Melt rheology of poly (lactic acid) plasticized by epoxidized soybean oil

This study investigated that epoxidized soybean oil (ESO) was blended as plasticizer with poly (lactic acid) (PLA) and its effects on the melt rheological properties, such as melt flow index, apparent shear viscosity, and melt strength of the blends. PLA was blended by the twin-screw plastic extruder at five mass fractions: 3%, 6%, 9%, 12%, and 15% (based on PLA mass). Melt flow index (MFI) was examined with a melt flow indexer. The results indicate that the blends of PLA/ESO had higher MFI than pure PLA, except for MFI at 9% reaching to the lowest point, even lower than that of pure PLA. Melt rheological properties were studied by a capillary rheometer in a temperature range of 160–180 °C. The blends ends exhibited shear-thinning behavior and the apparent shear viscosity was well described by the power law in this shear rate region. The melt strength of PLA plasticized with 6% ESO reached the maximums. ESO was more effective in increasing the melt strength at the mass fractions less than 6%, which could toughen the blends to some extent. Therefore, the authors suggested the optimum addition level of 6%–9% ESO will get good melt rheological performance balance. Biography: XU Yuqiong (1974–), female, Ph.D., research direction: polymer composites.     

玻璃包覆铁基合金微丝制备微熔池的稳定性

保持微熔池稳定是采用玻璃包覆熔融纺丝法连续稳定制备微丝的前提.采用理论计算分析了感应加热器结构参数、加热电流、微熔池的体积、微熔池在感应加热器中的位置等因素对铁基合金微熔池温度和所受悬浮力的影响,获得了保持微熔池稳定的合理工艺参数.在合适的拉丝温度(1280℃左右)下,增大感应加热器锥角和下锥孔高度,减小感应加热器高度、下锥孔半径以及微熔池中心与下锥孔上端面之间的距离,均有利于提高铁基合金微熔池所受悬浮力;减小电流的同时减小微熔池的体积(质量),有利于减小重力与悬浮力差值.在本文研究条件下,整体感应加热器的合理结构尺寸为:感应加热器锥角120～130°,感应加热器高度12～14mm,下锥孔高度2～4mm,下锥孔半径3～4mm.微熔池中心与感应加热器下锥孔上端面之间的合理距离为4～6mm,合适的微熔池质量为1.5～2.0g.采用结构优化的整体感应加热器,并通过连续进料使微熔池的体积(质量)保持基本不变,实现了玻璃包覆铁基合金微丝的连续稳定制备.     

宽厚板包晶钢的保护渣

针对包晶钢的凝固特性,研发了高碱度、高结晶速率、低结晶温度及低热流密度保护渣,并在宝钢3#连铸机上进行了试验研究.现场试验四个浇次的结果表明,使用改进渣的试验流铸坯无纵裂发生,而使用原渣的对比流铸坯裂纹率达到5%.优化保护渣有效防止了铸坯表面纵裂的发生.     

An experimental study of tin partition between melt and aqueous fluid in F/Cl-coexisting magma

In order to investigate the formation mechanism of tin ores associated with F-bearing granite, an ex-perimental study of tin partition between F-bearing granitic melt and coexisting HCl-bearing aqueous fluid was conducted at 850℃ and 100MPa with fo2 approaching NNO. Geochemical behavior of tin was traced by changes in starting solid materials with different alumina saturation index ASI, in F content and in starting fluids of various HCl concentrations. The results show that DSn increases with ASI of melt and peraluminous melt is favorable for tin partition into aqueous fluid in the F/Cl-coexisting sys-tem. Aqueous fluid of higher HCl concentrations is advantageous for enrichment of tin. Furthermore, chlorine contents in glass run products correlate positively with F and Cl contents in the magma. In the F/Cl-coexisting system, granitic melts with high F contents (> ~1 wt%) could extract and enrich tin in the melt which can serve as a reservoir for the formation of tin ores. However, the partition coefficient of tin would increase significantly when F contents in the melt were below 1 wt%. Therefore, the de-crease of F contents is favorable to the partition of tin into aqueous fluid with high HCl contents, thus promoting deposition of hydrothermal tin ores.     

