密胺树脂/硼酸锌双层包覆微胶囊化红磷的制备及其在阻燃聚烯烃中的应用

描述了采用密胺树脂和硼酸锌连续双层包覆微胶囊化红磷(MRP)的最新制备方法。采用红外光谱、电子能谱和透射电镜等分析手段对其进行了表征，并证实红磷已被完全包覆。实验数据表明：经包覆的MRP的热稳定性获得了明显改善，吸水率和磷化氢的发生量均大大减少。MRP作为阻燃助剂应用于聚烯烃阻燃材料表现出了良好的阻燃效果。实时红外和热失重测量以及扫描电镜观察表明：其阻燃机制是红磷受热时与树脂反应促进了含磷膨胀炭层的形成，从而提高了材料的热稳定性，碳层起到了隔氧、隔热作用，而且主要在凝聚相中发挥其阻燃作用。     

乙苯脱氢铁系催化剂的穆斯堡尔谱研究

用穆斯堡尔法对乙苯脱氢铁系催化剂在反应条件下进行了研究。结果表明,反应前催化剂中的铁主要以α-Fe_2O_3和α-FeOOH的形式存在,在反应中主要组分为Fe_3O_4。用K_2CO_3和α-Fe_2O_3在高温下加热可以生成KFeO_2,后者在室温下很不稳定,在同样条件下很容易转化为Fe_3O_4。但钾的存在可促进催化剂中Fe~(3+)还原为Fe~(2+),有利于电子的交换,对催化活性起着助催作用。     

Guest sorption and desorption in the metal-organic framework [Co(INA)(2)] (INA=isonicotinate)--evidence of intermediate phases during desorption

The metal-organic framework [Co(INA)(2)]x0.5EtOH (INA = isonicotinate, NC(5)H(4)-4-CO(2)(-)), was synthesised under solvothermal conditions. Its X-ray crystal structure shows channels containing ethanol guests which are hydrogen-bonded to carboxylate oxygens of the framework. The pyridyl rings of the framework alternate between 'open' and 'closed' positions along the channels resulting in large variation in the channel cross-sectional area from ca. 1.4 by 2.3 A at the narrowest point to 4.9 by 5.3 A at the widest. Despite the very small windows, the ethanol guests (of van der Waals diameter ca. 4.2-6.1 A) may be reversibly desorbed and sorbed into the structure quantitatively, as shown by in situ variable-temperture IR spectroscopy and XRPD. The single-crystal structure of the desolvated form [Co(INA)(2)] shows that there is no change in the overall connectivity on desolvation, but the rotational positions of the pyridine rings are altered. This suggests that pyridyl rotation may occur to allow guests to pass in and out. When the synthesis was conducted in 1-propanol solvent [Co(INA)(2)]x0.5Pr(n)OHxH(2)O, was obtained, and a single-crystal X-ray structure revealed the same overall connectivity as in but with pyridine rings disordered over closed and open positions. There was no evidence of included guests from X-ray crystallography, suggesting that they are also highly disordered. Variable-temperature XRPD performed on bulk samples showed peaks which were unsymmetrical and exhibited shoulders, suggesting that for each pattern obtained the material actually consisted of several closely-related phases. The movements of the peaks during desolvation showed the presence of intermediate phases before the final desolvated product was formed. The peak positions of the intermediate phases matched more closely with the calculated pattern for than with or, suggesting that they may have disordered structures similar to. The results also suggest that the intermediate phase represents an initial increase in volume before a larger decrease in volume occurs to give the final desolvated material.     

EFFECT OF MOLECULAR WEIGHT OF PDMS ON MORPHOLOGY AND MECHANICAL PROPERTIES OF PP/PDMS BLENDS

 A series of polydimethylsiloxane (PDMS) with varied molecular weights (Mw = 3  106, 1  106 and 0.5  106) were melt blended with PP to investigate the effect of PDMS molecular weight (MW) on the morphology and mechanical properties of PP/PDMS blends. Scanning electron microscopic (SEM) examination showed that the size of PDMS domains was dependent on the MW of PDMS. It was found that the lower the value of PDMS MW, the better dispersion of the PDMS domains in the PP matrix. Tensile and Izod impact tests revealed that the addition of PDMS with lower MW would lead to a more significant increase in impact strength of the blends compared with the blends with higher MW ones, while the influence of the molecular weight on tensile strengths of the blends was relatively small in the MW range studied. Differential scanning calorimetry (DSC) results also showed that the crystallization temperature of PP was increased with decreasing PDMS MW, indicating a better nucleation capability of lower MW of PDMS. Melting flow rate (MFR) measurements indicated that the processibility of PP could be enhanced by adding PDMS, and again the lower MW PDMS resulted in better data. Our work demonstrates that not only the processibility but also the mechanical properties of PP could be enhanced to a more significant degree by using low MW PDMS than the higher ones.     

