high concentration, the rate constant decreased with the increasing concentrations of the drugs.
The experimental results reveal that the sequence of antibiotic activity of selenomorpholines is: N-selenomorpholinemethyl
succinimide and its hydrochloride>N-(α-selenomorpholinebenzyl) succinimide.
Authors:Shen Xuesong, Wang Tao, Jin Meihua, Zhao Chunxia, Qin Xuelian, Liu Hanfu, Qiu Zhuangping and Liu Yi
A thermal dynamic model of nanoformulations entrapped in artesunate liposomes was established and biological thermodynamics was applied for investigation of the drug formulations. Effects of artesunate liposomes on the growth metabolism of Escherichia coli were studied by microcalorimetry. The results showed that (1) Comparison of artesunate and artesunate liposomes, the thermogenesis curves of E. coli were significant different in the metabolic process: lag phase (AB), log phase (BC), stationary phase (CD), and decline phase (DE); (2) Linear fit of the data of total metabolic heat of E. coli effected by different concentration artesunate (1–300 μg), the equation can be obtained as follows: Y = 364720.61−1075.25x, R = 0.9985; Linear fit of the data of total metabolic heat of E. coli effected by different concentration artesunate liposomes (30–120 μg), the linear equation can be obtained as follows: Y = 54251.5765−35.71122x, R = 0.98345; (3) The half inhibitory concentration IC50 was 50.05 μg/mL, the relative sensitivity was obviously different; (4) Artesunate liposomes having better sustained release properties as compare to artesunate.
Authors:Lung-Chang Tsai, Jyun-Wei Chen, Hung-Yi Hou, Shang-Hao Liu and Chi-Min Shu
The decomposition of organic peroxides by their relatively weak oxygen linkage and hydroperoxide radical in the presence of reaction solution is one of the thermal hazards for triggering a runaway reaction. Runaway incidents may occur in oxidation reactors, vacuum condensation reactors, tank lorries, or storage tanks. In NFPA 432 organic peroxides in NFPA 432 are classified as flammable. The exothermic behaviors of solid organic peroxides, dicumene peroxide, benzoyl peroxide, and lauroyl peroxide, were determined by differential scanning calorimetry (DSC), and vent sizing package 2 (VSP2). Relevant data detected by DSC provided thermal stability information, such as exothermic onset temperature (T0), maximum heat-releasing peak (Tmax), and heat of decomposition (ΔHd). VSP2 was used to perform the bench scale situation for pushing the expected or unexpected reaction to undergo runaway reaction. Onset temperature, maximum pressure, self-heating rate ((dT dt−1)max), and pressure-release rate ((dP dt−1)max) were therefore obtained and explained. These results are essentially crucial in process design for an inherently safer approach.
Authors:Chun-Ping Lin, Jo-Ming Tseng, Yi-Ming Chang, Shang-Hao Liu, Yen-Chun Cheng and Chi-Min Shu
This study investigated the role played by green thermal analysis technology in promoting the use of resources, preventing
pollution, reducing energy consumption and protecting the environment. The chemical tert-butyl peroxybenzoate (TBPB) has been widely employed in the petrifaction industries as an initiator of polymerization formation
agent. This study established the thermokinetic parameters and thermal explosion hazard for a reactor containing TBPB via
differential scanning calorimetry (DSC). To simulate thermokinetic parameters, a 5-ton barrel reactor of liquid thermal explosion
model was created in this study. The approach was to develop a precise and effective procedure on thermal decomposition, runaway,
and thermal hazard properties, such as activation energy (Ea), control temperature (CT), critical temperature (TCR), emergency temperature (ET), heat of decomposition (∆Hd), self-accelerating decomposition temperature (SADT), time to conversion limit (TCL), total energy release (TER), time to maximum rate under isothermal condition (TMRiso), etc. for a reactor containing TBPB. Experimental results established the features of thermal decomposition and huge size
explosion hazard of TBPB that could be executed as a reduction of energy potential and storage conditions in view of loss