[C10H8N2]3[PMo12O40]·3H2O的合成、结构和表征研究

采用水热法合成一种新型的无机-有机多金属氧酸盐[C10H8N2]3[PMo12O40].3H2O.通过对其进行组成分析,并进行红外光谱,X-射线衍射和差热分析证实该化合物是目标产物且具有Keggin结构.在化合物中,[PMo12O40]3-是具有Keggin结构的建筑单元且与联吡啶偶合配位.     

PLA/热塑性淀粉和PLA/亚麻纤维可降解复合材料的性能研究

使用熔融共混方法,制备了PLA/热塑性淀粉(PLA/TPS)和PLA/亚麻纤维(PLA/FF)复合材料.研究结果表明,随着热塑性淀粉或者亚麻纤维用量的增加,PLA复合材料的拉伸强度和断裂伸长率都有所降低;而PLA的结晶速率呈现显著增大,并且晶粒细化;添加热塑性淀粉或者亚麻纤维,能够增加PLA复合材料的降解速率.     

螺旋芯棒式吹膜模头熔体流动特性的数值模拟

对吹塑薄膜螺旋芯棒式模头内熔体的流动现象进行了三维数值模拟。结果表明,随着螺槽的逐渐消退,螺槽内熔体的速度由入口处的沿螺槽方向流动逐渐变为沿模头轴向流动,而环形间隙内熔体的速度在入口处存在较小的环形分量,随间隙厚度的增加逐渐变为沿轴向流动。沿挤出方向,螺槽中熔体的压力等值线由垂直于螺槽逐渐变为垂直于轴向,环形间隙中熔体的压力等值线由倾斜于轴向逐渐变为垂直于轴向。     

颗粒粒度及钾长石含量对矿渣微晶玻璃析晶能力的影响

利用k值法计算了不同颗粒粒度下不同钾长石添加量高炉渣微晶玻璃的晶化能和析晶动力学参数,采用DSC、XRD及SEM等测试手段研究了粉体粒度和钾长石含量对微晶玻璃析晶能力的影响。结果表明,颗粒粒度对微晶玻璃析晶能力影响显著,微晶玻璃析晶能力随颗粒粒度减小而增大;钾长石对微晶玻璃析晶能力有一定促进作用,但随着粉体粒度的减小而逐渐减弱,钾长石含量过高时,不利于微晶玻璃析晶,钾长石添加量应以5 wt%左右为宜。在5℃/min升温速度下,球磨60 h,添加5 wt%钾长石的样品具有较好的微观形貌,其主晶相为镁黄长石,晶体成颗粒状,晶粒均匀且结合紧密。     

不同硅铝比的Beta/MCM-41复合分子筛的合成和性能

分别以四乙基氢氧化铵和十六烷基三甲基溴化铵作为微孔相和介孔相的模板,采用两步晶化法制备了4种具有不同硅铝比,含微孔和介孔双模孔结构的Beta/McM-41复合分子筛.采用X射线衍射、N2吸附-脱附对Beta/MCM-41复合分子筛的结构进行了表征,利用吡啶吸附红外光谱(Py-FTIR)以及正庚烷裂解作为探针反应,对不同硅铝比的Beta/MCM-41复合分子筛的酸量和催化性能进行了研究.实验结果表明,随投料硅铝比的增加,复合分子筛介孔相有序性逐渐提高,微孔相的结晶度逐渐减小,酸量降低,正庚烷裂解的转化率明显下降.说明该复合分子筛的性能可随硅铝比的变化进行调变.     

NiTiZrAlCuSiB块体非晶合金等温晶化动力学

利用铜模铸造法制备了Ni42Cu5Ti20Zr21Al8Si3.5B0.5块体非晶合金,采用示差扫描量热计（DSC）对此块体非晶合金的等温晶化动力学进行了研究。应用函数z（φ）证明了JMA模型能够用于描述所研究的Ni基非晶合金的等温晶化动力学。结果表明：该合金的等温晶化行为始于一维界面控制地形核及长大,等温晶化的主要阶段为Avrami指数大于3.0的三维形核及长大过程。等温局部晶化激活能Um0.50为561.95kJ/mol,表明该Ni基非晶合金具有很高的热稳定性。