Novel alginate-poly(L-histidine) microcapsules as drug carriers: in vitro protein release and short term stability

Spherical, smooth-surfaced and mechanically stable alginate-poly(L-histidine) (PLHis) microcapsules with narrow particle size distributions were prepared by incubating calcium alginate beads in aqueous solutions of PLHis. The in vitro release characteristics, drug loading and encapsulation efficiency of the microcapsules were investigated using bovine erythrocytes hemoglobin (Hb) as a model drug. The results showed that the concentration of Ca(2+) ions had a considerable effect on the drug loading, encapsulation efficiency and in vitro release behavior of the microcapsules. When the concentration of CaCl(2) in the PLHis solution was increased from 0 to 3.0% (w/v), the drug loading and encapsulation efficiency decreased significantly from 38.0 to 4.3% and from 92.9 to 8.0%, respectively, while the total cumulative release of Hb from microcapsules in phosphate buffered saline solution (PBS, pH 6.8) decreased from 96.2 to 72.8% in 24 h. No significant protein release was observed during 70 h of incubation in hydrochloric acid solution (pH 1.2). However, under neutral conditions (PBS, pH 6.8), the Hb was completely and stably released within 24-70 h. An explosion test showed that the stability of alginate-PLHis microcapsules depended strongly on the concentration of PLHis and the calcium ions in solution. [Diagram: see text] Microscopy photo of Hb-loaded alginate-PLHis microcapsules.     

Conduction stability of high-density polyethylene/carbon black composites due to electric field action

Conduction stability of high-density polyethylene/carbon black (HDPE/CB) composites with a CB volume fraction slightly above the percolation threshold is studied in relation to electric field action at various ambient temperatures below the melting point of HDPE. It is found that resistance of the composites shows considerable changes after the electric field is switched off. Influence of irradiation crosslinking of HDPE on the conduction stability is also discussed.     

氯化镧对自由基的影响研究

通过检测肠组织丙二醛(MDA)、超氧化物歧化酶(SOD)、髓过氧化物酶(MPO)、过氧化氢酶(CAT)量,表明氯化镧在大鼠伤后1 d提高肠道SOD和CAT的活性、伤后3 d提高SOD的活性、伤后5 d降低MPO的活性,使MDA的量产生减少.     

Thermal Emulsion Polymerization without any Conventional Initiators and Emulsifiers

Stable poly(styrene-co-sodium styrene sulfonate) (P(St-NaSS) nanoparticles with broader size distribution were synthesized by thermal emulsion polymerization without any conventional initiators and emulsifiers. The obtained polymer nanoparticles have higher ξ potential, and the particle sizes have broad distribution. The stability of polymer particles originated from the addition of small amounts of ionic comonomer, NaSS, which can act as an emulsifier in somewhat. The monomer conversion could reach up to about 28 wt% in 48 h, and did not increase by further polymerization when higher polymerization temperature (120 ℃) was employed. This polymerization system may be give some further understand for mechanism of emulsion polymerization.     

含热致液晶性共聚酯的聚砜共混物

将一种含萘环的热致液晶性共聚酯与聚砜树脂熔融共混并挤塑成条。毛细管流变性测试表明，这一共聚酯降低了共混物的表观粘度，甚至低于其本身的粘度。共混物受剪切作用形成了各向异性的微纤增强结构，并具有皮芯结构，在液晶聚俣物含量低到２％与０．５％的样条中仍有共聚酯微纤形成。共聚酯微纤提高了聚砜的力学性能，含２０％共聚酯共混物挤塑条的位伸模量为聚砜树脂的二倍半。     

反应原料组成对单分散苯乙烯微球粒径及其分布的影响

采用分散聚合工艺制备微米级单分散聚苯乙烯微球，并对分散聚合反应的内部影响因素(分散稳定剂、助稳定剂、单体、引发剂)进行了研究．结果表明，随着分散稳定剂和助稳定剂用量的增加，聚苯乙烯微球的粒径减小；随着单体和引发剂用量的增加，聚苯乙烯微球的粒径增大．分散稳定剂和单体用量是影响聚苯乙烯微球粒径分布的两个主要内部因素．